Faculty Bibliography

Background: The majority of benign colorectal lesions can be removed using endoscopic mucosal resection techniques. For lesions that are tethered down, nonlifting, invasive or in anatomically challenging locations, advanced endoscopic techniques or surgical resection are typically required. A novel endoscopic full-thickness resection (FTR) device (FTRD, Ovesco Endoscopy, Tuebingen, Germany) was recently approved for use in the United States. Safety and efficacy data on the use of this device have not previously been reported from North America. We present our initial experience with the over-the-scope FTRD in a series of consecutive patients treated in our center. Study Design: We performed a single-center retrospective cohort study, of consecutive patients who underwent endoscopic FTR since its approval in mid-2017. All procedures were performed by a single experienced endoscopist who received training in the use of the device. Primary outcomes were technical success, R0 resection, and adverse events. Patient demographics, indication, and procedural characteristics were collected and analyzed. Method: Routine colonoscopy with an adult colonoscope was advanced to the lesion to be resected. The peripheries of the lesions were marked with a specific cautery probe in four quadrants. The colonoscope was then withdrawn and a second colonoscope with the attached hood, clip, snare, and sleeve was re-introduced and advanced to the lesion. An alligator forceps was used to grasp the lesion to pull it into the hood. The full thickness 'bearclaw' clip was then deployed followed immediately by snare excision of the entrapped tissue. The tissue was pinned, measured, and then sent to pathology. Results: FTR was attempted in a total of 10 patients (Table 1). The primary indication for FTR was non-lifting adenoma (5 patients, 50%). For three patients the indication was an inaccessible location (appendiceal/diverticular), and another two were referred for removal of subepithelial carcinoids. The size of the lesions averaged 16 mm and ranged up to 40 mm in one patient in whom a hybrid resection (EMR + FTR) was performed. The majority of lesions were flat (Paris class IIc or IIa + IIc). Technical success was achieved in nine of ten patients (Table 2). For one 89-year old patient, the procedure was aborted due to difficulties in advancing the FTRD through a tortuous sigmoid colon. Procedure duration averaged 71 minutes. R0 resection of the lesion was achieved in eight patients (pathology pending in one) in whom the FTR device was deployed. One significant adverse event was recorded: the FTR device clip was not deployed prior to full thickness snare incision in one patient resulting in a large perforation. The defect edges were then approximated and the FTR clip was deployed with successful closure of the perforation with no adverse sequela

BACKGROUND AND AIMS: Wide-area transepithelial sampling (WATS) with computer-assisted 3-dimensional analysis is a sampling technique that combines abrasive brushing of the Barrett's esophagus (BE) mucosa followed by neural network analysis to highlight abnormal-appearing cells. METHODS: We performed a randomized trial of referral BE patients undergoing surveillance at 16 medical centers. Subjects received either biopsy followed by WATS, or vice versa. The primary outcome was rate of detection of HGD/EAC using WATS in conjunction with biopsy compared with biopsy alone using standard histopathologic criteria. Secondary aims included evaluating neoplasia detection rates (1) based on the procedure order (WATS vs biopsy first) (2) of each procedure separately, and (3) the additional time required for WATS. RESULTS: One hundred sixty patients (mean age 63.4 years, 76% male; 95% white) completed the trial. The median circumferential and maximal BE extents were 1.0 (IQR: 0.0-5.0) cm and 4.0 (IQR, 2.0-8.0) cm, respectively. The diagnostic yield for biopsy alone was as follows: HGD/EAC, 7 (4.4%); low-grade dysplasia (LGD), 28 (17.5%); non-dysplastic BE (NDBE), 106 (66.25%); and no BE, 19 (11.9%). The addition of WATS to biopsy yielded an additional 23 cases of HGD/EAC (absolute increase, 14.4%; 95% CI, 7.5%-21.2%). Among these 23 patients, 11 were classified by biopsy as NDBE, and 12 as LGD/IND; 14 received biopsy and 9 WATS first (p=NS) and the majority (n=21; 91.7%) had a prior dysplasia history. WATS added average of 4.5 minutes to the procedure. CONCLUSION: Results of this multicenter, prospective, randomized trial demonstrate that the use of WATS in a referral BE population increases the detection of HGD/EAC.

Group testing estimation, which utilizes pooled rather than individual units for testing, has been an ongoing area of research for over six decades. While it is often argued that such methods can yield large savings in terms of resources and/or time, these benefits depend very much on the initial choice of pool sizes. In fact, when poor group sizes are used, the results can be much worse than those obtained using standard techniques. Tools for addressing this problem in the literature have been based on either large sample results or prior knowledge of the parameter being estimated, with little guidance when these assumptions are not met. In this paper, we introduce and study random walk designs for choosing pool sizes when only a small number of tests can be run and prior knowledge is vague. To illustrate these methods, application is made to the estimation of prevalence for two diseases among Australian chrysanthemum crops.

Introduction: Cholangiocarcinoma and pancreatic adenocarcinoma account for over 190,000 new clinical cases of pancreatobiliary malignancy worldwide annually. For palliation of obstructive jaundice in these patients, plastic or self-expanding metal stent (SEMS) are placed. However, re-occlusion rates for currently available stents range as high as 36% for uncovered metal stents, 25% for covered metal stents and 52% for plastic stents. Tissue ingrowth accounts for up to 76% of occlusions of bare metal stents.1, 2, 3, 4 Stent occlusion can result in recurrent obstruction and typically requires endoscopic re-intervention. Therefore there is a real clinical need to reduce tissue ingrowth and improve biliary stent patency rates. Aims & Methods: In this study we developed and tested a controlled-release paclitaxel-eluting SEMS designed to prevent tissue hyperplasia and stent occlusion. A 4 cm length uncovered, laser-cut nitinol stent was coated with a polymer matrix allowing slow release of paclitaxel. Naive Yucatan swine were assigned to one of three stent groups: bare control (n=3, no polymer), standard dose paclitaxel (n=6, 149.4 mg paclitaxel) and challenge dose (n=3, 538.0 mg paclitaxel. Two stents were endoscopically implanted in each swine from its assigned group, one in the intrahepatic/hilar region and a second in the common bile duct placed proximal to the papilla. Stents were assessed for migration via digital radiographs for the first 2 weeks and then monthly via endoscopy using SpyGlassTM DS cholangioscopy and cholangiography with a targeted 6 month study endpoint. Results: At 30 days post-implant, no significant tissue reaction to any stent was observed. However, all animals displayed mild biofilm formation and increased intraductal mucus production. Substantial dilation of the common bile duct was observed in 5/11 animals with no apparent relationship between drug coating and duct dilation. At 60 days post-implant, moderate mucus and biofilm formation was observed within the stent, however in only 3 animals biliary ductal dilation persisted and the majority of stents were fully apposed to the duct wall. Although some animals displayed minimal tissue hyperplasia at the proximal end of the stents, no tissue overgrowth or stent embedding was observed in any animal. Up to 60 days post-implant, no persistent clinical symptoms were observed in any animal. Stents in one standard dose animal migrated out of the bile duct between days 15 and 30, this animal is not included in patency results reported. At both 30 and 60 day timepoints, no apparent differences in outcome were observed among the three study groups. Conclusion: At this mid-study follow-up, paclitaxel-eluting stents appear to be safe for use in naive tissue and do not negatively impact function of the biliary system, even at challenge condition doses. Although the cause of bile duct dilation observed in all stent groups has not been conclusively identified, we hypothesize the cause may be distal stent impaction and intermittent (clinically insignificant) obstruction of the papilla and/or stent, resulting in retained mucus and bile. Bile duct dilation, in turn, has reduced the opportunity for tissue overgrowth in all stent groups, which was expected to occur in the bare stent control group by 60 days post-implant5. Given the observed 60% reduction in number of dilated ducts between days 30 and 60, we expect increased rate of apposition. Ongoing efforts include continued follow-up for an additional 120 days, and in a second cohort, determination of in vivo drug release rates in the bile duct over a 30 day period. Future cholangioscopic and histopathological assessment of these swine will further clarify the safety and effectiveness of paclitaxel stent coatings to mediate bile duct tissue ingrowth