Characterization of Renal Cell Carcinoma Using Agent Detection Imaging: Comparison with Gray-Scale US

OBJECTIVE: We wanted to compare the imaging features of renal cell carcinoma (RCC) and their diagnostic accuracy on agent detection imaging (ADI) and gray-scale ultrasonography (US). MATERIALS AND METHODS: Thirty non-consecutive patients (age range; 32-80 years, mean age; 53.7 years) with 30 RCCs were examined with gray-scale US and with ADI in conjunction with using SH U 508A. We described the imaging features of the renal tumors obtained from ADI according to their enhancement pattern, the intratumoral anechoic areas and the presence of any pseudocapsule. The imaging features and diagnostic accuracy of ADI and gray-scale US were then compared. RESULTS: On the ADI exam, the RCCs were shown as being heterogeneous in 87% of the cases (26/30), homogeneous in 7% of the cases (2/30), and there was peripheral irregular enhancement in 7% of the cases (2/30). Intratumoral anechoic areas and pseudocapsule were seen in 87% and 77% of the RCCs on the ADI exam, whereas these features were seen in 53% and 17% of the cases on the gray-scale US, respectively. The diagnostic sensitivity, specificity, and accuracy for RCC with ADI were 97%, 93%, and 95%, respectively. However, those for RCC with using gray-scale US were 70%, 86%, and 78%, respectively. There was a significant difference for the diagnostic accuracy of RCC between ADI and gray-scale US (p < 0.05). CONCLUSION: Agent detection imaging can help visualize the enhancement pattern of RCC and improve the diagnostic accuracy of this tumor by better displaying the intratumoral anechoic areas and the pseudocapsule than does the gray-scale US.