Faculty Bibliography

AIM/OBJECTIVE:A randomized controlled trial (RCT) was conducted to test the null hypothesis that there is no difference in complication rates and length of stay (LOS) between laparoscopic right colectomy (LRC) and laparoscopic-assisted colonoscopic polypectomy (LACP) for endoscopically unresectable polyps of the right colon. METHOD/METHODS:A single-centre RCT (NCT01986699) was conducted on patients with polyps of the right colon deemed by the gastroenterologist to be unresectable. Patients underwent a repeat colonoscopy with biopsy by an interventional endoscopist and were allocated to LRC or LACP. Patients with a nonlift sign, dysplasia, adenocarcinoma, inflammatory bowel disease or familial adenomatous polyposis were excluded from the trial. The study was powered to detect a 73% difference in the LOS which required 17 patients in each arm with an α error of 0.05 and a power of 95%. RESULTS:Thirty-four patients were comparable for age (P = 0.919), gender (P = 0.364), body mass index (P = 0.634), American Society of Anesthesiologists class (P = 0.388) and previous abdominal surgery (P = 0.366). There was no significant difference in the preoperative morphology (P = 0.485), location (P = 0.297), size (P = 0.690) or histology of the polyps (P = 0.779). LRC patients experienced a longer operating time (180 vs 90 min; P = 0.001), required more intravenous infusion (3.1 vs 2.0 l; P = 0.025), took significantly longer to pass flatus (2.88 vs 1.44 days; P < 0.001), resumed solid food later (3.94 vs 1.69 days; P < 0.001) and had a longer postoperative LOS (4.94 vs 2.63 days; P < 0.001). Postoperative complications (P = 0.656), readmissions (P = 0.5) and reoperations (P = 0.5) did not differ. Final size (P = 0.339) and histology (P = 0.104) of the polyps did not differ. There were four cancers in the LRC arm. At follow-up colonoscopy with biopsy of the scar in 10 patients at 15.3 months, one patient had recurrence of the polyp at the site of the previous LACP. CONCLUSION/CONCLUSIONS:LACP and LRC had similar complication rates, but LOS was shorter after LACP.

Image textures in computed tomography colonography (CTC) have great potential for differentiating non-neoplastic from neoplastic polyps and thus can advance the current CTC detection-only paradigm to a new level with diagnostic capability. However, image textures are frequently compromised, particularly in low-dose CT imaging. Furthermore, texture feature extraction may vary, depending on the polyp spatial orientation variation, resulting in variable results. To address these issues, this study proposes an adaptive approach to extract and analyze the texture features for polyp differentiation. Firstly, derivative (e.g. gradient and curvature) operations are performed on the CT intensity image to amplify the textures with adequate noise control. Then Haralick co-occurrence matrix (CM) is used to calculate texture measures along each of the 13 directions (defined by the first and second order image voxel neighbors) through the polyp volume in the intensity, gradient and curvature images. Instead of taking the mean and range of each CM measure over the 13 directions as the so-called Haralick texture features, Karhunen-Loeve transform is performed to map the 13 directions into an orthogonal coordinate system so that the resulted texture features are less dependent on the polyp orientation variation. These simple ideas for amplifying textures and stabilizing spatial variation demonstrated a significant impact for the differentiating task by experiments using 384 polyp datasets, of which 52 are non-neoplastic polyps and the rest are neoplastic polyps. By the merit of area under the curve of receiver operating characteristic, the innovative ideas achieved differentiation capability of 0.8016, indicating the CTC diagnostic feasibility.

Most previous efforts in developing computer-aided detection (CADe) of colonic polyps apply similar measures or parameters to detect polyps regardless of their locations under an implicit assumption that all the polyps reside in a similar local environment, e.g. on a relatively flat colon wall. In reality, this implicit assumption is frequently invalid, because the haustral folds can have a very different local environment from that of the relatively flat colon wall. We conjecture that this assumption may be a major cause of missing the detection of polyps, especially small polyps (<10 mm linear size) located on the haustral folds. In this paper, we take the concept of adaptiveness and present an adaptive paradigm for CADe of colonic polyps. Firstly, we decompose the complicated colon structure into two simplified sub-structures, each of which has similar properties, of (1) relatively flat colon wall and (2) ridge-shaped haustral folds. Then we develop local environment descriptions to adaptively reflect each of these two simplified sub-structures. To show the impact of the adaptiveness of the local environment descriptions upon the polyp detection task, we focus on the local geometrical measures of the volume data for both the detection of initial polyp candidates (IPCs) and the reduction of false positives (FPs) in the IPC pool. The experimental outcome using the local geometrical measures is very impressive such that not only the previously-missed small polyps on the folds are detected, but also the previously miss-removed small polyps on the folds during FP reduction are retained. It is expected that this adaptive paradigm will have a great impact on detecting the small polyps, measuring their volumes and volume changes over time, and optimizing their management plan.

BACKGROUND: Controversy still exists regarding colonic mucosal abnormalities in patients with portal hypertension (portal colopathy). The aims of this study were to better define portal colopathy and to identify risk factors for these colonic mucosal abnormalities. METHODS: We reviewed the medical records of 437 patients with cirrhosis and portal hypertension and 224 with irritable bowel syndrome (control patients) who underwent colonoscopy over a 6-year period. RESULTS: Individuals with portal hypertension were significantly more likely than control patients to have colitis-like abnormalities (38% vs. 3%, p < 0.001) and vascular lesions (13% vs. 3%, p < 0.001). In the multivariate model, portal hypertensive gastropathy (odds ratio 5.64: 95% CI [3.39, 9.41]; p < 0.001), 2+ or larger esophageal varices (odds ratio 4.76: 95% CI [2. 78, 8.15]; p < 0.001), and Child-Pugh class C cirrhosis (odds ratio 2.64: 95% CI [1.40, 4.97]; p = 0.003) were independently associated with an increased risk of having portal colopathy, whereas the use of beta-blockers independently decreased the risk of having these findings (odds ratio 0.23: 95% CI [0.13, 0.40]; p < 0.001). Mucosal biopsies of the colon in patients with colitis-like abnormalities revealed a mild, nonspecific inflammatory infiltrate with edema and vascular ectasias in the majority of cases. CONCLUSIONS: Mucosal abnormalities in portal colopathy include edema, erythema, granularity, friability, and vascular lesions, findings that may be confused with colitis. A standardized grading system to classify the endoscopic appearance and severity of portal colopathy should be adopted