Faculty Bibliography

Background: Small renal masses (SRM) are comprised of a heterogeneous group of tumors with some having malignant potential. Although surgery is the standard treatment for SRMs, emerging data suggests that surgery in the elderly or morbidly ill patients may be unnecessary and may adversely impact non-oncologic outcomes. We analyzed a population-based cohort of patients to identify predictors of surveillance and assess the impact of surveillance on overall survival, kidney cancer-specific survival and cardiovascular (CV) events, compared with surgery. Methods: From surveillance, epidemiology, and end results (SEER) cancer registry data linked with Medicare claims, we performed a retrospective cohort study of patients 66 years of age or older who received surgery or surveillance for SRM (< 4 cm) diagnosed between 2000 to 2007. Propensity score methods were used to control for potential confounders in multivariable analysis. Results: Of 8,317 patients, 5,706 (70%) underwent surgery and 2,611 (31%) underwent surveillance. The use of surveillance increased from 25% in 2000 to 37% in 2007 (p < 0.001). During a median follow-up of 58 months, 2,053 (25%) patients had at least one CV event and 2,078 (25%) patients died, including 277 (3%) who died of kidney cancer. Compared with surgery, surveillance was associated with a significantly lower risk of death from any cause (hazard ratio [HR], 0.84; CI, 0.75-0.94) and of suffering a CV event (HR, 0.79; CI 0.70-0.89), controlling for patient and disease characteristics. Kidney cancer-specific survival did not differ by treatment approach (HR, 0.89; CI, 0.66-1.21). Conclusions: There is increasing utilization of surveillance as an initial treatment strategy for patients with SRMs. For older patients with SRM, surveillance does not appear to adversely affect kidney cancer-specific survival, while surgery may be associated with CV complications and an increased risk of death from any cause. Surveillance should be considered an option for patients with SRM who ar!

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.

PURPOSE: To assess the utility of apparent diffusion coefficient (ADC) values obtained from diffusion-weighted imaging (DWI) in distinguishing high-grade bladder cancer with and without metastatic disease. MATERIALS AND METHODS: Seventeen patients with histologically confirmed high-grade bladder cancer who underwent pelvic magnetic resonance imaging (MRI) at 1.5T including DWI using b-values of 0, 400, and 800 sec/mm(2) were assessed. Histologic findings and follow-up imaging were used to establish the reference standard in terms of metastatic disease. Two radiologists independently recorded ADC of all lesions following a training session, with their results averaged. Mann-Whitney U-test, receiver operating characteristic (ROC) curve analysis and intraclass correlation coefficient (ICC) were used for data analysis. RESULTS: Metastatic disease was characterized as present or absent in eight and nine patients, respectively. ADC was significantly lower among cases with metastatic disease than among cases without metastatic disease, both within the entire cohort (1.07 +/- 0.18 x 10(-3) mm(2) /s vs. 1.45 +/- 0.22 x 10(-3) mm(2) /s; P = 0.002) and within the subset of patients with muscle-invasive tumor (1.06 +/- 0.19 x 10(-3) mm(2) /s vs. 1.45 +/- 0.23 x 10(-3) mm(2) /s; P = 0.017). Area under the ROC curve for identifying metastatic disease using ADC was 0.944, with optimal threshold of 1.21 x 10(-3) mm(2) /s, which was associated with a sensitivity of 87.5%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 90.0%. Interreader agreement for ADC was excellent (ICC = 0.91). CONCLUSION: In this preliminary study, ADC was significantly different between cases of high-grade urothelial carcinoma of the bladder with and without metastatic disease. These results may have value in assessing the metastatic potential of patients with localized high-grade tumors of the bladder. J. Magn. Reson. Imaging 2012;. (c) 2012 Wiley Periodicals, Inc.