Utility of multiphasic multidetector computed tomography in discriminating between clear cell renal cell carcinomas...

To investigate if multiphasic multidetector computed tomography (MDCT) enhancement profiles can distinguish clear cell renal cell carcinomas (ccRCCs) with high carbonic anhydrase-IX (CA-IX) expression from ccRCCs with low CA-IX expression.

With IRB approval for this retrospective study, we derived a cohort of 105 histologically proven ccRCCs with preoperative 4-phase renal mass MDCT from 2001 to 2013. Following manual segmentation, the computer-assisted detection algorithm selected a 0.5-cm-diameter region of maximal attenuation within each lesion in each phase. CA-IX expression level was determined by immunohistochemical staining of tumor specimens. In the high and low CA-IX expression subgroups, the magnitude of enhancement and washout were compared using t tests; the performance of contrast washout in differentiating between subgroups was assessed with logistic regression analysis.

ccRCCs with high and low CA-IX expression both exhibited peak enhancement in the corticomedullary phase. ccRCCs with high CA-IX expression demonstrated significantly greater relative nephrographic washout than those with low CA-IX expression (18.4% vs. 7.8%, p = 0.03). ccRCCs with high CA-IX expression had greater relative excretory washout than ccRCCs with low CA-IX expression with a trend toward significance (33.4% vs. 25.2%, p = 0.05). After controlling for tumor size and stage, for distinguishing ccRCCs with high and low CA-IX expression, relative excretory washout had a sensitivity, negative predictive value, accuracy, and positive predictive value of 99% (65/66), 88% (7/8), 69% (72/105), and 67% (65/97), respectively.

Relative nephrographic and excretory washout may have the potential to help distinguish ccRCCs with high and low CA-IX expression, but this requires further validation.