Faculty Bibliography

BACKGROUND: Previous studies have shown accelerated gastric emptying after sleeve gastrectomy. This study aimed to determine whether a correlation exists between immediate postoperative gastroduodenal transit time and weight loss after laparoscopic sleeve gastrectomy (LSG). Specifically, correlation tests were conducted to determine whether more rapid transit after LSG correlated with increased weight loss. METHODS: Data were collected from an institutional review board-approved electronic registry. All LSGs were performed over a 40-Fr bougie, starting 5 to 7 cm proximal to the pylorus. Gastroduodenal transit time (antrum to duodenum) was calculated from a postoperative day 1 esophagram. Pearson's correlation coefficient was used for statistical analysis. RESULTS: The analysis included 62 consecutive LSG patients. The mean gastroduodenal transit time was 12.3 +/- 19.8 s. Almost all the patients (99 %) had a transit time less than 60 s. The mean percentage of excess weight loss (%EWL) was 23.8 +/- 9.8 % at 3 months, 37.9 +/- 11.8 % at 6 months, and 52.2 +/- 10.8 % at 12 months. No correlation was found between gastroduodenal transit time and %EWL at 3, 6, or 12 months. CONCLUSION: No correlation was found between gastroduodenal transit time and weight loss after LSG.

Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria((R)) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Purpose: To retrospectively assess whether magnetic resonance (MR) imaging with opposed-phase and in-phase gradient-echo (GRE) sequences and MR feature analysis can differentiate angiomyolipomas (AMLs) that contain minimal fat from clear cell renal cell carcinomas (RCCs), with particular emphasis on small (<3-cm) masses. Materials and Methods: Institutional review board approval and a waiver of informed consent were obtained for this HIPAA-compliant study. MR images from 108 pathologically proved renal masses (88 clear cell RCCs and 20 minimal fat AMLs from 64 men and 44 women) at two academic institutions were evaluated. The signal intensity (SI) of each renal mass and spleen on opposed-phase and in-phase GRE images was used to calculate an SI index and tumor-to-spleen SI ratio. Two radiologists who were blinded to the pathologic results independently assessed the subjective presence of intravoxel fat (ie, decreased SI on opposed-phase images compared with that on in-phase images), SI on T1-weighted and T2-weighted images, cystic degeneration, necrosis, hemorrhage, retroperitoneal collaterals, and renal vein thrombosis. Results were analyzed by using the Wilcoxon rank sum test, two-tailed Fisher exact test, and multivariate logistic regression analysis for all renal masses and for small masses. A P value of less than .05 was considered to indicate a statistically significant difference. Results: There were no differences between minimal fat AMLs and clear cell RCCs for the SI index (8.05% +/- 14.46 vs 14.99% +/- 19.9; P = .146) or tumor-to-spleen ratio (-8.96% +/- 16.6 and -15.8% +/- 22.4; P = .227) when all masses or small masses were analyzed. Diagnostic accuracy (area under receiver operating characteristic curve) for the SI index and tumor-to-spleen ratio was 0.59. Intratumoral necrosis and larger size were predictive of clear cell RCC (P < .001) for all lesions, whereas low SI (relative to renal parenchyma SI) on T2-weighted images, smaller size, and female sex correlated with minimal fat AML (P < .001) for all lesions. Conclusion: The diagnostic accuracy of opposed-phase and in-phase GRE MR imaging for the differentiation of minimal fat AML and clear cell RCC is poor. In this cohort, low SI on T2-weighted images relative to renal parenchyma and small size suggested minimal fat AML, whereas intratumoral necrosis and large size argued against this diagnosis. (c) RSNA, 2012.

BACKGROUND: Surgical correction of hiatal hernia (HH) during bariatric surgery has been found to improve patient outcomes and decrease reoperation rate. Although barium esophagram is more sensitive than endoscopy for detection of HH, accurate preoperative diagnosis remains a challenge. The aim of this study is to determine whether diagnostic accuracy improves by utilizing right anterior oblique (RAO) esophagram technique instead of the commonly used upright technique when comparing to the gold standard of intraoperative detection. METHODS: All patients undergoing bariatric surgery were prospectively evaluated for HH by barium esophagram. After the first 69 patients, the technique was changed from upright to RAO. Hiatal hernia was assessed intraoperatively by laxity of the phrenoesophageal ligament and, if present, was repaired posteriorly. Two board-certified radiologists specializing in gastrointestinal radiology, who were blinded to the intraoperative results, retrospectively reviewed the esophagrams. Consensus reads were utilized for divergent opinions. Sensitivity and specificity were calculated for each technique. RESULTS: Between 2008 and 2010, a total of 388 patients underwent preoperative esophagrams (69 upright, 388 RAO). For upright esophagram, sensitivity was 50 % and specificity was 97 %. For RAO esophagram, sensitivity was 70 % and specificity was 77 %. RAO had a lower percentage of false negatives (11 vs. 21 %) than upright esophagram. CONCLUSIONS: The use of RAO technique for preoperative esophagram is more sensitive for diagnosis of hiatal hernia than upright esophagram. If surgeons desire routine preoperative esophagram, RAO technique is the best.

OBJECTIVE: The purpose of this study was to evaluate the utility of multiparametric MRI in localization of the index lesion of prostate cancer. MATERIALS AND METHODS: Fifty-one patients who underwent 3-T MRI of the prostate with a pelvic phased-array coil that included T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences before prostatectomy were included. Six radiologists assessed all images to identify the lesion most suspicious of being the index lesion, which was localized to one of 18 regions. A uropathologist using the same 18-region scheme reviewed the prostatectomy slides to localize the index lesion. MRI performance was assessed by requiring either an exact match or an approximate match (discrepancy of up to one region) between the MRI and pathologic findings in terms of assigned region. RESULTS: The pathologist identified an index lesion in 49 of 51 patients. In exact-match analysis, the average sensitivity was 60.2% (range, 51.0-63.3%), and the average positive predictive value (PPV) was 65.3% (range, 61.2-69.4%). In approximate-match analysis, the average sensitivity was 75.9% (range, 65.3-69.6%), and the average PPV was 82.6% (range, 79.2-91.4%). The sensitivity was higher for index lesions with a Gleason score greater than 6 in exact-match (74.8% vs 15.3%, p < 0.001) and approximate-match (88.7% vs 36.1%, p = < 0.001) analyses and for index lesions measuring at least 1 cm in approximate-match analysis (80.3% vs 58.3%, p = 0.016). In exact-match analysis, 30.0%, 44.9%, and 79.1% of abnormalities found with one, two, and three MRI parameters represented the index lesion (p < 0.001). CONCLUSION: The sensitivity and PPV of multiparametric MRI for index lesion localization were moderate, although they improved in the setting of more aggressive pathologic features and a greater number of abnormal MRI parameters, respectively.