Patent Grant
9042967
A device and method for fluorescence-based imaging and monitoring is disclosed. In particular, the device and method may be suitable for monitoring biochemical and/or biological and non-biological substances, such as in wound care, for both human and animal applications.
Wound care is a major clinical challenge. Healing and chronic non-healing wounds are associated with a number of biological tissue changes including inflammation, proliferation, remodeling of connective tissues and, a common major concern, bacterial infection. A proportion of wound infections are not clinically apparent and contribute to the growing economic burden associated with wound care, especially in aging populations. Currently, the gold-standard wound assessment includes direct visual inspection of the wound site under white light combined with indiscriminate collection of bacterial swabs and tissue biopsies resulting in delayed, costly and often insensitive bacteriological results. This may affect the timing and effectiveness of treatment. Qualitative and subjective visual assessment only provides a gross view of the wound site, but does not provide information about underlying biological and molecular changes that are occurring at the tissue and cellular level. A relatively simple and complementary method that exploits ‘biological and molecular’ information to improve the early identification of such occult change is desirable in clinical wound management. Early recognition of high-risk wounds may guide therapeutic intervention and provide response monitoring over time, thus greatly reducing both morbidity and mortality due especially to chronic wounds.
Wound care and management is major clinical challenge that presents a significant burden and challenge to health care globally [Bowler et al., Clin Microbiol Rev. 2001, 14:244-269; Cutting et al., Journal of Wound Care. 1994, 3:198-201; Dow et al., Ostomy/Wound Management. 1999, 45:23-40]. Wounds are generally classified as, wounds without tissue loss (e.g. in surgery), and wounds with tissue loss, such as burn wounds, wounds caused as a result of trauma, abrasions or as secondary events in chronic ailments (e.g., venous stasis, diabetic ulcers or pressure sores and iatrogenic wounds such as skin graft donor sites and dermabrasions, pilonidal sinuses, non-healing surgical wounds and chronic cavity wounds). Wounds are also classified by the layers involved, superficial wounds involve only the epidermis, partial thickness wounds involve only epidermis and dermis, and full thickness wounds involve the subcutaneous fat or deeper tissue. Although restoration of tissue continuity after injury is a natural phenomenon, infection, quality of healing, speed of healing, fluid loss and other complications that enhance the healing time represents a major clinical challenge. The majority of wounds heal without any complication. However, chronic non-healing wounds involving progressively more tissue loss result in a large challenge for wound-care practitioners and researchers. Unlike surgical incisions where there is relatively little tissue loss and wounds generally heal without significant complications, chronic wounds disrupt the normal process of healing which is often not sufficient in itself to effect repair. Delayed healing is generally a result of compromised wound physiology [Winter (1962) Nature. 193:293-294] and typically occurs with venous stasis and diabetic ulcers, or prolonged local pressure as in immuno-suppressed and immobilized elderly individuals. These chronic conditions increase the cost of care and reduce the patient's quality of life. As these groups are growing in number, the need for advanced wound care products will increase.
Conventional clinical assessment methods of acute and chronic wounds continue to be suboptimal. They are usually based on a complete patient history, qualitative and subjective clinical assessment with simple visual appraisal using ambient white light and the ‘naked eye’, and can sometimes involve the use of color photography to capture the general appearance of a wound under white light illumination [Perednia (1991) J Am Acad Dermatol. 25: 89-108]. Regular re-assessment of progress toward healing and appropriate modification of the intervention is also necessary. Wound assessment terminology is non-uniform, many questions surrounding wound assessment remain unanswered, agreement has yet to be reached on the key wound parameters to measure in clinical practice, and the accuracy and reliability of available wound assessment techniques vary. Visual assessment is frequently combined with swabbing and/or tissue biopsies for bacteriological culture for diagnosis. Bacterial swabs are collected at the time of wound examination and have the noted advantage of providing identification of specific bacterial/microbial species [Bowler, 2001; Cutting, 1994; Dow, 1999; Dow G. In: Krasner et al. eds. Chronic Wound Care: A Clinical Source Book for Healthcare Professionals, 3rd ed. Wayne Pa.: HMP Communications. 2001:343-356]. However, often, multiple swabs and/or biopsies are collected randomly from the wound site, and some swabbing techniques may in fact spread the microorganisms around with the wound during the collection process thus affecting patient healing time and morbidity [Dow, 1999]. This may be a problem especially with large chronic (non-healing) wounds where the detection yield for bacterial presence using current swabbing and biopsy protocols is suboptimal (diagnostically insensitive), despite many swabs being collected. Thus, current methods for obtaining swabs or tissue biopsies from the wound site for subsequent bacteriological culture are based on a non-targeted or ‘blind’ swabbing or punch biopsy approach, and have not been optimized to minimize trauma to the wound or to maximize the diagnostic yield of the bacteriology tests. In addition, obtaining swabs and biopsy samples for bacteriology can be laborious, invasive, painful, costly, and more importantly, bacteriological culture results often take about 2-3 days to come back from the laboratory and can be inconclusive [Serena et al. (2008) Int J Low Extrem Wounds. 7(1):32-5.; Gardner et al., (2007) WOUNDS. 19(2):31-38], thus delaying accurate diagnosis and treatment [Dow, 1999]. Thus, bacterial swabs do not provide real-time detection of infectious status of wounds. Although wound swabbing appears to be straightforward, it can lead to inappropriate treatment, patient morbidity and increased hospital stays if not performed correctly [Bowler, 2001; Cutting, 1994; Dow, 1999; Dow, 2001]. The lack of a non-invasive imaging method to objectively and rapidly evaluate wound repair at a biological level (which may be at greater detail than simply appearance or morphology based), and to aid in targeting of the collection of swab and tissue biopsy samples for bacteriology is a major obstacle in clinical wound assessment and treatment. An alternative method is highly desirable.
As wounds (chronic and acute) heal, a number of key biological changes occur at the wound site at the tissue and cellular level [Cutting, 1994]. Wound healing involves a complex and dynamic interaction of biological processes divided into four overlapping phases—haemostasis, inflammation, cellular proliferation, and maturation or remodeling of connective tissues—which affect the pathophysiology of wound healing [Physiological basis of wound healing, in Developments in wound care, PJB Publications Ltd., 5-17, 1994]. A common major complication arising during the wound healing process, which can range from days to months, is infection caused by bacteria and other microorganisms [Cutting, 1994; Dow, 1999]. This can result in a serious impediment to the healing process and lead to significant complications. All wounds contain bacteria at levels ranging from contamination, through colonization, critical colonization to infection, and diagnosis of bacterial infection is based on clinical symptoms and signs (e.g., visual and odorous cues).
The most commonly used terms for wound infection have included wound contamination, wound colonisation, wound infection and, more recently, critical colonisation. Wound contamination refers to the presence of bacteria within a wound without any host reaction [Ayton M. Nurs Times 1985, 81(46): suppl 16-19], wound colonisation refers to the presence of bacteria within the wound which do multiply or initiate a host reaction [Ayton, 1985], Critical colonisation refers to multiplication of bacteria causing a delay in wound healing, usually associated with an exacerbation of pain not previously reported but still with no overt host reaction [Falanga et al., J Invest Dermatol 1994, 102(1): 125-27; Kingsley A, Nurs Stand 2001, 15(30): 50-54, 56, 58].
Wound infection refers to the deposition and multiplication of bacteria in tissue with an associated host reaction [Ayton, 1985]. In practice the term ‘critical colonisation’ can be used to describe wounds that are considered to be moving from colonisation to local infection. The challenge within the clinical setting, however, is to ensure that this situation is quickly recognized with confidence and for the bacterial bioburden to be reduced as soon as possible, perhaps through the use of topical antimicrobials. Potential wound pathogens can be categorised into different groups, such as, bacteria, fungi, spores, protozoa and viruses depending on their structure and metabolic capabilities [Cooper et al., Wound Infection and Microbiology.: Medical Communications (UK) Ltd for Johnson & Johnson Medical, 2003]. Although viruses do not generally cause wound infections, bacteria can infect skin lesions formed during the course of certain viral diseases. Such infections can occur in several settings including in health-care settings (hospitals, clinics) and at home or chronic care facilities. The control of wound infections is increasingly complicated, yet treatment is not always guided by microbiological diagnosis. The diversity of micro-organisms and the high incidence of polymicrobic flora in most chronic and acute wounds gives credence to the value of identifying one or more bacterial pathogens from wound cultures. The early recognition of causative agents of wound infections can assist wound care practitioners in taking appropriate measures. Furthermore, faulty collagen formation arises from increased bacterial burden and results in over-vascularized friable loose granulation tissue that usually leads to wound breakdown [Sapico et al. (1986) Diagn Microbiol Infect Dis. 5:31-38].
Accurate and clinically relevant wound assessment is an important clinical tool, but this process currently remains a substantial challenge. Current visual assessment in clinical practice only provides a gross view of the wound site (e.g., presence of purulent material and crusting). Current best clinical practice fails to adequately use the critically important objective information about underlying key biological changes that are occurring at the tissue and cellular level (e.g., contamination, colonization, infection, matrix remodeling, inflammation, bacterial/microbial infection, and necrosis) since such indices are i) not easily available at the time of the wound examination and ii) they are not currently integrated into the conventional wound management process. Direct visual assessment of wound health status using white light relies on detection of color and topographical/textural changes in and around the wound, and thus may be incapable and unreliable in detecting subtle changes in tissue remodeling. More importantly, direct visual assessment of wounds often fails to detect the presence of bacterial infection, since bacteria are occult under white light illumination. Infection is diagnosed clinically with microbiological tests used to identify organisms and their antibiotic susceptibility. Although the physical indications of bacterial infection can be readily observed in most wounds using white light (e.g., purulent exudate, crusting, swelling, erythema), this is often significantly delayed and the patient is already at increased risk of morbidity (and other complications associated with infection) and mortality. Therefore, standard white light direct visualization fails to detect the early presence of the bacteria themselves or identify the types of bacteria within the wound.
Implantation and grafting of stem cells have recently become of interest, such as for wound care and treatment. However, it is currently challenging to track the proliferation of stem cells after implantation or grafting. Tracking and identifying cancer cells have also been challenging. It would be desirable if such cells could be monitored in a minimally-invasive or non-invasive way.
It is also useful to provide a way for detecting contamination of other target surfaces, including non-biological targets.
A device and method for fluorescence-based monitoring is disclosed. In some aspects, the device comprises an optical (e.g., fluorescence and/or reflectance) device for real-time, non-invasive imaging of biochemical and/or organic substances, for example wounds. This device may be compact, portable, and/or hand-held, and may provide high-resolution and/or high-contrast images. Such a device may be easily integrated into current wound care practice. This imaging device may rapidly and conveniently provide the clinician/health care worker with valuable biological information of a wound: including imaging of connective tissue changes, early detection of bacterial contamination/infection. The device may also facilitate wound margin delineation, image-guided collection of bacterial swab/biopsy samples, imaging of exogenous molecular biomarker-targeted and activated optical (e.g., absorption, scattering, fluorescence, reflectance) contrast agents, and may permit longitudinal monitoring of therapeutic response for adaptive intervention in wound management. By exploiting wireless capabilities with dedicated image analysis and diagnostic algorithms, the device may be integrated seamlessly into telemedicine (e.g., E-health) infrastructure for remote-access to specialists in wound care. Such a device may also have applications outside wound care, including early detection of cancers, monitoring of emerging photodynamic therapies, detection and monitoring of stem cells, and as an instrument in the dermatology and cosmetology clinics, in addition to other applications.
In some aspects, there is provided a device for fluorescence-based imaging and monitoring of a target comprising: a light source emitting light for illuminating the target, the emitted light including at least one wavelength or wavelength band causing at least one biomarker associated with the target to fluoresce; and a light detector for detecting the fluorescence.
In some aspects, there is provided a kit for fluorescence-based imaging and monitoring of a target comprising: the device as described above; and a fluorescing contrast agent for labelling the biomarker at the target with a fluorescent wavelength or wavelength band detectable by the device.
In some aspects, there is provided a method for fluorescence-based imaging and monitoring a target comprising: illuminating the target with a light source emitting light of at least one wavelength or wavelength band causing at least one biomarker to fluoresce; and detecting fluorescence of the at least one biomarker with an image detector.
b shows an example of a clinical wound care facility using a device for fluorescence-based monitoring;
Wound progression is currently monitored manually. The National Pressure Ulcer Advisory Panel (NPUAP) developed the Pressure Ulcer Scale for Healing (PUSH) tool that outlines a five-step method of characterizing pressure ulcers. This tool uses three parameters to determine a quantitative score that is then used to monitor the pressure ulcer over time. The qualitative parameters include wound dimensions, tissue type, and the amount of exudate or discharge, and thermal readings present after the dressing is removed. A wound can be further characterized by its odor and color. Such an assessment of wounds currently does not include critical biological and molecular information about the wound. Therefore, all descriptions of wounds are somewhat subjective and noted by hand by either the attending physician or the nurse.
What is desirable is a robust, cost-effective non-invasive and rapid imaging-based method or device for objectively assessing wounds for changes at the biological, biochemical and cellular levels and for rapidly, sensitively and non-invasively detecting the earliest presence of bacteria/microorganisms within wounds. Such a method or device for detection of critical biological tissue changes in wounds may serve an adjunctive role with conventional clinical wound management methods in order to guide key clinico-pathological decisions in patient care. Such a device may be compact, portable and capable of real-time non-invasive and/or non-contact interrogation of wounds in a safe and convenient manner, which may allow it to fit seamlessly into routine wound management practice and user friendly to the clinician, nurse and wound specialist. This may also include use of this device in the home-care environment (including self-use by a patient), as well as in military battlefield environments. In addition, such an image-based device may provide an ability to monitor wound treatment response and healing in real-time by incorporating valuable ‘biologically-informed’ image-guidance into the clinical wound assessment process. This may ultimately lead to potential new diagnosis, treatment planning, treatment response monitoring and thus ‘adaptive’ intervention strategies which may permit enhancement of wound-healing response at the individual patient level. Precise identification of the systemic, local, and molecular factors underlying the wound healing problem in individual patients may allow better tailored treatment.
A number of imaging technologies have become available that offer the potential to satisfy the requirements for improved clinical diagnosis and treatment of disease. Of these, fluorescence imaging appears to be promising for improving clinical wound assessment and management. When excited by short wavelength light (e.g., ultraviolet or short visible wavelengths), most endogenous biological components of tissues (e.g., connective tissues such collagen and elastins, metabolic co-enzymes, proteins, etc.) produce fluorescence of a longer wavelength, in the ultraviolet, visible, near-infrared and infrared wavelength ranges [DaCosta et al., Photochem Photobiol. 2003 October, 78(4):384-92]. The most clinically mature of emerging optically-based imaging technologies, tissue autofluorescence imaging has been used to improve the endoscopic detection of early cancers and other diseases in the gastrointestinal tract [Dacosta (2002) J Gastroenterol Hepatol. Suppl:S85-104], the oral cavity [Poh et al., Head Neck. 2007 January, 29(1):71-6], and lungs [Hanibuchi et al., (2007) J Med. Invest. 54:261-6] and bladder [D'Hallewin et al. (2002) Eur Urol. 42(5):417-25] in a minimally-invasive manner.
Tissue autofluorescence imaging provides a unique means of obtaining biologically relevant information of normal and diseased tissues in real-time, thus allowing differentiation between normal and diseased tissue states [DaCosta, 2003; DaCosta et al. J Clin Pathol. 2005, 58(7):766-74]. This is based, in part, on the inherently different light-tissue interactions (e.g., abosption and scattering of light) that occur at the bulk tissue and cellular levels, changes in the tissue morphology and alterations in the blood content of the tissues. In tissues, blood is a major light absorbing tissue component (i.e., a chromophore). This type of technology is suited for imaging disease in hollow organs (e.g., GI tract, oral cavity, lungs, bladder) or exposed tissue surfaces (e.g., skin). Despite this indication, current endoscopic fluorescence imaging systems are large, involve complex diagnostic algorithms and expensive, and to date, such instruments are mainly found in large clinical centers and very few systems are commercially available. Currently, no such optical or fluorescence-based imaging device exists for wound imaging. However, since wounds are readily accessible, an autofluorescence imaging device may be useful for rapid, non-invasive and non-contact real-time imaging of wounds, to detect and exploit the rich biological information of the wound to overcome current limitations and improve clinical care and management.
A method and device for fluorescence-based imaging and monitoring is disclosed. One embodiment of the device is a portable optical digital imaging device. The device may utilize a combination of white light, tissue fluorescence and reflectance imaging, and may provide real-time wound imaging, assessment, recording/documenting, monitoring and/or care management. The device may be hand-held, compact and/or light-weight. This device and method may be suitable for monitoring of wounds in humans and animals.
Other uses for the device may include:
The device may generally comprise: i) one or more excitation/illumination light sources and ii) a detector device (e.g., a digital imaging detector device), which may be combined with one or more optical emission filters, or spectral filtering mechanisms, and which may have a view/control screen (e.g., a touch-sensitive screen), image capture and zoom controls. The device may also have: iii) a wired and/or wireless data transfer port/module, iv) an electrical power source and power/control switches, and/or v) an enclosure, which may be compact and/or light weight, and which may have a mechanism for attachment of the detector device and/or a handle grip. The excitation/illumination light sources may be LED arrays emitting light at about 405 nm (e.g., +/−5 nm), and may be coupled with additional band-pass filters centered at about 405 nm to remove/minimize the side spectral bands of light from the LED array output so as not to cause light leakage into the imaging detector with its own optical filters. The digital imaging detector device may be a digital camera, for example having at least an ISO800 sensitivity, but more preferably an ISO3200 sensitivity, and may be combined with one or more optical emission filters, or other equally effective (e.g., miniaturized) mechanized spectral filtering mechanisms (e.g., acousto-optical tunable filter or liquid crystal tunable filter). The digital imaging detector device may have a touch-sensitive viewing and/or control screen, image capture and zoom controls. The enclosure may be an outer hard plastic or polymer shell, enclosing the digital imaging detector device, with buttons such that all necessary device controls may be accessed easily and manipulated by the user. Miniature heat sinks or small mechanical fans, or other heat dissipating devices may be imbedded in the device to allow excess heat to be removed from the excitation light sources if required. The complete device, including all its embedded accessories and attachments, may be powered using standard AC/DC power and/or by rechargeable battery pack. The complete device may also be attached or mounted to an external mechanical apparatus (e.g., tripod, or movable stand with pivoting arm) allowing mobility of the device within a clinical room with hands-free operation of the device. Alternatively, the device may be provided with a mobile frame such that it is portable. The device may be cleaned using moist gauze wet with water, while the handle may be cleansed with moist gauze wet with alcohol. The device may include software allowing a user to control the device, including control of imaging parameters, visualization of images, storage of image data and user information, transfer of images and/or associated data, and/or relevant image analysis (e.g., diagnostic algorithms).
A schematic diagram of an example of the device is shown in
The digital image acquisition device 1 has a lens 2, which may be aligned to point at the target object 10 and may detect the optical signal that emanates from the object 10 or surface. The device has an optical filter holder 3 which may accommodate one or more optical filters 4. Each optical filter 4 may have different discrete spectral bandwidths and may be band-pass filters. These optical filters 4 may be selected and moved in from of the digital camera lens to selectively detect specific optical signals based on the wavelength of light. The device may include light sources 5 that produce excitation light to illuminate the object 10 in order to elicit an optical signal (e.g., fluorescence) to be imaged with, for example, blue light (e.g., 400-450 nm), or any other combination of single or multiple wavelengths (e.g., wavelengths in the ultraviolet/visible/near infrared/infrared ranges).
The light source 5 may comprise a LED array, laser diode and/or filtered lights arranged in a variety of geometries. The device may include a method or apparatus 6 (e.g., a heatsink or a cooling fan) to dissipate heat and cool the illumination light sources 5. The device may include a method or apparatus 7 (e.g., an optical band-pass filter) to remove any undesirable wavelengths of light from the light sources 5 used to illuminate the object 10 being imaged. The device may include a method or apparatus 8 to use an optical means (e.g., use of compact miniature laser diodes that emit a collimated light beam) to measure and determine the distance between the imaging device and the object 10. For example, the device may use two light sources, such as two laser diodes, as part of a triangulation apparatus to maintain a constant distance between the device and the object 10. Other light sources may be possible. The device may also use ultrasound, or a physical measure, such as a ruler, to determine a constant distance to maintain. The device may also include a method or apparatus 9 (e.g., a pivot) to permit the manipulation and orientation of the excitation light sources 5, 8 so as to manoeuvre these sources 5,8 to change the illumination angle of the light striking the object 10 for varying distances.
The target object 10 may be marked with a mark 11 to allow for multiple images to be taken of the object and then being co-registered for analysis. The mark 11 may involve, for example, the use of exogenous fluorescence dyes of different colours which may produce multiple distinct optical signals when illuminated by the light sources 5 and be detectable within the image of the object 10 and thus may permit orientation of multiple images (e.g., taken over time) of the same region of interest by co-registering the different colours and the distances between them. The digital image acquisition device 1 may include one or more of: an interface 12 for a head-mounted display; an interface 13 for an external printer; an interface 14 for a tablet computer, laptop computer, desk top computer or other computer device; an interface 15 for the device to permit wired or wireless transfer of imaging data to a remote site or another device; an interface 16 for a global positioning system (GPS) device; an interface 17 for a device allowing the use of extra memory; and an interface 18 for a microphone.
The device may include a power supply 19 such as an AC/DC power supply, a compact battery bank, or a rechargeable battery pack. Alternatively, the device may be adapted for connecting to an external power supply. The device may have a housing 20 that houses all the components in one entity. The housing 20 may be equipped with a means of securing any digital imaging device within it. The housing 20 may be designed to be hand-held, compact, and/or portable. The housing 20 may be one or more enclosures.
Referring still to
An example of a device for fluorescence-based monitoring is described below. All examples are provided for the purpose of illustration only and are not intended to be limiting. Parameters such as wavelengths, dimensions, and incubation time described in the examples may be approximate and are provided as examples only.
In this example, the devices uses two violet/blue light (e.g., 405 nm+/−10 nm emission, narrow emission spectrum) LED arrays (Opto Diode Corporation, Newbury Park, Calif.), each situated on either side of the imaging detector assembly as the excitation or illumination light sources. These arrays have an output power of approximately 1 Watt each, emanating from a 2.5×2.5 cm2, with a 70-degree illuminating beam angle. The LED arrays may be used to illuminate the tissue surface from a distance of about 10 cm, which means that the total optical power density on the skin surface is about 0.08 W/cm2. At such low powers, there is no known potential harm to either the target wound or skin surface, or the eyes from the excitation light. However, it may be inadvisable to point the light directly at any individual's eyes during imaging procedures. It should also be noted that 405 nm light does not pose a risk to health according to international standards formulated by the International Electrotechnical Commission (IEC), as further detailed on the website:
http://www.iec.ch/online_news/etech/arch—2006/etech—0906/focus.htm
The one or more light sources may be articulated (e.g., manually) to vary the illumination angle and spot size on the imaged surface, for example by using a built in pivot, and are powered for example through an electrical connection to a wall outlet and/or a separate portable rechargeable battery pack. Excitation/illumination light may be produced by sources including, but not limited to, individual or multiple light-emitting diodes (LEDs) in any arrangement including in ring or array formats, wavelength-filtered light bulbs, or lasers. Selected single and multiple excitation/illumination light sources with specific wavelength characteristics in the ultraviolet (UV), visible (VIS), far-red, near infrared (NIR) and infrared (IR) ranges may also be used, and may be composed of a LED array, organic LED, laser diode, or filtered lights arranged in a variety of geometries. Excitation/illumination light sources may be ‘tuned’ to allow the light intensity emanating from the device to be adjusted while imaging. The light intensity may be variable. The LED arrays may be attached to individual cooling fans or heat sinks to dissipate heat produced during their operation. The LED arrays may emit narrow 405 nm light, which may be spectrally filtered using a commercially available band-pass filter (Chroma Technology Corp, Rockingham, Vt., USA) to reduce potential ‘leakage’ of emitted light into the detector optics. When the device is held above a tissue surface (e.g., a wound) to be imaged, the illuminating light sources may shine a narrow-bandwidth or broad-bandwidth violet/blue wavelength or other wavelength or wavelength band of light onto the tissue/wound surface thereby producing a flat and homogeneous field within the region-of-interest. The light may also illuminate or excite the tissue down to a certain shallow depth. This excitation/illumination light interacts with the normal and diseased tissues and may cause an optical signal (e.g., absorption, fluorescence and/or reflectance) to be generated within the tissue.
By changing the excitation and emission wavelengths accordingly, the imaging device may interrogate tissue components (e.g., connective tissues and bacteria in a wound) at the surface and at certain depths within the tissue (e.g., a wound). For example, by changing from violet/blue (˜400-500 nm) to green (˜500-540 nm) wavelength light, excitation of deeper tissue/bacterial fluorescent sources may be achieved, for example in a wound. Similarly, by detecting longer wavelengths, fluorescence emission from tissue and/or bacterial sources deeper in the tissue may be detected at the tissue surface. For wound assessment, the ability to interrogate surface and/or sub-surface fluorescence may be useful, for example in detection and potential identification of bacterial contamination, colonization, critical colonization and/or infection, which may occur at the surface and often at depth within a wound (e.g., in chronic non-healing wounds). In one example, Referring to
Example embodiments of the device are shown in
This light signal produced by the excitation/illumination light sources may be detected by the imaging device using optical filter(s) (e.g., those available from Chroma Technology Corp, Rockingham, Vt., USA) that reject the excitation light but allow selected wavelengths of emitted light from the tissue to be detected, thus forming an image on the display. There is an optical filter holder attached to the enclosure frame in from of the digital camera lens which may accommodate one or more optical filters with different discrete spectral bandwidths, as shown in b) and c) of
These band-pass filters may be selected and aligned in front of the digital camera lens to selectively detect specific optical signals from the tissue/wound surface based on the wavelength of light desired. Spectral filtering of the detected optical signal (e.g., absorption, fluorescence, reflectance) may also be achieved, for example, using a liquid crystal tunable filter (LCTF), or an acousto-optic tunable filter (AOTF) which is a solid-state electronically tunable spectral band-pass filter. Spectral filtering may also involve the use of continuous variable filters, and/or manual band-pass optical filters. These devices may be placed in front of the imaging detector to produce multispectral, hyperspectral, and/or wavelength-selective imaging of tissues.
The device may be modified by using optical or variably oriented polarization filters (e.g., linear or circular combined with the use of optical wave plates) attached in a reasonable manner to the excitation/illumination light sources and the imaging detector device. In this way, the device may be used to image the tissue surface with polarized light illumination and non-polarized light detection or vice versa, or polarized light illumination and polarized light detection, with either white light reflectance and/or fluorescence imaging. This may permit imaging of wounds with minimized specular reflections (e.g., glare from white light imaging), as well as enable imaging of fluorescence polarization and/or anisotropy-dependent changes in connective tissues (e.g., collagens and elastin) within the wound and surrounding normal tissues. This may yield useful information about the spatial orientation and organization of connective tissue fibers associated with wound remodeling during healing [Yasui et al., (2004) Appl. Opt. 43: 2861-2867].
All components of the imaging device may be integrated into a single structure, such as an ergonomically designed enclosed structure with a handle, allowing it to be comfortably held with one or both hands. The device may also be provided without any handle. The device may be light weight, portable, and may enable real-time digital imaging (e.g., still and/or video) of any target surface (for example, the skin and/or oral cavity, which is also accessible) using white light, fluorescence and/or reflectance imaging modes. The device may be scanned across the body surface for imaging by holding it at variable distances from the surface, and may be used in a lit environment/room to image white light reflectance/fluorescence. The device may be used in a dim or dark environment/room to optimize the tissue fluorescence signals, and minimize background signals from room lights. The device may be used for direct (e.g., with the unaided eye) or indirect (e.g., via the viewing screen of the digital imaging device) visualization of wounds and surrounding normal tissues.
The device may also be embodied as not being hand-held or portable, for example as being attached to a mounting mechanism (e.g., a tripod or stand) for use as a relatively stationary optical imaging device for white light, fluorescence and reflectance imaging of objects, materials, and surfaces (e.g., a body). This may allow the device to be used on a desk or table or for ‘assembly line’ imaging of objects, materials and surfaces. In some embodiments, the mounting mechanism may be mobile.
Other features of this device may include the capability of digital image and video recording, possibly with audio, methods for documentation (e.g., with image storage and analysis software), and wired or wireless data transmission for remote telemedicine/E-health needs. For example, e) and f) of
In order to demonstrate the capabilities of the imaging device in wound care and other relevant applications, a number of feasibility experiments were conducted using the particular example described. It should be noted that during all fluorescence imaging experiments, the Sony camera (Sony Cybershot DSC-T200 Digital Camera, Sony Corporation, North America) settings were set so that images were captured without a flash, and with the ‘Macro’ imaging mode set. Images were captured at 8 megapixels. The flash was used to capture white light reflectance images. All images were stored on the xD memory card for subsequent transfer to a personal computer for long-term storage and image analysis.
All white light reflectance and fluorescence images/movies captured with the device were imported into Adobe Photoshop for image analysis. However, image analysis software was designed using MatLab™ (Mathworks) to allow a variety of image-based spectral algorithms (e.g., red-to-green fluorescence ratios, etc) to be used to extract pertinent image data (e.g., spatial and spectral data) for quantitative detection/diagnostic value. Image post-processing also included mathematical manipulation of the images.
Imaging of Bacteriological Samples
The imaging device may be useful for imaging and/or monitoring in clinical microbiology laboratories. The device may be used for quantitative imaging of bacterial colonies and quantifying colony growth in common microbiology assays. Fluorescence imaging of bacterial colonies may be used to determine growth kinetics. Software may be used to provide automatic counting of bacterial colonies.
To demonstration the utility of the device in a bacteriology/culture laboratory, live bacterial cultures were grown on sheep's blood agar plates. Bacterial species included streptococcus pyogenes, serratia marcescens, staphylococcus aureus, staphylococcus epidermidis, escherichia coli, and pseudomonas aeruginosa (American Type Culture Collection, ATCC). These were grown and maintained under standard incubation conditions at 37° C. and used for experimentation when during ‘exponential growth phase’. Once colonies were detected in the plates (˜24 h after inoculation), the device was used to image agar plates containing individual bacterial species in a darkened room. Using violet/blue (about 405 nm) excitation light, the device was used to image both combined green and red autofluorescence (about 490-550 nm and about 610-640 nm emission) and only red autofluorescence (about 635+/−10 nm, the peak emission wavelength for fluorescent endogenous porphyrins) of each agar plate. Fluorescence images were taken of each bacterial species over time for comparison and to monitor colony growth.
Reference is now made to
High spatial resolution of the camera detector combined with significant bacterial autofluorescence signal-to-noise imaging with the device allowed detection of very small (e.g., <1 mm diameter) colonies. The device provided a portable and sensitive means of imaging individual bacterial colonies growing in standard agar plates. This provided a means to quantify and monitor bacterial colony growth kinetics, as seen in c), as well as potentially monitoring response to therapeutic intervention, with antibiotics or photodynamic therapy (PDT) as examples, over time using fluorescence. Therefore, the device may serve as a useful tool in the microbiology laboratory.
In addition to providing detecting of bacterial strains, the device may be used for differentiating the presence and/or location of different bacterial strains (e.g., Staphylococcus aureus or Pseudomonas aeguginosa), for example in wounds and surrounding tissues. This may be based on the different autofluorescence emission signatures of different bacterial strains, including those within the 490-550 nm and 610-640 nm emission wavelength bands when excited by violet/blue light, such as light around 405 nm. Other combinations of wavelengths may be used to distinguish between other species on the images. This information may be used to select appropriate treatment, such as choice of antibiotic.
Such imaging of bacteriology samples may be applicable to monitoring of wound care.
Use in Monitoring of Wound Healing
The device may be scanned above any wound (e.g., on the body surface) such that the excitation light may illuminate the wound area. The wound may then be inspected using the device such that the operator may view the wound in real-time, for example, via a viewer on the imaging device or via an external display device (e.g., heads-up display, a television display, a computer monitor, LCD projector or a head-mounted display). It may also be possible to transmit the images obtained from the device in real-time (e.g., via wireless communication) to a remote viewing site, for example for telemedicine purposes, or send the images directly to a printer or a computer memory storage. Imaging may be performed within the routine clinical assessment of patient with a wound.
Prior to imaging, fiduciary markers (e.g., using an indelible fluorescent ink pen) may be placed on the surface of the skin near the wound edges or perimeter. For example, four spots, each of a different fluorescent ink color from separate indelible fluorescent ink pens, which may be provided as a kit to the clinical operator, may be placed near the wound margin or boundary on the normal skin surface. These colors may be imaged by the device using the excitation light and a multispectral band filter that matches the emission wavelength of the four ink spots. Image analysis may then be performed, by co-registering the fiduciary markers for inter-image alignment. Thus, the user may not have to align the imaging device between different imaging sessions. This technique may facilitate longitudinal (i.e., over time) imaging of wounds, and the clinical operator may therefore be able to image a wound over time without need for aligning the imaging device during every image acquisition.
In addition, to aid in intensity calibration of the fluorescence images, a disposable simple fluorescent standard ‘strip’ may be placed into the field of view during wound imaging (e.g., by using a mild adhesive that sticks the strip to the skin temporarily). The strip may be impregnated with one or several different fluorescent dyes of varying concentrations which may produce pre-determined and calibrated fluorescence intensities when illuminated by the excitation light source, which may have single (e.g., 405 nm) or multiple fluorescence emission wavelengths or wavelength bands for image intensity calibration. The disposable strip may also have the four spots as described above (e.g., each of different diameters or sizes and each of a different fluorescent ink color with a unique black dot placed next to it) from separate indelible fluorescent ink pens. With the strip placed near the wound margin or boundary on the normal skin surface, the device may be used to take white light and fluorescence images. The strip may offer a convenient way to take multiple images over time of a given wound and then align the images using image analysis. Also, the fluorescent ‘intensity calibration’ strip may also contain an added linear measuring apparatus, such as a ruler of fixed length to aid in spatial distance measurements of the wounds. Such a strip may be an example of a calibration target which may be used with the device to aid in calibration or measuring of image parameters (e.g., wound size, fluorescence intensity, etc.), and other similar calibration target may be used.
It may be desirable to increase the consistency of imaging results and to reproduce the distance between the device and the wound surface, since tissue fluorescence intensity may vary slightly if the distance changes during multiple imaging sessions. Therefore, in an embodiment, the device may have two light sources, such as low power laser beams, which may be used to triangulate individual beams onto the surface of the skin in order to determine a fixed or variable distance between the device and the wound surface. This may be done using a simply geometric arrangement between the laser light sources, and may permit the clinical operator to easily visualize the laser targeting spots on the skin surface and adjust the distance of the device from the wound during multiple imaging sessions. Other methods of maintaining a constant distance may include the use of ultrasound, or the use of a physical measure, such as a ruler.
Use in White Light Imaging
The device may be used to take white light images of the total wound with normal surrounding normal tissues using a measuring apparatus (e.g., a ruler) placed within the imaging field of view. This may allow visual assessment of the wound and calculation/determination of quantitative parameters such as the wound area, circumference, diameter, and topographic profile. Wound healing may be assessed by planimetric measurements of the wound area at multiple time points (e.g., at clinical visits) until wound healing. The time course of wound healing may be compared to the expected healing time calculated by the multiple time point measurements of wound radius reduction using the equation R=√{square root over (A)}/π (R, radius; A, planimetric wound area; constant 3.14). This quantitative information about the wound may be used to track and monitor changes in the wound appearance over time, in order to evaluate and determine the degree of wound healing caused by natural means or by any therapeutic intervention. This data may be stored electronically in the health record of the patient for future reference. White light imaging may be performed during the initial clinical assessment of the patient by the operator.
Use in Autofluorescence Imaging
The device may be designed to detect all or a majority of tissue autofluorescence (AF). For example, using a multi-spectral band filter, the device may image tissue autofluorescence emanating from the following tissue biomolecules, as well as blood-associated optical absorption, for example under 405 nm excitation: collagen (Types I, II, III, IV, V and others) which appear green, elastin which appears greenish-yellow-orange, reduced nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), which emit a blue-green autofluorescence signal, and bacteria/microorganisms, most of which appear to have a broad (e.g., green and red) autofluorescence emission.
Image analysis may include calculating a ratio of red-to-green AF in the image. Intensity calculations may be obtained from regions of interest within the wound images. Pseudo-coloured images may be mapped onto the white light images of the wound.
Examples in Wound Healing
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To test the ability of the device to detect connective tissues and several common bacteria present in typical wounds, a sample of pig meat with simulated wounds was prepared by applying six bacterial species to each of six small 1.5 cm2 wound incision sites on the skin surface: streptococcus pyogenes, serratia marcescens, staphylococcus aureus, staphylococcus epidermidis, escherichia coli, and pseudomonas aeruginosa. An additional small incision was made in the meat skin, where no bacteria were added, to serve as a control. However, it was expected that bacteria from the other six incisions sites would perhaps contaminate this site in time. The device was used to image the bacteria-laden meat sample using white light reflectance and violet/blue light-induced tissue autofluorescence emission, using both a dual emission band (450-505 nm and 590-650 nm) emission filter and a single band (635+/−10 nm) emission filter, on the left and a single band filter over the course of three days, at 24 h time intervals, during which the meat sample was maintained at 37° C. Imaging was also performed on the styrofoam container on which the meat sample was stored during the three days.
The device mapped biodistribution of bacteria within the wound site and on the surrounding skin and thus may aid in targeting specific tissue areas requiring swabbing or biopsy for microbiological testing. Furthermore, using the imaging device may permit the monitoring of the response of the bacterially-infected tissues to a variety of medical treatments, including the use of antibiotics and other therapies, such as photodynamic therapy (PDT), hyperbaric oxygen therapy (HOT), low level light therapy, or anti-Matrix Metalloproteinase (MMP). The device may be useful for visualization of bacterial biodistribution at the surface as well as within the tissue depth of the wound, and also for surrounding normal tissues. The device may thus be useful for indicating the spatial distribution of an infection.
sUse of Device with Contrast Agents in Monitoring Wounds
The device may be used with exogenous contrast agents, for example the pro-drug aminolaevulinic acid (ALA) at a low dose. ALA may be topically administered to the wound, and imaging may be performed 1-3 hours later for enhanced red fluorescence of wound bacteria.
The pro-drug aminolaevulinic acid (ALA) induces porphyrin formation in almost all living cells. Many bacteria species exposed to ALA are able to induce protoporphyrin IX (PpIX) fluorescence. The use of ultra-low dose ALA may induce PpIX formation in the bacteria and hence may increase the red fluorescence emission, which may enhance the red-to-green fluorescence contrast of the bacteria imaged with the device. ALA is non-fluorescent by itself, but PpIX is fluorescent at around 630 nm, 680 and 710 nm, with the 630 nm emission being the strongest. The imaging device may then be used to image the green and red fluorescence from the wound and the surrounding tissues. The time needed to obtain significant/appreciable increase in red (e.g., peak at 630 nm) fluorescence using the imaging device after the ALA (˜20 μg/mL) was applied to the wound ranges from 10-30 mins, but this time can be optimized, and depends also on the ALA dose which can also be optimized.
Thus, a clinical operator can premix the ALA, which is usually provided commercially in lyophilized form with physiological saline or other type of commercially available cream/ointment/hydrogel/dressing etc., at a given dose and administer the agent topically by spraying it, pouring it, or carefully applying the agent to the wound area prior to imaging. Approximately 10-30 mins afterwards, although this time may vary, fluorescence imaging may be performed in a dimly lit or dark room. Bacteria occult under white light and perhaps poorly autofluorescent may appear as bright red fluorescent areas in and around the wound. The fluorescence images may be used to direct targeted swabbing, biopsy and/or fine needle aspirates of the wound for bacterial culturing based on the unique bacterial fluorescence signal, and this may be done at different depths, for superficial and deep wounds.
The device may also be used in conjunction with exogenous ‘pro-drug’ agents, including, but not limited to, ALA which is FDA approved for clinical therapeutic indications, to increase the endogenous production of porphyrins in bacteria/microorganisms and thereby increase the intensities of unique ‘porphyrin’ fluorescence signals emanating from these bacteria to improve the detection sensitivity and specificity of the device. Thus, the device may be used to conveniently image photosensitizer-induced fluorescence (e.g., PpIX) in bacteria, growing in culture or in patients' wounds for subsequent image-guided targeted swabbing/biopsy or treatment, for example using photodynamic therapy (PDT) or hyperbaric oxygen therapy (HOT). The device when used with for example consumable, commercially available fluorescence contrast agents has the ability to increase the signal-to-background for sensitive detection of bacteria, in and around wounds. It should be noted that ALA is commercially available.
In one example, the device was used to image live bacterial culture (staphylococcus aureus, grown on agar plates for 24 h prior to imaging) using violet/blue excitation light. After 30 mins of incubation of staphyloccous aureus ˜20 μg/mL of ALA at 37° C., a significant increase in red fluorescence from the bacteria was detected, compared with those colonies that did not receive any ALA. Thus, the device may exploit the use of contrast agent strategies to increase the signal-to-background for sensitive detection of bacteria, in wounds for example. The time needed for the ALA to increase the PpIX fluorescence of bacteria in culture to significant levels was approximately 0.5 h which suggests that this approach may be clinically practical. Tests on simulated bacterially-contaminated meat samples revealed similar results to those obtained from bacterial culture. Topical application of 0.2 μg/mL ALA by spraying onto wounds on pig skin resulted in a dramatic increase of bacterial porphyrin red fluorescence contrast approximately 2 h after ALA administration. This demonstrates that the device may allow for detection of bacterial contamination with fluorescence imaging within the wound sites and elsewhere on the skin surface, which was previously occult under white light imaging.
Use with Exogenous Molecular-Targeted and Activated Imaging Agents
The availability of commercially available fluorescence molecular bacteriological detection and viability kits may offer another use for the device in wound care. Such kits may be used to rapidly quantitatively distinguish live and dead bacteria, even in a mixed population containing a range of bacterial types. Conventional direct-count assays of bacterial viability are typically based on metabolic characteristics or membrane integrity. However, methods relying on metabolic characteristics often only work for a limited subset of bacterial groups, and methods for assessing bacterial membrane integrity commonly have high levels of background fluorescence. Both types of determinations also suffer from being very sensitive to growth and staining conditions.
Suitable exogenous optical molecular targeting probes may be prepared using commercially available fluorescence labeling kits, such as the Alexa Fluor active esters and kits (e.g., Zenon Antibody Labeling Kits and or EnzChek Protease Assay Kits, Invitrogen) for labeling proteins, monoclonal antibodies, nucleic acids and oligonuicleotides (Invitrogen). For example, these fluorescent dye bioconjugates cover the following wavelength ranges: Alexa Fluor 350, Alexa Fluor 405, Alexa Fluor 430, Alexa Fluor 488, Alexa Fluor 500, Alexa Fluor 514, Alexa Fluor 532, Alexa Fluor 546, Alexa Fluor 555, Alexa Fluor 568, Alexa Fluor 594, Alexa Fluor 610, Alexa Fluor 633, Alexa Fluor 635, Alexa Fluor 647, Alexa Fluor 660, Alexa Fluor 680, Alexa Fluor 700 and Alexa Fluor 750 dyes, where the number stated refers to the excitation wavelength of the dye. These kits may offer well-differentiated fluorescence emission spectra, providing many options for multicolor fluorescence detection and fluorescence resonance energy transfer, based on the appropriate selection of fluorescence emission filters with the imaging device. The fluorescence dyes offer high absorbance at wavelengths of maximal output of common excitation sources, they are bright and unusually photostable fluorescence of their bioconjugates, and offer good water solubility of the reactive dyes for ease of conjugation within the clinical exam room and resistance of the conjugates to precipitation and aggregation. The dyes' fluorescence spectra are insensitive to pH over a broad range, which makes them particularly useful for wound imaging, since wound pH can vary. In addition, other commercial or non-commercial fluorescent agents exist which may be appropriate for biological imaging of wounds and may be combined with the described device, including fluorescent blood pooling agents and various wound-enzyme or protease activated probes from V isEn Medical (Boston, Mass., USA), for example.
These targeting fluorescent bioconjugates may be prepared using such labeling kits prior to the clinical exam of the wound using the imaging device in fluorescence mode, and may be stored in light-tight containers to avoid photobleaching. Such fluorescence bioconjugates may be prepared in solution at a known and appropriate concentration prior to fluorescence imaging of the wound using the device, and then administered/applied directly to the wound and surrounding normal tissues either topically (e.g., via aerosol/spray, lavage techniques), or given orally in a drink or systemically via intravenous injection. Such dyes may target specific biological components depending on the targeting moiety, and may include: bacteria, fungi, yeast, spores, virus, microbes, parasites, exudates, pH, blood vessels, reduced nicotinamide adenine dinucleotide (NADH), falvin adenine dinucleotide (FAD), microorganisms, specific types of connective tissues (e.g., collagens, elastin), tissue components, vascular endothelial growth factor (VEGF), endothelial growth factor (EGF), epithelial growth factor, epithelial cell membrane antigen (ECMA), hypoxia inducible factor (HIF-1), carbonic anhydrase IX (CAIX), laminin, fibrin, fibronectin, fibroblast growth factor, transforming growth factors (TGF), fibroblast activation protein (FAP), enzymes (e.g., caspases, matrix metalloproteinases (MMPs), etc.), tissue inhibitors of metalloproteinases (e.g., TIMPs), nitric oxide synthase (NOS), inducible and endothelial NOS, lysosomes in cells, macrophages, neutrophils, lymphocytes, hepatocyte growth factor (HGF), anti-neuropeptides, neutral endopeptidase (NEP), granulocyte-macrophage colony stimulating factor (GM-CSF), neutrophil elastases, cathepsins, arginases, fibroblasts, endothelial cells and keratinocytes, keratinocyte growth factor (KGF), macrophage inflammatory protein-(MIP-2), macrophage inflammatory protein-2 (MIP-2), and macrophage chemoattractant protein-1 (MCP-1), polymorphonuclear neutrophils (PMN) and macrophages, myofibroblasts, interleukin-1 (IL-1) and tumour necrosis factor (TNF), nitric oxide (NO) (Kit from Calbiochem, Model DAF-2 DA), and c-myc and beta-catenin, circulating endothelial progenitor cells (EPCs) from the bone marrow. Exogenous optical agents may include, but are not limited to, any of the following: activated molecular beacons (e.g., targeted), nanoparticles having fluorescent agents (e.g., labeled on the surface and/or containing or carrying fluorescent agents), and scattering or absorbing nanoparticles (e.g., gold, silver).
The LIVE/DEAD BacLight™ Bacterial Viability Kits (from Invitrogen, Molecular Probes) assay utilizes mixtures of SYTO® 9 green fluorescent nucleic acid stain and the red fluorescent nucleic acid stain, propidium iodide, although these fluorescent dyes may be exchanged for other existing or emerging fluorescent agents. These stains differ both in their spectral characteristics and in their ability to penetrate healthy bacterial cells. When used alone, the SYTO 9 stain labels bacteria with both intact and damaged membranes. In contrast, propidium iodide penetrates only bacteria with damaged membranes, competing with the SYTO 9 stain for nucleic acid binding sites when both dyes are present. When mixed in recommended proportions, SYTO 9 stain and propidium iodide produce green fluorescent staining of bacteria with intact cell membranes and red fluorescent staining of bacteria with damaged membranes. Thus, live bacteria with intact membranes fluoresce green, while dead bacteria with damaged membranes fluoresce red. The background remains virtually non-fluorescent. Consequently, the ratio of green to red fluorescence intensities may provide a quantitative index of bacterial viability.
Live and dead bacteria may be viewed separately or simultaneously by the imaging device with suitable optical filter sets. As well, similar fluorescence assay kits are available for Gram sign (i.e., positive/negative) identification of bacteria, which is a useful parameter in wound treatment planning, and may be used in conjunction with the imaging device. Such fluorescence agents are general and applicable to most bacteria types, and may be used to determine bacterial viability and/or Gram sign either directly on/within the wound or on ex vivo swab- or tissue biopsy-derived culture samples obtained from the wound site (e.g., superficially or at depth) for real-time quantitative assessment using the imaging device. Such fluorescence fluorescent agents may be prepared in solution in advance at a known and appropriate concentration prior to fluorescence imaging of the wound using the device, and then administered/applied directly to the wound and surrounding normal tissues either topically (e.g., via aerosol/spray, lavage techniques), or perhaps systemically via intravenous injection. Imaging may then be performed accordingly after a defined time for the agents to react with the targets. A washing off of unlabeled agents may be required prior to imaging with the device. For this, physiological saline may be used. Target-bound fluorescent agent may remain within the wound and surrounding tissues for fluorescence imaging.
Therefore, when used with fluorescent reporter systems the imaging device may provide a relatively rapid means of assessing bacterial viability following exposure to antimicrobial agents. The ability to repeatedly measure the same patients or animals may reduce variability within the treatment experiments and allowed equal or greater confidence in determining treatment efficacy. This non-invasive and portable imaging technology may reduce the number of animals used during such studies and has applications for the evaluation of test compounds during drug discovery.
A number of commercially available organic fluorophores have properties that are dependent on hydrogen ion concentration, rendering them useful as probes for measuring pH, and they typically have pH sensitive UV/visible absorption properties. The majority of commercially available pH sensitive fluorescent dyes employed in intracellular studies provide a reduced fluorescent signal in acidic media or alternatively the pKa of the dye is outside the critical intracellular pH window of between 5-8 pH units. However, other pH-sensitive fluorescent agents respond by increasing their fluorescence intensities. For example, Invitrogen/Molecular Probes offers a variety of fluorescent pH indicators, their conjugates and other reagents for pH measurements in biological systems. Among these are several probes with unique optical response and specialized localization characteristics: for example, visible light-excitable SNARF pH indicators enable researchers to determine intracellular pH in the physiological range using dual-emission or dual-excitation ratiometric techniques, thus providing useful tools for confocal laser-scanning microscopy and flow cytometry. LysoSensor probes, as well as indicators based on the Oregon Green fluorophore, may be used to estimate the pH in a cell's acidic organelles. There are also fluorescent pH indicators coupled to dextrans which may be used. Following loading into cells, indicator dextrans may be well retained, may not bind to cellular proteins and may have a reduced tendency to compartmentalize. Again, such fluorescent agents may be prepared in solution in advance at a known and appropriate concentration prior to fluorescence imaging of the wound using the device, and then administered/applied directly to the wound and surrounding normal tissues either topically (e.g., via aerosol/spray, lavage techniques), systemically or for example, via intravenous injection, or orally.
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In addition to fluorescence-enhancing pro-drugs, advances in medicine have enabled widespread use of fluorescent biomarkers to diagnose disease on a molecular level. The accurate measurement of the fluorescent biomarker signal in biological tissues may be a critical parameter towards gaining biomolecular information about disease progression and treatment response, but has historically posed a significant challenge. To date, this type of advanced molecular imaging has not been reported for wound care.
The device described herein may also be used in combination with fluorescent, light-scattering, or light-absorbing exogenous fluorescence contrast agents that can be used passively and/or targeted to unique and specific molecular targets within the wound to improve the detection and diagnosis of wound infection. These targets may be any biological and/or molecular component in the wound or normal surrounding tissues that have a known detection and/or diagnostic value (e.g., normal tissue and wound biomarkers). All exogenous agents may be delivered to the wound either topically and/or systemically, and may include, but are not limited to, any exogenous agent/drug (e.g., encapsulated liposomes, beads or other biocompatible carrier agents) that can be coupled/conjugated with an appropriate wavelength-selected fluorescent/scattering moiety (e.g., organic fluorescent dyes, quantum dots and other fluorescent semi-conductor nano-particles, colloidal metals (e.g., gold, silver, etc.)). Fluorescent and/or light scattering agents/probes, and/or chromogenic (i.e., absorption) agents/dyes may be prepared using standard bioconjugation techniques to include moieties for targeting specific biomarkers. Such moieties may include monoclonal antibodies (e.g., whole and/or fragments), and other tissue-specific moieties (including, but not limited to, peptides, oligomers, aptamers, receptor-binding molecules, enzyme inhibitors, toxins, etc.). The device may also be used for imaging in situ activatable promoter-controlled expression of light generating proteins in preclinical wound models. Furthermore, wound infections may also be detected using the imaging device and then treated using photothermal therapies, such as light-absorbing gold nanoparticles conjugated with specific antibodies which specifically target bacteria.
The device may also be used with other molecular-sensing agents, such as ‘molecular beacons’ or “smart probes”, which produce fluorescence only in the presence of unique and specific biological targets (e.g., enzymes associated with wound health). Such probes may be useful for identifying specific bacterial species or GRAM signing, for example. For example, cutaneous wound healing is a highly complex process involving five overlapping phases (inflammation, granulation tissue formation, epithelialization, matrix production, and remodeling) associated with a number of migratory and remodeling events that are believed to require the action of matrix metalloproteinases (MMPs) and their inhibitors, TIMPs. In vivo analyses of human acute and chronic wounds as well as of a variety of different wound healing models have implicated a functional role of MMPs and TIMPs during normal wound repair, whereas deregulation of their activity is thought to contribute to impaired wound healing. Degradation of extracellular matrices is needed to remove damaged tissue and provisional matrices and to permit vessel formation and re-epithelialization. In contrast, in chronic or non-healing wounds over-expression of proteinases in their inactive form is thought to contribute to the underlying pathology and to inhibit normal tissue repair processes. Molecular beacons are activatable fluorescent reporters that use the fluorescence resonance energy transfer (FRET) principle to control fluorescence emission in response to specific biological stimuli. They usually comprise a disease-specific linker that brings a quencher close to a fluorophore to silence its fluorescence. Upon specific linker-target interactions (e.g., nucleic acid hybridization, protease-specific peptide cleavage, phospholipase-specific phospholipids cleavage), the quencher is removed from the vicinity of the fluorophore to restore its fluorescence. These smart probes may offer several orders of magnitude sensitivity than targeted probes because of the built-in high degree of signal amplification from nonfluorescent to highly fluorescent. Depending on their specific linker-target interactions, they may also be capable of interrogating specific molecular abnormality at the protein or gene expression levels. Because of these advantages, the smart probes have been recently hailed as “a quantum leap” over traditional probes for early cancer detection. Such exogenous agents may be used, for example, for relatively rapid, non-invasive, sensitive and specific optical detection of wound infections, to identify specific bacterial/microorganism species present and in situ microbial diagnosis, to monitor the health status of the wound, and to report in real-time on the effectiveness of treatment and care.
In addition, when used in combination with exogenous optical agents, the device may be used to identity patients minimally responsive to various established and experimental treatments, enabling rapid non-invasive or non-contact visual quantitative assessment of treatment response to make timely changes in therapy in order to optimize treatment outcomes.
Furthermore, real-time monitoring of antimicrobial effects in vitro and within animal model test systems using the imaging device may enhance basic understanding of the action of antibiotics and facilitate unique studies of disease in vivo.
EXAMPLES
The device was also able to detect spreading of the bacteria over the surface of the meat over time. d) shows an image at Day 1, and f) shows an image at Day 3, as the meat sample was maintained at 37° C. Red fluorescence can be seen in some of the wound sites (5, 6) in c). As shown in d) and magnified in e), after 24 h, the device detects a dramatic increase in bacterial autofluorescence from wound site 5) escherichia coli and 6) pseudomonas aeruginosa, with the latter producing significant green and red autofluorescence. c) and e) show the device detecting fluorescence using a dual band (450-505 nm green and 590-650 nm) on the left and a single band filter (635+/−10 nm) on the right, of the wound surface. As shown in f), by Day 3, the device detects the significant increase in bacterial autofluorescence (in green and red) from the other wound sites, as well as the bacterial contamination (indicated by the arrow in f) on the styrofoam container in which the meat sample was kept. The device was also able to detect spreading of the bacteria over the surface of the meat. This demonstrates the real-time detection of bacterial species on simulated wounds, the growth of those bacteria over time, and the capability of the device to provide longitudinal monitoring of bacterial growth in wounds. The device may provide critical information on the biodistribution of the bacteria on the wound surface which may be useful for targeting bacterial swabbing and tissue biopsies. Note, in d) and f), the intense green fluorescence signal from endogenous collagen at the edge of the pig meat sample.
This example demonstrates the use of the device for real-time detection of biological changes in connective tissue and bacterial growth based on autofluorescence alone, suggesting a practical capability of the device to provide longitudinal monitoring of bacterial growth in wounds.
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In addition to detection of bacteria in wounds and on the skin surface, the device was also able to identify suspicious areas of muscle tissue, which may then be interrogated further by surgery or targeted biopsy for pathological verification, or by other optical means such as fluorescence spectroscopy using a fiber optic probe. Also, it detected contamination by various bacteria on the surface of the Styrofoam container on which the meat sample was kept. Autofluorescence of the bacteria appears as streaks of green and red fluorescence under violet/blue excitation light from the various bacterial species previously applied to the meat.
In order to determine the autofluorescence characteristics of bacteria growing in culture and in the simulated skin wounds, hyperspectral/multispectral fluorescence imaging was used to quantitatively measure the fluorescence intensity spectra from the bacteria under violet/blue light excitation. Reference is now made to
This example shows that bacteria emit green and red autofluorescence, with some species (e.g., pseudomonas aeruginosa) producing more of the former. Escherichia coli produced significant red autofluorescence from endogenous porphyrins. Such intrinsic spectral differences between bacterial species are significant because it may provide a means of differentiating between different bacterial species using autofluorescence alone. Excitation-emission matrices (EEMs) were also measured for each of the bacterial species used in these pilot studies, which confirmed that under violet/blue light excitation, all species produced significant green and/or red fluorescence, the latter being produced by porphyrins. Spectral information derived from excitation-emission matrices may aid in optimizing the selection of excitation and emission wavelength bandwidths for use with optical filters in the imaging device to permit inter-bacterial species differentiating ex vivo and in vivo. In this way, the device may be used to detect subtle changes in the presence and amount of endogenous connective tissues (e.g. collagens and elastins) as well as bacteria and/or other microorganisms, such as yeast, fungus and mold within wounds and surrounding normal tissues, based on unique autofluorescence signatures of these biological components.
In addition to fluorescence-enhancing pro-drugs, advances in medicine have enabled widespread use of fluorescent biomarkers to diagnose disease on a molecular level. The accurate measurement of the fluorescent biomarker signal in biological tissues may be a critical parameter towards gaining biomolecular information about disease progression and treatment response, but has historically posed a significant challenge. To date, this type of advanced molecular imaging has not been reported for wound care. With the use of the device described here, imaging and monitoring of such biomarkers for diagnosis purposes may be possible.
Imaging of Wound Models using Exogenous Contrast Agents
When used to assess wounds, tissue autofluorescence imaging may detect relative changes in connective tissue remodeling during wound healing as well as the early presence of bacteria either contaminating, colonizing and/or infecting wounds (including, but not limited to, bacterially-induced production of wound exudate and inflammation). When most wounds are illuminated by violet/blue light, endogenous tissues in the connective tissue matrix (e.g., collagen and elastin) emit a characteristic strong green fluorescent signal, while endogenous bacteria emit a unique red fluorescence signal due to the production of endogenous porphyrins. These bacteria include, but are not limited to, common species typically found at wound sites (e.g., staphylococcus, streptococcus, e. coli, and pseudomonas species). By using autofluorescence, critical wound information is obtained in real-time to provide a means of early detection of key biological determinants of wound health status, which may aid in stratifyng patients for optimized wound care and treatment.
The pro-drug aminolaevulinic acid (ALA) induces porphyrin formation in almost all living cells. Many bacteria species exposed to ALA are able to induce protoporphyrin IX (PpIX) fluorescence [Dietel et al., (2007). Journal of Photochemistry and Photobiology B: Biology. 86: 77-86]. The use of ultra-low dose ALA to induce PpIX formation in the bacteria and hence increase the red fluorescence emission was investigated, in order to enhance the red-to-green fluorescence contrast of the bacteria with the imaging device. The device was used to image live bacterial culture (staphylococcus aureus, grown on agar plates for 24 h prior to imaging) using violet/blue excitation light, as seen in
In a), the device was used to image live bacterial culture (staphylococcus aureus, grown on agar plates for 24 h prior to imaging) under white light (circles). In b), violet/blue excitation light reveals the bacterial red autofluorescence, which is discernable from the background weak green autofluorescence from the agar growth medium. In c), to increase the red-to-green fluorescence contrast of the staphyloccous aureus against the background agar, an ultra-low dose (−20 μg/mL) of the photosensitizer aminolevulinic acid (ALA, in phosphate buffered saline) commonly used in photodynamic therapy (PDT) was added topically to some of the colonies in the agar plate (noted as ‘ALA+’ in the circles), while the rest of the agar plate was ALA-negative. After 30 mins of incubation at 37° C., the device was again used to image the agar plate under violet/blue light excitation, thus revealing a significant increase in red fluorescence (from ALA-induced protoporphyrin IX, PpIX) from the staphylococcus aureus bacteria, compared with those colonies (square) that did not receive any ALA. Comparing b) with c) shows that the addition of ALA may be beneficial for increased bacterial fluorescence. d) shows the RBG image from c) with the green fluorescence from the agar plate removed, thus revealing the increased red bacterial fluorescence in the s. aureus colonies treated with ALA. This demonstrates the ability of the device to exploit the use of contrast agent strategies to increase the signal-to-background for sensitive detection of bacteria, in wounds for example. The time needed for the ALA to increase the PpIX fluorescence to detectable levels was 30 mins which suggests that this technical approach may also be clinically practical. Furthermore, this also demonstrates that the device may be used to conveniently image photosensitizer fluorescence (e.g., PpIX) in bacteria, growing in culture or in patients' wounds for subsequent treatment using PDT.
After 30 mins of incubation of staphyloccous aureus ˜20 μg/mL of ALA at 37° C., a significant increase in red fluorescence from the bacteria was detected, compared with those colonies (square) that did not receive any ALA. This demonstrates the ability of the device to exploit the use of contrast agent strategies to increase the signal-to-background for sensitive detection of bacteria, in wounds for example. The time needed for the ALA to increase the PpIX fluorescence of bacteria in culture to significant levels was approximately 0.5 h which suggests that this technical approach may also be clinically practical. Tests on simulated bacterially-contaminated meat samples revealed similar results to those obtained from bacterial culture. Topical application of 0.2 μg/mL ALA by spraying onto wounds on pig skin resulted in a dramatic increase of bacterial porphyrin red fluorescence contrast approximately 2 h after ALA administration. This may allow detection of bacterial contamination with fluorescence imaging within the wound sites and elsewhere on the skin surface, which was previously occult under white light imaging, as demonstrated with reference to
Referring to
In c), the non-toxic pro-drug aminolevulinic acid (ALA) (0.2 mg/mL) was applied topically to the skin surface in order to determine if bacterial fluorescence may be enhanced. The result, approximately 1 h after ALA administration, was a dramatic increase in bacterial porphyrin fluorescence (bright red fluorescence) both on the skin tissue and wound sites, as well as on the surface of the styrofoam container on which the meat sample was kept (arrows). This illustrates the possibilities for biopsy targeting by fluorescence image-guidance, and the use of the device for detection and subsequent treatment of infected areas using PDT, for example.
The device may also be used in conjunction with exogenous ‘pro-drug’ agents, including, but not limited to, ALA which is FDA approved for clinical therapeutic indications, to increase the endogenous production of porphyrins in bacteria/microorganisms and thereby increase the intensities of unique ‘porphyrin’ fluorescence signals emanating from these bacteria to improve the detection sensitivity and specificity of the device. Thus, the device may be used to conveniently image photosensitizer-induced fluorescence (e.g., PpIX) in bacteria, growing in culture or in patients' wounds for subsequent image-guided targeted swabbing or biopsy, or treatment using photodynamic therapy (PDT) [Jori et al. Lasers Surg Med. 2006 June; 38(5):468-81; Dougherty et al. (1998) J. Natl. Cancer Inst. 90, 889-905; Carruth (1998) Int. J. Clin. Pract. 52, 39-42; Bissonnette et al. (1997) Dermatol. Clin. 15, 507-519]. PDT may provide an adjunct to current antibiotic treatment or an alternative where antibiotics no longer are working (e.g., drug-resistant strains). The available evidence suggests that multi-antibiotic resistant strains are as easily killed by PDT as naive strains, and that bacteria may not readily develop resistance to PDT. This may be vital for treating wounds in patients undergoing cancer therapy, HIV patients who demonstrate resistance to antibiotics and the elderly with persistent oral infections [Hamblin et al. (2004) Photochem Photobiol Sci. 3:436-50].
The device may be used to detect bacteria or micro-organisms in the wound and surrounding normal tissues using low power excitation/illumination blue/violet light, but may also be used immediately afterwards for destroying them, for example using PDT or other therapies. By using high-power red excitation/illumination light, endogenous porphyrins in bacteria or microorganisms can be destroyed within the wound site by PDT. Therefore, this device may have the capability to serve as an all-in-one non-invasive or non-contact ‘find and treat’ instrument for clinical wound care. Furthermore, once bacteria or microorganisms are detected, the device may be used to treat and/or disinfect the wound site with PDT, and then the site may be re-imaged soon afterwards to determine the effectiveness of the PDT treatment. In some embodiments, the device may be used only for detection/diagnostic purposes only and may not perform any therapeutic treatment itself. The device may be used continuously until the entire wound and surrounding normal tissue have been disinfected, and the wound may be monitored thereafter in a longitudinal manner as part of standard clinical follow up. Fluorescence images from the device may be used to determine the biodistribution of the PDT photosensitizer or photoproducts [Gudgin et al. (1995) J. Photochem. Photobiol. B: Biol. 29, 91-93; Konig et al. (1993) J. Photochem. Photobiol. B: Biol. 18, 287-290], since most of these are intrinsically fluorescent, and thus the device may serve as a means to target the PDT treatment light. The device may therefore guide, via imaging, the completeness of the PDT treatment. Similarly, the device may be used to guide other therapies.
Since some photosensitizers are known to photobleach [Jongen et al. (1997) Phys. Med. Biol. 42, 1701-1716; Georgakoudi et al. (1997) Photochem. Photobiol. 65, 135-144; Rhodes et al. (1997) J. Investig. Dermatol. 108, 87-91; Grossweiner (1986) Lasers Surg. Med. 6, 462-466; Robinson et al. (1998) Photochem. Photobiol. 67. 140-149; Rotomskis et al. (1996) J. Photochem. Photobiol. B: Biol. 33, 61-67] the fluorescence imaging capability of the device may be used to determine the extent or rate of photobleaching of the photosensitizer. This information may be useful for optimizing PDT dosimetry [Grossweiner (1997) J. Photochem. Photobiol. B: Biol. 38, 258-268] in order to ensure adequate treatment of the disease, while at the same time minimizing damage to surrounding normal tissues. The device, with excitation light sources which may be selected for specific excitation wavelengths and intensities, in an embodiment, may be used to also deliver the light for PDT combined with any commercially available and/or experimental PDT photosensitizers. Therefore, it may have utility in existing clinical PDT indications (e.g., for the skin surface or hollow organs) and/or within the arena of commercial/academic research and development of future PDT photosensitive agents, both pre-clinically and clinically.
This device may be used as an imaging and/or monitoring device in clinical microbiology laboratories. For example, the device may be used for quantitative imaging of bacterial colonies and quantifying colony growth in common microbiology assays. Fluorescence imaging of bacterial colonies may be used to determine growth kinetics.
Imaging of Blood in Wounds
Angiogenesis, the growth of new blood vessels, is an important natural process required for healing wounds and for restoring blood flow to tissues after injury or insult. Angiogenesis therapies, which are designed to “turn on” new capillary growth, are revolutionizing medicine by providing a unified approach for treating crippling and life-threatening conditions. Angiogenesis is a physiological process required for wound healing. Immediately following injury, angiogenesis is initiated by multiple molecular signals, including hemostatic factors, inflammation, cytokine growth factors, and cell-matrix interactions. New capillaries proliferate via a cascade of biological events to form granulation tissue in the wound bed. This process may be sustained until the terminal stages of healing, when angiogenesis is halted by diminished levels of growth factors, resolution of inflammation, stabilized tissue matrix, and endogenous inhibitors of angiogenesis. Defects in the angiogenesis pathway impair granulation and delay healing, and these are evident in chronic wounds [Tonnesen et al. (2000) J Investig Dermatol Symp Proc. 5(1):40-6]. By illuminating the tissue surface with selected narrow wavelength bands (e.g., blue, green and red components) of light or detecting the reflectance of white light within several narrow bandwidths of the visible spectrum (e.g., selected wavelengths of peak absorption from the blood absorption spectrum of white light), the device may also be used to image the presence of blood and microvascular networks within and around the wound, including the surrounding normal tissue, thus also revealing areas of erythema and inflammation.
Reference is now made to
The regulation of angiogenesis over time during wound repair in vivo has been largely unexplored, due to difficulties in observing events within blood vessels. Although initial tests of the imaging device were exploratory, simple modification of the existing prototype device may allow longitudinal imaging of dynamic changes in blood supply and microvascular networks during the wound healing process in vivo.
Imaging of Skin and Oral Cavity
This device may be suitable for imaging the skin, the mouth and the oral cavity. The device may allow for detection of connective tissue changes due to minor cutaneous injuries (e.g., cuts, abrasions) and endogenous bacteria found commonly on normal skin (e.g., Propionibacterium acnes, or P. acnes).
This device may also be suitable for multi-spectral imaging and/or monitoring of dental plaques, carries and/or cancers in the oral cavity. The device may be used to detect the presence of plaques, periodontal diseases, carries and cancers, as well as local oral infections, based on the presence of unique autofluorescence signatures in abnormal or cancerous tissues. The device may use white light, fluorescence, with or without autofluorescence or exogenous fluorescent agents, and reflectance imaging to provide real-time detection and diagnosis of periodontal disease, plaques, and carries and cancers in the oral cavity. The device may record the images for medical record cataloguing. Unlike the direct (i.e., naked eye) viewing approach used by an existing product such as the VELscope System, by Vancouver-based company LED Medical Diagnostics Inc. (LED-MD), the present device may provide digital imaging and recording of tissue white light, fluorescence and reflectance information.
In dermatology, the device may be used to detect bacteria on normal skin. For example,
Such a capability to image and document the presence and biodistribution of bacteria on the skin surface makes the device potentially useful in the dermatology and cosmetology fields. For example, fluorescence imaging may be performed prior to, during and after application of dermatological treatment and/or pharmaceutical/cosmetic formulations (e.g., topical creams, drugs and other antibiotics, skin disinfecting agents, acne treatments, etc.) to the normal and abnormal skin conditions, including but not limited to scarring, hyper-pigmentation, acne, psoriasis, eczema, rashes, etc. Fluorescence/reflectance image-guided tattoo removal (e.g., using surgery or available laser treatments) may also be an option with the device. The device was also used to image minor cuts, scrapes and abrasions on patients skin and under violet/blue light, tissue autofluorescence from connective tissue components (e.g., collagen and elastin) from the wound site and surrounding normal skin aided in detecting white light-occult changes in connective tissues during minor cutaneous wound healing (as seen in
In addition, the device may be used to image the mouth and oral cavity, particularly in the embodiment where the device is small and compact. Pilot imaging studies showed that the device may detect endogenous bacteria in the oral cavity (e.g., on the tongue surface and between teeth on the gum line), suggesting a use in clinical detection of caries and periodontal disease [Pretty (2006) J Dent. 34(10):727-39]. Additionally, tissue autofluorescence has been shown to be useful in detecting oral cancers [Kois et al. (2006) Dent Today. 25(10):94, 96-7]. The device may be used to detect early cancers in the oral cavity based on differences in optical properties (e.g., absorption, scattering, autofluorescence) between normal, pre- and neoplastic oral tissues. In addition, the device may be used to ‘scan’ the oral cavity for mucosal cancers, and monitor the response to therapy.
In general, the device may be used to image and/or monitor targets such as a skin target, an oral target, an ear-nose-throat target, an ocular target, a genital target, an anal target, and any other suitable targets on a subject.
Use in Malignant wounds
A malignant wound is also known as tumor necrosis, a fungating wound, ulcerating cancerous wound, or malignant cutaneous wound. A malignant wound can be an emotional and physical challenge for patients, families and even for the experienced clinician. Fungating and ulcerating wounds can be unsightly, malodorous and painful. These wounds may be indicators of disease progression, and may become infected leading to delayed/impeded healing and associated morbidity and thus, reduced quality of life for patients.
Many cancer patients live with the knowledge that their disease is both progressive and incurable. For a significant minority of these people this reality may be present in the form of a malodorous, exuding, necrotic skin lesion, which can be a constant physical reminder of disease progression (Mortimer P S. In: Doyle et al. editors. Oxford Textbook of Palliative Medicine (2nd ed). Oxford: Oxford University Press, 1998, 617-27; Englund F. RCN Contact 1993; Winter: 2-3). These lesions are commonly known as ‘fungating wounds’, the term ‘fungating’ referring to a malignant process of both ulcerating and proliferative growth (Grocott P. J Wound Care 1995; 4(5): 240-2). Lesions that have a predominantly proliferative growth pattern may develop into a nodular ‘fungus’ or ‘cauliflower’ shaped lesion, whereas a lesion that is ulcerating will produce a wound with a crater-like appearance (Grocott P. J Wound Care 1999, 8(5): 232-4; Collier M. Nurs Times 1997; 93(44): suppl 1-4). Such lesions may also present with a mixed appearance of both proliferating and ulcerating areas (Young T. Community Nurse 1997; 3(9): 41-4).
A malignant wound may develop in one of the following ways:
Malignant wounds are often difficult to manage related to their location, odor, excessive exudates, and propensity for bleeding. Every malignant wound may be unique in its appearance and presenting symptoms. The common symptoms associated with malignant wounds include malodor, excessive exudates, infection, bleeding, maceration and excoriation of peri wound skin, pruritis, pain, poor aesthetics and cosmetic effects of dressings. Currently, the approach to care is mainly holistic and primarily palliative with the aim to control symptoms at the wound site and reduce the impact of the wound on the patient's daily life, primarily by identifying bacterial/microbial infection(s) and monitoring for signs of healing. Unless the pathology is controlled these wounds are not expected to heal.
The described device may be useful for performing clinical assessment of such wounds (e.g., physical and biological examination). The device may provide: a means of thorough image-based wound assessment at baseline and at regular intervals throughout treatment (i.e., longitudinal monitoring), wound assessment including location, size of wound, color, type and amount of any discharge or drainage, serial white light (e.g., for color changes) and fluorescence (e.g., for tissue structural, cellular, biological, and molecular changes) images of chronic malignant wounds, and may provide assessment of any signs and symptoms of infection in real-time, that would affect treatment planning and efficacy. The device may be integrated into the current clinical practice for assessment and care of such malignant wounds.
Imaging of Exogenous Fluorescence Contrast Agents
The development of highly efficient analytical methods capable of probing biological systems at system level is an important task that is required in order to meet the requirements of the emerging field of systems biology. Optical molecular imaging is a very powerful tool for studying the temporal and spatial dynamics of specific biomolecules and their interactions in real time in vivo. Several recent advances in optical molecular imaging have occurred, such as the development of molecular probes that make imaging brighter, more stable and more biologically informative (e.g., FPs and semiconductor nanocrystals, also referred to as quantum dots), the development of imaging approaches that provide higher resolution and greater tissue penetration, and applications for measuring biological events from molecule to organism level. These advances may also be applied to disease diagnosis (e.g., wound care) and pharmaceutical screening. However, current fluorescence imaging devices are large, complicated and involve expensive optical components and very sensitive camera detectors which makes such systems extremely expensive. The device developed here offers an alternative to these cost-limiting systems for preclinical or research studies as well as possible clinical translation of such methods.
Reference is now made to
Referring still to
To improve the use of fluorescence contrast agents in preclinical research and eventually for clinical translation of optical molecular imaging technologies, it is desirable to be able to relatively rapidly differentiate and identify various fluorescent agents. In e) and f), the device was also used as a means of relatively rapidly identifying which fluorescence contrast agents were in the syringes prior to injection, which was not possible under standard white light, demonstrating the utility of the device as a cost-effective fluorescence-image guided technology for providing useful information quickly during fluorescence-image guided surgical and/or PDT procedures, where fluorescent compounds are commonly used, possibly even in emerging wound care techniques.
Fluorescence-Image Guided Surgery
An emerging area is the use of fluorescence imaging for diagnostic screening and image-guided surgery. Overcoming limitations of standard surgery using white light, fluorescence images may be used to aid in surgical resection of tumors in vivo based on fluorescence (e.g., either autofluorescence or fluorescence from exogenous targeted/non-targeted contrast agents) as well as checking for completeness of tumor removal (e.g., clear margins). Fluorescence-image guided surgery has demonstrated improvements in survival, pre-clinically and clinically [Bogaards et al. (2004) Lasers Surg Med. 35:181-90]. For example, during exploratory surgery on a rat, the device may provide standard white light imaging of the surgical field.
Reference is now made to
The device was also used for real-time detection of exogenous fluorescent contrast agents (e.g., for labeled cell tracking and fate in vivo experiments, for tissue engineering studies in regenerative medicine, etc.) in an animal model. For this, during surgery, the device was used in fluorescence mode to image the presence of red fluorescent QDots injected within the heart muscle and lungs of the rat (d). Under violet/blue excitation light, the red QDots can be easily detected within the heart (e) and the lungs (f), which appear dark due to the high concentration of blood in these organs, demonstrating the utility of the device for guiding and targeting biopsies or microsurgical procedures, especially those aimed at detection and removal of cancers (e.g., using autofluorescence or fluorescence contrast enhancement). Note the bright red autofluorescence detected by the device from digested food material in the colon. In g), the device demonstrated its utility in imaging fluorescent tumor phantoms commonly used in small animal imaging research. Solid spherical polymer tumor phantoms doped with fluorescent dye were prepared in varying sizes and placed within the surgical field to demonstrate the capability of the device in providing rapid ‘high contrast’ fluorescence imaging in small animal cancer models.
These results show that the device may be useful in detecting sub-mm sized lesions with fluorescence guidance, which may be useful for targeting biopsies or microsurgical procedures, especially those aimed at detection and removal of cancers (e.g., using autofluorescence or fluorescence contrast enhancement). The device also may have utility in imaging fluorescent tumor phantoms commonly used in small animal imaging research.
Use in Clinical Care
Although current wound management practice aims to decrease the morbidity and mortality of wounds in patients, a limitation is the availability of health care resources. The potential of incorporating the technology of telemedicine into wound care needs is currently being explored. Wound care is a representation of the care of chronic and debilitating conditions that require long-term specialized care. The major effect of improved living conditions and advances in health care globally has led to people living longer. Therefore, the percentage of worlds' elderly and those with chronic medical conditions that would require medical attention is rising. With the escalating costs of health care, and the push of the industry towards outpatient care, this is a part of the health care crisis that is demanding immediate attention.
The present device may provide biologically-relevant information about wounds and may exploit the emerging telemedicine (e.g., E-health) infrastructure to provide a solution for mobile wound care technology and may greatly impact wound health care treatment. Wound care accounts for a large percentage of home visits conducted by nurses and health care workers. Despite best practices some wounds do not heal as expected and require the services of a clinical specialist. The device described here may enable access to specialized clinical resources to help treat wounds from the convenience of the patient's home or chronic care facility, which decreases travel time for clients, increases availability to clinical wound specialists, and may reduce costs to the health care system.
Different uses of the imaging device have been discussed for wound assessment, monitoring and care management. The device may be used to detect and monitor changes in connective tissues (e.g., collagen, elastin) and blood/vascular supply during the wound healing process, monitor tissue necrosis and exudate in wounds based on fluorescence, detect and diagnose wound infections including potentially indicating critical ‘clinically significant’ categories of the presence of bacteria or micro-organisms (e.g., for detecting contamination, colonization, critical colonization and infection) at the surface and deep within wounds [Kingsley, Ostomy Wound Manage. 2003 July; 49(7A Suppl):1-7], provide topographic information of the wound, and identify wound margins and surrounding normal tissues. Tissue fluorescence and reflectance imaging data may be ‘mapped’ onto the white light images of the wound thereby permitting visualization within the wound and the surrounding normal tissues of essential wound biochemical and photobiological (e.g., fluorescence) information, which has not been possible to date. Real-time imaging of wounds may be performed over time to monitoring changes in wound healing, and to potentially monitor the effectiveness of treatments by providing useful information about underlying biological changes that are occurring at the tissue/cellular level (e.g., matrix remodeling, inflammation, infection and necrosis). This may provide quantitative and objective wound information for detection, diagnosis and treatment monitoring in patients. In particular, the device may be used to monitor and/or track the effectiveness of therapy at a biological level (e.g., on a bacterial level), which may provide more information than monitoring only the macroscopic/morphological appearance using white light.
The device may provide real-time non-invasive image-guided biopsy targeting, clinical procedural guidance, tissue characterization, and may enable image-guided treatment using conventional and emerging modalities (e.g., PDT). In addition, use of the imaging device may be used to correlate critical biological and molecular wound information obtained by fluorescence (e.g., endogenous tissue autofluorescence and/or administration of exogenous molecular-biomarker targeted fluorescence contrast agents) with existing and emerging clinical wound care assessment and treatment guides, such as the NERDS and STONES guidelines proposed by Sibbald et al. (Sibbald et al. Increased Bacterial Burden and Infection: The Story of NERDS and STONES. ADV SKIN WOUND CARE 2006; 19:447-61). The fluorescence imaging data obtained with the device may be used to characterize, spatially and spectrally, bacterial balance and burden at the superficial and deep levels of wounds. The device may provide real-time non-invasive image-guided biopsy targeting, clinical procedural guidance, tissue characterization, and may enable image-guided treatment using conventional and emerging modalities (e.g., photodynamic therapy, PDT). The device may be used within the clinical setting and integrated into conventional clinical wound care regimens, and may have a distinct role in areas of infectious diseases. It should be noted as well that this device may also be used for real-time analysis, monitoring and care for chronic and acute wounds in animals and pets, via conventional veterinary care.
This device may allow real-time wound healing assessment for a large patient cohort base. In particular, elderly people, diabetics, immuno-suppressed and immobilized individuals have an increased incidence of chronic wounds and other dermal afflictions that result from poor circulation and immobility, e.g. pressure ulcers such as bed sores, venous stasis ulcers, and diabetic ulcers. These chronic conditions greatly increase the cost of care and reduce the patient's quality of life. As these groups are growing in number, the need for advanced wound care products will increase. This device may impact patient care by allowing a cost-effective means of monitoring chronic and acute wounds in a number of settings, including hospitals, ambulatory clinics, chronic care facilities, in-home-visit health care, emergency rooms and other critical areas in health care facilities. Further, such a ‘hand-held’ and portable imaging device may be easily carried and used by nursing and ambulance staff. Early identification of scarring, which is related to connective tissue production and re-modeling of the wound, and bacterial infections may be detected and treated appropriately, something that is currently difficult. In addition, recent developments in advanced wound-care products including multiple dressing types (e.g., film, hydrocolloid, foam, anti-microbial, alginate, non-adherent, impregnated), hydrogels, wound cleansers and debriding agents, tissue engineered products (e.g., skin replacements, substitutes, and tissue-engineered products such as synthetic polymer-based biological tissue and growth factors), wound cleansers, pharmacological products, and physical therapies may also benefit from the device developed here as it may allow image-based longitudinal monitoring of the effectiveness of such treatments. Physical therapies may include hydrotherapy, electrical stimulation, electromagnetic stimulation devices, ultraviolet therapy, hyperbaric oxygen therapy, ultrasound devices, laser/light emitting diode (LED) devices, and wound imaging/documentation.
Wound tissue analysis is typically required for the assessment of the healing of skin wounds. Percentage of the granulation tissue, fibrin and necrosis in the wound, and their change during treatment may provide useful information that may guide wound treatment. Image analysis may include advanced statistical pattern recognition and classification algorithms to identify individual pixels within the fluorescence wound images collected with the device based on the optical information of the wound and surrounding normal tissue. Thus, image analysis may allow wound images to be mapped into various components of the wound, including total wound area, epithelialization, granulation, slough, necrotic, hypergranulation, infected, undermining, and surrounding tissue margins. This has an added advantage of providing relatively rapid determination of wound healing rates, as well as informing guide patient management decisions.
This device may be easily integrated into existing health-care computer infrastructures (e.g., desktop and pocket PCs used by a growing number of physicians or other health care professionals) for longitudinal image cataloguing for patient wound management within the conventional clinical environment. The wireless receiving and transmission of data capabilities of the device may allow monitoring of wound care and healing remotely through existing and future wireless telemedicine infrastructure. The device may be used to transfer essential medical data (e.g., wound health status) via the interne or over wireless services, such as cellular telephone, PDA or Smartphone services, to remote sites which may permit remote medical interventions, with a further utility in military medical applications for battlefield wound management. The device may allow real-time surface imaging of wound sites and may be easily carried by point-of-care personnel in clinical settings. Using cost-effective highly sensitive commercially available digital imaging devices, such as digital cameras, cellular phones, PDAs, laptop computers, tablet PCs, webcams, and Smart phones, etc. as the image capture or recording component, the device may offer image-based documentation of wound healing and tracking of treatment effectiveness. Also, this technology may be adapted to also function in ‘wireless’ mode to permit remote medical interventions by potentially adapting it for use with high-resolution digital cameras embedded in commercially-available cellular telephones.
By using web-based telemedicine and remote medical monitoring infrastructure, the imaging device may be integrated into a ‘store-and-forward’ concept of wound assessment systems. In addition to providing digital images, such a system may present a comprehensive set of clinical data that meet the recommendations of clinical practice guidelines. The presently-disclosed device may integrate into a computer-based wound assessment system (e.g., with image analysis software) to be used by a health care facility to enhance existing clinical databases and support the implementation of evidence—based practice guidelines. Such an integrated telemedicine infrastructure may be used for monitoring patients at home or in long-term-care facilities, who may benefit from routine monitoring by qualified clinicians but currently do not have access to this care. This device may be further developed into a portable handheld point-of-care diagnostic system, which may represent a major advance in detecting, monitoring, treating, and preventing infectious disease spread in the developed and developing worlds. This knowledge may significantly improve the diagnostic tools available to practitioners who treat chronic wounds in settings where quantitative cultures are inaccessible.
The device may allow digital imaging with optical and digital zooming capabilities (e.g., those embedded in commonly available digital imaging devices). Still or video image quality may be in ‘high-definition’ format to achieve high spatial resolution imaging of the tissue surface. Images may be recorded as still/freeze frame and/or in video/movie format and printed using standard imaging printing protocols which do (e.g., connected via USB) or do not (e.g., PictBridge) require a personal computer. The images/video data may be transferred to a personal computer for data archival storage and/or image viewing and/or analysis/manipulation. The device may also transfer data to a printer or personal computer using wired or wireless capabilities (e.g., Bluetooth). Visualization may be performed on the hand-held device screen and/or in addition to simultaneous viewing on a video screen/monitor (e.g., head-mounted displays and glasses) using standard output video cables. This device may display, in combination or separately, optical wavelength and fluorescence/reflectance intensity information with spatial dimensions of the imaged scene to allow quantitative measurements of distances (e.g., monitoring changes tissue morphology/topography) over time. The device may also allow digital image/video storage/cataloguing of images and related patient medical data, for example using dedicated software with imaging analysis capabilities and/or diagnostic algorithms.
Image Analysis
Image analysis may be used together with the device to quantitatively measure fluorescence intensities and relative changes in multiple fluorescence spectra (e.g., multiplexed imaging) of the exogenous optical molecular targeting probes in the wound and surrounding normal tissues. The biodistributions of the fluorescent probes may be determined based on the fluorescence images collected and these may be monitored over time between individual clinical wound imaging sessions for change. By determining the presence and relative changes in abundance quantitatively, using the device, of each and all of the spectrally-unique fluorescent probes, the clinical operator may determine in real-time or near real-time the health and/or healing status and response to treatment over time of a given wound, for example by using a look-up table in which specific tissue, cellular and molecular signals are displayed in correlation to wound health, healing and response status, an example of which is shown in
Image analysis techniques may be used to calibrate the initial or first images of the wound using a portable fluorescent standard placed within the field of view during imaging with the device. The image analysis may also permit false or pseudo color display on a monitor for differentiating different biological (e.g., tissue, cellular, and molecular) components of the wound and surrounding normal tissues including those biomarkers identified by autofluorescence and those identified by the use of exogenous targeted or untargeted fluorescence/absorption contrast agents.
Examples of such biomarkers are listed in promotes the homing of these EPCs to the site of injury, where they participate in neovasculogenesis. In a murine model of diabetes (right), eNOS phosphorylation in the bone marrow is impaired, which directly limits EPC mobilization from the bone marrow into the circulation. SDF-1α expression is decreased in epithelial cells and myofibroblasts in the diabetic wound, which prevents EPC homing to wounds and therefore limits wound healing. It has been shown that establishing hyperoxia in wound tissue (e.g., via HBO therapy) activated many NOS isoforms, increased NO levels, and enhanced EPC mobilization to the circulation. However, local administration of SDF-1
was required to trigger homing of these cells to the wound site. These results suggest that HBO therapy combined with SDF-1
administration may be a potential therapeutic option to accelerate diabetic wound healing alone or in combination with existing clinical protocols.
Pre-assigned color maps may be used to display simultaneously the biological components of the wound and surrounding normal tissues including connective tissues, blood, microvascularity, bacteria, microorganisms, etc. as well as fluorescently labeled drugs/pharmacological agents. This may permit visualization in real-time or near real-time (e.g., less than 1 minute) of the health, healing and infectious status of the wound area.
The image analysis algorithms may provide one or more of the following features:
Patient Digital Image Management
Basic Image Processing and Analysis
Report Generation
Large Library of Automated Solutions
Although image analysis algorithm, techniques, or software have been described, this description also extends to a computing device, a system, and a method for carrying out this image analysis.
Stem Cell Therapy and Cancer Monitoring
The device may be used for imaging and detection of cancers in humans and/or animals. The device may be used to detect cancers based on inherent differences in the fluorescence characteristics between such cancers and surrounding normal tissues in patients. This device may also be used for image-based detection of cancers in pets, for example within veterinary settings.
The device may also be used as a research tool for multi-spectral imaging and monitoring of cancers in experimental animal models of human diseases (e.g., wound or cancers). The device may be used to detect and/or image the presence of cancers and track tumor growth in animals models of cancer, particularly using fluorescent (e.g., in the visible and NIR wavelength ranges) protein transfected tumor cell lines.
The imaging device may be used in conjunction with both existing and emerging cell therapies useful for reconditioning of chronic wounds and accelerating their healing. For this, fluorescently labeled stem cells may be administered to the wound site prior to imaging with the device. Pluripotential stem cells (PSCs), the precursors to all more specialized stem cells, are capable of differentiating into a variety of cell types, including fibroblasts, endothelial cells and keratinocytes, all of which are critical cellular components for healing. A recent report on an uncontrolled clinical trial suggests that direct application of autologous bone marrow and its cultured cells may accelerate the healing of non-healing chronic wounds (Badiavas et al. Arch Dermatol 2003; 139(4): 510-16). Considering the pathophysiological abnormalities present in chronic wounds there is the potential that stem cells may reconstitute dermal, vascular and other components required for optimal healing. The device may be used to visualize and track the labeled stem cells at the wound site over time, and determine their biodistribution and therapeutic effect. Using exogenous fluorescence molecular-targeted agents, for example as described above, may confirm differentiation of the stem cells in vivo and may also aid in determining the response of the wound to this treatment.
For example, this device may be used to identify, track and/or monitor cancer tumor stem cells and stem cells in general (e.g., in preclinical small animal experimental models of cancers and other clinical models). An example is shown in the Figures. The device may also be useful for imaging of clinical cell therapies, including treatment of diseases using stem cells.
Reference is now made to
Referring now to
This device may be used for multi-spectral imaging and detection of cancers in humans and animals. This device may be also used to detect cancers based on inherent differences in the fluorescence characteristics between such cancers and surrounding normal tissues in patients. This device may also be used for image-based detection of cancers in animals such as pets or livestock, for example within veterinary settings.
This device may also be suitable as a research tool for multi-spectral imaging and monitoring of cancers in experimental animal models of human diseases (e.g., wound and cancers). The device may be used to detect and/or image the presence of cancers and may be used to track tumor growth in animals models of cancer, particularly using fluorescent (e.g., in the visible and NM wavelength ranges) protein transfected tumor cell lines.
Image-Guidance
The device may also be useful for providing fluorescent image-guidance, for example in surgical procedures, even without the use of dyes or markers. Certain tissues and/or organs may have different fluorescent spectra (e.g., endogenous fluorescence) when viewed using the imaging device, or example under certain excitation light conditions.
Bioengineered Skin
Several bioengineered skin products or skin equivalents have become available commercially for the treatment of acute and chronic wounds, as well as burn wounds. These have been developed and tested in human wounds. Skin equivalents may contain living cells, such as fibroblasts or keratinocytes, or both, while others are made of acellular materials or extracts of living cells (Phillips. J Dermatol Surg Oncol 1993; 19(8): 794-800). The clinical effect of these constructs is 15-20% better than conventional ‘control’ therapy, but there is debate over what constitutes an appropriate control. Bioengineered skin may work by delivering living cells which are known as a ‘smart material’ because they are capable of adapting to their environment. There is evidence that some of these living constructs are able to release growth factors and cytokines (Falanga et al. J Invest Dermatol 2002; 119(3): 653-60). Exogenous fluorescent molecular agents may be used in conjunction with such skin substitutes to determine completeness of engraftment as well as biological response of the wound to the therapy. The healing of full-thickness skin defects may require extensive synthesis and remodeling of dermal and epidermal components. Fibroblasts play an important role in this process and are being incorporated in the latest generation of artificial dermal substitutes.
The imaging device described here may be used to determine the fate of fibroblasts seeded in skin substitute and the influence of the seeded fibroblasts on cell migration and dermal substitute degradation after transplantation to wound site can be determined. Wounds may be treated with either dermal substitutes seeded with autologous fibroblasts or acellular substitutes. Seeded fibroblasts, labeled with a fluorescent cell marker, may then be detected in the wounds with fluorescence imaging device and then quantitatively assessed using image analysis, for example as described above.
Polymer-Based Therapeutic Agents
There are a number of commercially available medical polymer products made for wound care. For example, Rimon Therapeutics produces Theramers™ (www.rimontherapeutics.com) which are medical polymers that have biological activity in and of themselves, without the use of drugs. Rimon Therapeutics produces the following wound care products, which can be made to be uniquely fluorescent, when excited by 405 nm excitation light: Angiogenic Theramer™, which induces new blood vessel development (i.e., angiogenesis) in wounds or other ischemic tissue; MI Theramer™, which inhibits the activity of matrix metalloproteases (MMPs), a ubiquitous group of enzymes that are implicated in many conditions in which tissue is weakened or destroyed; AM Theramer™, a thermoplastic that kills gram +ve and gram −ve bacteria without harming mammalian cells; and ThermaGel™, a polymer that changes from a liquid to a strong gel reversibly around body temperature. These can each be made to be fluorescent by addition of fluorescent dyes or fluorescent nanoparticles selected to be excited, for example, at 405 nm light with longer wavelength fluorescence emission. By using the imaging device, the application of such fluorescent polymer agents may be guided by fluorescent imaging in real-time. This may permit the Theramer agent to be accurately delivered/applied (e.g., topically) to the wound site. Following application of the agent to the wound, the fluorescent imaging device may then be used to quantitatively determine the therapeutic effects of the Theramers on the wound as well as track the biodistribution of these in the wound over time, in vivo and non-invasively. It may also be possible to add a molecular beacon, possibly having another fluorescent emission wavelength, to the MI Theramer™ that can fluoresce in the presence of wound enzymes (e.g., MMPs), and this may indicate in real-time the response of the wound to the MI Theramer™. It may be possible to use one fluorescence emission for image-guided Theramer application to the wound site and another different fluorescence emission for therapeutic response monitoring, and other fluorescence emissions for other measurements. The relative effectiveness of MMP inhibition and antimicrobial treatments may be determined simultaneously over time. Using image analysis, real-time comparison of changes in fluorescence of these signals in the wound may be possible. This adds a quantitative aspect to the device, and adds to its clinical usefulness.
It should be noted that other custom bio-safe fluorescence agents may be added to the following materials which are currently used for wound care. The fluorescent material may then be imaged and monitored using the device.
Other wound care products that may be imaged using the disclosed device include Theramers, silver-containing gels (e.g., hydrogels), artificial skin, ADD stem cells, anti-matrix metalloproteinases, and hyaluronic acid. Fluorescent agents may be added to other products to allow for imaging using the device. In some cases, the products may already be luminescent and may not require the addition of fluorescent agents.
The device may be used also to monitor the effects of such treatments over time.
Application for Food Products
The imaging device may also be useful for monitoring food products (e.g., meat products) for contamination. This may be useful, for example, in food/animal product preparation in the meat, poultry, dairy, fish, and agricultural industries. The device may be used as part of an integrated multi-disciplinary approach to analytical laboratory services within this sector, which may provide capabilities including image-based detection of contamination and guidance for obtaining samples for testing. The device may be used for real-time detection, identification and monitoring of level of bacterial and other microbial meat contamination/adulteration of food products. It may be used for bacterial contamination tracking in the food processing plant environment, and thus may provide an image-based method for determining food safety and quality. In embodiments where the device is hand-held, compact and portable, the imaging device may be useful in food preparation areas to determine safety of food products from bacterial/microbial contamination. The device may also be used for relatively rapid detection and analysis of bacteria/microbes in meat samples (and on preparation surfaces) collected or sampled, for example as part of food-safety and quality regulated inspection process, during processing and in finished food products. This device may be used in the meat, horticulture and aquaculture industries in implementing food safety inspection/detection procedures that meet the requirements for food safety and quality. The device may be used to detect food contaminants, for example contaminants found in the meat, poultry, dairy and fish industries. This technology may be useful for as a fecal contaminant detection system, since fecal bacteria produce porphyrins which may be readily detected by the device.
Detection and accurate identification of foodborne pathogens, such as Listeria monocytogenes (LM), in food samples and processing lines may be critical both for ensuring food quality assurance and tracing of bacterial pathogen outbreaks within the food supply. Current detection methods employed in food production and processing facilities typically rely on multiple random surface sampling of equipment (e.g., swabbing), and subsequent molecular-based diagnostic assays (e.g., real-time polymerase chain reaction, RT-PCR) which may provide quantitative confirmation of the presence of LM, typically within 24-72 h. However, given time and cost restraints, typically only randomized selected zones of a given food production facility are tested for pathogen contamination at a time, and the significant potential of under-sampling during the “first pass” surface swabbing of equipment may result in undetected pathogens causing catastrophic health and economic consequences. In addition, the inability to i) rapidly sample all surface areas during the “first pass” swabbing to identify areas with high infection probability, ii) to visually document this initial screening process (e.g. no imaging methods available to date), iii) the delay in obtaining laboratory results, iv) the high-costs associated with current methods, and v) more importantly, the potential of missing deadly pathogen infections have prompted efforts to improve the early and accurate detection of food-born pathogens cost-effectively.
The device may be useful in providing a relatively rapid and accurate way of detecting such pathogens. The device may be used with an assay of a multi-coloured fluorescence probe ‘cocktail’ (e.g., a combination of two or more contrast agents) which may unequivocally identify (and may make visible) only viable Listeria monocytogenes from other Listeria species using highly-specific gene probe technology. This may allow specific detection of living LM in real-time, potentially minimizing the need for standard time-consuming enrichment methods. This method may also be expanded to include detection of other pathogens of interest, including Enterobacter sakazakii, Camylobacter species (C. coli, C. jejuni and C. lari), coliform bacteria and bacteria of the species E. coli (including lactose- and indol-negative Escherichia coli-strains), Salmonella, all bacteria belonging to the species Staphylococcus aureus and separately all bacteria belonging to the genus Staphylococcus, and Pseudomonas aeguginosa. Other bacteria may be detectable by selecting a suitable probe or combination of probes. For example a combination of two or more contrast agents may be designed to be specific to a certain bacteria, and may result in a unique detectable fluorescent signature when imaged using the imaging device.
The imaging device may be used (e.g., when combined with applied exogenous bacteria-specific contrast agents, including a multi-targeted probe or a combination of probes) for relatively rapid “first pass” screening of food-preparation and handling surfaces for targeted swabbing and microbiological testing. This device may allow relatively rapid image-based surveillance of any surface of equipment and food products and may capture the fluorescence signature of food-borne bacteria/pathogens in real-time. The device may be used in combination with, for example, an assay of a multi-coloured fluorescence probe ‘cocktail’ (and combinations thereof) which may unequivocally identify (and may make visible) only viable Listeria monocytogenes from other Listeria species using highly-specific gene probe technology, as described above. Such a probe ‘cocktail’ may be designed to specifically target certain pathogens based on a specific combination of probes known to be sensitive to such pathogens, and known to give a signature fluorescence response. In addition to detection of such pathogens, the device may allow for the presence and/or location of different strains to be differentiated, based on their different signature fluorescence response.
Surface Contamination
The imaging device may be useful for detection of surface contamination, such as for detection of ‘surface bacterial contamination’ in health care settings. This device may be used for detecting and imaging of the presence of bacteria/microbes and other pathogens on a variety of surfaces/materials/instruments (in particular those related to surgery) in hospitals, chronic care facilities, and old age homes, where contamination is the leading source of infection. The device may be used in conjunction with standard detection, identification and enumeration of indicator organisms and pathogens strategies.
Forensic Uses
The use of the imaging device to image surface contaminants and targets may be useful in forensic applications. For example, the device may be useful for forensic detection of latent finger prints and biological fluids on non-biological surfaces. The device may offer a relatively inexpensive, compact and portable means of digitally imaging (e.g., with white light, fluorescence and/or reflectance) latent finger prints and biological fluids, and other substances of forensic interest. The former may be made fluorescent using commercially available finger print fluorescence dyes, and the latter may be detected either using autofluorescence of the fluids or exogenously applied ‘targeted’ fluorescent dye agents (such as Luminol). Images may be recorded digitally. The device may also be used during autopsy procedures to detect bruising
The imaging device may also be used to detect latent fingerprints, for example by using a fluorescent dye to enhance the finger print ridges on a table surface. This may be done, for example, by including fluorescent dye combined with superglue (e.g., cyanoacrylate) to develop fingerprint contrast against background surfaces. Far-red and near-infrared fluorescent dyes may be used to reduce the potential of background autofluorescent. These data suggest the use of the imaging device for relatively rapid image-based detection of non-biological and biological contaminants as well as fingerprints, for example, in forensic applications. (405 nm excitation, 500-550 nm emission (green), >600 nm emission (red)).
The device may also be useful in anti-counterfeit applications.
Cataloguing
The imaging device may be allow for fluorescent-based cataloguing of animals, such as laboratory animals.
Kits for Device
The imaging device may be provided in a kit, for example including the device and a fluorescing contrast agent. The contrast agent may be any one or more of those described above. For example, the contrast agent may be for labeling a biomarker in a wound, where the kit is for wound monitoring applications.
Cosmetic or Dermatology Uses
The imaging device may also be used for imaging cosmetic or dermatological products.
The imaging device may be used in white light and fluorescence modes to improve the administration of these treatments as well as monitor their effectiveness over time non-invasively and quantitatively. The device may be used in combination with other imaging modalities, for example thermal imaging methods, among others.
This device may also be used to test anti-bacterial, antibiotic, or disinfectant agents. Fluorescence imaging provided by this device may be used, for example in combination with white light imaging, to quantitatively detect the effectiveness of pharmaceutical treatments in bacterial cultures and other model systems, during drug discovery, optimization, and evaluation, for example for wound treatment.
All examples and embodiments described herein are for the purpose of illustration only and are not intended to be limiting. A person skilled in the art would understand that other variations are possible. All references mentioned are hereby incorporated by reference in their entirety.
This is a §371 national stage application of PCT/CA2009/000680 filed internationally on May 20, 2009, which claims priority to U.S. Provisional Application No. 61/054,780, filed on May 20, 2008, the entire contents of each of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2009/000680 | 5/20/2009 | WO | 00 | 2/7/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/140757 | 11/26/2009 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20110117025 A1 | May 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61054780 | May 2008 | US |
