Renal cell carcinoma: real-time contrast-enhanced ultrasound findings.

<bold>Objective: </bold>To investigate the findings of renal cell carcinomas (RCCs) on contrast-enhanced ultrasound (CEUS). <bold>Methods: </bold>CEUS features of 84 RCCs confirmed by pathologic examination in 81 patients were retrospectively analyzed. A contrast-specific mode and a sulfur hexafluoride-filled microbubble contrast agent were used for CEUS. The enhancement pattern, extent, and dynamic change in the cortical, corticomedullary, and late phases were evaluated. <bold>Results: </bold>On CEUS, the emergence of tumor enhancement was earlier in two nodules (2.4%), simultaneous in 71 (84.5%), and later in 11 (13.1%), in comparison with the adjacent renal cortex. Seventy-four RCC nodules (88.1%) showed hyper-enhancement (n = 2) or iso-enhancement (n = 72) during the cortical phase, and the remaining 10 (11.9%) showed hypo-enhancement. Twenty-three nodules (27.4%) showed homogeneous enhancement and 61 (72.6%) inhomogeneous enhancement. In the corticomedullary phase, the nodules showed hypo-enhancement in 68 (81.0%) and iso-enhancement in 16 (19.0%). In the late phase, all RCCs showed the same enhancement pattern as that shown in the corticomedullary phase. Seventy-two (85.7%) nodules showed a clear perilesional rim-like enhancement in late phase. <bold>Conclusions: </bold>Hyper- or iso-enhancement during the cortical phase, subsequent washout in late phase, inhomogeneous enhancement, and perilesional rim-like enhancement are clues for RCCs, which might be useful for characterization of RCCs. [ABSTRACT FROM AUTHOR]