Parallel factor analysis of ovarian autofluorescence as a cancer diagnostic

Multimodal Optical Imaging of Ex Vivo Fallopian Tubes to Distinguish Early and Occult Tubo-Ovarian Cancers

Background: There are currently no effective screening measures to detect early or occult tubo-ovarian cancers, resulting in late-stage detection and high mortality. This work explores whether an optical imaging catheter can detect early-stage tubo-ovarian cancers or precursor lesions where they originate in the fallopian tubes. Methods: This device collects co-registered optical coherence tomography (OCT) and autofluorescence imaging (AFI). OCT provides three-dimensional assessment of underlying tissue structures; autofluorescence imaging provides functional contrast of endogenous fluorophores. Ex vivo fallopian tubes (n = 28; n = 7 cancer patients) are imaged; we present methods for the calculation of and analyze eleven imaging biomarkers related to fluorescence, optical attenuation, and OCT texture for their potential to detect tubo-ovarian cancers and other lesions of interest. Results: We visualize folded plicae, vessel-like structures, tissue layering, hemosiderin deposits, and regions of fibrotic change. High-grade serous ovarian carcinoma appears as reduced autofluorescence paired with homogenous OCT and reduced mean optical attenuation. Specimens containing cancerous lesions demonstrate a significant increase in median autofluorescence intensity and decrease in Shannon entropy compared to specimens with no lesion. Non-cancerous specimens demonstrate an increase in optical attenuation in the fimbriae when compared to the isthmus or the ampulla. Conclusions: We conclude that this approach shows promise and merits further investigation of its diagnostic potential.

Sub-millimeter endoscope demonstrates feasibility of in vivo reflectance imaging, fluorescence imaging, and cell collection in the fallopian tubes

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.

Ultraminiature optical design for multispectral fluorescence imaging endoscopes

A miniature wide-field multispectral endoscopic imaging system was developed enabling reflectance and fluorescence imaging over a broad wavelength range. At 0.8-mm diameter, the endoscope can be utilized for natural orifice imaging in small lumens such as the fallopian tubes. Five lasers from 250 to 642 nm are coupled into a 125 - ? m diameter multimode fiber and transmitted to the endoscope distal tip for illumination. Ultraviolet and blue wavelengths excite endogenous fluorophores, which can provide differential fluorescence emission images for health and disease. Visible wavelengths provide reflectance images that can be combined for pseudo-white-light imaging and navigation. Imaging is performed by a 300 - ? m diameter three-element lens system connected to a 3000-element fiber. The lens system was designed for a 70-deg full field of view, working distance from 3 mm to infinity, and 40% contrast at the Nyquist cutoff of the fiber bundle. Measured performance characteristics are near design goals. The endoscope was utilized to obtain example monochromatic, pseudo-white-light, and composite fluorescence images of phantoms and porcine reproductive tract. This work shows the feasibility of packaging a highly capable multispectral fluorescence imaging system into a miniature endoscopic system that may have applications in early detection of cancer.

Novel population of small tumour-initiating stem cells in the ovaries of women with borderline ovarian cancer

Small stem cells with diameters of up to 5 μm previously isolated from adult human ovaries indicated pluripotency and germinal lineage, especially primordial germ cells, and developed into primitive oocyte-like cells in vitro. Here, we show that a comparable population of small stem cells can be found in the ovarian tissue of women with borderline ovarian cancer, which, in contrast to small stem cells in "healthy" ovaries, formed spontaneous tumour-like structures and expressed some markers related to pluripotency and germinal lineage. The gene expression profile of these small putative cancer stem cells differed from similar cells sorted from "healthy" ovaries by 132 upregulated and 97 downregulated genes, including some important forkhead box and homeobox genes related to transcription regulation, developmental processes, embryogenesis, and ovarian cancer. These putative cancer stem cells are suggested to be a novel population of ovarian tumour-initiating cells in humans.

Multispectral fluorescence imaging of human ovarian and fallopian tube tissue for early-stage cancer detection

With early detection, 5-year survival rates for ovarian cancer exceed 90%, yet no effective early screening method exists. Emerging consensus suggests over 50% of the most lethal form of the disease originates in the fallopian tube. Twenty-eight women undergoing oophorectomy or debulking surgery provided informed consent for the use of surgical discard tissue samples for multispectral fluorescence imaging. Using multiple ultraviolet and visible excitation wavelengths and emissions bands, 12 fluorescence and 6 reflectance images of 47 ovarian and 31 fallopian tube tissue samples were recorded. After imaging, each sample was fixed, sectioned, and stained for pathological evaluation. Univariate logistic regression showed cancerous tissue samples had significantly lower intensity than noncancerous tissue for 17 image types. The predictive power of multiple image types was evaluated using multivariate logistic regression (MLR) and quadratic discriminant analysis (QDA). Two MLR models each using two image types had receiver operating characteristic curves with area under the curve exceeding 0.9. QDA determined 56 image type combinations with perfect resubstituting using as few as five image types. Adaption of the system for future in vivo fallopian tube and ovary endoscopic imaging is possible, which may enable sensitive detection of ovarian cancer with no exogenous contrast agents.

Time-serial Assessment of Drug Combination Interventions in a Mouse Model of Colorectal Carcinogenesis Using Optical Coherence Tomography

Optical coherence tomography (OCT) is a high-resolution, nondestructive imaging modality that enables time-serial assessment of adenoma development in the mouse model of colorectal cancer. In this study, OCT was utilized to evaluate the effectiveness of interventions with the experimental antitumor agent α-difluoromethylornithine (DFMO) and a nonsteroidal anti-inflammatory drug sulindac during early [chemoprevention (CP)] and late stages [chemotherapy (CT)] of colon tumorigenesis. Biological endpoints for drug interventions included OCT-generated tumor number and tumor burden. Immunochistochemistry was used to evaluate biochemical endpoints [Ki-67, cleaved caspase-3, cyclooxygenase (COX)-2, β-catenin]. K-Ras codon 12 mutations were studied with polymerase chain reaction-based technique. We demonstrated that OCT imaging significantly correlated with histological analysis of both tumor number and tumor burden for all experimental groups (P < 0.0001), but allows more accurate and full characterization of tumor number and burden growth rate because of its time-serial, nondestructive nature. DFMO alone or in combination with sulindac suppressed both the tumor number and tumor burden growth rate in the CP setting because of DFMO-mediated decrease in cell proliferation (Ki-67, P < 0.001) and K-RAS mutations frequency (P = 0.04). In the CT setting, sulindac alone and DFMO/sulindac combination were effective in reducing tumor number, but not tumor burden growth rate. A decrease in COX-2 staining in DFMO/sulindac CT groups (COX-2, P < 0.01) confirmed the treatment effect. Use of nondestructive OCT enabled repeated, quantitative evaluation of tumor number and burden, allowing changes in these parameters to be measured during CP and as a result of CT. In conclusion, OCT is a robust minimally invasive method for monitoring colorectal cancer disease and effectiveness of therapies in mouse models.

In vivo time-serial multi-modality optical imaging in a mouse model of ovarian tumorigenesis

Identification of the early microscopic changes associated with ovarian cancer may lead to development of a diagnostic test for high-risk women. In this study we use optical coherence tomography (OCT) and multiphoton microscopy (MPM) (collecting both two photon excited fluorescence [TPEF] and second harmonic generation [SHG]) to image mouse ovaries in vivo at multiple time points. We demonstrate the feasibility of imaging mouse ovaries in vivo during a long-term survival study and identify microscopic changes associated with early tumor development. These changes include alterations in tissue microstructure, as seen by OCT, alterations in cellular fluorescence and morphology, as seen by TPEF, and remodeling of collagen structure, as seen by SHG. These results suggest that a combined OCT-MPM system may be useful for early detection of ovarian cancer.

Enhanced visibility of colonic neoplasms using formulaic ratio imaging of native fluorescence

BACKGROUND AND OBJECTIVES

Colonoscopy is the preferred method for colon cancer screening, but can miss polyps and flat neoplasms with low color contrast. The objective was to develop a new autofluorescence method that improves image contrast of colonic neoplasms.

STUDY DESIGN/MATERIALS AND METHODS

We selected the three strongest native fluorescence signals and developed a novel method where fluorescence images are processed in a ratiometric formula to represent the likely cellular and structural changes associated with neoplasia. Native fluorescence images of fresh surgical specimens of the colon containing normal mucosa, polypoid and flat adenomas as well as adenocarcinoma were recorded using a prototype multi-spectral imager. Sixteen patients, with a mean age of 62 years (range 28-81) undergoing elective resection for colonic neoplasms were enrolled. High contrast images were seen with fluorescence from tryptophan (Tryp), flavin adenine dinucleotide (FAD) and collagen.

RESULTS

When the image intensity of Tryp was divided pixel by pixel, by the intensities of FAD and collagen, the resulting formulaic ratio (FR) images were of exceptionally high contrast. The FR images of adenomas and adenocarcinomas had increased Weber contrast.

CONCLUSIONS

FR imaging is a novel imaging process that represents the likely metabolic and structural changes in colonic neoplasia that produces images with remarkably high contrast.

Two-photon excited fluorescence imaging of endogenous contrast in a mouse model of ovarian cancer

BACKGROUND AND OBJECTIVE

Ovarian cancer has an extremely high mortality rate resulting from poor understanding of the disease. In order to aid understanding of disease etiology and progression, we identify the endogenous fluorophores present in a mouse model of ovarian cancer and describe changes in fluorophore abundance and distribution with age and disease.

STUDY DESIGN/MATERIALS AND METHODS

A mouse model of ovarian cancer was created by dosing with 4-vinylcyclohexene diepoxide, which induces follicular apoptosis (simulating menopause), and 7,12-dimethylbenz[a]anthracene, a known carcinogen. Imaging of ovarian tissue was completed ex vivo with a multiphoton microscope using excitation wavelength of 780 nm and emission collection from 405 to 505 nm. Two-photon excited fluorescence images and corresponding histologic sections with selective stains were used to identify endogenous fluorophores.

RESULTS

The majority of collected fluorescence emission was attributed to NADH and lipofuscin, with additional contributions from collagen and elastin. Dim cellular fluorescence from NADH did not show observable changes with age. Changes in ovarian morphology with disease development frequently caused increased fluorescence contributions from collagen and adipose tissue-associated NADH. Lipofuscin fluorescence was much brighter than NADH fluorescence and increased as a function of both age and disease.

CONCLUSIONS

Our finding of NADH fluorescence patterns similar to that seen previously in human ovary, combined with the observation of lipofuscin accumulation with age and disease also seen in human organs, suggests that the findings from this model may be relevant to human ovarian disease. Increased lipofuscin fluorescence might be used as an indicator of disease in the ovary and this finding warrants further study.

Wide-field spectral imaging of human ovary autofluorescence and oncologic diagnosis via previously collected probe data

With no sufficient screening test for ovarian cancer, a method to evaluate the ovarian disease state quickly and nondestructively is needed. The authors have applied a wide-field spectral imager to freshly resected ovaries of 30 human patients in a study believed to be the first of its magnitude. Endogenous fluorescence was excited with 365-nm light and imaged in eight emission bands collectively covering the 400- to 640-nm range. Linear discriminant analysis was used to classify all image pixels and generate diagnostic maps of the ovaries. Training the classifier with previously collected single-point autofluorescence measurements of a spectroscopic probe enabled this novel classification. The process by which probe-collected spectra were transformed for comparison with imager spectra is described. Sensitivity of 100% and specificity of 51% were obtained in classifying normal and cancerous ovaries using autofluorescence data alone. Specificity increased to 69% when autofluorescence data were divided by green reflectance data to correct for spatial variation in tissue absorption properties. Benign neoplasm ovaries were also found to classify as nonmalignant using the same algorithm. Although applied ex vivo, the method described here appears useful for quick assessment of cancer presence in the human ovary.