Ovarian cancer is the deadliest gynecological cancer, with most cases of high-grade serous ovarian carcinoma originating as serous tubal intraepithelial carcinoma (STIC) lesions in the fallopian tube epithelium. The Cell-Acquiring Fallopian Endoscope (CAFE) was designed to optically detect these STIC lesions and collect cells from the suspicious site for further analysis. While approximately 0.93 mm in diameter, the CAFE is able to perform multispectral fluorescence imaging (MFI), white light imaging for navigation, and cell collection. Each of these modalities is useful to locating potentially pathological areas. To find these regions, the CAFE looks for alterations of the autofluorescence of the tissue. Upon identification of a potential STIC lesion, a scrape biopsy collects cells from the region of interest. The prototype CAFE achieved an imaging resolution of 88 μm at a 5 mm distance, and 45° full field of view in air. When tested on ex vivo porcine tissue, hemocytometry counts determined that on the order of 105 cells per scrape biopsy could be collected. Current progress on the CAFE includes cell collection testing on ex vivo porcine and human tissue, and improvements in the imaging resolution.
Early detection of cancer is crucial for improving patient survival. High resolution optical imaging is ideal to image cellular abnormalities indicative of early cancer. For tissues located deep within the body, such as the pancreato-biliary ducts, high resolution imaging must be implemented endoscopically due to the limited penetration depth of light. We are developing a minimally invasive high numerical aperture (HNA) microendoscope system capable of simultaneous co-registered multiphoton imaging (two-photon excited fluorescence, second harmonic generation, three-photon excited fluorescence, and third harmonic generation) of small diameter ductal tissues, such as the pancreato-biliary ducts. Imaging of the epithelial layer is achieved via helical scanning of the 1.5 mm diameter endoscope with a fixed focus. The endoscope distal end optics act as both the illumination and collection mechanism, with the core of the dual clad fiber (DCF) carrying femtosecond laser excitation light, and the inner cladding of the DCF carrying multiphoton emission. Designing HNA optics at the 1 mm diameter size scale is challenging, time consuming, and may be expensive. To complete development of the proximal components of the system, we designed a low numerical aperture (LNA) reflectance & single photon fluorescence system using low cost off the shelf optical components to aid in the development of software and the testing of proximal system hardware components. Additionally, rapid, low-cost design and fabrication of HNA optics with 3D printing is presented.
Significance: Most cases of high-grade serous ovarian carcinoma originate as serous tubal intraepithelial carcinoma (STIC) lesions in the fallopian tube epithelium (FTE), enabling early endoscopic detection.
Aim: The cell-acquiring fallopian endoscope (CAFE) was built to meet requirements for locating potentially pathological tissue indicated by an alteration in autofluorescence or presence of a targeted fluorophore. A channel was included for directed scrape biopsy of cells from regions of interest.
Approach: Imaging resolution and fluorescence sensitivity were measured using a standard resolution target and fluorescence standards, respectively. A prototype was tested in ex vivo tissue, and collected cells were counted and processed.
Results: Measured imaging resolution was 88 μm at a 5-mm distance, and full field of view was ∼45 deg in air. Reflectance and fluorescence images in ex vivo porcine reproductive tracts were captured, and fit through human tracts was verified. Hemocytometry counts showed that on the order of 105 cells per scrape biopsy could be collected from ex vivo porcine tissue.
Conclusions: All requirements for viewing STIC in the FTE were met, and collected cell counts exceeded input requirements for relevant analyses. Our benchtop findings suggest the potential utility of the CAFE device for in vivo imaging and cell collection in future clinical trials.
Multimodal imaging is an advantageous method to increase the accuracy of disease classification. As an example, we and others have shown that optical coherence tomography images and fluorescence spectroscopy contain complementary information that can increase the sensitivity and specificity for cancer detection. A common challenge in multimodal imaging is image co-registration. The different images are often taken with separate imaging setups, making it challenging to precisely image the same tissue area or co-register the images computationally. To solve this problem, we have developed a co-registered multimodal imaging system that images the same tissue location with reflectance, multi-photon, and optical coherence microscopy. The co-registration mechanism is a dual-clad fiber that integrates with a scanning microscope or scanning endoscope, collecting all three signals using the same optical path. In the current implementation, optical coherence tomography utilizes a 1300 nm super luminescent diode, multi-photon signals are excited by a custom femtosecond 1400 nm fiber laser producing two- and three-photon signals in the 460-900 nm band, and reflectance imaging operates at 561 nm. The system separates the different signals using fiber wavelength division multiplexers, a dual-clad fiber coupler, and dichroic mirrors to deliver the different signals to the corresponding detector. This wavelength selection enables the system to work passively, meaning that there is no need for devices such as filter wheels. Using the scanning microscope configuration, we have obtained multimodal images of ex-vivo ovine ovary tissue.
Recent discoveries suggest that ovarian cancer has its origins in the oviducts (Fallopian tubes) and may exist as intraepithelial carcinoma for up to 6 years. One route of access to the oviducts and ovaries is through the wall of the vagina. We have developed an approximately 3.8 mm diameter rigid salpingoscope for surveillance of high-risk women and early detection of ovarian cancer. The salpingoscope contains multiple advanced imaging modalities, as well as a channel for instillation of saline or dyes, and another channel for introduction of biopsy forceps. The single optical channel combines the modalities of multispectral fluorescence and reflectance wide-field imaging, multiphoton microscopy (MPM), and optical coherence tomography (OCT). Multiple modalities through a single channel are achieved by a novel lens system with dichroic coatings which create separate optical paths for visible wavelengths (low numerical aperture (NA) imaging) and near-infrared wavelengths (high NA imaging). A quartered piezoelectric tube actuator scans a dual-clad fiber with added mass to facilitate both relatively slow (OCT) and fast (wide field and MPM) scanning. Visible wavelength laser diodes are the source for wide field reflectance and fluorescence imaging, with remitted light collected through 12 high NA multimode fibers. A novel femtosecond laser with near-infrared output provides the source for OCT and MPM, with remitted light collected through the core and inner cladding of the dual-clad fiber, respectively. Detectors include high sensitivity photodiodes for wide field, a linear array with spectrometer for OCT, and photomultiplier tubes to collect twoand three-photon signals for MPM imaging.
A multimodality endoscope system has been designed for early detection of ovarian cancer. Multiple illumination and detection systems must be integrated in a compact, stable, transportable configuration to meet the requirements of a clinical setting. The proximal configuration presented here supports visible light navigation with a large field of view and low resolution, high resolution multiphoton microscopy (MPM), and high resolution optical coherence microscopy (OCM). All modalities are integrated into a single optical system in the endoscope. The system requires two light sources: a green laser for visible light navigation and a compact fiber based femtosecond laser for MPM and OCM. Using an inline wavelength division multiplexer, the two sources are combined into a single mode fiber. To accomplish OCM, a fiber coupler is used to separate the femtosecond laser into a reference arm and signal arm. The reflected reference arm and the signal from the sample are interfered and wavelength separated by a reflection grating and detected using a linear array. The MPM signal is collimated and goes through a series of filters to separate the 2nd and 3rd harmonics as well as twophoton excitation florescence (2PEF) and 3PEF. Each signal is independently detected on a photo multiplier tube and amplified. The visible light is collected by multiple high numerical aperture fibers at the endoscope tip which are bundled into one SMA adapter at the proximal end and connected to a photodetector. This integrated system design is compact, efficient and meets both optical and mechanical requirements for clinical applications.
While Optical Coherence Microscopy (OCM), Multiphoton Microscopy (MPM), and narrowband imaging are powerful imaging techniques that can be used to detect cancer, each imaging technique has limitations when used by itself. Combining them into an endoscope to work in synergy can help achieve high sensitivity and specificity for diagnosis at the point of care. Such complex endoscopes have an elevated risk of failure, and performing proper modelling ensures functionality and minimizes risk. We present full 2D and 3D models of a multimodality optical micro-endoscope to provide real-time detection of carcinomas, called a salpingoscope. The models evaluate the endoscope illumination and light collection capabilities of various modalities. The design features two optical paths with different numerical apertures (NA) through a single lens system with a scanning optical fiber. The dual path is achieved using dichroic coatings embedded in a triplet. A high NA optical path is designed to perform OCM and MPM while a low NA optical path is designed for the visible spectrum to navigate the endoscope to areas of interest and narrowband imaging. Different tests such as the reflectance profile of homogeneous epithelial tissue were performed to adjust the models properly. Light collection models for the different modalities were created and tested for efficiency. While it is challenging to evaluate the efficiency of multimodality endoscopes, the models ensure that the system is design for the expected light collection levels to provide detectable signal to work for the intended imaging.
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