Autofluorescence patterns in short-term cultures of normal cervical tissue

Combination of fluorescence visualization and iodine solution-guided surgery for local control of early tongue cancer

The control of enclosed oral epithelial dysplasia is important for the control of oral cancer. Fluorescence visualization and iodine solution are able to detect oral epithelial dysplasia and surrounding oral cancer. The purpose of this study was to clarify the effectiveness of combining fluorescence visualization and iodine solution-guided surgery for early tongue cancer. Participants comprised 264 patients with primary early tongue cancer who underwent surgery. The surgical margin was set at 10 mm outside the clinical tumour, and 5 mm outside the area of fluorescence visualization loss, and 5mm outside the iodine unstained area. The 5-year disease-free survival rate was 87.1% vs 76.1% (P = 0.016) and the 5-year local control rate was 98.6% vs 93.0% (P = 0.008) for combination-guided surgery when compared to conventional surgery. Positive margin rates were 0% for cancer, and 6.5% and 0% for low- and high-grade dysplasia, respectively, with combination-guided surgery (P = 0.257). Multivariate analysis revealed that combination-guided surgery (odds ratio 0.140, 95% confidence interval 0.045-0.437; P < 0.001) and intraoperative frozen section examination (odds ratio 0.302; 95% confidence interval 0.115-0.791; P = 0.015) were significantly associated with local control. The combination of fluorescence visualization and iodine solution are effective in selecting surgical margins for early tongue cancer.

Quantitative Immunofluorescent Imaging of Immune Cells in Mucosal Tissues

Understanding the interplay between commensals, pathogens, and immune cells in the skin and mucosal tissues is critical to improve prevention and treatment of a myriad of diseases. While high-parameter flow cytometry is the current gold standard for immune cell characterization in blood, it is less suitable for mucosal tissues, where structural and spatial information is lost during tissue disaggregation. Immunofluorescence overcomes this limitation, serving as an excellent alternative for studying immune cells in mucosal tissues. However, the use of immunofluorescent microscopy for analyzing clinical samples is hampered by a lack of high-throughput quantitative analysis techniques. In this chapter, we describe methods for sectioning, staining, and imaging whole sections of human foreskin tissue. We also describe methods to automate immune cell quantification from immunofluorescent images, including image preprocessing and methods to quantify both circular and irregularly shaped immune cells using open-source software.

Non-Invasive Early Detection of Oral Cancers Using Fluorescence Visualization with Optical Instruments

Simple Summary

Oral cancer has a high mortality rate. Then, oral cancer screening is needed for early detection and treatment. Fluorescence visualization is non-invasive, convenient, and in real-time, and examinations can be repeated. Our study aimed to show the usefulness of oral cancer screening with fluorescence visualization. A total of 502 patients were performed using fluorescence visualization that was analyzed using subjective and objective evaluation. Results of this study, subjective evaluation for detection oral cancer was high sensitivity and low specificity, while objective evaluation using imaging processing analysis was high sensitivity and high specificity. Therefore, oral cancer screening using fluorescence visualization is useful for the detection of oral cancer. The widespread use of this screening can reduce the mortality rate of oral cancer.

Abstract

Background: Oral cancer screening is important for early detection and early treatment, which help improve survival rates. Biopsy is the gold standard for a definitive diagnosis but is invasive and painful, while fluorescence visualization is non-invasive, convenient, and real-time, and examinations can be repeated using optical instruments. The purpose of this study was to clarify the usefulness of fluorescence visualization in oral cancer screening. Methods: A total of 502 patients, who were examined using fluorescence visualization with optical instruments in our hospitals between 2014 and 2019, were enrolled in this study. The final diagnosis was performed by pathological examination. Fluorescence visualization was analyzed using subjective and objective evaluations. Results: Subjective evaluations for detecting oral cancer offered 96.8% sensitivity and 48.4% specificity. Regarding the objective evaluations, sensitivity and specificity were 43.7% and 84.6% for mean green value, 55.2% and 67.0% for median green value, 82.0% and 44.2% for coefficient of variation of value, 59.6% and 45.3% for skewness, and 85.1% and 75.8% for value ratio. For the sub-analysis of oral cancer, all factors on objective and subjective evaluation showed no significant difference. Conclusions: Fluorescence visualization with subjective and objective evaluation is useful for oral cancer screening.

Discriminating different grades of cervical intraepithelial neoplasia based on label-free phasor fluorescence lifetime imaging microscopy

This study proposed label-free fluorescence lifetime imaging and phasor analysis methods to discriminate different grades of cervical intraepithelial neoplasia (CIN). The human cervical tissue lesions associated with cellular metabolic abnormalities were detected by the status changes of important coenzymes in cells and tissues, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD). Fluorescence lifetime imaging microscopy (FLIM) was used to study human cervical tissues, human cervical epithelial cells, and standard samples. Phasor analysis was applied to reveal the interrelation between the metabolic changes and cancer development, which can distinguish among different stages of cervical lesions from low risk to high risk. This approach also possessed high sensitivity, especially for healthy sites of CIN3 tissues, and indicated the dominance of the glycolytic pathway over oxidative phosphorylation in high-grade cervical lesions. This highly adaptive, sensitive, and rapid diagnostic tool exhibits a great potential for cervical precancer diagnosis.

Sperm Gatekeeping: 3D Imaging Reveals a Constricted Entrance to Zebra Finch Sperm Storage Tubules

Females across many internally fertilizing taxa store sperm, often in specialized storage organs in their reproductive tracts. In birds, several hundred sperm storage tubules exist in the utero-vaginal junction of the oviduct, and there is growing evidence that sperm storage in these tubules is selective. The mechanisms underlying female sperm storage in birds remain unknown because of our limited ability to make three-dimensional, live observations inside the large, muscular avian oviduct. Here, we describe a new application of fluorescence selective plane illumination microscopy to optically section oviduct tissue from zebra finch Taeniopygia guttata females label free by harnessing tissue autofluorescence. Our data provide the first description of the three-dimensional structure of sperm storage organs in any vertebrate to the best of our knowledge and reveal the presence of gate-like constricted openings that may play a role in sperm selection.

Label-free imaging and spectroscopy for early detection of cervical cancer

The label-free imaging and spectroscopy method was studied on cervical unstained tissue sections obtained from 36 patients. The native fluorescence spectra of tissues are analyzed by the optical redox ratio (ORR), which is defined as fluorescence intensity ratio between NADH and FAD, and indicates the metabolism change with the cancer development. The ORRs of normal tissues are consistently higher than those of precancer or cancerous tissues. A criterion line of ORR at 5.0 can be used to discriminate cervical precancer/cancer from normal tissues. The sensitivity and specificity of the native fluorescence spectroscopy method for cervical cancer diagnosis are determined as 100% and 91%. Moreover, the native fluorescence spectroscopy study is much more sensitive on the healthy region of cervical precancer/cancer patients compared with the traditional clinical staining method. The results suggest label-free imaging and spectroscopy is a fast, highly sensitive and specific method on the detection of cervical cancer.

Optical redox imaging indices discriminate human breast cancer from normal tissues

Our long-term goal was to investigate the potential of incorporating redox imaging technique as a breast cancer (BC) diagnosis component to increase the positive predictive value of suspicious imaging finding and to reduce unnecessary biopsies and overdiagnosis. We previously found that precancer and cancer tissues in animal models displayed abnormal mitochondrial redox state. We also revealed abnormal mitochondrial redox state in cancerous specimens from three BC patients. Here, we extend our study to include biopsies of 16 patients. Tissue aliquots were collected from both apparently normal and cancerous tissues from the affected cancer-bearing breasts shortly after surgical resection. All specimens were snap-frozen and scanned with the Chance redox scanner, i.e., the three-dimensional cryogenic NADH/Fp (reduced nicotinamide adenine dinucleotide/oxidized flavoproteins) fluorescence imager. We found both Fp and NADH in the cancerous tissues roughly tripled that in the normal tissues ( p < 0.05 ). The redox ratio Fp/(NADH + Fp) was ? 27 % higher in the cancerous tissues ( p < 0.05 ). Additionally, Fp, or NADH, or the redox ratio alone could predict cancer with reasonable sensitivity and specificity. Our findings suggest that the optical redox imaging technique can provide parameters independent of clinical factors for discriminating cancer from noncancer breast tissues in human patients.

Modifications of Cellular Autofluorescence Emission Spectra under Oxidative Stress Induced by 1 α,25dihydroxyvitamin D3 and its Analog EB1089

We attempted to characterize the cellular autofluorescence phenomenon of living HL-60 cells and to appraise its modifications under oxidative stress conditions induced by 1α,25(OH)2D3 (VD3) and its analog EB1089. Autofluorescence emission spectra of human promyelocytic HL-60 leukemic cells were monitored using laser scanning confocal microspectrofluorometry under UV excitation. Evaluation of reactive oxygen species (ROS) release was performed using the 2′,7′-dichlorodihydrofluorescein diacetate (H2-DCFDA) staining and fluorescence emission measurement. VD3 (1, 10, 100 nM) or EB1089 (0.1, 1 and 10 nM) induces a decrease in autofluorescence emission intensity that can be attributed to the oxidation of the coenzyme nicotinamide adenine dinucleotide (phosphate) NAD(P)H into NAD(P)+. A dose-dependent increase (p<0.05) in ROS release is observed in VD3- and EB1089-treated cells. As compared with VD3- or EB1089-treated cells, doxorubicin-VD3 or doxorubicin-EB1089 treatments strongly decrease the autofluorescence intensity and induce a higher release of ROS (p<0.05). The association of antioxidants (N-acetyl cysteine, superoxide dismutase, catalase) with VD3 or EB1089 induce a more limited autofluorescence decrease and a weaker ROS generation, as compared with VD3 and EB1089 treated cells. In conclusion, the free radicals release, generated by VD3 and EB1089, was associated with the decrease in autofluorescence emission and can be modulated by doxorubicin and antioxidants.

5-aminolevulinic-acid-based fluorescence spectroscopy and conventional colposcopy for in vivo detection of cervical pre-malignancy

Background

Sensitized fluorescence diagnostics are based on selective accumulation of photosensitizer in the tissue where carcinogenesis has started. The present study compared topical 5-aminolevulinic acid (5-ALA)-based fluorescence spectroscopy (FS) in vivo with conventional colposcopy for cervical intraepithelial neoplasia (CIN) detection.

Methods

We enrolled 48 patients who were referred for colposcopy because of high-grade changes in cervical cytology. Every inspected cervix was divided in to quadrants, and there were 174 quadrants included in the study. Each patient had a cytological smear, colposcopy, FS and histopathological analysis. For FS, 3% 5-ALA cream was used topically and after an average 135 min incubation, fluorescence spectra were recorded from the cervix in vivo. FS and colposcopy results were correlated with histopathology.

Results

All spectra were evaluated by a ratio of the protoporphyrin IX fluorescence intensity at 634 nm and autofluorescence intensity at 510 nm. For proper grouping of low-risk and high-risk cases, a threshold of 3.87 was calculated. Data per quadrant showed that FS had higher sensitivity than colposcopy (71.7% vs 67.4%) but specificity was greater for colposcopy (86.6% vs 75.6%). Combination of the methods showed higher sensitivity (88.0% vs 67.4%) but reduced specificity (88.0% and 69.5%), but it had the highest number of correctly identified high-risk changes and the highest (79.3%) accuracy. Data for each patient showed FS sensitivity of 91.2%, which was greater than for colposcopy (88.2%). Higher overdiagnosis resulted in decreased specificity for fluorescence methodology—71.4% versus 78.6% for colposcopy. In both cases, accuracy was 85.4% and effectiveness was >80%, which means that both methods can be used to determine high-risk cervical intraepithelial neoplasia. The diagnostic sensitivity of 97.1% for this complementary diagnosis indicates that it could be the best choice for detection of high-risk changes.

Conclusions

5-ALA-based FS is an objective method, requiring short-term administration for appropriate fluorescence measurements. FS is a promising diagnostic tool with similar accuracy as colposcopy but with the potential advantage of providing objective results.

Novel advancements in colposcopy: historical perspectives and a systematic review of future developments

OBJECTIVE

To describe novel innovations and techniques for the detection of high-grade dysplasia.

MATERIALS AND METHODS

Studies were identified through the PubMed database, spanning the last 10 years. The key words (["computerized colposcopy" or "digital colposcopy" or "spectroscopy" or "multispectral digital colposcopy" or "dynamic spectral imaging", or "electrical impedance spectroscopy" or "confocal endomicroscopy" or "confocal microscopy"or "optical coherence tomography"] and ["cervical dysplasia" or cervical precancer" or "cervix" or "cervical"]) were used. The inclusion criteria were published articles of original research referring to noncolposcopic evaluation of the cervix for the detection of cervical dysplasia. Only English-language articles from the past 10 years were included, in which the technologies were used in vivo, and sensitivities and specificities could be calculated.

RESULTS

The single author reviewed the articles for inclusion. Primary search of the database yielded 59 articles, and secondary cross-reference yielded 12 articles. Thirty-two articles met the inclusion criteria.

CONCLUSIONS

An instrument that globally assesses the cervix, such as computer-assisted colposcopy, optical spectroscopy, and dynamic spectral imaging, would provided the most comprehensive estimate of disease and is therefore best suited when treatment is preferred. Electrical impedance spectroscopy, confocal microscopy, and optical coherence tomography provide information at the cellular level to estimate histology and are therefore best suited when deferment of treatment is preferred. If a device is to eventually replace the colposcope, it will likely combine technologies to best meet the needs of the target population, and as such, no single instrument may prove to be universally appropriate. Analyses of false-positive rates, additional colposcopies and biopsies, cost, and absolute life-savings will be important when considering these technologies and are limited thus far.

Early detection of high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopic imaging

Quantitative spectroscopy has recently been extended from a contact-probe to wide-area spectroscopic imaging to enable mapping of optical properties across a wide area of tissue. We train quantitative spectroscopic imaging (QSI) to identify cervical high-grade squamous intraepithelial lesions (HSILs) in 34 subjects undergoing the loop electrosurgical excision procedure (LEEP subjects). QSI's performance is then prospectively evaluated on the clinically suspicious biopsy sites from 47 subjects undergoing colposcopic-directed biopsy. The results show the per-subject normalized reduced scattering coefficient at 700 nm (An) and the total hemoglobin concentration are significantly different (p<0.05) between HSIL and non-HSIL sites in LEEP subjects. An alone retrospectively distinguishes HSIL from non-HSIL with 89% sensitivity and 83% specificity. It alone applied prospectively on the biopsy sites distinguishes HSIL from non-HSIL with 81% sensitivity and 78% specificity. The findings of this study agree with those of an earlier contact-probe study, validating the robustness of QSI, and specifically An, for identifying HSIL. The performance of An suggests an easy to use and an inexpensive to manufacture monochromatic instrument is capable of early cervical cancer detection, which could be used as a screening and diagnostic tool for detecting cervical cancer in low resource countries.

Ex vivo optical metabolic measurements from cultured tissue reflect in vivo tissue status

Optical measurements of metabolism are ideally acquired in vivo; however, intravital measurements are often impractical. Accurate ex vivo assessments would greatly broaden the applicability of optical measurements of metabolism. We investigate the use of live tissue culture experiments to serve as a surrogate for in vivo metabolic measurements. To validate this approach, NADH and FAD fluorescence intensity and lifetime images were acquired with a two-photon microscope from hamster cheek pouch epithelia in vivo, from biopsies maintained in live tissue culture up to 48 h, and from flash-frozen and thawed biopsies. We found that the optical redox ratio (fluorescence intensity of NADH/FAD) of the cultured biopsy was statistically identical to the in vivo measurement until 24 h, while the redox ratio of the frozen-thawed samples decreased by 15% (p<0.01). The NADH mean fluorescence lifetime (τm) remained unchanged (p>0.05) during the first 8 h of tissue culture, while the NADH τm of frozen-thawed samples increased by 13% (p<0.001). Cellular morphology did not significantly change between in vivo, cultured, and frozen-thawed tissues (p>0.05). All results were consistent across multiple depth layers in this stratified squamous epithelial tissue. Histological markers for proliferation and apoptosis also confirm the viability of tissues maintained in culture. This study suggests that short-term ex vivo tissue culture may be more appropriate than frozen-thawed tissue for optical metabolic and morphologic measurements that approximate in vivo status.

Fluorescence spectroscopy: a new approach in cervical cancer

OBJECTIVE

To study the diagnostic potential of fluorescence spectroscopy and its comparison with different screening methods, including Pap smear and colposcopy, in detecting early cervical neoplasia.

METHOD

The study was conducted on patients with gynecological complaints. A full gynecological workup of the patients was done along with Pap smear and colposcopy. Cervical biopsy was done in suspected cases and fresh tissue was sent to IIT for spectroscopy.

RESULT

There is a definite increase in NADH fluorescence (67.4 %) and a decrease in collagen fluorescence (74 %) in dysplastic tissues. When epithelial fluorescence and stromal fluorescence are considered together, diagnostic accuracy is increased to 96.5 %.

CONCLUSION

The clinical diagnosis of cervical neoplasia by spectroscopic methods is potentially a reliable, fast, and cost-effective alternative to the conventional smear test which needs trained personnel for its interpretation. Research is still continuing to obtain a statistically significant cutoff value from in vitro studies and then use them for in vivo study.

Accuracy of optical spectroscopy for the detection of cervical intraepithelial neoplasia without colposcopic tissue information; a step toward automation for low resource settings

Optical spectroscopy has been proposed as an accurate and low-cost alternative for detection of cervical intraepithelial neoplasia. We previously published an algorithm using optical spectroscopy as an adjunct to colposcopy and found good accuracy (sensitivity=1.00 [95% confidence interval (CI)=0.92 to 1.00], specificity=0.71 [95% CI=0.62 to 0.79]). Those results used measurements taken by expert colposcopists as well as the colposcopy diagnosis. In this study, we trained and tested an algorithm for the detection of cervical intraepithelial neoplasia (i.e., identifying those patients who had histology reading CIN 2 or worse) that did not include the colposcopic diagnosis. Furthermore, we explored the interaction between spectroscopy and colposcopy, examining the importance of probe placement expertise. The colposcopic diagnosis-independent spectroscopy algorithm had a sensitivity of 0.98 (95% CI=0.89 to 1.00) and a specificity of 0.62 (95% CI=0.52 to 0.71). The difference in the partial area under the ROC curves between spectroscopy with and without the colposcopic diagnosis was statistically significant at the patient level (p=0.05) but not the site level (p=0.13). The results suggest that the device has high accuracy over a wide range of provider accuracy and hence could plausibly be implemented by providers with limited training.

Detecting high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopy and per-patient normalization

This study develops a spectroscopic algorithm for detection of cervical high grade squamous intraepithelial lesions (HSILs). We collected reflectance and fluorescence spectra with the quantitative spectroscopy probe to measure nine spectroscopic parameters from 43 patients undergoing standard colposcopy with directed biopsy. We found that there is improved accuracy for distinguishing HSIL from non-HSIL (low grade SIL and normal tissue) when we "normalized" spectroscopy parameters by dividing the values extracted from each clinically determined suspicious site by the corresponding value extracted from a clinically normal squamous site from the same patient. The "normalized" scattering parameter (A) at 700nm, best distinguished HSIL from non-HSIL with sensitivity and specificity of 89% and 79% suggesting that a simple, monochromatic instrument measuring only A may accurately detect HSIL.

Optical technologies and molecular imaging for cervical neoplasia: a program project update

There is an urgent global need for effective and affordable approaches to cervical cancer screening and diagnosis. In developing nations, cervical malignancies remain the leading cause of cancer-related deaths in women. This reality may be difficult to accept given that these deaths are largely preventable; where cervical screening programs have been implemented, cervical cancer-related deaths have decreased dramatically. In developed countries, the challenges of cervical disease stem from high costs and overtreatment. The National Cancer Institute-funded Program Project is evaluating the applicability of optical technologies in cervical cancer. The mandate of the project is to create tools for disease detection and diagnosis that are inexpensive, require minimal expertise, are more accurate than existing modalities, and can be feasibly implemented in a variety of clinical settings. This article presents the status and long-term goals of the project.

On-the-fly detection of changes on and below the surface in epithelium mucosal tissue architecture from scattered light

In this paper we present a technique to raise a flag on the fly when a transition occurs between different mucosal architectures on or below the surface. The segmentation is based on a novel difference metric for detecting an abrupt change in the parameters extracted from a Stochastic Decomposition Method (SDM) that models the scattered light reflected from the mucosal tissue structure over an area (2-D scan) illuminated by an optical sensor (fiber) emitting light at either one wavelength or with white light. This work has the potential to enhance the endoscopist's ability to locate and identify abnormal mucosal architectures in particular when the disease is developing below the surface and hence becoming hidden during colonoscopy or endoscopic examination. It also has also potential in helping deciding as to when and where to take biopsies; steps that should lead to improvement in the diagnostic yield.

Accuracy of optical spectroscopy for the detection of cervical intraepithelial neoplasia: Testing a device as an adjunct to colposcopy

Testing emerging technologies involves the evaluation of biologic plausibility, technical efficacy, clinical effectiveness, patient satisfaction, and cost-effectiveness. The objective of this study was to select an effective classification algorithm for optical spectroscopy as an adjunct to colposcopy and obtain preliminary estimates of its accuracy for the detection of CIN 2 or worse. We recruited 1,000 patients from screening and prevention clinics and 850 patients from colposcopy clinics at two comprehensive cancer centers and a community hospital. Optical spectroscopy was performed, and 4,864 biopsies were obtained from the sites measured, including abnormal and normal colposcopic areas. The gold standard was the histologic report of biopsies, read 2 to 3 times by histopathologists blinded to the cytologic, histopathologic, and spectroscopic results. We calculated sensitivities, specificities, receiver operating characteristic (ROC) curves, and areas under the ROC curves. We identified a cutpoint for an algorithm based on optical spectroscopy that yielded an estimated sensitivity of 1.00 [95% confidence interval (CI) = 0.92-1.00] and an estimated specificity of 0.71 [95% CI = 0.62-0.79] in a combined screening and diagnostic population. The positive and negative predictive values were 0.58 and 1.00, respectively. The area under the ROC curve was 0.85 (95% CI = 0.81-0.89). The per-patient and per-site performance were similar in the diagnostic and poorer in the screening settings. Like colposcopy, the device performs best in a diagnostic population. Alternative statistical approaches demonstrate that the analysis is robust and that spectroscopy works as well as or slightly better than colposcopy for the detection of CIN 2 to cancer.

Can we see epithelium tissue structure below the surface using an optical probe?

This paper answers the question of whether it is possible to detect changes below the surface in epithelium layered structures using a Stochastic Decomposition Method (SDM) that models the scattered light reflected from the layered structure over an area (2-D scan) illuminated by an optical sensor (fibre) emitting light at either one wavelength or with white light. Our technique correlates the differential changes in the reflected tissue texture with the morphological and physical changes that occur in the tissue occurring inside the structure. This work has great potential for detecting changes in mucosal structures and may lead to enhanced endoscopy when the disease is developing to the outside of the mucosal structure and hence becoming hidden during colonoscopy or endoscopic examination. Tests are performed on layered tissue phantoms, and the results obtained show great effectiveness of the model and method in picking up changes in the morphology of the layered tissue phantoms occurring below the surface. We also establish the robustness of the model to changes in viewing depth by testing it on phantoms viewed at different depths. We show that the model is robust to within a 4-mm-deep viewing range.

Repeatability of tissue fluorescence measurements for the detection of cervical intraepithelial neoplasia

We examined intensity and shape differences in 378 repeated spectroscopic measures of the cervix. We examined causes of variability such as presence of precancer or cancer, pathologic tissue type, menopausal status, hormone or oral contraceptive use, and age; as well as technology related variables like generation of device and provider making exam. Age, device generation, and provider were statistically significantly related to intensity differences. Provider and device generation were related to shape differences. We examined the order of measurements and found a decreased intensity in the second measurement due to hemoglobin absorption. 96% of repeat measurements had classification concordance of cervical intraepithelial neoplasia.

Enhancement factor in low-coherence enhanced backscattering and its applications for characterizing experimental skin carcinogenesis

We experimentally study potential mechanisms by which the enhancement factor in low-coherence enhanced backscattering (LEBS) can probe subtle variations in radial intensity distribution in weakly scattering media. We use enhanced backscattering of light by implementing either (1) low spatial coherence illumination or (2) multiple spatially independent detections using a microlens array under spatially coherent illumination. We show that the enhancement factor in these configurations is a measure of the integrated intensity within the localized coherence or detection area, which can exhibit strong dependence on small perturbations in scattering properties. To further evaluate the utility of the LEBS enhancement factor, we use a well-established animal model of cutaneous two-stage chemical carcinogenesis. In this pilot study, we demonstrate that the LEBS enhancement factor can be substantially altered at a stage of preneoplasia. Our animal result supports the idea that early carcinogenesis can cause subtle alterations in the scattering properties that can be captured by the LEBS enhancement factor. Thus, the LEBS enhancement factor has the potential as an easily measurable biomarker in skin carcinogenesis.

Effect of anatomy on spectroscopic detection of cervical dysplasia

It has long been speculated that underlying variations in tissue anatomy affect in vivo spectroscopic measurements. We investigate the effects of cervical anatomy on reflectance and fluorescence spectroscopy to guide the development of a diagnostic algorithm for identifying high-grade squamous intraepithelial lesions (HSILs) free of the confounding effects of anatomy. We use spectroscopy in both contact probe and imaging modes to study patients undergoing either colposcopy or treatment for HSIL. Physical models of light propagation in tissue are used to extract parameters related to tissue morphology and biochemistry. Our results show that the transformation zone, the area in which the vast majority of HSILs are found, is spectroscopically distinct from the adjacent squamous mucosa, and that these anatomical differences can directly influence spectroscopic diagnostic parameters. Specifically, we demonstrate that performance of diagnostic algorithms for identifying HSILs is artificially enhanced when clinically normal squamous sites are included in the statistical analysis of the spectroscopic data. We conclude that underlying differences in tissue anatomy can have a confounding effect on diagnostic spectroscopic parameters and that the common practice of including clinically normal squamous sites in cervical spectroscopy results in artificially improved performance in distinguishing HSILs from clinically suspicious non-HSILs.

In vivo imaging of in situ motility of fresh and liquid stored ram spermatozoa in the ewe genital tract

The fertility of ram semen after cervical insemination is substantially reduced by 24 h of storage in liquid form. The effects of liquid storage on the transit of ram spermatozoa in the ewe genital tract was investigated using a new procedure allowing direct observation of the spermatozoa in the genital tract. Ejaculated ram spermatozoa were double labeled with R18 and MitoTracker Green FM, and used to inseminate ewes in estrus either cervically through the vagina or laparoscopically into the base of the uterine horns. Four hours after insemination, the spermatozoa were directly observedin situusing fibered confocal fluorescence microscopy in the base, middle and tip of the uterine horns, the utero-tubal junction (UTJ) and the oviduct. The high resolution video images obtained with this technique allowed determination of the distribution of spermatozoa and individual motility in the lumen of the ewe's genital tract. The results showed a gradient of increasing concentration of spermatozoa from the base of the uterus to the UTJ 4 h after intra-uterine insemination into the base of the horns. The UTJ was shown to be a storage region for spermatozoa before their transfer to the oviduct. Thein vitrostorage of spermatozoa in liquid form decreased their migration through the cervix and reduced the proportion of motile spermatozoa and their straight line velocity at the UTJ and their transit into the oviduct.

Optical imaging for cervical cancer detection: solutions for a continuing global problem

Cervical cancer is the leading cause of cancer death for women in developing countries. Optical technologies can improve the accuracy and availability of cervical cancer screening. For example, battery-powered digital cameras can obtain multi-spectral images of the entire cervix, highlighting suspicious areas, and high-resolution optical technologies can further interrogate such areas, providing in vivo diagnosis with high sensitivity and specificity. In addition, targeted contrast agents can highlight changes in biomarkers of cervical neoplasia. Such advances should provide a much needed global approach to cervical cancer prevention.

The clinical effectiveness of optical spectroscopy for the in vivo diagnosis of cervical intraepithelial neoplasia: where are we?

OBJECTIVE

In this review, we evaluate the diagnostic efficacy of optical spectroscopy technologies (fluorescence and reflectance spectroscopy) for the in vivo diagnosis of cervical neoplasia using both point probe and multispectral imaging approaches.

METHODS

We searched electronic databases using the following terms: cervical cancer, cervical intraepithelial neoplasia, squamous intraepithelial lesion, and spectroscopy, fluorescence spectroscopy, or reflectance spectroscopy. We included studies that evaluated fluorescence and reflectance spectroscopy devices for in vivo diagnosis, compared those results with biopsy results, and reported on the sensitivity and specificity of the devices tested.

RESULTS

Twenty-six studies, including seven phase II trials and one randomized clinical trial, met our acceptability criteria. We found several important differences across the studies including device approach (multispectral versus point probe), study population, disease classification system, and disease threshold. This heterogeneity prevented formal combination of sensitivity and specificity results.

CONCLUSION

Optical spectroscopy has similar performance to colposcopy and may help localize lesions and therefore be an effective adjunct to colposcopy. Reports on the diagnostic accuracy of these devices should use common thresholds for the construction of receiver operating characteristic curves to enable comparisons with standard technologies and facilitate their adoption. Optical spectroscopy has also been identified for possible use as ASCUS triage and primary screening, yet neither has been sufficiently evaluated to warrant a conclusion as to their suitability in this role.

Characterization of Raman spectra measured in vivo for the detection of cervical dysplasia

Raman spectroscopy has been shown to have the potential for providing differential diagnosis in the cervix with high sensitivity and specificity in previous studies. The research presented here further evaluates the potential of near-infrared Raman spectroscopy to detect cervical dysplasia in a clinical setting. Using a portable system, Raman spectra were collected from the cervix of 79 patients using clinically feasible integration times (5 seconds on most patients). Multiple Raman measurements were taken from colposcopically normal and abnormal areas prior to the excision of tissue. Data were processed to extract Raman spectra from measured signal, which includes fluorescence and noise. The resulting spectra were correlated with the corresponding histopathologic diagnosis to determine empirical differences between different diagnostic categories. Using histology as the gold standard, logistic regression discrimination algorithms were developed to distinguish between normal ectocervix, squamous metaplasia, and high-grade dysplasia using independent training and validation sets of data. An unbiased estimate of the accuracy of the model indicates that Raman spectroscopy can distinguish between high-grade dysplasia and benign tissue with sensitivity of 89% and specificity of 81%, while colposcopy in expert hands was able to discriminate with a sensitivity and specificity of 87% and 72%.

Targeting spectral signatures of progressively dysplastic stratified epithelia using angularly variable fiber geometry in reflectance Monte Carlo simulations

A key component of accurate spectroscopic-based cancer diagnostics is the ability to differentiate spectral variations resulting from epithelial tissue dysplasia. Such measurement may be enhanced by discretely probing the optical properties of the epithelial tissue where the morphological and biochemical features vary according to tissue depths. More precisely, layer-specific changes in tissue optical properties correlated to cellular dysplasia can be determined by conventional reflectance spectroscopy when it is coupled with angularly variable fiber geometry. Thus, this study addresses how angularly variable fiber geometry can resolve spatially specific spectral signatures of tissue pathology by interpreting and analyzing the reflectance spectra of increasingly dysplastic epithelial tissue in reflectance-mode Monte Carlo simulation. Specifically, by increasing the obliquity of the collection fibers from 0 to 40 deg in the direction facing toward the illumination fiber, the spectral sensitivity to tissue abnormalities in the epithelial layer is thereby improved, whereas orthogonal fibers are more sensitive to the changes in the stromal layer.

Experimental evaluation of angularly variable fiber geometry for targeting depth-resolved reflectance from layered epithelial tissue phantoms

The present study focuses on enhancing the sensitivity and specificity of spectral diagnosis in a stratified architecture that models human cervical epithelia by experimentally demonstrating the efficacy of using angularly variable fiber geometry to achieve the desired layer selection and probing depths. The morphological and biochemical features of epithelial tissue vary in accordance with tissue depths; consequently, the accuracy of spectroscopic diagnosis of epithelial dysplasia may be enhanced by probing the optical properties of this tissue. In the case of cellular dysplasia, layer-specific changes in tissue optical properties may be optimally determined by reflectance spectroscopy when specifically coupled with angularly variable fiber geometry. This study addresses the utility of using such angularly variable fiber geometry for resolving spatially specific spectra of a two-layer epithelial tissue phantom. Spectral sensitivity to the scattering particles embedded in the epithelial phantom layer is shown to significantly improve as the obliquity of the collection fibers increases from 0 to 40 deg. Conversely, the orthogonal fibers are found to be more sensitive to changes in the stromal phantom layer.

Fluorescence spectroscopy of anin vitro model of human cervical precancer identifies neoplastic phenotype

The clinical diagnosis of cervical neoplasia by spectroscopic methods is potentially a reliable, fast and cost-effective alternative to the conventional smear test. However, it is currently limited by significant inter-patient variation in the spectroscopic properties of the cervix. Characterisation of suitable in vitro models of the spectroscopic changes that take place during neoplastic progression may prove to be a significant step towards the successful development of reliable in vivo systems. In this study, we used organotypic epithelial raft culture as an in vitro model of cervical tissue to analyse changes in the fluorescence properties of surface squamous epithelium that are associated with the development of neoplastic disease. Collagen plugs lined by primary human keratinocytes (PHKs) were used to model the normal cervical epithelium, and plugs lined by cells of the SiHa line were used as a model of neoplastic cervical tissue. Fluorescence emission spectra of these rafts were recorded at excitation wavelengths in the 250-330 nm range, complementing previous work published at longer wavelengths. Normalised, truncated emission spectra were analysed using multivariate principal component analysis. We successfully distinguished between in vitro models of normal and neoplastic cervical tissue and demonstrated a differential effect of acetic acid, which enhances the discrimination of normal from neoplastic tissue. Identification of these differences between in vitro organotypic epithelial rafts may ultimately aid the discrimination of cervical lesions in vivo.

Single- and two-photon spectral imaging of intrinsic fluorescence of transformed human hepatocytes

Autofluorescence (AF) originating from the cytoplasmic region of mammalian cells has been thoroughly investigated; however, AF from plasma membranes of viable intact cells is less well known, and has been mentioned only in a few older publications. Herein, we report results describing single- and two-photon spectral properties of a strong yellowish-green AF confined to the plasma-membrane region of transformed human hepatocytes (HepG2) grown in vitro as small three-dimensional aggregates or as monolayers. The excitation-emission characteristics of the membrane AF indicate that it may originate from a flavin derivative. Furthermore, the AF was closely associated with the plasma membranes of HepG2 cells, and its presence and intensity were dependent on cell metabolic state, membrane integrity and presence of reducing agents. This AF could be detected both in live intact cells and in formaldehyde-fixed cells.

Autofluorescence spectroscopy of epithelial tissues

Autofluorescence of rabbit and human epithelial tissues were studied by using a depth-resolved fluorescence spectroscopy system with multiple excitations. Keratinization was found to be common in the squamous epithelium. Strong keratin fluorescence with excitation and emission characteristics similar to collagen were observed in the topmost layer of the keratinized squamous epithelium. The keratin signal created interference in the assessment of the endogenous fluorescence signals (NADH/FAD fluorescence in epithelium and collagen fluorescence in stroma) associated with the development of epithelial precancer. Furthermore, the keratinized epithelial layer attenuated the excitation light and reduced the fluorescence signals from underlying tissue layers. The autofluorescence of columnar epithelium was found to be dominated by NADH and FAD signals, identical to the autofluorescence measured from nonkeratinized squamous epithelium. The study also demonstrated that a fluorescence signal excited at 355 nm produced sufficient contrast to resolve the layered structure of epithelial tissue, while the signal excited at 405 nm provided the information for a good estimation of epithelial redox ratios that are directly related to tissue metabolism. Overall, the depth-resolved measurements are crucial to isolate the fluorescence signals from different sublayers of the epithelial tissue and provide more accurate information for the tissue diagnosis.

Model-based analysis of clinical fluorescence spectroscopy for in vivo detection of cervical intraepithelial dysplasia

We present a mathematical model to calculate the relative concentration of light scatterers, light absorbers, and fluorophores in the epithelium and stroma. This mathematical description is iteratively fit to the fluorescence spectra measured in vivo, yielding relative concentrations of each molecule. The mathematical model is applied to a total of 493 fluorescence measurements of normal and dysplastic cervical tissue acquired in vivo from 292 patients. The estimated parameters are compared with histopathologic diagnosis to evaluate their diagnostic potential. The mathematical model is validated using fluorescence spectra simulated with known sets of optical parameters. Subsequent application of the mathematical model to in vivo fluorescence measurements from cervical tissue yields fits that accurately describe measured data. The optical parameters estimated from 493 fluorescence measurements show an increase in epithelial flavin adenine dinucleotide (FAD) fluorescence, a decrease in epithelial keratin fluorescence, an increase in epithelial light scattering, a decrease in stromal collagen fluorescence, and an increase in stromal hemoglobin light absorption in dysplastic tissue compared to normal tissue. These changes likely reflect an increase in the metabolic activity and loss of differentiation of epithelial dysplastic cells, and stromal angiogenesis associated with dysplasia. The model presented here provides a tool to analyze clinical fluorescence spectra yielding quantitative information about molecular changes related to dysplastic transformation.

Depth-sensitive reflectance measurements using obliquely oriented fiber probes

Computer simulation is used to facilitate the design of fiber-probe geometries that enable enhanced detection of optical signals arising from specific tissue depths. Obtaining understanding of the relationship between fiber-probe design and tissue interrogation is critical when developing strategies for optical detection of epithelial precancers that originate at known depths from the tissue surface. The accuracy of spectroscopic diagnostics may be enhanced by discretely probing the optical properties of epithelium and underlying stroma, within which the morphological and biochemical features vary as a function of depth. While previous studies have investigated controlling tissue-probing depth for fluorescence-based modalities, in this study we focus on the detection of reflected light scattered by tissue. We investigate how the depth of optical interrogation may be controlled through combinations of collection angles, source-detector separations, and numerical apertures. We find that increasing the obliquity of collection fibers at a given source-detector separation can effectively enhance the detection of superficially scattered signals. Fiber numerical aperture provides additional depth selectivity; however, the perturbations in sampling depth achieved through this means are modest relative to the changes generated by modifying the angle of collection and source-detection separation.

Multiphoton microscopy of endogenous fluorescence differentiates normal, precancerous, and cancerous squamous epithelial tissues

This study characterizes the morphologic features and the endogenous fluorescence in the stratified squamous epithelia of the 7,12-dimethylbenz(a)anthracene-treated hamster cheek pouch model of carcinogenesis using multiphoton laser scanning microscopy (MPLSM). MPLSM allows high-resolution, three-dimensional image data to be collected deeper within thick tissue samples with reduced phototoxicity compared with single-photon imaging. Three-dimensional image stacks of normal (n = 13), precancerous (dysplasia, n = 12; carcinoma in situ, n = 9) and cancerous tissue [nonpapillary squamous cell carcinoma (SCC), n = 10, and papillary SCC, n = 7] sites in the hamster cheek pouch were collected in viable, unsectioned tissue biopsies at a two-photon excitation wavelength of 780 nm. Five features were quantified from the MPLSM images. These included nuclear density versus depth, keratin layer thickness, epithelial thickness, and the fluorescence per voxel in the keratin and epithelial layers. Statistically significant differences in all five features were found between normal and both precancerous and cancerous tissues. The only exception to this was a lack of statistically significant differences in the keratin fluorescence between normal tissues and papillary SCCs. Statistically significant differences were also observed in the epithelial thickness of dysplasia and carcinoma in situ, and in the keratin layer thickness of dysplasia and SCCs (both nonpapillary and papillary). This work clearly shows that three-dimensional images from MPLSM of endogenous tissue fluorescence can effectively distinguish between normal, precancerous, and cancerous epithelial tissues. This study provides the groundwork for further exploration into the application of multiphoton fluorescence endoscopy in a clinical setting.

A pilot study for a screening trial of cervical fluorescence spectroscopy

Fluorescence spectroscopy is a promising technology for detection of epithelial precancers and cancers. In preparation for a multicenter phase II screening trial, a pilot trial was conducted to test data collection and patient examination procedures, use data forms, time procedures, and identify problems with preliminary data analysis. Women 18 years of age and older underwent a questionnaire, a complete history, and a physical examination, including a pan-colposcopy of the lower genital tract. A fiber-optic probe measured fluorescence excitation-emission matrices at 1-3 cervical sites for 58 women. The data collection procedures, data forms, and procedure times worked well, although collection times for all the clinical data take an average of 28 min. The clinical team followed procedures well, and the data could be retrieved from the database at all sites. The multivariate analysis algorithm correctly identified squamous normal tissue 99% of the time and columnar normal tissue only 7%. The assessment of ploidy from monolayer samples was not accurate in this small sample. The study was successful as a pilot trial. We learned who participated, who withdrew, how often abnormalities were present, and that algorithms that have worked extremely well in previous studies do not work as well when a few study parameters are changed. The current algorithm for diagnosis identified squamous normal tissue very accurately and did less well for columnar normal tissue. Inflammation may be an explanation for this phenomenon. Fluorescence spectroscopy is a promising technology for the detection of epithelial precancers and cancers. The screening trial of fluorescence and reflectance spectroscopy was successful.

Vision enhancement system for detection of oral cavity neoplasia based on autofluorescence

BACKGROUND

Early detection of squamous cell carcinoma (SCC) in the oral cavity can improve survival. It is often difficult to distinguish neoplastic and benign lesions with standard white light illumination. We evaluated whether a technique that capitalizes on an alternative source of contrast, tissue autofluorescence, improves visual examination.

METHODS

Autofluorescence of freshly resected oral tissue was observed visually and photographed at specific excitation/emission wavelength combinations optimized for response of the human visual system and tissue fluorescence properties. Perceived tumor margins were indicated for each wavelength combination. Punch biopsies were obtained from several sites from each specimen. Sensitivity and specificity were evaluated by correlating histopathologic diagnosis with visual impression.

RESULTS

Best results were achieved with illumination at 400 nm and observation at 530 nm. Here, sensitivity and specificity were 91% and 86% in discrimination of normal tissue from neoplasia. This compares favorably with white light examination, in which sensitivity and specificity were 75% and 43%.

CONCLUSIONS

Oral cavity autofluorescence can be easily viewed by the human eye in real time. Visual examination of autofluorescence enhances perceived contrast between normal and neoplastic oral mucosa in fresh tissue resections.

Investigation of fiber-optic probe designs for optical spectroscopic diagnosis of epithelial pre-cancers

BACKGROUND AND OBJECTIVES

The first objective of this study was to evaluate the performance of fluorescence spectroscopy for diagnosing pre-cancers in stratified squamous epithelial tissues in vivo using two different probe geometries with (1) overlapping versus (2) non-overlapping illumination and collection areas on the tissue surface. Probe (1) and probe (2) are preferentially sensitive to the fluorescence originating from the tissue surface and sub-surface tissue depths, respectively. The second objective was to design a novel, angled illumination fiber-optic probe to maximally exploit the depth-dependent fluorescence properties of epithelial tissues.

STUDY DESIGN/MATERIALS AND METHODS

In the first study, spectra were measured from epithelial pre-cancers and normal tissues in the hamster cheek pouch and analyzed with a non-parametric classification algorithm. In the second study, Monte Carlo modeling was used to simulate fluorescence measurements from an epithelial tissue model with the angled illumination probe.

RESULTS

An unbiased classification algorithm based on spectra measured with probes (1) and (2), classified pre-cancerous and normal tissues with 78 and 94% accuracy, respectively. The angled illumination probe design provides the capability to detect fluorescence from a wide range of tissue depths in an epithelial tissue model.

CONCLUSIONS

The first study demonstrates that fluorescence originating from sub-surface tissue depths (probe (2)) is more diagnostic than fluorescence originating from the tissue surface (probe (1)) in the hamster cheek pouch model. However in general, it is difficult to know a priori the optimal probe geometry for pre-cancer detection in a particular epithelial tissue model. The angled illumination probe provides the capability to measure tissue fluorescence selectively from different depths within epithelial tissues, thus obviating the need to select a single optimal probe design for the fluorescence-based diagnosis of epithelial pre-cancers.

Effect of probe pressure on cervical fluorescence spectroscopy measurements

Fluorescence spectroscopy is a promising technology for detection of epithelial precancers and cancers. While age and menopausal status influence measurements in the cervix, other variables do not significantly affect the diagnosis. In this study we examine probe pressure as a variable. A fiber optic probe to measure fluorescence spectra at different calibrated levels of pressure was designed and tested. A pilot study was conducted measuring fluorescence excitation emission matrices in 20 patients at light, medium, and firm pressure. Spectroscopic data were pre-processed and analyzed to compare mean peak intensities as a function of pressure. Further statistical analyses tested for differences in intensities at each excitation/emission wavelength pair. Four providers made measurements from 41 sites; 33 yielded good quality spectroscopic data (22 squamous normal, 7 squamous abnormal, 3 columnar normal, 1 transformation zone) from 17 of 20 patients. At all pressure levels, abnormal tissue showed less fluorescence intensity than normal tissue, and post-menopausal patients showed higher fluorescence intensity than premenopausal patients, consistent with previous analyses. A permutation analysis suggests that pressure does not significantly affect fluorescence intensity or lineshape. While other studies are needed to confirm these findings, this study suggests that fluorescence spectroscopy is a robust technology likely not influenced by fiber optic probe pressure.

Autofluorescence spectroscopy of normal and malignant human breast cell lines

The fluorescence of tryptophan, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD) were characterized in normal human breast cells as well as in malignant human breast cells of similar and dissimilar genetic origins. Fluorescence measurements of each cell line were made over a wide range of cell concentrations, and the fluorescence per cell was determined from the slope in the linear range of the fluorescence intensity vs cell concentration plot. All of the malignant cells showed a statistically significant decrease in the tryptophan fluorescence per cell relative to that of the normal cells. No statistically significant differences were observed in the NAD(P)H or FAD fluorescence per cell between the normal and any of the malignant cell types. NAD(P)H fluorescence was also imaged from monolayers of the normal and malignant cells (of similar genetic origin) using two-photon fluorescence microscopy. A statistically significant decrease in the NAD(P)H fluorescence with malignancy was observed, suggesting that fluorescence imaging of single cells or the cell monolayer preparation may provide more contrast than volume-averaged fluorescence measurements of cells in suspension. In conclusion, the differences in normal and malignant human breast tissue fluorescence spectra may be attributed in part to differences in the intrinsic cellular fluorescence of normal and malignant breast epithelial cells.