Faculty Bibliography

PURPOSE: The aim of this study was to use intravoxel incoherent motion diffusion-weighted imaging to discriminate subtypes of renal neoplasms and to assess agreement between intravoxel incoherent motion (perfusion fraction, fp) and dynamic contrast-enhanced magnetic resonance imaging (MRI) metrics of tumor vascularity. SUBJECTS AND METHODS: In this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved prospective study, 26 patients were imaged at 1.5-T MRI using dynamic contrast-enhanced MRI with high temporal resolution and diffusion-weighted imaging using 8 b values (range, 0-800 s/mm). Perfusion fraction (fp), tissue diffusivity (Dt), and pseudodiffusivity (Dp) were calculated using biexponential fitting of the diffusion data. Apparent diffusion coefficient (ADC) was calculated with monoexponential fit using 3 b values of 0, 400, and 800 s/mm. Dynamic contrast-enhanced data were processed with a semiquantitative method to generate model-free parameter cumulative initial area under the curve of gadolinium concentration at 60 seconds (CIAUC60). Perfusion fraction, Dt, Dp, ADC, and CIAUC60 were compared between different subtypes of renal lesions. Perfusion fraction was correlated with CIAUC60. RESULTS: We examined 14 clear cell, 4 papillary, 5 chromophobe, and 3 cystic renal cell carcinomas (RCCs). Although fp had higher accuracy (area under the curve, 0.74) for a diagnosis of clear cell RCC compared with Dt or ADC, the combination of fp and Dt had the highest accuracy (area under the curve, 0.78). The combination of fp and Dt diagnosed papillary RCC and cystic RCC with 100% accuracy, and clear cell RCC and chromophobe RCC, with 86.5% accuracy. There was significant strong correlation between fp and CIAUC60 (r = 0.82; P < 0.001). CONCLUSION: Intravoxel incoherent motion parameters fp and Dt can discriminate renal tumor subtypes. Perfusion fraction demonstrates good correlation with CIAUC60 and can assess degree of tumor vascularity without the use of exogenous contrast agent.

Background The presence of muscularis propria invasion by bladder cancer is a key factor in prognosis and treatment decisions, although may be missed by biopsy due to sampling error. MRI has shown potential for detection of muscle invasion but has not specifically been evaluated for this purpose in the setting of bladder cancer patients without evidence of muscle invasion on initial biopsy. Purpose To evaluate the role of MRI in detection of muscularis propria invasion by bladder cancer following a pathologic diagnosis of non-invasive tumor. Material and Methods This retrospective study included 23 patients who underwent pelvic MRI following a pathologic diagnosis of bladder cancer without muscularis propria invasion and in whom additional histologic evaluation was performed following MRI. Two radiologists in consensus reviewed T2-weighted images to identify those cases suspicious for muscle invasion on MRI. The radiologists identified whether cases suspicious for invasion demonstrated disruption of the T2-hypointense muscularis layer of the bladder wall, peri-vesical fat stranding, and peri-vesical soft tissue nodularity. Findings were compared with pathologic results obtained after MRI. Results Suspicion was raised for muscle invasion in eight of 23 cases, four of which exhibited invasion on follow-up pathology. No case without suspicion on MRI exhibited invasion on follow-up pathology. Therefore, sensitivity and specificity were 100% and 79%, respectively. Among individual findings, muscularis disruption on T2WI exhibited sensitivity of 100% and specificity of 79%, peri-vesical fat stranding exhibited sensitivity and specificity of 50% and 84%, and peri-vesical soft tissue nodularity exhibited sensitivity and specificity of 25% and 100%. Conclusion MRI demonstrated high sensitivity for detection of muscle invasion in cases of bladder cancer without invasion on initial histologic assessment. Muscularis disruption on T2WI appeared to exhibit a better combination of sensitivity and specificity than did peri-vesical changes.

Mucinous cystadenocarcinomas of the urachus are rare. Mucinous benign or premalignant tumors are even rarer, yet pose a challenge in diagnosis and management. We report a case of a 66-year-old man with lower abdominal pain who had a large cystic tumor at the dome of the bladder. En-bloc resection of the tumor with partial cystectomy revealed mucinous cystadenocarcinoma in situ. We reviewed the characteristics of all seven previously reported cases. These tumors are pre-malignant and can cause significant morbidity and mortality. They need to be treated similar to conventional mucinous cystadenocarcinoma by wide surgical resection and partial cystectomy.

Over the last two decades, there has been a rising incidence of renal tumors, particularly, small renal masses (<4 cm) resulting in a downward size and stage migration. This has brought about a paradigm shift in the management of newly diagnosed renal masses, such that nephron-sparing surgery, minimally invasive techniques, and active surveillance are frequently considered preferable to the historical gold standard of open radical nephrectomy. Population-based cohort studies indicate, however, that the widespread adoption of these techniques has been relatively slow and incomplete leading to significant disparities in the delivery of care throughout the country. Further investigation is required to determine the barriers to diffusion of new techniques and technology as well as to ensure equal access to quality care in the United States.