Patent Application
20220082500
The present disclosure relates to a tissue phantom, and in one exemplary embodiment, a breast tissue phantom. The phantom may be used to calibrate an imaging device that is used to identify one or more of residual cancer cells, precancerous cells, and satellite lesions in a surgical site such as a surgical cavity or in a tissue specimen removed from a surgical cavity, such as breast tissue removed during Breast Conserving Surgery (“BCS”). In addition, the disclosed tissue phantoms may be used to train or educate surgeons (or others) to identify one or more of residual cancer cells, precancerous cells, and satellite lesions in a surgical site that become visible in a surgical site or in an excised tissue specimen through use of an imaging device. The device also may be used to identify potential interactions between different types of imaging and/or contrast agents used together during surgery, such as BCS, to make residual cancer cells, precancerous cells, satellite lesions, and/or other malignant cells in surgical cavities, tissue specimens, lymph nodes, or other areas visible to the surgeon.
Surgery is one of the oldest types of cancer therapy and is an effective treatment for many types of cancer. Oncology surgery may take different forms, dependent upon the goals of the surgery. For example, oncology surgery may include biopsies to diagnose or determine a type or stage of cancer, tumor removal to remove some or all of a tumor or cancerous tissue, exploratory surgery to locate or identify a tumor or cancerous tissue, debulking surgery to reduce the size of or remove as much of a tumor as possible without adversely affecting other body structures, and palliative surgery to address conditions caused by a tumor such as pain or pressure on body organs.
In surgeries in which the goal is to remove the tumor(s) or cancerous tissue, surgeons often face uncertainty in determining if all cancer has been removed. The surgical bed, or tissue bed, from which a tumor is removed, may contain residual cancer cells, i.e., cancer cells that remain in the surgical margin of the area from which the tumor is removed. If these residual cancer cells remain in the body, the likelihood of recurrence and metastasis increases. Often, the suspected presence of the residual cancer cells, based on examination of surgical margins of the excised tissue during pathological analysis of the tumor, leads to a secondary surgery to remove additional tissue from the surgical margin.
For example, breast cancer, the most prevalent cancer in women, is commonly treated by breast conservation surgery (BCS), e.g., a lumpectomy, which removes the tumor while leaving as much healthy breast tissue as possible. Treatment efficacy of BCS depends on the complete removal of malignant tissue while leaving enough healthy breast tissue to ensure adequate breast reconstruction, which may be poor if too much breast tissue is removed. Traditionally, tumor margins are visualized under standard white light (WL) in an operating room in order to determine the effectiveness of the BCS procedure.
Imaging devices may also be used to evaluate specimen tissue for the presence of cancer cells. For example, imaging devices may be used to determine the amount of cancer cells, if any, remaining after a BCS procedure, thus determining the efficacy of the procedure. Imaging devices may also be used to provide guidance during the BCS procedure. Calibration of the imaging devices, as well as training and/or education of the persons using the imaging devices to identify residual cancer cells will contribute to the efficacy of removing residual cancer cells during BCS.
The present disclosure may demonstrate one or more of the above-mentioned desirable features. Other features and/or advantages may become apparent from the description that follows.
In accordance with one aspect of the present disclosure, a tissue phantom includes a first portion having the optical properties of healthy tissue and a second portion having the optical properties of cancerous tissue.
In accordance with another aspect of the present disclosure, a method of calibrating an optical instrument. The method including illuminating a tissue phantom with excitation light from the optical instrument, detecting optical emissions emitted by the tissue phantom in response to illumination with the excitation light, and calibrating the optical instrument based upon the detected fluorescence.
The present disclosure can be understood from the following detailed description either alone or together with the accompanying drawings. The drawings are included to provide a further understanding of the disclosed teachings and are incorporated in and constitute a part of this specification. The drawings illustrate one or more example embodiments of the present disclosure and together with the description serve to explain various principles and operations.
Tissue phantoms, as discussed herein, may be used to calibrate an imaging device and/or to provide practice for an operating surgeon. For example, the tissue phantoms may represent and mimic the optical properties of “normal” or “healthy” tissue. Additionally, the tissue phantoms may include one or more portions that represent and mimic the optical properties of diseased or abnormal tissue such as “cancerous” tissue.
In alternative embodiments, the tissue phantom may be configured to include more than one component of a tissue and can be used to calibrate an imaging device or other device configured to distinguish one tissue component from another or locate one tissue component relative to another. In addition to calibration, the phantom can also be used for training purposes. For example, the phantom may be configured to represent human breast tissue and may contain different components/tissue types such as adipose tissue, connective tissue, and vasculature and the phantom can be used to train surgeons to locate the blood or vasculature relative to the adipose or connective tissue with an imaging device.
In another example, the tissue phantom may be used to train new users of a fluorescence imaging device to correctly identify tissues based on their fluorescence (e.g., identifying red tumor against green/pink connective/adipose tissue background). Or to show how certain tissues would fluoresce when imaged with such a device (blood shows up dark red/black for example, which may not be intuitive to new users).
As noted above, in accordance with one aspect of the present disclosure, the tissue phantom is configured to include a “normal” or “healthy” tissue portion and one or more “diseased” or “abnormal” tissue portions. The healthy tissue of the tissue phantom can be any type of tissue and the diseased tissue or “target” tissue of the tissue phantom can be chosen to mimic any disease found in the particular type of healthy tissue modeled by the tissue phantom. The examples provided herein discuss a breast tissue phantom having one or more areas of diseased tissue, i.e., cancerous tissue or tumors. It should be understood that these examples are non-limiting examples only and that the concept of a tissue phantom comprising healthy and diseased tissue is applicable to many other types of human and animal tissues and their diseases. Although discussed herein with regard to breast tissue, it is possible to use the present disclosure as a guide to create a tissue phantom representative of any tissue having a disease based on the optical properties for normal tissue and diseased tissue for the particular tissue and disease of interest. For example, knowing the absorption coefficient and reduced scattering coefficient of the chosen tissue type (for both normal and diseased tissues) at the wavelength that is being used for excitation would permit the creation of a phantom for a particular tissue having a particular disease as described herein. To create such a custom tissue phantom, information regarding how the tissue appears when imaged using a particular excitation light source and optical filter combination would be relied upon. For example, a fluorescence emission spectrum and/or fluorescence images of the tissues would provide the information needed. Examples of diseased tissue that have optical properties that may differ from the optical properties of healthy tissue include inflamed tissue (e.g., rheumatoid arthritis), fibrotic tissue, and ischemic tissue.
For example, in accordance with the present disclosure, tissue phantoms representative of healthy or diseased tissues that may be created in as disclosed herein may include: spinal cord, brain, skin, limbs (sarcoma), oral cavity, prostate, cervix, colon, thyroid, ovaries, lymph nodes, lungs, pancreas, esophagus, muscle, bone, cartilage, uterus, or vagina. This list is intended to provide examples only and is not intended to limit the range of possible phantoms created in accordance with the present disclosure. In exemplary embodiments of a phantom configured to represent healthy tissue and abnormal or diseased tissue such as “cancerous tissue,” the “cancerous tissue” of the phantom contains a material that will cause the “cancerous tissue” of the phantom, when illuminated with excitation light having a known wavelength, to fluoresce or emit light having a wavelength which will allow detection/visualization of the “cancerous tissue” relative to the healthy tissue. For example, in some embodiments, a tissue phantom in accordance with the present disclosure may comprise “healthy tissue” configured to fluoresce green when illuminated with excitation light having a wavelength of between about 400 nm and about 450 nm. In addition, the tissue phantom may comprise “cancerous tissue” configured to fluoresce red when illuminated with the same excitation light having a wavelength of between about 400 nm and about 450 nm. An example of the material included in the “cancerous tissue” of the phantom that fluoresces a red color when illuminated with excitation light having a wavelength between about 400 nm and about 450 nm is the porphyrin PpIX. Alternatively, other fluorophores can be used to represent tissues that are different from healthy tissue, also referred to herein as “target tissue.” For example, indocyanine green (ICG), a green dye such as Pacific Green (https://www.thermofisher.com/ca/en/home/life-science/cell-analysis/fluorophores/pacific-green-dye.html), IRDye 800CW, or other fluorophores of interest may be used. In an example embodiment where blood or vasculature is the “target tissue,” ICG may be used in the portion of the phantom that represents the blood or vasculature.
In the example breast tissue phantoms disclosed herein, PpIX has been selected as the fluorophore of interest. PpIX is a fluorescent molecule that, when excited by the appropriate excitation light, emits a red fluorescence. The PpIX molecule is naturally broken down by healthy tissue (non-cancerous tissue) in a patient to Heme. Thus, healthy tissue does not contain PpIX and therefore does not emit the red fluorescence. However, cancerous tissue is not able to process PpIX and, thus, the PpIX collects in the cancerous tissue. The PpIX collected in cancer cells, when excited by light emitted by an imaging device and having a wavelength of between about 400 nm and about 450 nm, fluoresces red, making the cancerous tissue appear red to the imaging device. This allows a user of the imaging device to determine the presence or absence of cancerous cells based upon the corresponding presence or absence of red fluorescence emitted by the PpIX molecules.
As disclosed herein, a tissue phantom may be used with an imaging device in order to determine the presence, location and/or amount of the “cancerous” tissue with respect to the “normal” tissue within the tissue phantom. Such results may then allow a user to calibrate the imaging device, if the concentration of PpIX within the tissue phantom is known by the user.
Exemplary devices, systems, and methods for detecting cancer cells containing PpIX or other induced porphyrins during surgical intervention are disclosed in U.S. Provisional Patent Application No. 62/625,983, filed Feb. 3, 2018 and entitled “Devices, Systems, and Methods for Tumor Visualization and Removal,” and in PCT/CA2019/000015, filed Feb. 1, 2019, entitled “Devices, Systems, and Methods for Tumor Visualization and Removal” and published as WO2019/148,268 on Aug. 8, 2019, the entire content of each of which is incorporated herein by reference.
During use of the tissue phantom for calibration of an imaging device, the imaging device may be inserted at least partially within a tissue phantom, such as a breast tissue phantom in accordance with the present disclosure and emit a desired wavelength of light to illuminate the tissue phantom. Illumination with the excitation light causes the “cancerous tissue” within the tissue phantom to fluoresce, as described above, thus making the cancerous tissue of the tissue phantom visible to the imaging device and to those observing the output of the imaging device. As discussed above, the “cancerous” tissue within the tissue phantom may fluoresce due to the presence of PpIX (or another fluorescent dye) contained within portions of the phantom.
The “normal” or “healthy” tissue of the tissue phantom does not include PpIX (or another fluorophore) and, therefore, does not fluoresce in the same manner, i.e., does not emit/reflect light at the same wavelength as the “cancerous tissue” when illuminated by the excitation light of the imaging device. However, the “normal” tissue of the tissue phantom is created to mimic normal healthy tissue, which autofluoresces when illuminated with the excitation light. Different healthy tissues emit different wavelengths of light in response to illumination by excitation light. Thus, when illuminating a tissue phantom with excitation light as disclosed herein, the different components of the phantom (healthy tissue, cancerous tissue) will emit different wavelengths of light in response. This allows the light emitted from the cancerous tissue to be distinguished from the light emitted by the healthy tissue of the tissue phantom and, thus, permits the surgeon to identify the presence of cancerous tissue and its location.
For example, for calibration of an imaging device configured to emit excitation light of between about 400 nm-450 nm, the tissue phantom has optical properties that allow the phantom to mimic the emission response of tissue illuminated with excitation light of between about 400 nm-450 nm. The optical properties of the tissue phantom can be narrowly tailored to mimic tissue response (of both healthy tissue and diseased tissue) to excitation by any range of excitation light. For example, the phantom can be formed to have optical properties that allow it to mimic tissue response to illumination by excitation light in the ultraviolet/blue range, near infrared range, and infrared range. For example, the present disclosure contemplates a tissue phantom having optical properties that mimic tissue response to illumination by excitation light in the following exemplary ranges: about 350 nm-about 400 nm, about 400 nm-about 450 nm, about 450 nm-about 500 nm, about 500 nm-about 550 nm, about 550 nm-about 600 nm, about 600 nm-about 650 nm, about 650 nm-about 700 nm, about 700 nm-about 750 nm, about 750 nm-about 800 nm, about 800 nm-about 850 nm, about 850 nm-about 900 nm, about 900 nm-about 950 nm, about 950 nm-about 1000 nm, and/or various combinations therefor. In certain non-limiting, exemplary embodiments disclosed herein, the tissue phantom is configured to respond to illumination with excitation light in the blue/violent range, for example 405 nm, in a manner the same or substantially the same as human or animal tissue.
The tissue phantoms disclosed herein also can be used to help identify an optimum amount of PpIX to be collected in cancerous cells in order for the fluorescence of the cancer cells to be detected by the imaging device and/or the surgeon. Using this information, it is possible to then determine the appropriate amount or dose of porphyrin-inducing composition that should be administered to the patient, for example prior to BCS, as well as the timing of the dosage. For example, as disclosed in U.S. Provisional Patent Application No. 62/625,967, filed Feb. 2, 2018 and entitled “Devices, Systems, and Methods for Tumor Visualization and Removal,” and in U.S. Provisional Patent Application No. 62/625,983, filed Feb. 3, 2018 and entitled “Devices, Systems, and Methods for Tumor Visualization and Removal,” and in PCT/CA2019/000015, filed Feb. 1, 2019, entitled “Devices, Systems, and Methods for Tumor Visualization and Removal” and published as WO2019/148,268 on Aug. 8, 2019, the entire content of each of which is incorporated herein by reference, the surgical subject or patient may be given a diagnostic dose (i.e., not a therapeutic dose) of a compound (imaging/contrast agent) such as the pro-drug aminolevulinic acid (ALA). As understood by those of ordinary skill in the art, dosages of ALA less than 60 mg/kg are generally considered diagnostic while dosages greater than 60 mg/kg are generally considered therapeutic. As disclosed herein, the diagnostic dosage of ALA may be greater than 0 mg/kg and less than 60 kg/mg, between about 10 mg/kg and about 50 mg/kg, between about 20 mg/kg and 40 mg/kg, and may be administered to the subject in a dosage of 5 mg/kg, 10 mg/kg, 15 kg/mg, 20 mg/kg, 25 mg/kg, 30 mg/kg, 35 mg/kg, 40 mg/kg, 45 mg/kg, 50 mg/kg, or 55 mg/kg. The ALA may be administered orally, intravenously, via aerosol, via immersion, via lavage, and/or topically. Although a diagnostic dosage is contemplated for visualization of the residual cancer cells, precancer cells, and satellite lesions, it is within the scope of the present disclosure to use the disclosed devices, systems, and methods to provide guidance during treatment and/or removal of these cells and/or lesions.
The ALA given to the patient induces porphyrin formation (protoporphyrin IX (PpIX)) in tumor/cancer cells present in the patient (
In exemplary embodiments, the non-activated, non-targeted compound configured to induce porphyrin in tumor/cancer cells, precancer cells, and/or satellite lesions is administered to a subject between about 15 minutes and about 6 hours before surgery, about 1 hour and about 5 hours before surgery, between about 2 hours and about 4 hours before surgery, or between about 2.5 hours and about 3.5 hours before surgery. These exemplary time frames allow sufficient time for the ALA to be converted to porphyrins in tumor/cancer cells, precancer cells, and/or satellite lesions. The ALA or other suitable compound may be administered orally, intravenously, via aerosol, via immersion, via lavage, and/or topically. Use of the tissue phantoms disclosed in the present application can determine at what concentration PpIX must be present in the phantom and, thus, the cancer cells of the subject administered the ALA, in order for the fluorescence of the cancer cells to be detected by the imaging device and/or the surgeon. Using this information, it is possible to then determine the appropriate amount of porphyrin-inducing composition that should be administered to the patient as well as the timing of the dosage, as discussed above.
The tissue phantoms disclosed herein are configured to have the same optical properties as human tissue that contains the target tissue or disease, such as cancer. Thus, for example, in the case of breast cancer, the tissue phantom may include a first portion that has the same optical properties as healthy skin/normal tissue, such as breast tissue. The tissue phantom also includes one or more second portions having the same optical properties as the diseased tissue, such as cancerous breast tissue. Thus, the breast tissue phantom “mimics” or is an on-the-bench representation of a human breast with breast cancer.
The first portion of the tissue phantom may comprise any material that is sufficient to mimic the optical properties of “normal” or “healthy” tissue, i.e., tissue that is not cancerous, to provide the tissue phantom with optical characteristics substantially the same as the optical characteristics of normal tissue. In some embodiments, the first portion of the tissue phantom may be made from a mixture of tris buffer and gelatin. The tris buffer aids to maintain the pH and stability of the tissue phantom, and the gelatin aids to provide a consistency that mimics an actual human or animal tissue. More specifically, the gelatin mixture allows the tissue phantom to cure into a long-lasting, reproducible shape that mimics the connective tissue found in human breast tissue. In other embodiments, the first portion of the tissue phantom may be formed of silicone, agar, or organic tissues from animals including chicken, pork, or beef.
Additionally, the first portion of the tissue phantom may include other components such as, for example, elements representative of hemoglobin and intralipid molecules. As discussed further below, the concentrations of the hemoglobin and intralipid molecules may be manipulated to adjust the optical properties of the tissue phantom such as scattering and absorption coefficients, isotropy, and/or turbidity. Sodium azide may also be added to the tissue phantom to provide an antibacterial agent that inhibits the growth of bacteria on the tissue phantom, thus increasing its longevity. Furthermore, the antibacterial agent may also help ensure that any visible fluorescence is not due to the presence of bacteria on or in the tissue phantom. The first portion of the tissue phantom may be made of one or more materials. In one example embodiment, the first portion of the tissue phantom may be homogenous throughout such that the tissue phantom comprises no more than a 2% variation in a full spectrum reflectance measurement throughout the phantom.
In some embodiments, the optical properties of the first portion of the tissue phantom may be selected by varying hemoglobin and/or intralipid concentrations. Hemoglobin concentrations may be varied to adjust the rate of absorption of incoming photons from, for example, an excitation light source of an imaging device. Intralipid concentrations may be varied to adjust for scattering of incoming excitation and/or other light from the imaging device. Hemoglobin and/or intralipid concentrations may be adjusted so that the material(s) of the tissue phantom substantially match the absorption and emission coefficients of “normal” tissue, such as normal breast tissue.
In some embodiments, the concentration of hemoglobin may range from approximately 0-50 μm. When using the high end of this range, the tissue phantom may produce a visibly stronger red fluorescence, which may be used to mimic the optical properties of tissue when the hemoglobin absorbs less light. When using the low end of this range, the tissue phantom may produce a visibly weaker red fluorescence, which may be used to mimic the optical properties of tissue when the hemoglobin absorbs more light. In some embodiments, the concentration of intralipids may range from approximately 0-20%.
In one example embodiment, the tissue phantom includes a hemoglobin concentration of 2.40 μM and an intralipid concentration of 1.20% for use with an imaging device that emits excitation light at a wavelength of 405 nm. This concentration of hemoglobin is below the normal concentration of hemoglobin in breast tissue, which typically ranges from 15-40 μM. The concentration of hemoglobin may be below the normal concentration because less hemoglobin is required in a tissue phantom (as compared with a patient's breast tissue) to match the desired absorption coefficient at 405 nm.
An example method for preparing tissue phantom material (healthy tissue material) is provided below:
Tissue Phantom Material
In accordance with the present teachings, the second portion(s) of the tissue phantom may include material configured to represent diseased tissue. In various exemplary embodiments, the tissue phantom includes material configured to represent diseased tissue, e.g., cancer in breast tissue. The material configured to represent diseased tissue may be incorporated into the tissue phantom in various ways, positioned within the healthy tissue portion of the phantom or separated from the healthy tissue portion of the phantom. For example, in one embodiment, the material configured to represent the diseased tissue may be disposed sporadically throughout the tissue phantom. In other embodiments, the material configured to represent the diseased tissue may be disposed in one distinct location within the tissue phantom in order to represent, for example, a tumor. Each location of the diseased tissue within the tissue phantom may include portions with varying concentrations of diseased tissue. In some embodiments, the tissue phantom may be composed of 3D printed cells, for example cells or tissue that are printed into desired shapes with densities and optical properties that substantially match those of human tissue. In one example, the tissue phantom is a 3D printed ear.
In accordance with the present disclosure, a tissue phantom includes a healthy tissue portion and a diseased tissue portion. In one example embodiment shown in
First member 12 and second member 17 may be attached together at middle portion 15. In some embodiments, first member 12 and second member 17 are two distinct components. In other embodiments, first member 12 and second member 17 form one unitary component. First member 12 and second member 17 of phantom 10 may each comprise any material that is sufficient to mimic optical properties of “normal” or “healthy” tissue, i.e., tissue that is not cancerous, to provide the phantom with optical characteristics substantially the same as the optical characteristics of normal tissue. Thus, first member 12 and second member 17 may separately or together form a portion of the phantom 10 that has the optical properties of healthy tissue. In some embodiments, first member 12 and/or second member 17 may be formed of a mixture of tris buffer and gelatin. First member 12 and second member 17 may be formed of the same or different materials. In one example embodiment, the material(s) of first member 12 and second member 17 may be homogenous throughout such that the healthy tissue portion of the tissue phantom 10 comprises no more than a 2% variation in a full spectrum reflectance measurement throughout the phantom.
In accordance with the present disclosure, the tissue phantom 10 includes a diseased tissue or cancerous tissue portion. In the example embodiment of
The tray may take on various shapes and configurations. An example configuration of tray 20 is illustrated in
Tray 20, including recesses 25, may be formed of a polymeric material, for example, polylactic acid (PLA). In some embodiments, tray 20 is coated, printed, and/or manufactured with a black paint, which acts an optical barrier between recesses 25 and second member 17 of tissue phantom 10. Thus, wavelengths emitted from an imaging device do not penetrate through recesses 25 and onto second member 17. These embodiments may allow for a more accurate determination of the optical properties detected in each recess 25, which may be used for calibration of an imaging device.
For calibration purposes, the size and location of recesses 25 may be dependent on their distance from the imaging device. In the example shown, each recess may have a diameter of 3.55 mm when the imaging device is intended to be disposed 2 cm from tray 20 during testing/calibration. See, for example,
One or more materials may be disposed within each recess 25. The materials include a first composition configured to have the optical properties of diseased tissue. In addition, a second material configured to cause the diseased tissue material to fluoresce in response to illumination with excitation light is included. These materials may be in solid or liquid form, or a combination thereof. In accordance with one example embodiment, the first composition may include any material that is capable of mimicking the optical properties of “cancerous” tissue to provide one or more portions of the phantom with optical characteristics substantially the same as the optical characteristics of cancerous tissue. The first composition may include, for example, agar, phosphate buffered saline (PBS), water, agarose, dimethyl sulfoxide (DMSO) and/or blood tissue. These components may be used to hold the second material in suspension in the solution.
The second material may include PpIX and/or another fluorescent dye. Each recess 25 may include a solution with a different concentration of PpIX and/or fluorescent dye, such that the concentration of PpIX or fluorophore in each recess differs from that of an adjacent recess 25. For example, a first recess may be a control that does not contain any PpIX or dye. A second recess may contain a small concentration of PpIX (and/or another fluorescent dye), a third recess may contain a relatively greater concentration of PpIX (and/or another fluorescent dye), a fourth recess may contain an even greater concentration of PpIX (and/or another fluorescent dye), etc. In one example, tray 10 has ten recesses 25 such that each recess has one of the following concentrations of PpIX: 0.001 μM, 0.005 μM, 0.01 μM, 0.05 μM, 0.1 μM, 0.5 μM, 1 μM, 5 μM, 10 μM, and 20 μM.
The solutions disposed within each recess 25 may mimic the optical properties of “cancerous tissue.” Thus, tray 20 may form a portion of tissue phantom 10 that has the optical properties of cancerous tissue.
The distal end of second member 17, where tray 20 is disposed, may include an opening 30 through which an optical power meter may be inserted into the tissue phantom. Opening 30, without an optical power meter, can be seen in
An opening 37 may also be created in the end of first member 12 to allow access to the interior of the tissue phantom and the cavity 35 defined therein, to permit an imaging device a field of view of the diseased portion of the tissue phantom represented by the contents of the recesses in tray 20. An imaging device may be inserted at least partially through opening 37. Thus, opening 37 may be of sufficient size to receive at least a portion of an imaging device configured to be placed within a body lumen or cavity or surgical cavity. The imaging device may pass through opening 37 to access cavity 35 in any manner that maintains the integrity of tissue phantom 10 while providing the ability for the imaging device to illuminate the diseased tissue material in recesses 25 with excitation light and to receive emissions responsive to illumination by the excitation light from the diseased tissue material in recesses 25.
Once assembled, tissue phantom 10 includes first and second members 12, 17 attached together with tray 20 disposed within cavity 35 and positioned on second member 17. Additionally, a variety of solutions are disposed within each recess 25 of tray 20, such that each recess 25 has a different concentration of, for example, PpIX. An optical power meter may then be inserted at least partially through cavity 30, and an imaging device may be inserted at least partially through cavity 35. The imaging device, once inserted within tissue phantom 10, will then emit an excitation light onto and/or within tissue phantom 10. As discussed above, any recess 25 that contains PpIX (or another fluorescent dye) will be illuminated by the excitation light and emissions, in response to the excitation light, from the material in the recesses will be received and captured by the imaging device. Such may allow a user to determine which concentrations of PpIX are detectable by the imaging device. The diseased tissue material in the recesses 25 may be excited individually or in a group. To allow the material in each recess 25 to be illuminated with excitation light individually, a dial or cover 42 may be placed over the recesses 25 such that only a single recess is visible at a time. An example dial 42 is shown in
The imaging device may emit white light (WL), fluorescence (FL), infrared (IR), or a mixture thereof. In some embodiments, the imaging device may emit excitation light at a wavelength from 350 nm to 450 nm and/or from 550 nm to 600 nm, and more specifically the imaging device may emit excitation light at a wavelength of 405 nm and/or 572 nm.
When illuminated with a wavelength of, for example, 405 nm, first member 12 and second member 17 will fluoresce in the same manner as healthy breast tissue, which autofluoresces under 405 nm excitation light and appears green in fluorescent images. Thus, the parts of the phantom 10 made to mimic healthy breast tissue will, for example, fluoresce green when illuminated with 405 nm excitation light. However, when the solutions within each recess 25 that contain PpIX are illuminated with a wavelength of, for example, 405 nm, the solutions will fluoresce in the same manner as cancerous breast tissue. Thus, the parts of the phantom 10 made to mimic cancerous tissue will, for example, fluoresce red when illuminated with 405 nm excitation light. This allows the cancerous tissue of the phantom to be distinguished from the healthy tissue of the phantom when both tissues are illuminated with the same excitation light, thus allowing a user to determine portions in tissue phantom that include the cancerous tissue.
Different concentrations of PpIX in each solution, will emit different wavelength intensities of light from tissue phantom 10. This allows the light emitted from each unique solution to be distinguished from the light emitted from a subsequent solution (with a different amount of PpIX). Additionally, this allows the light emitted from first and second end portions 12, 17 (the healthy tissue) to be distinguished from the light emitted from recesses 25 (the cancerous tissue). Therefore, a user can identify the presence of cancerous tissue and its location within tissue phantom 10.
Because the different concentrations of PpIX in each recess 25 emit different intensities of light from tissue phantom 10, a user may use tissue phantom 10 to calibrate an optical instrument. More specifically, an optical instrument may be used to illuminate tissue phantom 10 with excitation light, for example excitation light having a wavelength of 405 nm. As discussed above, a first solution disposed in a first recess 25 may have a first concentration of PpIX, and a second solution disposed in a second recess 25 may have a second concentration of PpIX. The first solution may emit a different intensity of light from the second solution when illuminated with the excitation light. A user may then calibrate the optical instrument by comparing the different concentrations of PpIX in the first and second solutions with the light emitted therefrom. Additionally or alternatively, a user may compare the amount of fluorescence from the first and second solutions with the concentrations of PpIX in order to calibrate the optical instrument.
The imaging device may also include a camera in order to capture the illuminated solution in recesses 25. Such results may then be displayed to a user.
In other embodiments of a tissue phantom, it may be desirable to remove the optical barrier provided by the tray 20, in order to visualize the “diseased tissue” or fluorophore representing the diseased tissue against the background of the “healthy tissue” forming the phantom 10. This may be accomplished in various ways such as, for example, placing the “diseased tissue” or fluorophore directly on the phantom material mimicking the healthy tissue, placing the “diseased tissue” or fluorophore on an optically clear surface (such as a microscope well slide) and then placing the clear surface on the phantom's “healthy tissue,” or by creating wells in the phantom's “healthy tissue” and placing the “diseased tissue” or fluorophore in the wells.
In one example embodiment, shown in
In another example embodiment, shown in
In the example embodiment shown in
In some embodiments, as shown in
In one example, the phantom may be formed as a full breast with a solid PpIX tumor inclusion. In this embodiment, a surgeon can palpate to locate the tumor as they would normally do prior to a surgery. The surgeon would then create an incision/surgical cavity accordingly. The surgeon would image the resected mass and the cavity to ensure clear margins.
In another example, the phantom may be formed as a full breast with a pre-made cavity containing a lumpectomy sample. Such an embodiment of the breast phantom would have a pre-made cavity and corresponding lumpectomy sample, both with positive margins (i.e., both including diseased or “cancerous” tissue that a surgeon could image). The cavity size and shape would be designed to allow the surgeon to manipulate an imaging device in accordance with the present disclosure in a variety of ways. This would allow surgeons to practice imaging at the bottom and sides of a surgical cavity, as well as under (premade) skin flaps.
As discussed above, the target tissue may be made identifiable by use a fluorophore. Although the example embodiments describe the use of PpIX, other fluorophores may be used. For example, a phantom in accordance with
In one example embodiment, a tissue phantom may include a first healthy tissue portion 305 and one or more target tissue portions 310, 315, 320. In the example shown in
In accordance with another aspect of the present disclosure, tissue phantoms may incorporate diseased cells in the “diseased” portion of the phantom. For example, in one example embodiment of a breast tissue phantom, the portion of the phantom configured to mimic cancerous tissue comprises carcinoma cells. In preparing this phantom, carcinoma cells were treated with 5-ALA, resuspended in tissue phantom material and injected under the surface of a normal or healthy tissue phantom to create a “tumor.” The tumor was resected from the breast tissue phantom, creating an excised tissue specimen or phantom lumpectomy. The phantom lumpectomy and the surgical cavity were examined using widefield fluorescence imaging. Residual carcinoma cells producing PpIX were visualized in the surgical cavity and at the margins of the excised lumpectomy. The image of FIG. 10 illustrates an example embodiment of a breast tissue phantom 400 comprising carcinoma cells in the diseased tissue portion 420 of the phantom. The PpIX-containing carcinoma cells and phantom material may be injected into the healthy phantom tissue 405 to form discrete diseased portions or tumors 420 in phantom 400.
An example process of making the carcinoma tumors for inclusion in the healthy tissue of the tissue phantom is described below and shown in the flowchart of
In accordance with another aspect of the present disclosure tissue phantoms may be used to determine a depth of healthy tissue through which diseased tissue can be detected, for example by an imaging device as described herein. A depth tissue phantom 500 is illustrated in
As an alternative to pouring phantom material over the chip, one or more thin film phantoms may be used. The phantom material can be used to create thin films with thickness around 100 μm or less, by dehydrating the liquid phantom material. This material can be used to mimic thin films of tissue to measure the depth below the tissue surface at which a fluorophore can still be detected using, for example, a depth phantom. See, for example,
In accordance with another aspect of the present disclosure, a tissue phantom may be used to identify potential interactions between different types of imaging and/or contrast agents used together during surgery, such as BCS, to make residual cancer cells, precancerous cells, satellite lesions, and/or other malignant cells in surgical cavities, tissue specimens, lymph nodes, or other areas visible to the surgeon.
During breast cancer surgery, surgeons may perform a biopsy on the sentinel lymph node(s) 600 surrounding the tumor. By using methods such as blue dye localization or radioactive tracers, surgeons can locate the sentinel lymph nodes to dissect them and determine if the cancer has metastasized from the original tumor. In breast cancer surgery, typically, the blue dye is subcutaneously injected in the tumor, the surrounding tissue (peri-tumor), or near the nipple, so that it may diffuse through the lymphatic vessels and reach the nearby sentinel lymph nodes, where it accumulates to turn blue. This allows surgeons to visualize the sentinel lymph nodes using conventional white lighting and the unaided eye. An example of this is shown in the image of
MB is typically administered in 3-5 mL volumes at a 1% concentration. It is suspected that MB has a strong ability to absorb light in the 550-700 nm wavelength spectrum. Under 405 nm excitation, protoporphyrin IX's (PpIX's) peak emission occurs at ˜635 nm, as shown in
Tissue phantoms in accordance with the present disclosure can be used to obtain a better understanding of this phenomenon to better appreciate its potential effect (if any) on the fluorescence detection of (tumor) PpIX fluorescence when MB (or similar blue dye) is used intraoperatively for SLN detection during breast cancer surgery.
The phantom material “recipe” can be modified to incorporate dyes, fluorophores, or other materials directly into the phantom material. In one example embodiment, a plurality of tissue phantoms were created, the phantoms having increasing concentrations of Methylene Blue (MB) in the phantom tissue material. A plurality of wells or recesses were then created in each tissue phantom. The wells in the phantoms were also created with punch biopsy tools although other methods can be used. In these wells, a mixture of PpIX, methylene blue, and phantom material was pipetted to form solid phantoms.
To create the MB tissue phantom, MB and PpIX were diluted in phantom material (PM), which was prepared as described below. When mixing PM with PpIX, for longevity and reproducibility, a proportion of PM>75% allows the mixture to solidify and minimizes the liquid content being absorbed by surrounding PM. A combination of PpIX diluted with PM to 5 μM PpIX and 90% PM proportion produces bright red FL when imaged.
As previously described with respect to other embodiments of a tissue phantom, the phantom material comprises two mixtures: a tris buffer and gelatin mixture. In preparing MB tissue phantoms, the formulation was adjusted to include methylene blue by combining cooled base phantom mixture with concentrated stocks of 100, 50, 10, 5, 1, and 0 μM methylene blue, to dilute by a factor of 10, which achieved a final concentration of 10, 5, 1, 0.5, 0.1, and 0 μM methylene blue phantom mixture. These mixtures were used to create 25 mL phantom samples with a gradient of methylene blue concentrations. Three different MB phantom models were created.
The first MB tissue phantom is designed to simulate the clinical scenario where, at the surgical margin, there is residual tumor (containing PpIX) that also contains MB within the tumor, and/or is surrounded by normal tissue containing MB. This first MB tissue phantom was used to measure which MB concentrations (in the tissue and within the tumor) are able to decrease the FL signal from a single concentration of PpIX. The phantoms 700 were designed as pucks, each with ten wells 725 cut with a punch biopsy tool. This was repeated for 3 punch biopsy sizes: 2 mm, 4 mm and 8 mm (The 8 mm phantoms had to be split into two “pucks” due to the relative size of the wells and the pucks,
Each phantom was imaged under FL imaging using an imaging device as described herein to determine the imaging effect of each concentration of MB on PpIX fluorescence.
A second MB tissue phantom 800 was created to measure how the FL from various concentrations of PpIX is affected by a given concentration of MB. Examples of these tissue phantoms 800 are shown in
A third MB tissue phantom 900 was made to test the effect of a thin layer of MB-containing tissue phantom covering normal tissue and tumor that do not contain MB. The third MB tissue phantom comprises a first part 905—a tissue phantom that does not contain MB and a second part comprising a thin film MB tissue phantom 930 similar to the thin film tissue phantoms described above. Each first part tissue phantom 905 has ten wells 925 cut, all identically filled with 5 μM PpIX and 89% PM (see
The MB tissue phantoms discussed herein were used to test the effect of blue dyes on PpIX, with the concentrations of the blue dye and PpIX both varied using different phantom models to isolate the impact of each concentration of blue dye on each concentration of PpIX. Such an experiment can also be conducted using phantoms that replace with PpIX with some other FL contrast agent such as ICG, IRDye800, or fluorescein. The blue dye can be replaced with another (clinically relevant) dye (such as for example Patent Blue V, Indigo Carmine, Isosulfan Blue, and specimen inking dyes such as, for example, India ink or other proprietary formulations of specimen inking dyes) to understand the interaction of the standard of care dye/material on the desired fluorescence signal.
It will be appreciated by those ordinarily skilled in the art having the benefit of this disclosure that the present disclosure provides various exemplary devices, systems, and methods for tumor visualization. Further modifications and alternative embodiments of various aspects of the present disclosure will be apparent to those skilled in the art in view of this description.
Furthermore, the devices and methods may include additional components or steps that were omitted from the drawings for clarity of illustration and/or operation. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the present disclosure. It is to be understood that the various embodiments shown and described herein are to be taken as exemplary. Elements and materials, and arrangements of those elements and materials, may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the present disclosure may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of the description herein. Changes may be made in the elements described herein without departing from the spirit and scope of the present disclosure and following claims, including their equivalents.
It is to be understood that the particular examples and embodiments set forth herein are non-limiting, and modifications to structure, dimensions, materials, and methodologies may be made without departing from the scope of the present disclosure.
Furthermore, this description's terminology is not intended to limit the present disclosure. For example, spatially relative terms—such as “beneath,” “below,” “lower,” “above,” “upper,” “bottom,” “right,” “left,” “proximal,” “distal,” “front,” and the like—may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., locations) and orientations (i.e., rotational placements) of a device in use or operation in addition to the position and orientation shown in the drawings.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about” if they are not already. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding technique.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
It should be understood that while the present disclosure has been described in detail with respect to various exemplary embodiments thereof, it should not be considered limited to such, as numerous modifications are possible without departing from the broad scope of the appended claims, including the equivalents they encompass.
This application claims priority to U.S. Provisional Application No. 62/793,839 (filed Jan. 17, 2019), titled “TISSUE PHANTOMS,” the entire contents of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/050379 | 1/17/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62793839 | Jan 2019 | US |
