ENDOSCOPIC APPROACH TO THE PANCREATOBILIARY TRACT USING NARROW BAND IMAGING

The role of pancreatoscopy in the diagnostic work-up of intraductal papillary mucinous neoplasms: a systematic review and meta-analysis

BACKGROUND

Confirming the diagnosis, invasiveness, and disease extent of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas is challenging. The aim of this study was to summarize the literature on the efficacy and safety of peroral pancreatoscopy (POP) in the diagnosis of IPMN, including the impact of pre- and intraoperative POP on the management of IPMN.

METHODS

The EMBASE, Medline Ovid, Web of Science, Cochrane CENTRAL, and Google Scholar databases were systematically searched for articles. Eligible articles investigated cohorts of patients who underwent POP for (suspected) IPMN.

RESULTS

25 articles were identified and included in this review; with 22 of these reporting on the diagnostic yield of POP in IPMN and 11 reporting on the effect of pre- or intraoperative POP on clinical decision-making. Cannulation and observation rates, and overall diagnostic accuracy were high across all studies. Frequently reported visual characteristics of IPMN were intraductal fish-egg-like lesions, hypervascularity, and granular mucosa. Overall, the adverse event rate was 12 %, primarily consisting of post-endoscopic retrograde cholangiopancreatography pancreatitis, with a pooled rate of 10 %, mostly of mild severity. Regarding the impact of POP on clinical decision-making, POP findings altered the surgical approach in 13 %-62 % of patients.

CONCLUSION

POP is technically successful in the vast majority of patients with (suspected) IPMN, has a consistently high diagnostic accuracy, but an adverse event rate of 12 %. Data on intraoperative pancreatoscopy are scarce, but small studies suggest its use can alter surgical management. Future studies are needed to better define the role of POP in the diagnostic work-up of IPMN.

Types of Peroral Cholangioscopy: How to Choose the Most Suitable Type of Cholangioscopy

OPINION STATEMENT

A number of case studies have described the usefulness of peroral cholangioscopy for diagnosis and therapy, performed by visualizing the inner cavity of the bile duct. Currently available types of peroral cholangioscopy include peroral videocholangioscopy (POCS) using a mother-baby scope system (MBSS), direct peroral videocholangioscopy (D-POCS), and SpyGlass™ Direct Visualization System (SGDVS). POCS started with cholangioscopy using MBSS, requiring two skilled endoscopists using two endoscopic systems. On the other hand, D-POCS and SGDVS were developed as single-operator techniques. In MBSS, the videocholangioscope is inserted into the bile duct through the accessory channel of a conventional therapeutic duodenoscope. MBSS enables comparatively easy scope insertion into the bile duct and stable scope positioning. POCS using MBSS provides excellent images and can be coupled with an image-enhanced function system. However, it has a smaller accessory channel, limiting the devices that can be used. Additionally, scope fragility is serious problem. D-POCS using an ultraslim upper endoscope has been introduced to overcome the drawback of POCS using MBSS. D-POCS has a larger working channel and requires only one endoscopist. D-POCS allows a greater variety of procedures under excellent imaging even with an image-enhanced function system; however, scope insertion is still challenging. SGDVS is designed for single-operator use and is dedicated to procedural purposes. It comprises a reusable optical probe and disposable delivery catheter, which has four-way deflected steering and dedicated irrigation channels. These features lead to good maneuverability, although image quality is poor due to its optical probe system. All systems' features should be recognized and the appropriate system used depending on the need. Cholangioscopy has shown dramatic progress from diagnosis to therapy with high future growth potential.

Can image-enhanced cholangioscopy distinguish benign from malignant lesions in the biliary duct?

A new video peroral cholangioscopy (POCS) has been developed with high-quality digital imaging, and its clinical use has been reported. Additionally, direct peroral cholangioscopy (D-POCS) using an ultraslim endoscope has been proposed recently. To improve the diagnostic yield of POCS or D-POCS, image-enhanced endoscopy has been used in combination. Chromoendoscopy with methylene blue staining (ME), autofluorescence imaging (AFI), and narrow-band imaging (NBI) has been evaluated in biliary tract diseases. Observation of the mucosal structure and vessels is reportedly important for distinguishing non-neoplasms from neoplasms. Therefore, NBI is the most promising tool among image-enhanced endoscopies as it can enhance visualization of the mucosal structure and vessels simultaneously. There are currently few reports that have evaluated the utility of POCS or D-POCS based on pathological findings. Thus, endoscopic findings of the bile duct mucosa have not yet been fully established. At present, POCS-guided biopsy should be carried out.

Near-infrared fluorescence cholangiopancreatoscopy: initial clinical feasibility results

BACKGROUND

The recent clinical propagation of targeted fluorescence agents brings a promising alternative in endoscopy by complementing visual disease detection with molecular biomarkers.

OBJECTIVE

Development of near-infrared (NIR) fluorescence cholangiopancreatoscopy in real-time and validation of its clinical use.

DESIGN

Feasibility study.

SETTING

Tertiary referral center at a large university hospital.

PATIENTS

Patients with pancreatic and biliary diseases.

INTERVENTIONS

Routine cholangiopancreatoscopy with additional wide-field NIR fluorescence imaging.

MAIN OUTCOME MEASUREMENTS

We adapted a miniature cholangioscope for real-time concurrent wide-field color and NIR fluorescence imaging. Illumination is provided through a custom-designed fiber bundle, and the acquired images are relayed via a dichroic beam splitter to 2 charge-coupled devices for simultaneous measurement. We characterize the sensitivity and resolution and demonstrate the clinical feasibility by detecting indocyanine green localization in 2 patients.

RESULTS

A spatial optical resolution of approximately 50 μm was achieved, and fluorescent dye concentrations of 17.3 nM could be detected. Elevated fluorescence signals were detected during clinical measurements, and biopsy specimens confirmed the presence of malignancy in both patients.

LIMITATIONS

Feasibility study, limited number of patients.

CONCLUSIONS

The results demonstrate that real-time wide-field fluorescence detection in the NIR range is possible in humans by using adapted endoscopes. The feasibility of detecting indocyanine green in the pancreatobiliary ducts is verified, suggesting that cancer screening at a molecular level might play an increasingly important role in the future.

Intraoperative pancreatoscopy with narrow band imaging: a novel method for assessment of resection margins in case of intraductal papillary mucinous neoplasm

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) is characterized by intraductal proliferation of neoplastic mucinous cells with a variable extent along the main duct or its branches. The lesion may be continuous or discontinuous. Skip lesions have been described in about 6-19% of cases. Complete resection without leaving behind any skip lesions is important, to such an extent that many groups suggest even total pancreatectomy, a major and morbid surgery.

METHODS

A 40 year-male patient with chronic pancreatitis presented with recent-onset diabetes mellitus and weight loss. Ultrasound and computed tomography (CT) scan showed a cystic lesion in the head and uncinate process of pancreas. Peroral pancreatoscopy showed villous projections with dilated tortuous vessel in the head, suspicious of IPMN. The duct beyond pancreatic head could not be visualized and remained unassessed. At pancreatoduodenectomy, pancreatoscopy with narrow band imaging (NBI) was done using flexible pancreatoscope through the cut end of the duct at the neck to assess the duct in the body and tail.

RESULTS

Pancreatoscopy with NBI showed a normal-looking resection margin and a skip lesion 1 cm beyond it. The revised resection margin confirmed the skip lesion on frozen section and also that the fresh cut margin was negative. The remaining duct in the body and tail was normal on pancreatoscopy. Total clearance of the disease could be achieved without a major procedure such as total pancreatectomy.

CONCLUSIONS

Intraoperative pancreatoscopy, especially with NBI, is a good diagnostic tool for IPMN and also helps in intraoperative decision-making of the resection margins.

Narrow band imaging versus conventional white light colonoscopy for the detection of colorectal polyps

BACKGROUND

It has been suggested that narrow band imaging colonoscopy (NBI) might be better for detection of colorectal polyps than white light colonoscopy (WLC).

OBJECTIVES

To compare standard or high definition white light colonoscopy with narrow band imaging colonoscopy for detection of colorectal polyps.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, and EMBASE to August 2011. We scanned bibliographies of relevant publications and wrote to experts for additional trials.

SELECTION CRITERIA

Two authors (NA and GB) independently applied the inclusion criteria and extracted the data to all potential studies without blinding.

DATA COLLECTION AND ANALYSIS

Authors extracted data independently. Trials with adequate randomisation, allocation concealment, and complete outcome data reporting, as well as without selective outcome reporting or other bias were classified as having a lowest risk of bias. Random-effects and fixed-effect meta-analyses were conducted.

MAIN RESULTS

We identified 11 randomised trials comparing WLC with NBI for detection of colorectal polyps. In total eight randomised trials with 3673 participants provided data for our analyses. There was no statistically significant difference between WLC (standard definition and high definition pooled) and NBI for the detection of patients with colorectal polyps (6 trials, n = 2832, RR 0.97, 95% CI 0.91 to 1.04), patients with colorectal adenomas (8 trials, n = 3673, RR 0.94, 95% CI 0.87 to 1.02), or patients with colorectal hyperplastic polyps (2 trials, n = 645, RR 0.87, 95% CI 0.76 to 1.00). Number of patients with at least one colorectal adenoma was not significantly different between WLC and NBI group irrespective of adenoma size (< 5 mm:RR 0.95, 95% CI 0.84 to 1.08, I(2) = 56%; 6 to 9 mm: RR 1.06, 95% CI 0.81 to 1.39, I(2) = 0%; ≥ 10 mm: RR 1.06, 95% CI 0.77 to 1.45, I(2) = 0%). Number of patients with at least one colorectal polyp, or colorectal adenoma was significantly lower in the standard definition WLC group compared to NBI group in fixed-effect meta-analysis (RR 0.87, 95% CI 0.78 to 0.97, I(2) = 78%; RR 0.87, 95% CI 0.77 to 0.99, I(2) = 0%, respectively), but not significantly different in random-effects meta-analysis (RR 0.86, 95% CI 0.68 to 1.10, I(2) = 78%). There was no statistically significant difference between high definition WLC and NBI in the number of patiens with at least one colorectal polyp or colorectal adenoma (RR 1.10, 95% CI 0.95 to 1.28; RR 0.87, 95% CI 0.77 to 0.99, I(2) = 0%, respectively).

AUTHORS' CONCLUSIONS

We could not find convincing evidence that NBI is significantly better than high definition WLC for the detection of patients with colorectal polyps, or colorectal adenomas. We found evidence that NBI might be better than standard definition WLC and equal to high definition WLC for detection the patients with colorectal polyps, or colorectal adenomas.