Is multidetector CT-scan able to detect T3a renal tumor before surgery?

Objective: To evaluate the diagnostic accuracy of multidetector Computed Tomography (MDCT) in predicting T3a renal cell carcinoma (RCC).Materials and methods: Preoperative MDCT of 96 patients with 100 pathologically proven RCC were assessed by two radiologists focusing on the presence of peritumoral fat, sinus fat or venous invasion for cT3a staging. Nature of tumor margins and the presence of peritumoral neovessels were also evaluated, as the influence of perinephric soft-tissue stranding in the interpretation of peritumoral fat.Results: Sensitivity for the identification of peritumoral fat, sinus fat or renal vein invasion was 77%, 86% and 86%, and specificity was 72%, 88% and 97%, respectively. Sensitivity and specificity in the prediction of T3a tumors were 72% and 70% respectively (κ score = 0.38 (0.29-0.47)). Among the 38 pT3 tumors, 6 (16%) were under-staged, and the neovessels and irregular tumor edge as secondary CT signs did not significantly increase the accuracy of the prediction of local invasion. Among the 62 confined tumors, 17 (27%) were over-staged as cT3 and among these 17 false positives cases, perinephric soft-tissue stranding was present in 14 cases.Conclusion: MDCT provides good results in detecting sinus fat, venous invasion and kidney-confined tumors, but evaluation of perinephric fat remains a difficult task, leading to reduced accuracy in T3a staging.