Effectiveness of Computed Tomography for Predicting the Nuclear Grade of Renal Cell Carcinoma

ABSTRACT

PURPOSE: Nuclear grade is one of the independent prognostic factors for renal cell carcinoma (RCC). We investigated the effectiveness of a preoperative CT scan for predicting the nuclear grade of clear cell RCC. MATERIALS AND METHODS: We retrospectively reviewed the medical records of patients who underwent surgery for renal lesions between January 2002 and December 2007. We analyzed the pathologic and radiologic reports of 65 patients who underwent radical nephrectomy for RCC and were diagnosed with clear cell RCC. The Hounsfield unit (HU) of the area with maximum enhancement (M) and the total area of the RCC (T) were measured during CT. Ratio values by nuclear grade were calculated by using formulas (M HU/aorta HU, T HU/aorta HU) to eliminate differences between individuals. RESULTS: A total of 65 cases of clear cell RCCs were classified according to Fuhrman nuclear grade. Five cases were grade I, 33 were grade II, 15 were grade III, and 12 were grade IV. There was a significant difference in CT enhancement between each nuclear grade, and lower nuclear grades tended to have an increased ratio of maximum enhancement (p=0.020). Fuhrman nuclear grade was divided into two groups low (Fuhrman grades I, II) and high (Fuhrman grades III, IV). The ratio of enhancement for the M area was significantly higher in the low Fuhrman nuclear grade group than in the high group (p=0.033). CONCLUSIONS: CT enhancement is inversely related to the nuclear grade of clear cell RCC. This study found that measuring the area of maximum enhancement in CT may be a useful method for presuming the pathologic nuclear grade of RCC, especially when the Fuhrman nuclear grade is divided into low and high groups.