Performance of Relative Enhancement on Multiphasic MRI for the Differentiation of Clear Cell Renal Cell Carcinoma (RCC) From Papillary and Chromophobe RCC Subtypes and Oncocytoma

OBJECTIVE. The objective of our study was to investigate the performance of relative enhancement on multiphasic MRI to differentiate clear cell renal cell carcinoma (RCC) from other RCC subtypes (papillary and chromophobe) and oncocytoma. MATERIALS AND METHODS. For this study, we derived a cohort of 34 clear cell RCCs, nine oncocytomas, 12 papillary RCCs, and 10 chromophobe RCCs with a preoperative multiphasic dynamic contrast-enhanced MRI study with up to four phases (i.e., unenhanced, corticomedullary, nephrographic, excretory) from 2005 to 2016. These groups were evaluated for multiphasic enhancement and were compared using Kruskal-Wallis and Mann-Whitney tests. ROC curves were constructed and logistic regression analyses were performed to evaluate the performance of multiphasic enhancement in differentiating clear cell RCCs from the other three groups. RESULTS. Clear cell RCCs exhibited significantly greater relative signal intensity compared with uninvolved renal cortex in the corticomedullary phase (mean, 2.9) than oncocytomas (-21.7, p = 0.001), papillary RCCs (-53.0, p < 0.001), and chromophobe RCCs (-21.0, p < 0.001). Relative signal intensity in the corticomedullary phase differentiated clear cell RCCs from oncocytomas with an AUC of 0.90 and with an accuracy of 84% (32/38), sensitivity of 90% (27/30), and specificity of 63% (5/8) after controlling for lesion size, patient age, and patient sex. Relative corticomedullary signal intensity differentiated clear cell RCCs from oncocytomas and other RCC subtypes with an AUC of 0.93 and with an accuracy of 90% (53/59), sensitivity of 90% (27/30), and specificity of 90% (26/29) after controlling for lesion size, patient age, and patient sex. CONCLUSION. Multiphasic MRI enhancement may assist in differentiating clear cell RCC from oncocytomas and other RCC subtypes, if validated in prospective studies.