Faculty Bibliography

Endoscopic ultrasound (EUS) continues to present a rich source of innovation, allowing it to evolve from a diagnostic procedure to a therapeutic modality. This was obvious from the numerous high-quality presentations at the 2014 Digestive Disease Week (DDW) held in Chicago, Illinois. This review discusses several of the presented abstracts of innovations in the field of EUS.

BACKGROUND: Lymph nodes (LNs) echofeatures on endoscopic ultrasound (EUS) and concurrent fine needle aspiration (FNA) are alternatives to highly invasive approaches for etiologic diagnosis of mediastinal lymphadenopathy (MLAD). AIMS: To evaluate the efficacy of LNs echofeatures and FNA via EUS to distinguish benign LNs from LNs involved by sarcoidosis, lymphoma, and metastasis in non-lung cancer patients. METHODS: A retrospective review of patients who underwent EUS-FNA for MLAD was performed. Echofeatures of LNs including echogenicity, margins, shape, and LN size were recorded. Final diagnosis was made based on surgical sampling or clinical diagnosis with long-term follow-up. Only patients diagnosed as benign MLAD, sarcoidosis, lymphoma, and metastasis included. Diagnostic value of echofeatures and FNA was evaluated. RESULTS: Included were 162 patients with final diagnosis of benign (68), sarcoidosis (33), lymphoma (20), and metastasis (41). The median LN along axis in the benign group [20.5 mm (6-76)] was significantly shorter than in the metastasis [28 mm (9-82)] and sarcoidosis [27 mm (17-50)] groups (p < 0.05). The median LN short axis in the benign group [11 mm (2-50)] was significantly shorter than in the metastasis [17 mm (5-44)] and lymphoma [16 mm (7-47)] groups (p < 0.05). No other echofeatures showed a discriminant value among the groups. When performing FNA, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EUS-FNA were 73.7, 100, 100, 72.2, and 84.4 %, respectively. CONCLUSION: Although benign MLAD tend to be smaller than other etiologies, echofeatures of LNs are not reliable etiologic diagnostic approach to MLAD. Therefore, FNA is suggested when feasible. However, due to relatively low sensitivity, LNs with benign FNA results should be subjected to further work-up if they are clinically suspicious.

PURPOSE: Progression of Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) is associated with accumulated genomic instability. Current risk stratification of BE for EAC relies on histological classification and grade of dysplasia. However, histology alone cannot assess the risk of patients with inconsistent or non-dysplastic BE histology. We, therefore, examined the presence and extent of genomic instability in advanced and less advanced BE histology using mutational load (ML). METHODS: ML summarized the presence and clonality of loss of heterozygosity (LOH) mutations and the emergence of new alleles, manifested as microsatellite instability (MSI) mutations, in ten genomic loci around tumor suppressor genes associated with EAC. The ML of 877 microdissected targets from BE biopsies was correlated to their histology. Histological targets were categorized into three levels: no ML, low ML, and high ML. RESULTS: Increasing ML correlated with increasingly severe histology. By contrast, proportions of targets that lacked mutations decreased with increasingly severe histology. A portion of targets with non-dysplastic and low-grade histology shared a similar ML as those with higher risk and EAC disease. The addition of MSI characterization to ML helped to differentiate the ML between advanced and less advanced histology. CONCLUSIONS: Given that EAC is associated with accumulated genomic instability, high ML in less severe histology may identify BE disease at greater risk of progression to EAC. ML may help to better manage BE in early histological stages and when histology alone provides insufficient information.

Objectives: Colonoscopy is the gold standard for colon cancer screening, by detecting and removing adenomatous polyps. However, polyps can be missed in the proximal mucosal folds with traditional forward viewing colonoscopy. The ARC EndoCuff is a disposable attachment placed on the tip of the colonoscope. With soft, hair-like projections, the EndoCuff (Image 1.) helps to flatten colon mucosal folds during scope withdrawal allowing for increased mucosal inspection. A new technique often has to allow for proficiency and the aim of our study is to assess the learning curve for EndoCuff by comparing adenoma detection rate (ADR) with successive weeks of operator experience. Methods: We retrospectively analyzed patients who underwent colonoscopy with Endocuff for any indication at an outpatient urban practice over a 3-week period. ADR was calculated for each week and weeks 2 and 3 were compared to week 1, which served as our control. Total number of EndoCuff procedures in week 1 were divided by total number of operators to determine the average procedures needed to overcome the learning curve. Colonoscopy reports were retrospectively reviewed and paired t-tests were performed to assess for significance between ADR for each week. Results: A total of 58 patients underwent EndoCuff during the 3-week period. A total of 15, 21, and 22 patients had procedure performed in weeks 1,2, and 3, respectively (Table 1.). A total of 4 operators participated in week 1 and number of procedures ranged from 2 to 5 with a mean of 3.75. ADR for week 1 was 20% which increased to 54.5% in week 2 (p=0.03) and reached its peak at 63.6% in week 3 (p=0.004). Given the significant improvement in week 2 compared to week 1, learning curve was approximated to be 4 procedures based on a total of 15 procedures performed in week 1 divided amongst four operators. Conclusions: Our results suggest that a learning curve does exists for EndoCuff and that ADR significantly increases with operator experience after 4 procedures. Overall, End!