Barrett's esophagus: current and future role of endosonography and optical coherence tomography

Esophageal cancer screening, early detection and treatment: Current insights and future directions

Esophageal cancer ranks among the most prevalent malignant tumors globally, primarily due to its highly aggressive nature and poor survival rates. According to the 2020 global cancer statistics, there were approximately 604000 new cases of esophageal cancer, resulting in 544000 deaths. The 5-year survival rate hovers around a mere 15%-25%. Notably, distinct variations exist in the risk factors associated with the two primary histological types, influencing their worldwide incidence and distribution. Squamous cell carcinoma displays a high incidence in specific regions, such as certain areas in China, where it meets the cost-effectiveness criteria for widespread endoscopy-based early diagnosis within the local population. Conversely, adenocarcinoma (EAC) represents the most common histological subtype of esophageal cancer in Europe and the United States. The role of early diagnosis in cases of EAC originating from Barrett's esophagus (BE) remains a subject of controversy. The effectiveness of early detection for EAC, particularly those arising from BE, continues to be a debated topic. The variations in how early-stage esophageal carcinoma is treated in different regions are largely due to the differing rates of early-stage cancer diagnoses. In areas with higher incidences, such as China and Japan, early diagnosis is more common, which has led to the advancement of endoscopic methods as definitive treatments. These techniques have demonstrated remarkable efficacy with minimal complications while preserving esophageal functionality. Early screening, prompt diagnosis, and timely treatment are key strategies that can significantly lower both the occurrence and death rates associated with esophageal cancer.

Prostate cancer diagnosis: the feasibility of needle-based optical coherence tomography

The objective of this study is to demonstrate the feasibility of needle-based optical coherence tomography (OCT) and functional analysis of OCT data along the full pullback trajectory of the OCT measurement in the prostate, correlated with pathology. OCT images were recorded using a commercially available C7-XR™ OCT Intravascular Imaging System interfaced to a C7 Dragonfly™ intravascular 0.9-mm-diameter imaging probe. A computer program was constructed for automated image attenuation analysis. First, calibration of the OCT system for both the point spread function and the system roll-off was achieved by measurement of the OCT signal attenuation from an extremely weakly scattering medium (Intralipid® 0.0005 volume%). Second, the data were arranged in 31 radial wedges (pie slices) per circular segments consisting of 16 A-scans per wedge and 5 axial B-scans, resulting in an average A-scan per wedge. Third, the decay of the OCT signal is analyzed over 50 pixels ([Formula: see text]) in depth, starting from the first found maximum data point. Fourth, for visualization, the data were grouped with a corresponding color representing a specific [Formula: see text] range according to their attenuation coefficient. Finally, the analyses were compared to histopathology. To ensure that each single use sterile imaging probe is comparable to the measurements of the other imaging probes, the probe-to-probe variations were analyzed by measuring attenuation coefficients of 0.03, 6.5, 11.4, 17, and 22.7 volume% Intralipid®. Experiments were repeated five times per probe for four probes. Inter- and intraprobe variation in the measured attenuation of Intralipid samples with scattering properties similar to that of the prostate was [Formula: see text] of the mean values. Mean attenuation coefficients in the prostate were [Formula: see text] for parts of the tissue that were classified as benign (SD: [Formula: see text], minimum: [Formula: see text], maximum: [Formula: see text]) and [Formula: see text] for parts of tissue that were classified as malignant (SD: [Formula: see text], minimum: [Formula: see text], maximum: [Formula: see text]). In benign areas, the tissue looked homogeneous, whereas in malignant areas, small glandular structures were seen. However, not all areas in which a high attenuation coefficient became apparent corresponded to areas of prostate cancer. This paper describes the first in-tissue needle-based OCT imaging and three-dimensional optical attenuation analysis of prostate tissue that indicates a correlation with pathology. Fully automated attenuation coefficient analysis was performed at 1300 nm over the full pullback. Correlation with pathology was achieved by coregistration of three-dimensional (3-D) OCT attenuation maps with 3-D pathology of the prostate. This may contribute to the current challenge of prostate imaging and the rising interest in focal therapy for reduction of side effects occurring with current therapies.

Endoscopic imaging: How far are we from real-time histology?

Currently, in gastrointestinal endoscopy there is increasing interest in high resolution endoscopic technologies that can complement high-definition white light endoscopy by providing real-time subcellular imaging of the epithelial surface. These ‘optical biopsy’ technologies offer the potential to improve diagnostic accuracy and yield, while facilitating real-time decision-making. Although many endoscopic techniques have preliminarily shown high accuracy rates, these technologies are still evolving. This review will provide an overview of the most promising high-resolution imaging technologies, including high resolution microendoscopy, optical coherence tomography, endocytoscopy and confocal laser endoscopy. This review will also discuss the application and current limitations of these technologies for the early detection of neoplasia in Barrett’s esophagus, ulcerative colitis and colorectal cancer.

Optical coherence tomography and Doppler optical coherence tomography in the gastrointestinal tract

Optical coherence tomography (OCT) is a noninvasive, high-resolution, high-potential imaging method that has recently been introduced into medical investigations. A growing number of studies have used this technique in the field of gastroenterology in order to assist classical analyses. Lately, 3D-imaging and Doppler capabilities have been developed in different configurations, which make this type of investigation more attractive. This paper reviews the principles and characteristics of OCT and Doppler-OCT in connection with analyses of the detection of normal and pathological structures, and with the possibility to investigate angiogenesis in the gastrointestinal tract.

Treatment of Barrett's esophagus with high-grade dysplasia

The incidence of esophageal adenocarcinoma is increasing in the USA, now accounting for at least 4% of US cancer-related deaths. Barrett's esophagus is the main risk factor for the development of esophageal adenocarcinoma. The annual incidence of development of adenocarcinoma in Barrett's esophagus is approximately 0.5% per year, representing at least a 30-40-fold increase in risk from the general population. High-grade dysplasia is known to be the most important risk factor for progression to adenocarcinoma. Traditionally, esophagectomy has been the standard treatment for Barrett's esophagus with high-grade dysplasia. This practice is supported by studies revealing unexpected adenocarcinoma in 29-50% of esophageal resection specimens for high-grade dysplasia. In addition, esophagectomy employed prior to tumor invasion of the muscularis mucosa results in 5-year survival rates in excess of 80%. Although esophagectomy can result in improved survival rates for early-stage cancer, it is accompanied by significant morbidity and mortality. Recently, more accurate methods of surveillance and advances in endoscopic therapies have allowed scientists and clinicians to develop treatment strategies with lower morbidity for high-grade dysplasia. Early data suggests that carefully selected patients with high-grade dysplasia can be managed safely with endoscopic therapy, with outcomes comparable to surgery, but with less morbidity. This is an especially attractive approach for patients that either cannot tolerate or decline surgical esophagectomy. For patients that are surgical candidates, high-volume centers have demonstrated improved morbidity and mortality rates for esophagectomy. The addition of laparoscopic esophagectomy adds a less invasive surgical resection to the treatment armanentarium. Esophagectomy will remain the gold-standard treatment of Barrett's esophagus with high-grade dysplasia until clinical research validates the role of endoscopic therapies. Current treatment strategies for Barrett's esophagus with high-grade dysplasia will be reviewed.

Optical coherence tomography in detection of dysplasia and cancer of the gastrointestinal tract and bilio-pancreatic ductal system

Optical coherence tomography (OCT) is an optical imaging modality that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10-25 times better (about 10 μm) than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1-3 mm, depending upon tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal (GI) tract and pancreatic-biliary ductal system. OCT imaging from the GI tract can be done in humans by using narrow-diameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the GI tract, or a side-view endoscope, inside a standard transparent ERCP catheter, for investigating the pancreatico-biliary ductal system. Esophagus and the esophago-gastric junction has been the most widely investigated organ so far; more recently, also duodenum, colon and pancreatico-biliary ductal system have been extensively investigated. OCT imaging of the gastro-intestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, and part of the submucosa. The technique may be, therefore, used to identify pre-neoplastic conditions of the GI tract, such as Barrett's epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis between neoplastic and non-neoplastic lesions.

The role of surveillance endoscopy and endosonography after endoscopic ablation of high-grade dysplasia and carcinoma of the esophagus

Barrett's esophagus (BE) with high-grade dysplasia (HGD) or early carcinoma treated with surgery or photodynamic therapy (PDT) is at risk of recurrence. The efficacy of endoscopic ultrasound (EUS) for surveillance after PDT is unknown. Our objective was to determine if EUS is superior to esophagogastroduodenoscopy (EGD) and/or CT scan for surveillance of BE neoplasia after PDT. The study was designed as a retrospective review with the setting as a tertiary referral center. Consecutive patients with BE with HGD or carcinoma in situ treated with PDT were followed with EUS, CT scan and EGD with jumbo biopsies every 1 cm at 3, 4, or 6-month intervals. Exclusion criteria was < 6 months of follow up and/or < 2 EUS procedures. Main outcome measurements were residual or recurrent disease discovered by any method. Results showed that 67/97 patients met the inclusion criteria (56 men and 11 women). Median follow-up was 16 months. Recurrent or residual adenocarcinoma (ACA) was detected in four patients during follow-up. EGD with random biopsies or targeted nodule biopsies detected three patients. EUS with endoscopic mucosal resection of the nodule confirmed T1 recurrence in one of these three. In the fourth patient, CT scan revealed perigastric lymphadenopathy and EUS-FNA (fine needle aspiration) confirmed adenocarcinoma. There were two deaths, one related to disease progression and one unrelated. The rate of recurrent/persistent ACA after PDT was 4/67 = 6%. EUS did not detect disease when EGD and CT were normal. Limitations of this study include non-blinding of results and preferential status of non-invasive imaging (CT) over EUS. Our experience suggests that EUS has little role in the surveillance of these patients, unless discrete abnormalities are found on EGD or cross-sectional imaging.

Optical coherence tomography: a review of clinical development from bench to bedside

Since its introduction, optical coherence tomography (OCT) technology has advanced from the laboratory bench to the clinic and back again. Arising from the fields of low coherence interferometry and optical time- and frequency-domain reflectometry, OCT was initially demonstrated for retinal imaging and followed a unique path to commercialization for clinical use. Concurrently, significant technological advances were brought about from within the research community, including improved laser sources, beam delivery instruments, and detection schemes. While many of these technologies improved retinal imaging, they also allowed for the application of OCT to many new clinical areas. As a result, OCT has been clinically demonstrated in a diverse set of medical and surgical specialties, including gastroenterology, dermatology, cardiology, and oncology, among others. The lessons learned in the clinic are currently spurring a new set of advances in the laboratory that will again expand the clinical use of OCT by adding molecular sensitivity, improving image quality, and increasing acquisition speeds. This continuous cycle of laboratory development and clinical application has allowed the OCT technology to grow at a rapid rate and represents a unique model for the translation of biomedical optics to the patient bedside. This work presents a brief history of OCT development, reviews current clinical applications, discusses some clinical translation challenges, and reviews laboratory developments poised for future clinical application.

Spectroscopy and fluorescence in esophageal diseases

Malignant tumors of the esophagus continue to be a major health issue associated with high mortality primarily because most present with symptoms of dysphagia or anaemia. The disease at that stage is advanced and not likely curable. The big issue for squamous dysplasia and that associated with BE is that only a small proportion are discovered in surveillance programs when they are asymptomatic, either because the patient lives in a high-incidence geographical area, has a family history, previously diagnosed head and neck cancer or chronic reflux, as in Barrett's. Current endoscopic methods are hampered by the endoscopist's inability to recognize subtle topographic clues of dysplasia, sampling errors related to biopsy protocols, and confounding inflammation-induced artifacts both for the endoscopist and pathologist. What is desperately needed would be a biomarker (e.g. serological, fecal, urinary) that selects patients for endoscopy. However, such a test is not yet on the horizon. This article examines the current status in practice and research of novel optically based 'bioendoscopic' devices (i.e. fluorescence spectroscopy and imaging, confocal fluorescence microendoscopy (CFM), light scattering spectroscopy (LSS), Raman spectroscopy (RS), and immunophotodiagnostic endoscopy) which may enhance the diagnosis of dysplasia in all patients undergoing conventional white light endoscopy. Perhaps these new technologies will lead to more cost-effective diagnosis, mapping (e.g. surface), and staging (e.g. depth) of dysplasia, thereby allowing timely cure by endoscopic means (e.g. EMR and/or PDT), biological interventions (e.g. Cox-2 inhibitors) rather than esophajectomy.

Present status of photodynamic therapy for high-grade dysplasia in Barrett's esophagus

GOALS

Review recent developments in Barrett's dysplasia including regulatory approval of porfimer sodium photodynamic therapy.

BACKGROUND

Barrett's esophagus is thought to be the result of long-standing gastroesophageal reflux disease and is known to be the most important risk factor for the development of esophageal adenocarcinoma. The natural history of Barrett's esophagus is not well known, but the annual incidence of invasive adenocarcinoma is estimated to be 0.5% (reported range, 0.2%-2.0%). This represents an increased risk for esophageal cancer of 30 to 60 times higher than normal subjects. As for colorectal cancer, malignant degeneration is Barrett's esophagus is thought to occur through a continuum of histologic stages: metaplasia, dysplasia and neoplasia. Barrett's high-grade dysplasia (formerly referred to as carcinoma in situ) is the histologic stage of disease that immediately precedes the development of invasive carcinoma.

CONCLUSIONS

Previously, Barrett's high-grade dysplasia patients were routinely referred for esophageal resection surgery based upon the assumption of inevitable progression to cancer, the high rate of undiagnosed synchronous cancers, and few treatment alternatives. Important developments in Barrett's high-grade dysplasia include recent publications regarding the natural history of Barrett's high-grade dysplasia and the regulatory approval for endoscopic ablation therapy using porfimer sodium photodynamic therapy (Photofrin PDT).