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.