Role of Contrast Enhancement and Corrected Attenuation Values of Renal Tumors in Predicting Renal Cell Carcinoma (RCC) Subtypes: Protocol for a Triphasic Multi-Slice Computed Tomography (CT) Procedure

BACKGROUND: To distinguish RCC subtypes based on contrast enhancement features of CT images. MATERIAL/METHODS: In total, 59 lesions from 57 patients were included. All patients underwent multi-slice CT imaging with a triphasic protocol, which included non-contrast, corticomedullary, nephrographic and urographic phases. Contrast enhancement features of renal masses were evaluated in terms of CT attenuation values (AV) and differences in contrast density; the aorta or renal parenchyma were evaluated based on corrected or relative values. RESULTS: Clear cell RCC (ccRCC) showed more intense contrast enhancement than other RCC subtypes. When differentiating ccRCC from other RCC subtypes, a cut-off AV of 86–89 HU, aorta-based corrected AV of 89–95 HU and renal parenchyma-based corrected AV of 87–95 HU showed a diagnostic accuracy of 81–86%, 86–88% and 74–78%, respectively, in the corticomedullary phase. Furthermore, a cutoff of 2.42–2.72 for the relative contrast enhancement ratio, a cutoff of 2.59–2.74 for the aorta-based corrected relative contrast enhancement ratio and a cutoff of 2.63–2.76 for the renal parenchyma-based attenuation ratio showed a diagnostic accuracy of 83–88%, 88–90% and 81%, respectively. CONCLUSIONS: The most reliable parameters for differentiating ccRCC from other RCC subtypes are aorta-based corrected AV and aorta-based corrected relative contrast enhancement values in the corticomedullary phase.