Impact Analysis of the Routine Use of Dual-Energy Computed Tomography for Characterization of Incidental Renal Lesions.

Objective The aim of this study was to quantify the prevalence of incidental, indeterminate renal lesions on routine contrast-enhanced abdominal computed tomography (CT) and the proportion of such lesions that could be exonerated by dual-energy CT (DECT) postprocessing as benign hyperdense cysts. Methods The reports for 2729 consecutive contrast-enhanced DECT scans in the emergency department setting were reviewed for the mention of any renal lesion. For scans with a reported lesion, images were reviewed to assess for the presence of an indeterminate lesion that could not be definitively characterized as benign. All indeterminate lesions were reviewed with DECT postprocessing by 2 radiologists to assess for enhancement and other imaging characteristics and characterized by readers as benign or not definitively benign. Agreement between readers was assessed statistically, and disagreement was resolved by consensus. Results Two thousand seven hundred twenty-nine scans were performed in 2406 unique patients; a renal lesion was reported in 805 unique patient scans (33.4%). Review of these 805 scans led to discovery of 137 indeterminate lesions in 125 scans (5.2% of patients). Of the 137 lesions, 70 (51.1%) were classified as benign hyperdense cysts by readers, with the remaining 67 lesions classified as not definitively benign (43 solid masses, 9 Bosniak IIF cysts, 8 Bosniak III cysts, 7 Bosniak IV cysts). Conclusions Incidental indeterminate renal lesions are common on routine contrast-enhanced CT. More than half of these lesions could potentially be exonerated with DECT as benign Bosniak II cysts, which could avert the need for further workup in 2.8% of patients undergoing routine abdominal CT.