Evaluation of hyperdense renal lesions incidentally detected on single-phase post-contrast CT using dual-energy CT

Objective: To investigate the utility of dual-energy CT (DECT) for differentiating between solid and benign cystic lesions presenting as hyperdense renal lesions incidentally detected on single-phase post-contrast CT. Methods: 90 hyperdense renal lesions incidentally detected on single-phase post-contrast CT were evaluated with follow-up DECT. DECT protocols included true non-contrast (TNC), DE corticomedullary and DE late nephrographic phase imaging. The CT numbers of hyperdense renal lesions were calculated on linearly blended and iodine overlay (IO) images, and the results were compared. Results: In total, 47 benign cystic and 43 solid renal lesions were analyzed. For differentiating between solid and benign cystic lesions on the two phases, the specificity and accuracy of all lesions and lesions <1.5 cm were statistically lower in IO images than in linearly blended images (p < 0.05), while those for lesions >= 1.5 cm were not statistically different between them (p > 0.05). For all types of lesions >= 1.5 cm, the CT numbers between linearly blended and IO images and between TNC and virtual non-contrast images were not statistically different (p > 0.05). Conclusion: DECT may be useful for differentiating between solid and benign cystic lesions presenting as hyperdense renal lesions incidentally detected on single-phase post-contrast CT, particularly with the size >= 1.5 cm. Advances in knowledge: DECT may be used to characterize hyperdense renal lesions >= 1.5 cm incidentally detected on single-phase post-contrast CT, without the use of TNC images.