OBJECTIVETo explore the possibility of predicting the histopathological types of small renal cell carcinoma (RCC) by analyzing the different ways of enhancement with multiphasic multidetector computed tomography (MDCT) of small renal cell carcinomas (diameter≤4 cm).

METHODSCT images of 93 cases, diagnosed as RCC by pathology, were analyzed retrospectively, including 70 clear cell renal cell carcinoma (CCRCC), 13 papillary renal cell carcinoma (PRCC) and 10 chromophobe renal cell carcinoma (CRCC). All of the cases were examined by multiphasic multidetector CT scanning.

RESULTSIn plain scans, 46 CCRCCs were homogeneous, 21 CCRCCs were heterogeneous with low-density area and 3 of them had calcification. CCRCCs were enhanced in contrast scan with a presence of "wash in and wash out" enhancement in general. 11 PRCCs were homogeneous and 2 PRCCs had calcification. Slight-homogeneous enhancement and "delayed enhancement" were present in the PRCCs. Six CRCCs were homogeneous and 2 were calcified, 2 CRCCs were heterogeneous with low-density area. The CRCCs presented as slight or moderate enhancement and 5 CRCCs as homogeneous enhancement, while one CRCC was "spoke-wheel-like enhancement", with a trend of "delayed enhancement". Statistically significant differences were revealed among the actual enhanced CT values, the ratio of enhanced CT value to aorta CT value in the corticomedullary phase, nephrographic phase and excretory phase between the CCRCCs and non-CCRCCs (P<0.001). The analysis of receiver operating characteristic curves (ROC) revealed that when the actual enhanced CT value of tumors in CMP larger than 84.2 HU, the ratio of actual enhanced CT value to aorta CT value at the same phase in CMP larger than 0.315 were used as criteria to diagnose CCRCCs and excluded non-CCRCCs, the diagnostic value was best.

CONCLUSIONSMDCT is of an important significance in the diagnosis and differential diagnosis of small CCRCCs and non-CCRCCs.