Diagnosis of urothelial tumors with a dedicated dual-source dual-energy MDCT protocol: preliminary results.

The purpose of this study was to evaluate the diagnostic performance of a dedicated dual-source dual-energy MDCT (DECT) protocol for the detection of urothelial tumors. A DECT protocol including furosemide and split-bolus contrast injection was used in 69 consecutive patients with suspected abnormalities of the urinary system. Thirteen patients were excluded because there was no follow-up available. In 56 patients, the final diagnosis was proven with endoscopy, biopsy, or follow-up and included urothelial tumors (n = 37) in 16 patients, other urinary tract pathologies (n = 9) in eight patients, and absence of lesions of the collecting system in 32 patients. The image series consisted of a dual-energy true unenhanced series, 35-second arterial phase, and 8-minute nephrographic-excretory phase and were analyzed retrospectively. True enhancement of all detected lesions was measured. On the basis of the DECT data of the contrast-enhanced images, virtual unenhanced series were created and iodine concentration was calculated using commercially available software. The attenuation difference between virtual unenhanced and contrast-enhanced images (virtual enhancement) was measured. CT findings were compared with the final diagnosis. Urothelial tumors were identified on 35-second series, 8-minute series, and both series combined, with sensitivity of 91.9% (95% CI, 78.1-98.2%), 83.4% (68.0-93.8%), and 97.3% (85.8-100%), respectively. Urothelial tumors showed stronger virtual enhancement (p = 0.02) and higher iodine concentration (p = 0.03) than lesions of other origin. Distinction between urothelial tumors and nontumoral lesions was possible with sensitivity of 91.9% (78.1-98.2%) when using a threshold concentration of at least 1.0 mg I/mL. Dual phase DECT with virtual unenhanced imaging and iodine concentration measurement appears to be a useful diagnostic test for urothelial tumors.