Patent Application
20090131801
The present invention relates generally to systems and processes for optical imaging of variable diameter lumens or hollow organs and, more particularly to, e.g., exemplary embodiments of apparatus and processes for optical imaging of pulmonary airways.
Lung cancer is the leading cause of cancer-related mortality in the western industrialized nations with a current 5-year survival rate under about 15%. (See Jemal A, Siegel R, Ward E, Murray T, Xu J, Thun M J. Cancer Statistics, 2007, CA: A Cancer Journal for Clinicians 2007; 57:43-66).
In the United States alone, lung cancer has been responsible for about 29% of all cancer-related deaths, approximately 160,000 deaths annually, more than breast, colorectal and prostate cancer combined. (See Jemal A, Siegel R, Ward E, Murray T, Xu J, Thun M J. Cancer Statistics, 2007, CA: A Cancer Journal for Clinicians 2007; 57:43-66; and Society AC, Cancer Facts & Figures 2007, American Cancer Society. Atlanta, 2007). Squamous cell carcinoma (SCC), or epidermoid carcinoma, accounts for 30% of all lung cancers (see Travis W D, Travis L B, S.S. D. Lung Cancer. Cancer 1995; 75:191-202) and in addition is the most lethal. The evolution of SCC occurs over many years in a step-wise progression, and generally presents in the main, lobar or segmental bronchi. (See id.) As smoking is the primary cause of SCC, lesions may develop multifocally, termed field carcinogenesis. (See Kerr K M, Pulmonary preinvasive neplasia, Journal of Clinical Pathology 2001; 54:257-271).
The initial stages may be characterized by a loss of the ciliated columnar epithelium, basal cell hyperplasia, and the development of cuboidal epithelium without cilia. (See id.) Disease progression generally continues with a development of squamous metaplasia, followed by various stages of dysplasia, carcinoma in situ, and finally invasive cancer. (See id.) In the early stages of disease development, the thickness of the lesions may be only a few cell layers deep (e.g., about 0.2-1 mm—see Hirsch F R, Franklin W A, Gazdar A F, Bunn P A. Early detection of lung cancer: clinical perspectives of recent advances in biology and radiology. Clinical Cancer Research 2001; 7:5-22) and may not be readily apparent with a conventional bronchoscopy (see Feller-Kopman D, Lunn W, Ernst A. Autofluorescence bronchoscopy and endobronchial ultrasound: a practical review, Annals of Thoracic Surgery 2005; 80:2395-2401), thus making the detection and diagnosis challenging.
Although significant efforts in the development of successful screening paradigms for the detection of lung cancer have been made, to date there is likely still no widely accepted and validated approach. Computed tomography (CT) and x-ray imaging typically does not detect early SCC as the lesions are generally radiographically occult. CT can predominately detect peripheral adenocarcinoma of the lung. The prevalence and high mortality rate associated with lung SCC and the lack of any widely accepted screening and surveillance tools can highlight the likely need for new imaging paradigms that will ultimately lead to a reduction in patient mortality.
Optical coherence tomography (OCT) is a non-contact optical imaging modality that affords tomographic images of tissue in resolutions comparable with architectural histology (e.g., approximately <10 μm). One of the concepts of OCT is similar to that of ultrasound where measuring the delay of the source, as it is reflected off subsurface structures in biological tissues, generates depth information. Unlike ultrasound, however, a broadband light source can be used in OCT and, due to the high speed of light propagation in tissue, optical reflectance may be measured using low coherence interferometry. The broadband source can be separated into two arms, a reference arm and a sample arm. When the optical path length of the light traveled by each arm is identical the combined light from each channel forms and interference pattern. Thus, to construct a single depth profile, the reference arm reflector can be translated effectively changing the optical length of the reference arm and hence the penetration depth of the measured signal in the tissue. Three-dimensional images may be subsequently comprised of two-dimensional arrays of individual depth profiles. OCT can be advantageous in that it is a non-contact imaging technology that relies on endogenous contrast and may not require a transducing medium.
Certain preliminary ex vivo studies have been conducted regarding the use of optical coherence tomography (OCT) in the diagnosis of bronchial pathology. (See Yang Y, Whiteman S C, van Pittius D G, He Y, Wang R K, Spiteri M A, Use of optical coherence tomography in delineating airways microstructure: comparison of OCT images to histpathological sections, Physics in Medicine and Biology 2004; 49:1247-1255; Ikeda N, Hayashi A, Iwasaki K, Tsuboi M, Usuda J, Kato H, Comprehensive diagnostic bronchoscopy of central type early stage lung cancer, Lung Cancer 2007; 56:295-302; Tsuboi M, Hayashi A, Ikeda N, Honda H, Kato Y, Ichinose S, et al., Optical coherence tomography in the diagnosis of bronchial lesions, Lung Cancer 2005; 49:387-394; and Whiteman S C, Yang Y, van Pittius D G, Stephens M, Parmer J, Spiteri M A, Optical coherence tomography: real-time imaging of bronchial airways microstructure and detection of inflammatory/neoplastic morphologic changes, Clinical Cancer Research 2006; 12:813-818). These studies have demonstrated that OCT can indeed be used to visualize and evaluate the pulmonary tissue. However, such studies have generally been limited to small proof of concept trials with no definitive diagnostic criteria being developed. In addition, endoscopic OCT has also been used to interrogate the bronchial mucosa in a limited in vivo human proof of principle study. (See Tsuboi M, Hayashi A, Ikeda N, Honda H, Kato Y, Ichinose S, et al., Optical coherence tomography in the diagnosis of bronchial lesions, Lung Cancer 2005; 49:387-394).
Since SCC and its precursors can often be multifocal, and may arise anywhere within the major airways, a diagnostic tool, system and/or method for evaluating this disease should be able to investigate long bronchial segments during a clinically viable procedure time (e.g., about 1-5 minutes). While OCT has shown some promise for imaging pulmonary airways, its relatively slow speed can prohibit the screening of sufficiently large areas to be clinically useful. Further, a second-generation OCT technology—frequency domain imaging (OFDI)—has been developed. (See Yun S H, Teamey G J, de Boer J F, Iftimia N, Bouma B E, High-speed optical frequency-domain imaging. Optics Express 2003; 11:2953-2963). One of the advantages of OFDI is that this technique/procedure can provide images at rates that may be 100× faster than conventional OCT. Therefore, OFDI can be utilized to screen the bronchial tree in a manner that can be compatible with the temporal requirements of the bronchoscopy procedure. Volumetric imaging of the upper airways can solve certain dilemmas associated with screening and managing patients with SCC.
Systems and processes for detecting and diagnosing squamous cell carcinoma in the pulmonary airways may be needed to detect and treat precancerous lesions prior to such lesions progressing to malignant invasive cancers. Early detection through OCT and consequent treatment can lead to a consequent reduction in the mortality associated with the disease. OCT imaging of the pulmonary airways is an emerging field. Imaging the bronchial mucosa with this new technology has been demonstrated; however, to date, the full potential may not have been reached.
Indeed, there may be a need to overcome at least some of the deficiencies described above.
One of the objectives of the exemplary embodiments of the present invention is to overcome certain deficiencies and shortcomings of the conventional apparatus, and provide exemplary embodiments of apparatus and processes for optical imaging of pulmonary airways.
For example, exemplary embodiments of an apparatus for obtaining data for at least one portion within at least one luminal or hollow sample can be provided. For example, the exemplary apparatus can include a first optical arrangement configured to transceive at least one electromagnetic radiation to and from the portion. A second arrangement may be provided that can at least partially enclose the first arrangement. At least one third arrangement may be provided which is configured to be actuated so as to expand, at least in part, beyond a periphery of the second arrangement. Such exemplary third arrangement can be structured to facilitate a fluid flow and/or a gas flow therethrough. Further, a fourth arrangement may be provided which can be structured to (i) actuate a particular number of the third arrangement and/or (ii) adjust a distance between at least two outer portions of the third arrangement. According to one exemplary embodiment, the third arrangement can be a plurality of the third arrangements.
According to one exemplary variant, the third arrangement can be a wire arrangement and/or a plastic arrangement. Such wire arrangement may have at least one wire strand and/or a cage. Further, the third arrangement can include a balloon arrangement. Further, the third arrangement can have an approximately circular or elliptical outer periphery—e.g., a circumference of the third arrangement may be adjustable by the fourth arrangement. In addition, the fourth arrangement can actuates the particular number of the third arrangements. The third arrangements may be spaced apart from one another by at least one predetermined distance. The predetermined distance can be provided such that upon a completed collapse of each of the third arrangements, outer portions of the each of the third arrangements may be prevented from substantially overlapping one another. The third arrangements can be configured to be actuated to expand so as to be associated with a plurality of portions within the at least one luminal and/or hollow sample.
In still another exemplary embodiment of the present invention, the third arrangement can be statically connected to the second arrangement, and the third arrangement translates over at least one portion thereof. The third arrangement can adjust the distance by translating itself and/or the fourth arrangement with respect to one another. Further, in at least a partially expanded state, the third arrangement can have an approximate shape of a cone. The portion can be within an airway of a patient, and the third arrangement may be structured to be insertable into the airway.
According to a further exemplary embodiment of the present invention, the distance can be a radius of an outer periphery of the at least one third arrangement. A fifth arrangement can be provided that substantially surrounds the fourth arrangement. For example, the fifth arrangement can be an endoscope, a laparascope, a bronchoscope, a cystoscope and/or a guide catheter.
20. The apparatus according to claim 16, wherein the third arrangements are configured to be actuated to expand so as to be associated with a plurality of portions within the at least one luminal or hollow sample.
Other features and advantages of the present invention will become apparent upon reading the following detailed description of embodiments of the invention, when taken in conjunction with the appended claims.
Further objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the present invention, in which:
Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention.
Herein, a detailed description of the principles of optical frequency domain imaging (OFDI) is provided, including preliminary results of comprehensive OFDI screening in an ex vivo swine airway.
Optical Frequency Domain Imaging Optical frequency domain imaging (OFDI) can be a high speed second generation OCT imaging technology. (See, e.g., Yun S H, Tearney G J, de Boer J F, Iftimia N, Bouma B E, High-speed optical frequency-domain imaging. Optics Express 2003; 11:2953-2963). In traditional time domain OCT, a broadband light source can be used to illuminate both a reference and a sample arm. When the back-scattered light from the two arms has traveled the same optical distance, an interference pattern is formed which can be detected by a receiver. Individual depth profiles, or a-lines can then be obtained by mechanically translating the reference arm through the desired imaging depth range. Unlike OCT, OFDI utilizes a rapidly tuned wavelength swept laser source. (See, e.g., Yun S H, Tearney G J, de Boer J F, Iftimia N, Bouma B E, High-speed optical frequency-domain imaging. Optics Express 2003; 11:2953-2963; Brinkmeyer E, Ulrich R, High-resolution OCDR in dispersive waveguide, Electronic Letters 1990; 26:413-4; Chinn S R, E. S, Fujimoto J G, Optical coherence tomography using a frequency-tunable optical source, Optics Letters 1997; 22:340-2; Golubovic B, Bouma B E, Tearney G J, Fujimoto J G, Optical frequency-domain reflectometry using rapid wavelength tuning of a Cr4+:forsterite laser, Optics Letters 1997; 22:1704-6; Lexer F, Hitzenberger C K, Fercher A F, Kulhavy M, Wavelength-tuning interferometry of intraocular distances, Applied Optics 1997; 36:6548-53; and Yun S H, Boudoux C, Tearney G J, Bouma B E, High-speed wavelength-swept semiconductor laser with a polygon-scanner-based wavelength filter, Optics Letters 2003; 28:1981-3).
As differing wavelengths may penetrate the tissue to different depths an entire depth profile can be obtained simultaneously during a single sweep of the source while the reference arm remains stationary. A detection of the spectrally resolved interference between the sample and the stationary reference arm can then generate the depth profile. The interference signal may be detected by a set of balanced receivers, and the depth profile can be obtained by determining the Fourier transform. Due to the elimination of the mechanical translation of the reference arm, significantly higher OFDI imaging speeds may be attainable. In addition, the sensitivity of OFDI can be considerably higher than that of OCT due to the Fourier integration in the processing of the OFDI signal. (See, e.g., Yun S H, Tearney G J, de Boer J F, Iftimia N, Bouma B E, High-speed optical frequency-domain imaging. Optics Express 2003; 11:2953-2963). As the signal to noise ratio in OCT and OFDI imaging systems is proportional to the image power reflected from the sample and the image resolution, and inversely proportional to the acquisition speed and depth range, it is possible to image samples and/or portions thereof at significantly higher image acquisition speeds, compared to conventional OCT, without sacrificing image quality.
For example, a-line rates of up to about 64 kHz can be achievable with the exemplary OFDI procedures and systems. One exemplary embodiment of the OFDI system is configured to acquire, process and display image data at a sustained a-line rate of, e.g., about 52 kHz, corresponding to an imaging speed of, e.g., about >25 frames/sec (e.g., frame size: 1536×2048). The wavelength swept source for this exemplary system can be centered at about 1320 nm and may have a free spectral range (tuning range) of about 111 nm. This corresponds to an image ranging depth of approximately 4 mm and an axial resolution of about 5 microns in tissue (e.g., about n=1.38).
Speed improvements of the exemplary embodiment of the OFDI procedures and systems over the traditional OCT facilitate the imaging of large tissue volumes at microscopic resolution. Faster image acquisition can also make the imaging less vulnerable to motion artifacts, which can be a desirable trait when dealing with in vivo applications.
To demonstrate the ability of the exemplary OFDI procedures and systems to image the layers of the bronchial mucosa, OFDI imaging may be performed in a swine ex vivo lung. For example, an 18 mm balloon catheter with an optical imaging window of about 5 cm was used to stabilize and centralize the optical inner core with respect to the bronchial mucosa. The exemplary probe was positioned within the left main bronchus extending up into the trachea and traversing the main carina. The balloon was then be inflated, and the inner optical core of the catheter was rotated and translated enabling us to acquire continuous spiral cross-sectional images.
Exemplary comprehensive exemplary volumetric images depicted in
These exemplary results demonstrate that a comprehensive volumetric microscopy in the pulmonary airways using the exemplary OFDI techniques and arrangement is possible, and that the exemplary OFDI imaging facilitates the visualization of the architectural layers in the bronchial wall.
Thus, with the exemplary OFDI imaging using the exemplary procedures and/or system of biological tissues, is possible to provide a 100-fold increase in imaging speed over traditional OCT. Due to the increased imaging speed, together with certain exemplary optical probe designs, comprehensive microscopy of the pulmonary airways in vivo may be possible. This capability to noninvasively obtain microscopic image data over large epithelial surface areas may aid in early diagnosis and intervention, resulting in a consequent reduction in morbidity and mortality associates with SCC of the lung.
One of the objectives of the present invention is to provide an accurate OFDI-based assessment system and method for the detection and diagnosis of dysplasic changes and early SCC in the bronchial mucosa. Screening the airways for the purpose of detecting possible lesions may prefer, for example, that the catheter function under the control of a standard bronchoscope. Surveillance of identified lesions, or assessment of segments of bronchial mucosa, may prefer the catheter to perform comprehensive volumetric imaging. For example, one exemplary catheter, to facilitate a fluent assessment of the airways without the need to repeatedly change imaging probes, may perform both the screening and surveillance functionalities.
Surveillance To effectively and accurately survey the pulmonary airways, a comprehensive imaging of large areas at microscopic resolution may be desirable, thereby likely eliminating or reducing unnecessary errors that may be attributed to missed diagnoses through sampling error. The exemplary catheter may be configured to acquire an automated circumferential three-dimensional imaging of the airways over predefined bronchial segments. To reduce OFDI imaging time and to facilitate an accurate placement of the catheter, the exemplary probe can serve in an ancillary capacity to the bronchoscope by operating through the access port. The exemplary catheter may also operate independently of the bronchoscope, and can include a stabilization device to centralize and brace the catheter relative to the bronchial wall. This exemplary stabilization device may be permeable to air (or fluid) to facilitate the typically physiological functioning of the airways.
Screening The exemplary catheter retracted into the bronchoscope, with tip still extending, e.g., several millimeters past the distal end of the bronchoscope to facilitate a clear viewing, may operate in the same style as the exemplary catheter described herein above. As the bronchoscope traverses the airways, the exemplary catheter may continuously obtain cross-sectional images of the bronchial wall microstructure. This exemplary catheter can be advantageous over other prior catheters in that, e.g., it may have a more suitable imaging focal length and a stiffer encasing sheath to limit vibrations from the rotating inner core. This exemplary mode of operation can facilitate the physician to perform real time screening of the airway mucosa for the presence of possible pathology.
A diagram of an exemplary embodiment of the OFDI apparatus according to the present invention is shown in
Preliminary results of three-dimensional imaging of the pulmonary airways obtained from the swine airway ex vivo are shown in
The exemplary luminal diameter of bronchial segments can decrease in the pulmonary airways with an increasing airway generation. Additionally, the lumen diameters may be subject to the presence of strictures or dilated regions within the bronchial tree or other organ to be imaged. One exemplary embodiment of the imaging probe according to the present invention can include a centering arrangement that may accommodate varying luminal diameters, lengths, and topology.
In particular,
Passage of air, and possibly of fluid, can be important in the normal functioning of the pulmonary airways. Conventional balloon based OFDI centering arrangements can substantially occlude the lumen, and, as a result, may make it difficult to provide for the passage of air or fluid through the airways.
In another exemplary embodiment of the present invention, the imaging probe can comprise at least one or multiple wire or plastic expandable umbrella-like arrangements 620 in series, as shown in an expanded state in
The foregoing merely illustrates the principles of the invention. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. Indeed, the arrangements, systems and methods according to the exemplary embodiments of the present invention can be used with and/or implement any SEE, OCT system, OFDI system, SD-OCT system or other imaging systems, and for example with those described in International Patent Publication WO2005/047813, U.S. Pat. No. 7,382,949, and U.S. Pat. No. 7,355,716, the disclosures of which are incorporated by reference herein in their entireties. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements and methods which, although not explicitly shown or described herein, embody the principles of the invention and are thus within the spirit and scope of the present invention. In addition, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly being incorporated herein in its entirety. All publications referenced herein above are incorporated herein by reference in their entireties.
The present invention relates to U.S. provisional Application No. 60/979,748 filed Oct. 12, 2007, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60979748 | Oct 2007 | US |
