The combined use of fluorescence, reflectance, and light-scattering spectroscopy for evaluating dysplasia in Barrett's esophagus

Real-time Tracking and Classification of Tumor and Nontumor Tissue in Upper Gastrointestinal Cancers Using Diffuse Reflectance Spectroscopy for Resection Margin Assessment

Importance

Cancers of the upper gastrointestinal tract remain a major contributor to the global cancer burden. The accurate mapping of tumor margins is of particular importance for curative cancer resection and improvement in overall survival. Current mapping techniques preclude a full resection margin assessment in real time.

Objective

To evaluate whether diffuse reflectance spectroscopy (DRS) on gastric and esophageal cancer specimens can differentiate tissue types and provide real-time feedback to the operator.

Design, Setting, and Participants

This was a prospective ex vivo validation study. Patients undergoing esophageal or gastric cancer resection were prospectively recruited into the study between July 2020 and July 2021 at Hammersmith Hospital in London, United Kingdom. Tissue specimens were included for patients undergoing elective surgery for either esophageal carcinoma (adenocarcinoma or squamous cell carcinoma) or gastric adenocarcinoma.

Exposures

A handheld DRS probe and tracking system was used on freshly resected ex vivo tissue to obtain spectral data. Binary classification, following histopathological validation, was performed using 4 supervised machine learning classifiers.

Main Outcomes and Measures

Data were divided into training and testing sets using a stratified 5-fold cross-validation method. Machine learning classifiers were evaluated in terms of sensitivity, specificity, overall accuracy, and the area under the curve.

Results

Of 34 included patients, 22 (65%) were male, and the median (range) age was 68 (35-89) years. A total of 14 097 mean spectra for normal and cancerous tissue were collected. For normal vs cancer tissue, the machine learning classifier achieved a mean (SD) overall diagnostic accuracy of 93.86% (0.66) for stomach tissue and 96.22% (0.50) for esophageal tissue and achieved a mean (SD) sensitivity and specificity of 91.31% (1.5) and 95.13% (0.8), respectively, for stomach tissue and of 94.60% (0.9) and 97.28% (0.6) for esophagus tissue. Real-time tissue tracking and classification was achieved and presented live on screen.

Conclusions and Relevance

This study provides ex vivo validation of the DRS technology for real-time differentiation of gastric and esophageal cancer from healthy tissue using machine learning with high accuracy. As such, it is a step toward the development of a real-time in vivo tumor mapping tool for esophageal and gastric cancers that can aid decision-making of resection margins intraoperatively.

Recent Advances in Biomedical Photonic Sensors: A Focus on Optical-Fibre-Based Sensing

In this invited review, we provide an overview of the recent advances in biomedical photonic sensors within the last five years. This review is focused on works using optical-fibre technology, employing diverse optical fibres, sensing techniques, and configurations applied in several medical fields. We identified technical innovations and advancements with increased implementations of optical-fibre sensors, multiparameter sensors, and control systems in real applications. Examples of outstanding optical-fibre sensor performances for physical and biochemical parameters are covered, including diverse sensing strategies and fibre-optical probes for integration into medical instruments such as catheters, needles, or endoscopes.

Spectral Endoscopy Enhances Contrast for Neoplasia in Surveillance of Barrett's Esophagus

Early detection of esophageal neoplasia enables curative endoscopic therapy, but the current diagnostic standard of care has low sensitivity because early neoplasia is often inconspicuous with conventional white-light endoscopy. Here, we hypothesized that spectral endoscopy could enhance contrast for neoplasia in surveillance of patients with Barrett's esophagus. A custom spectral endoscope was deployed in a pilot clinical study of 20 patients to capture 715 in vivo tissue spectra matched with gold standard diagnosis from histopathology. Spectral endoscopy was sensitive to changes in neovascularization during the progression of disease; both non-dysplastic and neoplastic Barrett's esophagus showed higher blood volume relative to healthy squamous tissue (P = 0.001 and 0.02, respectively), and vessel radius appeared larger in neoplasia relative to non-dysplastic Barrett's esophagus (P = 0.06). We further developed a deep learning algorithm capable of classifying spectra of neoplasia versus non-dysplastic Barrett's esophagus with high accuracy (84.8% accuracy, 83.7% sensitivity, 85.5% specificity, 78.3% positive predictive value, and 89.4% negative predictive value). Exploiting the newly acquired library of labeled spectra to model custom color filter sets identified a potential 12-fold enhancement in contrast between neoplasia and non-dysplastic Barrett's esophagus using application-specific color filters compared with standard-of-care white-light imaging (perceptible color difference = 32.4 and 2.7, respectively). This work demonstrates the potential of endoscopic spectral imaging to extract vascular properties in Barrett's esophagus, to classify disease stages using deep learning, and to enable high-contrast endoscopy. SIGNIFICANCE: The results of this pilot first-in-human clinical trial demonstrate the potential of spectral endoscopy to reveal disease-associated vascular changes and to provide high-contrast delineation of neoplasia in the esophagus. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3415/F1.large.jpg.

Time-Resolved Synchronous Fluorescence for Biomedical Diagnosis

This article presents our most recent advances in synchronous fluorescence (SF) methodology for biomedical diagnostics. The SF method is characterized by simultaneously scanning both the excitation and emission wavelengths while keeping a constant wavelength interval between them. Compared to conventional fluorescence spectroscopy, the SF method simplifies the emission spectrum while enabling greater selectivity, and has been successfully used to detect subtle differences in the fluorescence emission signatures of biochemical species in cells and tissues. The SF method can be used in imaging to analyze dysplastic cells in vitro and tissue in vivo. Based on the SF method, here we demonstrate the feasibility of a time-resolved synchronous fluorescence (TRSF) method, which incorporates the intrinsic fluorescent decay characteristics of the fluorophores. Our prototype TRSF system has clearly shown its advantage in spectro-temporal separation of the fluorophores that were otherwise difficult to spectrally separate in SF spectroscopy. We envision that our previously-tested SF imaging and the newly-developed TRSF methods will combine their proven diagnostic potentials in cancer diagnosis to further improve the efficacy of SF-based biomedical diagnostics.

Fluorescence spectroscopy incorporated in an Optical Biopsy System for the detection of early neoplasia in Barrett's esophagus

Endoscopic surveillance is recommended for patients with Barrett's esophagus (BE) to detect high-grade intraepithelial neoplasia (HGIN) or early cancer (EC). Early neoplasia is difficult to detect with white light endoscopy and random biopsies are associated with sampling error. Fluorescence spectroscopy has been studied to distinguish non-dysplastic Barrett's epithelium (NDBE) from early neoplasia. The Optical Biopsy System (OBS) uses an optical fiber integrated in a regular biopsy forceps. This allows real-time spectroscopy and ensures spot-on correlation between the spectral signature and corresponding physical biopsy. The OBS may provide an easy-to-use endoscopic tool during BE surveillance. We aimed to develop a tissue-differentiating algorithm and correlate the discriminating properties of the OBS with the constructed algorithm to the endoscopist's assessment of the Barrett's esophagus. In BE patients undergoing endoscopy, areas suspicious for neoplasia and endoscopically non-suspicious areas were investigated with the OBS, followed by a correlating physical biopsy with the optical biopsy forceps. Spectra were correlated to histology and an algorithm was constructed to discriminate between HGIN/EC and NDBE using smoothed linear dicriminant analysis. The constructed classifier was internally cross-validated and correlated to the endoscopist's assessment of the BE segment. A total of 47 patients were included (39 males, age 66 years): 35 BE patients were referred with early neoplasia and 12 patients with NDBE. A total of 245 areas were investigated with following histology: 43 HGIN/EC, 66 low-grade intraepithelial neoplasia, 108 NDBE, 28 gastric or squamous mucosa. Areas with low-grade intraepithelial neoplasia and gastric/squamous mucosa were excluded. The area under the receiver operating characteristic curve of the constructed classifier was 0.78. Sensitivity and specificity for the discrimination between NDBE and HGIN/EC of OBS alone were 81% and 58% respectively. When OBS was combined with the endoscopist's assesssment, sensitivity was 91% and specificity 50%. If this protocol would have guided the decision to obtain biopsies, half of the biopsies would have been avoided, yet 4/43 areas containing HGIN/EC (9%) would have been inadvertently classified as unsuspicious. In this study, the OBS was used to construct an algorithm to discriminate neoplastic from non-neoplastic BE. Moreover, the feasibility of OBS with the constructed algorithm as an adjunctive tool to the endoscopist's assessment during endoscopic BE surveillance was demonstrated. These results should be validated in future studies. In addition, other probe-based spectroscopy techniques may be integrated in this optical biopsy forceps system.

Portable optical fiber probe-based spectroscopic scanner for rapid cancer diagnosis: a new tool for intraoperative margin assessment

There continues to be a significant clinical need for rapid and reliable intraoperative margin assessment during cancer surgery. Here we describe a portable, quantitative, optical fiber probe-based, spectroscopic tissue scanner designed for intraoperative diagnostic imaging of surgical margins, which we tested in a proof of concept study in human tissue for breast cancer diagnosis. The tissue scanner combines both diffuse reflectance spectroscopy (DRS) and intrinsic fluorescence spectroscopy (IFS), and has hyperspectral imaging capability, acquiring full DRS and IFS spectra for each scanned image pixel. Modeling of the DRS and IFS spectra yields quantitative parameters that reflect the metabolic, biochemical and morphological state of tissue, which are translated into disease diagnosis. The tissue scanner has high spatial resolution (0.25 mm) over a wide field of view (10 cm × 10 cm), and both high spectral resolution (2 nm) and high spectral contrast, readily distinguishing tissues with widely varying optical properties (bone, skeletal muscle, fat and connective tissue). Tissue-simulating phantom experiments confirm that the tissue scanner can quantitatively measure spectral parameters, such as hemoglobin concentration, in a physiologically relevant range with a high degree of accuracy (<5% error). Finally, studies using human breast tissues showed that the tissue scanner can detect small foci of breast cancer in a background of normal breast tissue. This tissue scanner is simpler in design, images a larger field of view at higher resolution and provides a more physically meaningful tissue diagnosis than other spectroscopic imaging systems currently reported in literatures. We believe this spectroscopic tissue scanner can provide real-time, comprehensive diagnostic imaging of surgical margins in excised tissues, overcoming the sampling limitation in current histopathology margin assessment. As such it is a significant step in the development of a platform technology for intraoperative management of cancer, a clinical problem that has been inadequately addressed to date.

Different optical properties between human hepatocellular carcinoma tissues and non-tumorous hepatic tissues in vitro

There has been an ongoing search for clinically acceptable methods for the accurate, efficient and simple diagnosis and prognosis of hepatocellular carcinoma (HCC). Optical spectroscopy is a technique with potential clinical applications to diagnose cancer diseases. The purpose of this study was to obtain the optical properties of HCC tissues and non-tumorous hepatic tissues and identify the difference between them. A total of 55 tissue samples (HCC tissue, n=38; non-tumorous hepatic tissue, n=17) were surgically resected from patients with HCC. The optical parameters were measured in 10-nm steps using single-integrating-sphere system in the wavelength range of 400 to 1800 nm. It was found that the optical properties and their differences varied with the wavelength for the HCC tissue and the non-tumorous hepatic tissue in the entire wavelength range of research. The absorption coefficient of the HCC tissue (1.48±0.99, 1.46±0.88, 0.86±0.61, 2.15±0.53, 0.54±0.10, 0.79±0.15 mm(-1)) was significantly lower than that of the non-tumorous hepatic tissue (2.79±1.73, 3.13±1.47, 3.06±2.79, 2.57±0.55, 0.62±0.10, 0.93±0.16 mm(-1)) at wavelengths of 400, 410, 450, 1450, 1660 and 1800 nm, respectively (P<0.05). The reduced scattering coefficient of HCC tissue (5.28±1.70, 4.91±1.54, 1.26±0.35 mm(-1)) and non-tumorous hepatic tissue (8.14±3.70, 9.27±3.08, 2.55±0.57 mm(-1)) was significantly different at 460, 500 and 1800 nm respectively (P<0.05). These results show different pathologic liver tissues have different optical properties. It provides a better understanding of the relationship between optical parameters and physiological characteristics in human liver tissues. And it would be very useful for developing a non-invasive, real-time, simple and efficient way for medical management of HCC in the future.

Models of light propagation in human tissue applied to cancer diagnostics

Optical methods such as reflectance and fluorescence spectroscopy are being investigated for their potential to aid cancer detection in a quantitative, minimally invasive manner. Mathematical models of reflectance and fluorescence provide an important link between measured optical data and biomedically-relevant tissue parameters that can be extracted from these data to characterize the presence or absence of disease. The most commonly-used mathematical models in biomedical optics are the diffusion approximation (DA) to the radiative transfer equation, Monte Carlo (MC) computational models of light transport, and semi-empirical models. This paper presents a review of the applications of these models to reflectance and endogenous fluorescence sensing for cancer diagnostics in human tissues. Specific examples are given for cervical, breast, and pancreatic tissues. A comparison of the DA and MC methods in two biologically-relevant regimes of optical parameter space will also be discussed.

Molecular imaging for guiding oncologic prognosis and therapy in esophageal adenocarcinoma

In the past 30 years, the incidence of esophageal adenocarcinoma (ACA) has increased significantly. Sadly, advances in treatment have not followed the same trend, and the prognosis for patients with esophageal ACA remains poor, with a 5-year survival rate of only 15%. Like most cancers, early detection is the key to improving prognosis, but this outcome has proven difficult in the esophagus for several reasons: 1) patients present with advanced disease because "alarm symptoms," such as dysphagia, occur at a late stage, and 2) high-grade dysplasia (HGD) and early ACA are not visible on routine surveillance endoscopy. Currently, the recommended surveillance strategy involves collection of random biopsies, an imperfect technique that is limited by sampling error and is infrequently used because of the considerable time and cost it requires. Even in patients with biopsy-proven dysplasia, adequate guidance for clinical management decisions is still lacking. Dysplasia alone is not an entirely reliable biomarker for the risk of progression to ACA because the natural history of this condition is extremely variable. Clearly, there is a need for additional biomarkers that can better characterize this disease and thus improve our ability to treat patients on an individual basis. As we better understand the molecular changes that lead to the development of this cancer, new molecular biomarkers are needed to allow for more personalized diagnoses, surveillance, and treatment. Targeted agents against epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and vascular endothelial growth factor (VEGF) are currently being evaluated for their role in combination chemotherapy for metastatic esophageal ACA. As these studies progress, a reliable approach for determining receptor status in individual patients is essential. Molecular imaging uses fluorescent probes that target specific cell-surface receptors, and has the potential to evaluate an individual patient's gene expression profile. By topically applying fluorescent probes to dysplastic epithelium during endoscopy, a variety of receptors can be visualized, and the response to treatment can be monitored in real time. This technique can mitigate the limitations of current surveillance protocols, allow for improved cancer detection, and be used for personalized treatment in the future.

Photon-tissue interaction model enables quantitative optical analysis of human pancreatic tissues

A photon-tissue interaction (PTI) model was developed and employed to analyze 96 pairs of reflectance and fluorescence spectra from freshly excised human pancreatic tissues. For each pair of spectra, the PTI model extracted a cellular nuclear size parameter from the measured reflectance, and the relative contributions of extracellular and intracellular fluorophores to the intrinsic fluorescence. The results suggest that reflectance and fluorescence spectroscopies have the potential to quantitatively distinguish among pancreatic tissue types, including normal pancreatic tissue, pancreatitis, and pancreatic adenocarcinoma.

Instrumentation to rapidly acquire fluorescence wavelength-time matrices of biological tissues

A fiber-optic system was developed to rapidly acquire tissue fluorescence wavelength-time matrices (WTMs) with high signal-to-noise ratio (SNR). The essential system components (473 nm microchip laser operating at 3 kHz repetition frequency, fiber-probe assemblies, emission monochromator, photomultiplier tube, and digitizer) were assembled into a compact and clinically-compatible unit. Data were acquired from fluorescence standards and tissue-simulating phantoms to test system performance. Fluorescence decay waveforms with SNR > 100 at the decay curve peak were obtained in less than 30 ms. With optimized data transfer and monochromator stepping functions, it should be feasible to acquire a full WTM at 5 nm emission wavelength intervals over a 200 nm range in under 2 seconds.

New Endoscopic Techniques: Challenges and Opportunities for Surgical Pathologists

In recent years, significant clinical and technological advances have been made in endoscopic methods for diagnosis and treatment of early gastrointestinal neoplasms. However, essential information related to these novel techniques and their implications for practicing surgical pathologists have largely been missing in the general pathology literature. This article provides a general introduction to these novel therapeutic and diagnostic methods, and discusses their indications, contraindications, and potential limitations. The article aims to enable surgical pathologists to interact more efficiently with basic scientists and clinical colleagues to help implement and improve the existing clinical methods and to advance the new technologies.

Strategies for high-resolution imaging of epithelial ovarian cancer by laparoscopic nonlinear microscopy

Ovarian cancer remains the most frequently lethal of the gynecologic cancers owing to the late detection of this disease. Here, by using human specimens and three mouse models of ovarian cancer, we tested the feasibility of nonlinear imaging approaches, the multiphoton microscopy (MPM) and second harmonic generation (SHG) to serve as complementary tools for ovarian cancer diagnosis. We demonstrate that MPM/SHG of intrinsic tissue emissions allows visualization of unfixed, unsectioned, and unstained tissues at a resolution comparable to that of routinely processed histologic sections. In addition to permitting discrimination between normal and neoplastic tissues according to pathological criteria, the method facilitates morphometric assessment of specimens and detection of very early cellular changes in the ovarian surface epithelium. A red shift in cellular intrinsic fluorescence and collagen structural alterations have been identified as additional cancer-associated changes that are indiscernible by conventional pathologic techniques. Importantly, the feasibility of in vivo laparoscopic MPM/SHG is demonstrated by using a "stick" objective lens. Intravital detection of neoplastic lesions has been further facilitated by low-magnification identification of an indicator for cathepsin activity followed by MPM laparoscopic imaging. Taken together, these results demonstrate that MPM may be translatable to clinical settings as an endoscopic approach suitable for high-resolution optical biopsies as well as a pathology tool for rapid initial assessment of ovarian cancer samples.

Spectral areas and ratios classifier algorithm for pancreatic tissue classification using optical spectroscopy

Pancreatic adenocarcinoma is one of the leading causes of cancer death, in part because of the inability of current diagnostic methods to reliably detect early-stage disease. We present the first assessment of the diagnostic accuracy of algorithms developed for pancreatic tissue classification using data from fiber optic probe-based bimodal optical spectroscopy, a real-time approach that would be compatible with minimally invasive diagnostic procedures for early cancer detection in the pancreas. A total of 96 fluorescence and 96 reflectance spectra are considered from 50 freshly excised tissue sites-including human pancreatic adenocarcinoma, chronic pancreatitis (inflammation), and normal tissues-on nine patients. Classification algorithms using linear discriminant analysis are developed to distinguish among tissues, and leave-one-out cross-validation is employed to assess the classifiers' performance. The spectral areas and ratios classifier (SpARC) algorithm employs a combination of reflectance and fluorescence data and has the best performance, with sensitivity, specificity, negative predictive value, and positive predictive value for correctly identifying adenocarcinoma being 85, 89, 92, and 80%, respectively.

Real-time intraoperative fluorescence imaging system using light-absorption correction

We present a novel fluorescence imaging system developed for real-time interventional imaging applications. The system implements a correction scheme that improves the accuracy of epi-illumination fluorescence images for light intensity variation in tissues. The implementation is based on the use of three cameras operating in parallel, utilizing a common lens, which allows for the concurrent collection of color, fluorescence, and light attenuation images at the excitation wavelength from the same field of view. The correction is based on a ratio approach of fluorescence over light attenuation images. Color images and video is used for surgical guidance and for registration with the corrected fluorescence images. We showcase the performance metrics of this system on phantoms and animals, and discuss the advantages over conventional epi-illumination systems developed for real-time applications and the limits of validity of corrected epi-illumination fluorescence imaging.

Optical spectroscopy detects histological hallmarks of pancreatic cancer

An empirical model was developed to interpret differences in the experimentally measured reflectance and fluorescence spectra of freshly excised human pancreatic tissues: normal, adenocarcinoma, and pancreatitis (inflammation). The model provided the first quantitative links between spectroscopic measurements and histological characteristics in the human pancreas. The reflectance model enabled the first (to our knowledge) extraction of wavelength resolved absorption and reduced scattering coefficients for normal and diseased human pancreatic tissues. The fluorescence model employed reflectance information to extract attenuation free "intrinsic" endogenous fluorescence spectra from normal pancreatic tissue, pancreatic adenocarcinoma, and pancreatitis. The method developed is simple, intuitive, and potentially useful for a range of applications in optical tissue diagnostics. This approach is potentially applicable to in vivo studies, because it can account for the absorptive effects of blood in tissues.

Advances in quantitative UV-visible spectroscopy for clinical and pre-clinical application in cancer

Methods of optical spectroscopy that provide quantitative, physically or physiologically meaningful measures of tissue properties are an attractive tool for the study, diagnosis, prognosis, and treatment of various cancers. Recent development of methodologies to convert measured reflectance and fluorescence spectra from tissue to cancer-relevant parameters such as vascular volume, oxygenation, extracellular matrix extent, metabolic redox states, and cellular proliferation have significantly advanced the field of tissue optical spectroscopy. The number of publications reporting quantitative tissue spectroscopy results in the UV-visible wavelength range has increased sharply in the past three years, and includes new and emerging studies that correlate optically measured parameters with independent measures such as immunohistochemistry, which should aid in increased clinical acceptance of these technologies.

Fluorescence and reflectance device variability throughout the progression of a phase II clinical trial to detect and screen for cervical neoplasia using a fiber optic probe

Large phase II trials of fluorescence and reflectance spectroscopy using a fiber optic probe in the screening and diagnostic settings for detecting cervical neoplasia have been conducted. We present accrual and histopathology data, instrumentation, data processing, and the preliminary results of interdevice consistencies throughout the progression of a trial. Patients were recruited for either a screening trial (no history of abnormal Papanicolaou smears) or a diagnostic trial (a history of abnormal Papanicolaou smears). Colposcopy identified normal and abnormal squamous, columnar, and transformation zone areas that were subsequently measured with the fiber probe and biopsied. In the course of the clinical trial, two generations of spectrometers (FastEEM2 and FastEEM3) were designed and utilized as optical instrumentation for in vivo spectroscopic fluorescence and reflectance measurements. Data processing of fluorescence and reflectance data is explained in detail and a preliminary analysis of the variability across each device and probe combination is explored. One thousand patients were recruited in the screening trial and 850 patients were recruited in the diagnostic trial. Three clinical sites attracted a diverse range of patients of different ages, ethnicities, and menopausal status. The fully processed results clearly show that consistencies exist across all device and probe combinations throughout the diagnostic trial. Based on the stratification of the data, the results also show identifiable differences in mean intensity between normal and high-grade tissue diagnosis, pre- and postmenopausal status, and squamous and columnar tissue type. The mean intensity values of stratified data show consistent separation across each of the device and probe combinations. By analyzing trial spectra, we provide more evidence that biographical variables such as menopausal status as well as tissue type and diagnosis significantly affect the data. Understanding these effects will lead to better modeling parameters when analyzing the performance of fluorescence and reflectance spectroscopy.

Computerized morphometry as an aid in determining the grade of dysplasia and progression to adenocarcinoma in Barrett's esophagus

The aims of this study were to use computerized morphometry in order to differentiate between the degree of dysplasia and to predict progression to invasive adenocarcinoma in Barrett's esophagus (BE). Biopsies from 97 patients with BE graded by a consensus forum of expert gastrointestinal pathologists were available for morphometrical analysis. The study group included 36 biopsies negative for dysplasia (ND), none of which progressed to carcinoma; 16 indefinite for dysplasia (IND) and 21 low-grade dysplasia (LGD), of which three progressed in each group and 24 high-grade dysplasia (HGD), of which 15 progressed to invasive carcinoma. Computerized morphometry was used for measuring indices of size, shape, texture, symmetry and architectural distribution of the epithelial nuclei. Low-grade dysplasia was best differentiated from the ND group by nuclear pseudostratification (P=0.036), pleomorphism (P<0.01), and chromatin texture (margination, P<0.01) and from the HGD group by nuclear area (P<0.01), pleomorphism (P<0.01), chromatin texture (margination, P<0.01), symmetry (P<0.01), and orientation (P=0.027). These results were validated on a new set of cases (n=55) using a neural network model, resulting in an accuracy of 89% for differentiating between the ND and LGD groups and 86% for differentiating between the LGD and HGD groups. Within the HGD group, univariate significant predictors of the progression interval to carcinoma were: indices of nuclear texture (heterogeneity: P=0.0019, s.d.-OD: P=0.005) and orientation: P=0.022. Nuclear texture (heterogeneity) was the only independent predictor of progression (P=0.004, hazard=11.54) by Cox's multivariate test. This study proposes that computerized morphometry is a valid tool for determining the grade of dysplasia in BE. Moreover, histomorphometric quantification of nuclear texture is a powerful tool for predicting progression to invasive adenocarcinoma in patients with HGD.

Assessment of oral premalignancy using elastic scattering spectroscopy

Optical spectroscopy systems have been involved in various clinical fields; however the main interest is still in the diagnosis of premalignant/malignant lesions. The aim of this study was to compare findings of Elastic Scattering Spectroscopy (ESS) with histopathology of oral tissues to see if this technique could be used as an adjunct or alternative to histopathology in identifying dysplasia. The technique involves the use of Mie scattering and is a simple non-invasive method of tissue interrogation. Twenty-five oral sites from 25 patients who presented with oral leukoplakia were examined by ESS using a pulsed xenon-arc lamp. Surgical biopsies were acquired from each of the examination sites. The results of the acquired spectra were then compared with histopathology. Two sets of spectra were obtained, and by using a linear discriminant analysis, a sensitivity of 72% and a specificity of 75% were obtained. These results are promising and could suggest that ESS may be able to identify dysplasia in oral tissues. To prove the usefulness of the ESS in dysplasia detection in oral tissues conclusively, a larger body of data is needed. We aim to continue this study to obtain more data in an attempt to increase the accuracy of the technique. Large, multi-centre trails are needed for each anatomical site, in order to gather more information about the differences between normal and dysplastic tissue.

Endoscopic treatment of high-grade dysplasia and early cancer in Barrett's oesophagus

Barrett's oesophagus is the premalignant precursor of oesophageal adenocarcinoma. Non-dysplastic metaplasia can progress to low-grade dysplasia, high-grade dysplasia, and finally to invasive cancer. Although the frequency of adenocarcinoma in patients with Barrett's oesophagus is low, surveillance is justified because the outcome of adenocarcinoma is poor. Oesophagectomy remains the standard treatment for patients with high-grade dysplasia and superficial carcinoma. However, it has been associated with substantial morbidity and mortality and some patients are judged unfit for surgery. In this review, the present status of less invasive procedures is discussed. Endotherapy preserves the integrity of the oesophagus and allows a better quality of life to patients at low risk of developing lymph-node metastases. Opposition to endoscopic treatment is based mainly on the identification of undetected foci of cancer and high-grade dysplasia in oesophagectomy samples. The current ablative techniques used are photodynamic therapy, argon plasma coagulation, laser treatment, and endoscopic mucosal resection.