q RSNA, 2016 Purpose:To evaluate the accuracy of computed tomography (CT) for diagnosis of internal hernia (IH) in patients who have undergone laparoscopic Roux-en-Y gastric bypass and to develop decision tree models to optimize diagnostic accuracy. Materials andMethods:This was a retrospective, ethics-approved study of patients who had undergone laparoscopic Roux-en-Y gastric bypass with surgically confirmed IH (n = 76) and without IH (n = 78). Two radiologists independently reviewed each examination for the following previously established CT signs of IH: mesenteric swirl, small-bowel obstruction (SBO), mushroom sign, clustered loops, hurricane eye, small bowel behind the superior mesenteric artery, and right-sided anastomosis. Radiologists also evaluated images for two new signs, superior mesenteric vein (SMV) "beaking" and "criss-cross" of the mesenteric vessels. Overall impressions for diagnosis of IH were recorded. Diagnostic accuracy and interobserver agreement were calculated, and multivariate recursive partitioning was performed to evaluate various decision tree models by using the CT signs. Results:Accuracy and interobserver agreement regarding the nine CT signs of IH showed considerable variation. The best signs were mesenteric swirl (sensitivity and specificity, 86%-89% and 86%-90%, respectively; k = 0.74) and SMV beaking (sensitivity and specificity, 80%-88% and 94%-95%, respectively; k = 0.83). Overall reader impression yielded the highest sensitivity and specificity (96%-99% and 90%-99%, respectively; k = 0.79). The decision tree model with the highest overall accuracy and sensitivity included mesenteric swirl and SBO, with a diagnostic odds ratio of 154 (95% confidence interval [CI]: 146, 161), sensitivity of 96% (95% CI: 87%, 99%), and specificity of 87% (95% CI: 75%, 93%). The decision tree with the highest specificity included SMV beaking and SBO, with a diagnostic odds ratio of 105 (95% CI: 101, 109), sensitivity of 90% (95% CI: 79%, 95%), and specificity of 92% (95% CI: 83%, 97%). Conclusion:The decision tree with the highest accuracy and sensitivity for diagnosis of IH included mesenteric swirl and SBO, the model with the highest specificity included SMV beaking and SBO, and the remaining signs showed lower accuracy and/or poor to fair interobserver agreement. Overall reader impression yielded the highest accuracy for diagnosis of IH, likely because alternate diagnoses not incorporated in the models were considered.q RSNA, 2016

Emerging evidence has confirmed that, following administration of a gadolinium-based contrast agent (GBCA), very small amounts of gadolinium will deposit in the brain of humans with intact blood-brain barriers. The literature is evolving rapidly and the degree to which gadolinium will deposit for a particular GBCA or class of GBCAs remains undetermined. Several studies suggest that linear GBCAs deposit more gadolinium in the brain compared with macrocyclic GBCAs; however, our understanding of the molecular composition of deposited gadolinium is preliminary, and the clinical significance of gadolinium deposition remains unknown. To date, there is no conclusive evidence linking gadolinium deposition in the brain with any adverse patient outcome. A panel of radiologists representing the Canadian Association of Radiologists was assembled to assist the Canadian medical imaging community in making informed decisions regarding the issue of gadolinium deposition in the brain. The objectives of the working group were: 1) to review the evidence from animal and human studies; 2) to systematically review existing guidelines and position statements issued by other organizations and health agencies; and 3) to formulate an evidence-based position statement on behalf of the Canadian Association of Radiologists. Based on our appraisal of the evidence and systematic review of 9 guidelines issued by other organizations, the working group established the following consensus statement. GBCA administration should be considered carefully with respect to potential risks and benefits, and only used when required. Standard dosing should be used and repeat administrations should be avoided unless necessary. Gadolinium deposition is one of several issues to consider when prescribing a particular GBCA. Currently there is insufficient evidence to recommend one class of GBCA over another. The panel considered it inappropriate to withhold a linear GBCA if a macrocyclic agent is unavailable, if hepatobiliary phase imaging is required, or if there is a history of severe allergic reaction to a macrocyclic GBCA. Further study in this area is required, and the evidence should be monitored regularly with policy statements updated accordingly.

To evaluate whether biopsy with vacuum-assisted biopsy (VAB) devices improves histologic underestimation rates of benign papillomas when compared to smaller bore core needle biopsy (CNB) devices. Patients with biopsy-proven benign papillomas with surgical resection or minimum 12 months follow-up were selected. Two breast pathologists reviewed all pathology slides of percutaneous and excisional biopsy specimens. Histologic underestimation rates for lesions biopsied with 10-12 Gauge (G) VAB were compared to those with 14G CNB. A total of 107 benign papillomas in 107 patients from two centers were included. There were 60 patients (mean age 57 years, SD 10.3 years) diagnosed with VAB and 47 patients (mean age 57.6 years, SD 11.3 years) with 14G CNB who underwent surgical excision or imaging follow-up. The upgrade rate to ductal carcinoma in situ or invasive carcinoma was 1.6% (1/60) with VAB and 8.5% (4/47) with 14G. Upgrade to atypia was 3.3% (2/60) after VAB and 10.6% (5/47) with CNB. The total underestimation rates were 5% (3/60) with VAB and 19.1% (9/47) with CNB. The odds of an upgrade to malignancy was 5.5 times higher with a 14G needle than VAB (95% CI: 0.592-50.853, p = 0.17). We observed a lower but not statistically significant upgrade rate to malignancy and atypia with the use of the 10-12 G VAB as compared with 14G CNB. When a papilloma without atypia is diagnosed with vacuum biopsy there is a high likelihood that it is benign; however, if surgical excision is not performed, long-term follow-up is still required.