Preoperative staging of renal cell carcinoma with multidetector CT

PURPOSE To evaluate the diagnostic accuracy of multidetector computed tomography (MDCT) for preoperative staging of renal cell carcinoma (RCC) using the 1997 TNM (tumor, node, metastasis) classification. MATERIALS AND METHODS We conducted a retrospective review of MDCT in 57 consecutive patients with RCC performed for tumor staging before radical (n = 51) or partial nephrectomy (n = 6). The scanning protocol of MDCT consisted of unenhanced and biphasic contrast-enhanced scans during corticomedullary and nephrographic phases. MDCT and surgical-histopathologic staging were performed using the 1997 TNM staging system. The results of MDCT were compared with the histopathological results. Agreement between the two staging methods was evaluated using the kappa (K) statistic. RESULTS Consistency between MDCT and histopathologic staging was excellent for T staging (K = 0.87), fair for N staging (kappa = 0.40), and excellent for M staging (kappa = 1.00). Fifty-one of 57 tumors were correctly staged, five overstaged and one understaged by MDCT, with an overall accuracy of 89%. MDCT was able to correctly identify and localize the extension of the tumor thrombus in all 10 patients. In the evaluation of nodal involvement, 42 of 57 patients (74%) were correctly staged, 11 (19%) overstaged, and four (7%) understaged. CONCLUSION MDCT with a dynamic contrast enhancement protocol is an accurate method for preoperative staging of RCC. MDCT with multiplanar reconstruction capability enables a reliable detection and characterization of the tumor, but the involvement of lymph nodes by tumor is still difficult to predict because it is based on node size criterion only.