Assess the added value of nonenhanced computed tomography (NECT) to contrast-enhanced CT (CECT) of the abdomen for characterization of hypervascular liver metastases and incidental findings. Institutional review board approved, Health Insurance Probability and Accountability Act compliant, retrospective study of patients with melanoma, neuroendocrine tumor, or thyroid cancer. First available triphasic abdomen CT after initial diagnosis was reviewed by 3 radiologists. The 3 most suspicious lesions were characterized on the CECT as benign or malignant and then recharacterized after reviewing the NECT with CECT. Incidental renal and adrenal lesions were characterized similarly. Diagnostic performance of CECT vs its combination with NECT was assessed. Statistical significance level was set at P < 0.05. A total of 81 patients were included (mean age = 55 years; 52% male; 64% with liver lesions; 27% and 11% with incidental renal and adrenal lesions, respectively). Percentage area under the curve and 95% CI of CECT vs combination with NECT for characterization of liver metastases was 98(94-100) vs 99(96-100) for reviewer 1 (P = 0.35), 93(86-100) vs 94(87-100) for reviewer 2 (P = 0.23), and 96(90-100) vs 99(97-100) for reviewer 3 (P = 0.32). Mean difference in area under the curve and 95% CI between 2 protocols for characterization of liver, renal, and adrenal lesions were -0.007(-0.05 to 0.04) (P = 0.63), -0.09(-0.25 to 0.07) (P = 0.22), and -0.01(-0.05 to 0.02) (P = 0.27), respectively. After addition of NECT, confidence level for lesion characterization increased 4%-15% for liver metastases, 18%-59% and 33%-67% for renal and adrenal lesions, respectively. In conclusion, while addition of NECT to CECT improved radiologist' confidence, there was no statistically significant change in characterization of hypervascular liver metastases or incidental renal and adrenal lesions.
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