Faculty Bibliography

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.

OBJECTIVE: The purpose of this study is to qualitatively and quantitatively assess MDCT urography performed with a high volume of low-concentration (240 mg I/mL) IV contrast agent supplemented with peroral hydration, IV furosemide, and IV saline. MATERIALS AND METHODS: This retrospective evaluation of 100 consecutive normal MDCT urograms was performed for clinical indication of hematuria; patients (76 men and 24 women) were 27-90 years old (mean [+/- SD] age, 60 +/- 15 years). Three radiologists evaluated the degree of opacification across six urinary tract segments (for a total of 1200 measurements per radiologist) on a 4-point scale (0-3). One radiologist measured the maximum short-axis diameter of the proximal, mid, and distal ureters in each patient. Mean opacification scores were calculated for each segment. Radiologist agreement was assessed by kappa coefficient and Spearman rank correlation. Ureteral diameter was correlated to degree of opacification using the Jonckheere-Terpstra trend test. A comparison with published studies using similar scoring methods was undertaken. RESULTS: Of 1200 measured ureteral segments, a total of 24 among the three radiologists were reported as nonopacified. The mean opacification scores ranged from 2.63 +/- 0.8 to 3.00 +/- 0.8. Calculated kappa coefficients are indicative of substantial agreement (> 0.61). The mean maximal ureteral diameters were 5.44 +/- 1.10, 6.32 +/- 1.54, and 5.32 +/- 1.55 mm for the proximal, mid, and distal ureters, respectively. For all three radiologists, the mean opacification scores increased as distention increased. The Spearman correlation and corresponding p value (p < 0.001) for the association between the distention with the opacification scores show significant correlation. The opacification scores and ureteral distention exceeded published results. CONCLUSION: An MDCT urography technique using high-volume low-concentration IV contrast, oral and IV hydration, and IV diuretic reliably optimizes urinary tract opacification and distention. A positive correlation was found between ureteral distention and opacification.

OBJECTIVE: The purpose of this study was to retrospectively correlate the imaging and pathologic features of multilocular cystic renal cell carcinoma (RCC), a low-grade neoplasm that has an excellent prognosis. MATERIALS AND METHODS: Institutional databases were searched for the period between 2001 and 2010 to identify cases of resected renal tumors that had been evaluated with CT or MRI and been analyzed by a uropathologist to confirm the histologic diagnosis of multilocular cystic RCC. The images (nine CT, 14 MRI) were reviewed, and a Bosniak cyst category was assigned. RESULTS: Of 23 confirmed cases of multilocular cystic RCC, imaging revealed seven lesions were Bosniak category IIF, 13 were category III, and three were category IV. Pathologic examination of the category IIF lesions revealed 99% fluid, 0.001-1% clear cells lining the septum, and 0% fibrosis. The category III lesions were 98-99% fluid, 1-2% clear cells, and 0% fibrosis. The category IV lesions were 20-40% fluid, 1-5% clear cells, and 60-80% fibrosis. The patient demographics were similar across groups. Clinical follow-up showed no evidence of recurrent or metastatic disease. CONCLUSION: Multilocular cystic RCC is a rare cystic lesion of the kidney that is low risk to the patient and benign in behavior. It has a variable imaging pattern, the Bosniak category ranging from IIF to IV. As multilocular cystic RCC lesions increase in complexity on images (higher Bosniak category), there is a corresponding increase in the volume of malignant cells lining the tumor and an increase in the presence of vascularized fibrous tissue. Regardless of the imaging appearance, the behavior of these tumors was benign in this study. Clinicians and radiologists should be aware that when this carcinoma is reported to occur, the patient has an excellent prognosis.

Introduction: The purpose of this study is to correlate gastric emptying after laparoscopic sleeve gastrectomy (LSG) and calculated sleeve size (based on radiographic characteristics and pathologic resection) with post-op weight loss. Methods: Data was collected from an IRB-approved electronic registry, including patient demographics, weight, and body mass index (BMI). All sleeves were done with 40Fr Bougie, starting 5-7 cm proximal to pylorus. Post-op esophagrams were evaluated by 2 attending radiologists who specialized in body-imaging for 1) post-op radiographic sleeve diameter near top of sleeve, mid-sleeve and in antrum and 2) antrum-to-duodenum transit time. Sleeve volume was calculated utilizing the formula for cylinder volume r2h, where r=radius of mid-sleeve and h=height of the sleeve from gastroesophageal junction to distal antrum. Resected gastric volume was calculated utilizing radius and length of resected specimen (based on path report.) Excess weight loss (%EWL) was calculated based on ideal body weight. Pearson's correlation coefficient was used to evaluate the association between: transit time and weight loss, sleeve volume and weight loss, and transit time and sleeve diameter. Results: 62 patients underwent LSG (21% concurrent hiatal hernia repair) between Jan 2009 and Jan 2011 at an urban safety-net hospital. The population was 84% female, average pre-op age and BMI was 42 years and 47.0 kg/m², respectively. The transit time (available in 60 patients) ranged from 0-88 seconds (mean=21.3, SD= 19.8). 99% of the patients demonstrated gastric emptying under 60 seconds. Mean radiographic diameter of mid-sleeve was 4.0 cm and mean radiographic height was 26.4 cm. Based on these dimensions, mean calculated sleeve volume (based on cylindrical volume) was 115 cm3 (+/-81.0). Mean resected gastric volume (based on pathology specimen) was 658 cm3 (+/-945). Mean %EWL at 3, 6, and 12 months was 23.8% (+/-9.8), 37.9% (+/-11.8) and 52.2% (+/-10.8). There was no correlation found between transit time and %EWL at 3, 6 or 12 months. When dichotomizing the data between those with transit time <30 seconds vs. >30 seconds, there was still no significant correlation. There was also no correlation found between calculated sleeve volume or resected gastric volume and %EWL at 3, 6 or 12 months. However, shorter transit times were correlated with smaller mid-sleeve diameter (r=0.295, p-value=0.022) and smaller antrum diameter (r=0.255, p-value=0.049) but were not significantly correlated with upper sleeve diameter (r=0.120, p-value=0.360). Conclusion: We found no correlation between transit time after sleeve gastrectomy and weight loss, between sleeve volume and weight loss, and between resected gastric volume and weight loss. However, shorter transit time was correlated with smaller mid-sleeve and antrum diameter; the clinical significance of this remains to be determined

Background: Hiatal hernia repair at the time of bariatric surgery improves patient outcome, decreases GERD symptoms and reduces the need for reoperation. The aim of this report is twofold: first, to compare the sensitivity of esophagram with surgical findings at the time of bariatric surgery, and second, to compare the sensitivities of upright versus right anterior oblique (RAO) recumbent esophagram in predicting the presence of hiatal hernia intraoperatively. Methods: Between 2008 and 2010, 389 patients undergoing bariatric surgery were prospectively evaluated for hiatal hernia by barium esophagram. 70 (18%) were performed only in the upright position and 319 (82%) only in the RAO recumbent position. Esophagram technique was changed from upright to recumbent because we hypothesized that we would be able to better detect hiatal hernia utilizing RAO recumbent technique. Hiatal hernia was assessed intraoperatively by laxity/dimpling of the phrenoesophageal ligament and, when present, was repaired posteriorly with permanent sutures. Results: Compared with the surgical findings, the sensitivity and specificity for upright esophagram was 50% and 97%, respectively. For recumbent esophagram, sensitivity was 70% and specificity was 77%. Recumbent esophagram had a lower percentage of false negatives than upright esophagram (11% vs. 21%). Conclusions: Use of a recumbent technique for preoperative esophagram has a higher sensitivity for diagnosis of hiatal hernia than upright esophagram. Routine use of recumbent esophagram results in increased preoperative detection of hiatal hernia and facilitates planning of crural closure

OBJECTIVE: The purpose of this study was to retrospectively describe the MRI features of the pathologically related entities renal oncocytoma and chromophobe renal cell carcinoma (RCC). MATERIALS AND METHODS: Twenty-eight cases of histologically proven renal oncocytoma and 15 of chromophobe RCC evaluated with preoperative MRI from January 2003 through June 2009 at our institution were independently reviewed for an array of MRI features by two radiologists blinded to the final histopathologic diagnosis. These features were tabulated and compared between chromophobe RCC and renal oncocytoma by use of the Mann-Whitney test and binary logistic regression. RESULTS: Renal oncocytoma and chromophobe RCC showed no significant difference in size or any of 16 qualitative imaging features (p = 0.0842-1.0, reader 1; p = 0.0611-1.0, reader 2). Microscopic fat, hemorrhage, cysts, infiltrative margins, perinephric fat invasion, renal vein invasion, enhancement homogeneity, and hypervascularity were each observed in less than 20% of cases by both readers. A central scar and segmental enhancement inversion (a recently described finding in which early contrast-enhanced images show relatively more enhanced and less enhanced intralesional components with inversion of their relative enhancement on later images) were observed by both readers in at least 10% of cases of both renal oncocytoma and of chromophobe RCC with no significant difference between the two entities (p = 0.2092-0.2960). CONCLUSION: We have presented the largest series to date of the MRI features of both renal oncocytoma and chromophobe RCC. These related entities exhibited similar findings, and no MRI features were reliable in distinguishing between them

The computed tomographic or magnetic resonance imaging appearance of solitary fibrous tumors of the abdominopelvic cavity has previously only been presented in the English literature as individual case reports. In this article, we present the cross-sectional imaging appearance of 5 such cases, all of which exhibited highly similar imaging features, including well-circumscribed margins, lack of invasion of adjacent structures, and avid enhancement. In view of these shared imaging features, it may be possible to suggest the diagnosis preoperatively. Given their unpredictable biologic behavior with infrequent reports of recurrent or metastatic disease, complete surgical excision and long-term follow-up for these lesions is recommended