Aim. Our aim is to assess the diagnostic potential of multiphasic contrast enhanced computed tomography for differentiation of the histological subtypes of renal cell carcinoma.
Patients and Methods: We prospectively evaluated 50 patients with renal masses previously detected by ultrasound. Multiphasic CT of the kidneys and urinary tract was done. The degree of enhancement was measured by calculating the difference in the HU between the corticomedullary and unenhanced phase scans and between the excretory and unenhanced phase scans. We assessed other parameters as size of the lesion, presence of hemorrhage and calcifications, pattern of enhancement, and lymphadenopathy. CT findings were compared with the histopathological results.
Results. In corticomedullary phase clear RCC had significantly higher CT HU measurement than papillary (107HU vs 41HU, p value=0.001) and chromophobe (107HU vs 71HU, p value=0.003), papillary RCC had significantly lower CT attenuation value than chromophobe (41HU vs 71HU, p value=0.022).
In nephrograhic phase clear RCC had significantly higher CT HU measurement than papillary (94HU vs 51HU, p value=0.001) and chromophobe (94HU vs 74HU, p value=0.031), papillary RCC had significantly lower CT HU measurement than chromophobe (51HU vs 74HU, p value=0.015). In corticomedullary phase, a cut-off value of ≥ 76 showed 87% sensitivity and 74% specificity for the discrimination between clear and non-clear RCC.
Conclusion. Multiphasic CT is capable of differentiating clear-cell RCC from papillary and chromophobe subtypes for preoperative assessment in patients with renal masses. It is considered a safe and confident method for local staging and prediction of the histological grade of RCC.