Optical coherence tomography to detect epithelial lesions of the main pancreatic duct: an Ex Vivo study

First interobserver agreement of optical coherence tomography in the bile duct: A multicenter collaborative study

Background and study aims  Optical coherence tomography (OCT) is a new technology available for evaluation of indeterminate biliary strictures. It allows under-the-surface visualization and preliminary studies have confirmed standardized characteristics associated with malignancy. The aim of this study is to evaluate the first interobserver agreement in identifying previously agreed upon OCT criteria and diagnosing of malignant versus benign disease. Patients and methods  Fourteen endoscopists were asked to review an atlas of reference clips and images of eight criteria derived from expert consensus A total of 35 de-identified video clips were then evaluated for presence of the eight criteria and for final diagnosis of malignant versus benign using the atlas as reference Intraclass correlation (ICC) analysis was done to evaluate interrater agreement. Results  Clips of 23 malignant lesions and 12 benign lesions were scored. Excellent interobserver agreement was seen with dilated hypo-reflective structures (0.85) and layering effacement (0.89); hyper-glandular mucosa (0.76), intact layering (0.81), and onion-skin layering (0.77); fair agreement was seen with scalloping (0.58), and thickened epithelium (0.4); poor agreement was seen with hyper-reflective surface (0.36). The diagnostic ICC for both neoplastic (0.8) and non-neoplastic (0.8) was excellent interobserver agreement. The overall diagnostic accuracy was 51 %, ranging from 43 % to 60 %. Conclusions  Biliary OCT is a promising new modality for evaluation of indeterminate biliary strictures. Interobserver agreement ranged from fair to almost perfect on eight previously identified criteria. Interobserver agreement for malignancy diagnosis was substantial (0.8). Further studies are needed to validate this data.

Optical coherence tomography of the pancreatic and bile ducts: are we ready for prime time?

Background and study aims  First-generation optical coherence tomography (OCT) has been shown to increase diagnostic sensitivity for malignant biliary and pancreatic-duct strictures. A newer OCT imaging system, NVision Volumetric Laser Endomicroscopy (VLE), allows for in vivo cross-sectional imaging of the ductal wall at the microstructure level during endoscopic retrograde cholangiopancreatography (ERCP). The aim of this study was to identify and evaluate characteristics on OCT that are predictive of benign and malignant strictures. Patients and methods  Consecutive patients from six centers who underwent OCT between September 2016 and September 2017 were included in a dedicated registry. OCT images were analyzed, and nine recurring characteristics were further assessed. Final diagnosis was based on histology and/or surgical pathology. Results  86 patients were included (49 % male, mean age 64.7). OCT was performed in the bile duct in 79 patients and the pancreatic duct in seven. Nine OCT characteristics were identified: dilated hypo-reflective structures (n = 7), onion-skin layering (n = 8), intact layering (n = 17), layering effacement (n = 25), scalloping (n = 20), thickened epithelium (n = 42), hyper-glandular mucosa (n = 13), prominent blood vessels (n = 6), and a hyper-reflective surface (n = 20). Presence of hyper-glandular mucosa, hyper-reflective surface and scalloping significantly increased the odds of malignancy diagnosis by 6 times more ( P  = 0.0203; 95 % CI 1.3 to 26.5), 4.7 times more ( P  = 0.0255; 95 % CI 1.2 to 18.0) and 7.9 times more ( P  = 0.0035; 95 % CI 1.97 to 31.8) respectively. Conclusion  By providing in-vivo cross-sectional imaging of the pancreatic and biliary duct wall, OCT technology may improve sensitivity in diagnosing malignant strictures and provide standardizable criteria predictive of malignancy.

The clinical usefulness of optical coherence tomography during cancer interventions

INTRODUCTION

Tumor detection and visualization plays a key role in the clinical workflow of a patient with suspected cancer, both in the diagnosis and treatment. Several optical imaging techniques have been evaluated for guidance during oncological interventions. Optical coherence tomography (OCT) is a technique which has been widely evaluated during the past decades. This review aims to determine the clinical usefulness of OCT during cancer interventions focussing on qualitative features, quantitative features and the diagnostic value of OCT.

METHODS

A systematic literature search was performed for articles published before May 2018 using OCT in the field of surgical oncology. Based on these articles, an overview of the clinical usefulness of OCT was provided per tumor type.

RESULTS

A total of 785 articles were revealed by our search, of which a total of 136 original articles were available for analysis, which formed the basis of this review. OCT is currently utilised for both preoperative diagnosis and intraoperative detection of skin, oral, lung, breast, hepatobiliary, gastrointestinal, urological, and gynaecological malignancies. It showed promising results in tumor detection on a microscopic level, especially using higher resolution imaging techniques, such as high-definition OCT and full-field OCT.

CONCLUSION

In the near future, OCT could be used as an additional tool during bronchoscopic or endoscopic interventions and could also be implemented in margin assessment during (laparoscopic) cancer surgery if a laparoscopic or handheld OCT device will be further developed to make routine clinical use possible.

In vivo optical spectroscopy for improved detection of pancreatic adenocarcinoma: a feasibility study

Pancreatic adenocarcinoma has a five-year survival rate of less than 6%. This low survival rate is attributed to the lack of accurate detection methods, which limits diagnosis to late-stage disease. Here, an in vivo pilot study assesses the feasibility of optical spectroscopy to improve clinical detection of pancreatic adenocarcinoma. During surgery on 6 patients, we collected spectrally-resolved reflectance and fluorescence in vivo. Site-matched in vivo and ex vivo data agreed qualitatively and quantitatively. Quantified differences between adenocarcinoma and normal tissues in vivo were consistent with previous results from a large ex vivo data set. Thus, optical spectroscopy is a promising method for the improved diagnosis of pancreatic cancer in vivo.

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.

Investigation of Oddi sphincter structure by optical coherence tomography in patients with biliary-type 1 dysfunction: a pilot in vivo study

BACKGROUND

Type 1 sphincter of Oddi dysfunction is a clinical entity characterised by biliary-type pain, elevated liver biochemical tests, and common bile duct dilation. Sphincter fibrosis is a common finding in this type of dysfunction and may require in some cases a differential diagnosis with a malignant intra-papillary disease. Optical coherence tomography permits high-resolution, real-time imaging of the sphincter of Oddi microstructure by a probe inserted into the common bile duct through an ERCP catheter. No data exist on the evaluation of sphincter of Oddi fibrosis by optical coherence tomography during ERCP in vivo.

OBJECTIVE

To assess the feasibility of optical coherence tomography investigation of the sphincter of Oddi structure and assess its potential for diagnosing type 1 sphincter of Oddi dysfunction.

PATIENTS

Ten consecutive patients, five with biliary-type 1 sphincter of Oddi dysfunction and five with pancreatic head/mid-body adenocarcinoma not involving the papillary region, who underwent both endoscopic ultrasound and therapeutic ERCP, were investigated by optical coherence tomography immediately before biliary sphincterotomy or stenting.

RESULTS

In all sphincter of Oddi dysfunction patients optical coherence tomography recognised a hyper-reflective intermediate, fibro-muscular layer, significantly thicker than in patients with non-pathological sphincter of Oddi (p<0.0001).

CONCLUSIONS

Optical coherence tomography imaging recognised an increased thickness and reflectance of the fibro-muscular layer of the sphincter of Oddi, very likely determined by fibrosis, and was not time-consuming; it can be safely used during ERCP to confirm the diagnosis in difficult cases. Its use in clinical practice has one important limitation since it requires magnification in the post-procedure computer analysis to obtain images useful for diagnosis.

Optical coherence tomography for bile and pancreatic duct imaging

Optical coherence tomography (OCT) is an optical imaging modality introduced in 1991 that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure in materials and biologic systems by measuring backscattered or backreflected infrared light. OCT has been used for biomedical applications where many factors affect the feasibility and effectiveness of any imaging technique. The highly scattering and absorbing living tissues greatly limit the application of optical imaging modalities. 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 pancreaticobiliary ductal system.

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.

Optical coherence tomography in inflammatory bowel disease: prospective evaluation of 35 patients

PURPOSE

Optical coherence tomography is a technique using infrared light in tissues of the gastrointestinal tract and human colon affected by inflammatory diseases. We evaluated whether there are specific patterns of optical coherence tomography for inflammatory bowel disease and compared the technique performance to the histology.

METHODS

Optical coherence tomography was performed in 35 patients (18 men; 31 ulcerative colitis, 4 Crohn's disease). The images were obtained from affected and normal colon at endoscopy. Two biopsies of the sites visualized were taken. Two endoscopists scored the images, and two pathologists, blind to the endoscopy and optical coherence tomography, performed the histologic evaluation.

RESULTS

Three optical coherence tomography patterns were identified: 1) mucosal backscattering alteration, 2) delimited dark areas, and 3) layered colonic wall. Compared with the histology, mucosal backscattering alteration was the most effective in recognizing the disease in patients (P = 0.007 in colon segments affected, and P < 0.001 in normal segments). The sensitivity and specificity have been 100 and 78 percent, respectively.

CONCLUSIONS

The in vivo optical coherence tomography correctly detected inflammatory bowel disease features in affected and apparently normal colon, and allowed to discriminate patterns for active ulcerative colitis and Crohn's disease.

Probing pancreatic disease using tissue optical spectroscopy

Pancreatic adenocarcinoma, one of the leading causes of cancer death in the United States, has a five-year survival rate of only 4%. Present detection methods do not provide accurate diagnosis in the disease's early stages. To investigate whether optical spectroscopy could potentially aid in early diagnosis and improve survival rates, reflectance and fluorescence spectroscopies were employed for the first time in a limited pilot study to probe freshly excised human pancreatic tissues (normal, pancreatitis, and adenocarcinoma) and in vivo human pancreatic cancer xenografts in nude mice. In human pancreatic tissues, measurements were associated with endogenous fluorophores NAD(P)H and collagen, as well as tissue optical properties, with larger relative collagen content detected in adenocarcinoma and pancreatitis than normal. Good correspondence was observed between spectra from adenocarcinoma and cancer xenograft tissues. Reflectance data indicated that adenocarcinoma had higher reflectance in the 430- to 500-nm range compared to normal and pancreatitis tissues. The observed significant differences between the fluorescence and reflectance properties of normal, pancreatitis, and adenocarcinoma tissues present an opportunity for future statistical validation on a larger patient pool and indicate a potential application of multimodal optical spectroscopy to differentiate between diseased and normal pancreatic tissue states.

Intraductal optical coherence tomography for investigating main pancreatic duct strictures

BACKGROUND AND STUDY AIMS

Optical coherence tomography (OCT) permits high-resolution imaging of tissue microstructures using a probe that can be inserted into the main pancreatic duct (MPD) through a standard endoscopic retrograde cholangiopancreatography (ERCP) catheter. This prospective study was designed to assess the diagnostic capacity of OCT to differentiate between nonneoplastic and neoplastic lesions in patients with MPD segmental strictures.

PATIENTS AND METHODS

Twelve consecutive patients with documented MPD segmental stricture were investigated by endoscopic ultrasonography (EUS), with fine-needle aspiration cytology if necessary, and ERCP, followed by brush cytology and OCT scanning.

RESULTS

OCT recognized a differentiated three-layer architecture in all cases with normal MPD or chronic pancreatitis, while in all the neoplastic lesions the layer architecture appeared totally subverted, with heterogeneous backscattering of the signal. The accuracy of OCT for detection of neoplastic tissue was 100% compared with 66.7% for brush cytology. In one case, neither OCT scanning nor brush cytology was possible because of the severity of the stricture.

CONCLUSIONS

This pilot study showed that OCT is feasible during ERCP, in cases of MPD segmental stricture, and was superior to brush cytology in distinguishing nonneoplastic from neoplastic lesions.

Optical coherence tomography evaluation of ulcerative colitis: the patterns and the comparison with histology

HYPOTHESIS

The optical coherence tomography (OCT) is an imaging modality based on infrared light backscattering properties of tissues. OCT studies documented the disappearance of crypts and the alteration in light backscattering as features of ulcerative colitis (UC) in human colon. This technique should be more and more able to identify tissue microstructures with a resolution that is nearly that of histology (optical biopsy).

AIM

To evaluate whether there are OCT patterns specific for UC and to compare the overall technique performance with the histology.

METHODS

A total of 27 patients (20-76 yr) with UC underwent OCT imaging during a total colonoscopy. The OCT images were collected both from affected and normal sites in active UC or disease in remission. Two biopsies of the same sites were acquired. The OCT images were separately scored. Two pathologists blinded to the endoscopic and OCT patterns scored the samples.

RESULTS

Three OCT patterns were identified: the mucosal backscattering alteration (MBA), the delimited dark areas (DDA), and the layered colonic wall (LCW). In colon affected segments of active and UC in remission, these patterns showed a good correspondence with the histology. Moreover, in 14/25 (56%) normal sites above the affected segment, the OCT documented the pathological features, confirmed only in 10/14 by the histology. Thus, the assessed sensitivity and specificity of OCT in normal segments of UC patients have been 100% and 69%, respectively.

CONCLUSIONS

The in vivo OCT correctly detected disease features in endoscopically affected colon segments, but even in apparently normal segments of UC patients.

New advances in pancreatic imaging

PURPOSE OF REVIEW

This review serves to highlight new technology and novel applications of existing techniques and their role in the management of pancreatic diseases, including acute and chronic pancreatitis, pancreatic cancer, and pancreatic cystic neoplasms.

RECENT FINDINGS

Contrast-enhanced ultrasound has shown promise in evaluating the severity of acute pancreatitis, staging pancreatic cancer, and predicting malignancy in cystic neoplasms. Optical coherence tomography within the pancreatic duct appears to be able to differentiate malignant and normal pancreatic ducts. Spectroscopy may prove useful in differentiating focal chronic pancreatitis from malignancy. Multidetector-row computed tomography may provide more accurate information regarding cancer respectability and differentiation between ductal type of intraductal papillary mucinous tumors.

SUMMARY

These new developments will help with the diagnosis and staging of pancreatic diseases.

Optical coherence tomography compared with histology of the main pancreatic duct structure in normal and pathological conditions: an 'ex vivo study'

BACKGROUND AND STUDY AIMS

Optical coherence tomography permits high-resolution imaging of tissue microstructures by a probe inserted into the main pancreatic duct through a standard ERCP catheter. The aim of this study was to compare optical coherence tomography images of the main pancreatic duct with histology and identify the optical coherence tomography pattern of the normal and pathological structure of the main pancreatic duct.

PATIENTS AND METHODS

Multiple sections of neoplastic and non-neoplastic segments of 10 consecutive surgical pancreatic specimens obtained from patients with pancreatic head adenocarcinoma were investigated by optical coherence tomography scanning within 1h of resection. One hundred optical coherence tomography findings were then compared with the corresponding histopathological diagnoses.

RESULTS

Main pancreatic duct wall architecture appeared at optical coherence tomography investigation as a three-layer structure with a different back-scattered signal from each layer. Optical coherence tomography imaging was concordant with histology in 81.8% and 18.75% of sections with normal tissue and chronic inflammatory changes. The K statistic between the two procedures was equal to 0.059 for non-neoplastic main pancreatic duct wall appearance. In all neoplastic sections optical coherence tomography showed a subverted layer architecture with heterogeneous back-scattering of the signal and was concordant with histology.

CONCLUSIONS

Optical coherence tomography provided images of main pancreatic duct wall structure that were concordant with histology in 100% of cases in presence of neoplastic ductal changes and did not have false-positive or negative results. Optical coherence tomography images were also concordant with histology in about 80% of cases with normal main pancreatic duct structure; however, the differential diagnosis between normal tissue and chronic pancreatitis or dysplastic changes appeared very difficult.

Main pancreatic duct, common bile duct and sphincter of Oddi structure visualized by optical coherence tomography: An ex vivo study compared with histology

BACKGROUND

Optical coherence tomography has been proposed to obtain high-resolution imaging of tissue structure of GI tract. Up till now, the optical coherence tomography appearance of the common bile duct, main pancreatic duct and sphincter of Oddi wall structure has not yet been defined.

AIMS

To compare, in a prospective study, optical coherence tomography images of pancreato-biliary ductal system with histology and identify the optical coherence tomography pattern of the normal wall structure of the ducts.

METHODS

Multiple sections of non-neoplastic segments of five consecutive ex vivo human pancreatic specimens were investigated by optical coherence tomography scanning within 1h of resection. Sixty optical coherence tomography images were compared with the corresponding histological findings.

RESULTS

Optical coherence tomography appearance of normal common bile duct, main pancreatic duct and sphincter of Oddi is characterized by a differentiated three-layer architecture with a regular surface and a homogeneous back-scattered signal, corresponding to the single layer of epithelial cells, the connective-muscular layer and the muscular or acinar structure, respectively. Optical coherence tomography and histology findings were concordant in all cases.

CONCLUSIONS

Optical coherence tomography was able to provide in real-time images of wall structure of the normal common bile duct, main pancreatic duct and sphincter of Oddi that are similar to those obtained by histology. These results suggest that optical coherence tomography could enable high-resolution images to be obtained from the pancreato-biliary system during an ERCP procedure.