Enhancement pattern on multiphasic CT has been used to subtype RCC. In a retrospective study of 298 cases of RCC and oncocytoma evaluated with 4-phase CT, multiphasic enhancement threshold helped to discriminate clear-cell RCC from oncocytoma with an accuracy of 77%, clear-cell RCC from papillary RCC with an accuracy of 85%, and clear-cell RCC from chromophobe RCC with an accuracy of 84% [38]. However, no prospective studies have validated the reported enhancement threshold, and accuracies of 77% to 85% may not be sufficient to change clinical management. CTU While there is no literature specifically evaluating the performance of CTU for indeterminate renal masses, CTU may be useful in this context. CTU that includes the acquisition of both unenhanced and nephrographic phase images would be expected to provide the same information as CT abdomen without and with IV contrast. The excretory phase images from CTU may provide additional information for differentiating between intrarenal urothelial carcinoma from centrally located RCC [39]. MRI Abdomen MRI is frequently used to characterize renal lesions. In one retrospective study of 120 patients, the specificity of MRI was significantly higher than that of CT in diagnosing RCC (68.1% versus 27.7%), whereas their sensitivities Indeterminate Renal Mass Ho et al [51] showed that the optimal percentage of enhancement threshold for distinguishing cysts from solid tumors on MRI was 15%. Hecht et al [52] reported that both quantitative and qualitative methods are sensitive in the detection of enhancement in a renal lesion on MRI and that subtracted images enable accurate assessment of tumor enhancement for intrinsically hyperintense lesions using qualitative methods. Although MRI without and with IV contrast is optimal for renal lesion characterization, MRI without IV contrast can also provide diagnostic information.
Indeterminate Renal Mass. Enhancement pattern on multiphasic CT has been used to subtype RCC. In a retrospective study of 298 cases of RCC and oncocytoma evaluated with 4-phase CT, multiphasic enhancement threshold helped to discriminate clear-cell RCC from oncocytoma with an accuracy of 77%, clear-cell RCC from papillary RCC with an accuracy of 85%, and clear-cell RCC from chromophobe RCC with an accuracy of 84% [38]. However, no prospective studies have validated the reported enhancement threshold, and accuracies of 77% to 85% may not be sufficient to change clinical management. CTU While there is no literature specifically evaluating the performance of CTU for indeterminate renal masses, CTU may be useful in this context. CTU that includes the acquisition of both unenhanced and nephrographic phase images would be expected to provide the same information as CT abdomen without and with IV contrast. The excretory phase images from CTU may provide additional information for differentiating between intrarenal urothelial carcinoma from centrally located RCC [39]. MRI Abdomen MRI is frequently used to characterize renal lesions. In one retrospective study of 120 patients, the specificity of MRI was significantly higher than that of CT in diagnosing RCC (68.1% versus 27.7%), whereas their sensitivities Indeterminate Renal Mass Ho et al [51] showed that the optimal percentage of enhancement threshold for distinguishing cysts from solid tumors on MRI was 15%. Hecht et al [52] reported that both quantitative and qualitative methods are sensitive in the detection of enhancement in a renal lesion on MRI and that subtracted images enable accurate assessment of tumor enhancement for intrinsically hyperintense lesions using qualitative methods. Although MRI without and with IV contrast is optimal for renal lesion characterization, MRI without IV contrast can also provide diagnostic information.