Patient characteristics and contrast agent.

ObjectiveThis study aimed to compare abdominopelvic computed tomography (APCT) image quality using low and high concentrations of a contrast agent in patients with cancer via a noninferiority design.MethodsThis study prospectively included 99 patients with malignancies who underwent dual-source APCT following injection of 1.5 mL/kg of iohexol 270 (low-concentration group). The control group included patients who were retrospectively matched 1:1 based on weight, body mass index, and sex. These patients (high-concentration group) received 1.1 or 1.2 mL/kg of iohexol 350, reconstructed at two tube voltages (80 kVp and 80/Sn150 kVp). The noninferiority margins were set at −0.21 for overall image quality. Two radiologists blindly and independently analyzed the subjective and objective image quality of matching focal lesions.ResultsA total of 198 patients with 102 focal lesions (44 liver lesions, 58 renal lesions) were assessed. The total iodine amount was slightly higher in the low-concentration group than in the high-concentration group without significant differences (24580.0 ± 3745.6 vs. 24190.2 ± 3954.3 mg I/mL; p = 0.051). Overall image quality did not differ significantly between the groups (2.6 ± 0.5 vs. 2.6 ± 0.5 on 80 kVp; p = 0.484; 3.4 ± 0.5 vs. 3.4 ± 0.6 on 80/Sn 150 kVp, p = 0.891). Margin sharpness and conspicuity also showed no significant differences between the low- and high-concentration groups at 80 kVp (p = 0.890, 0.103) and 80/Sn 150 kVp images (p = 0.278, 0.369). Liver attenuation was slightly higher in the low-concentration than in the high-concentration group (80 kVp, 127.3 ± 16.8 vs. 122.4 ± 13.0, p = 0.013; 80 kVp/Sn 150 kVp, 108.2 ± 13.3 vs. 104.5 ± 10.9, p = 0.025). No major or minor adverse reactions occurred during or immediately after contrast agent injection in either group. Five patients in the low-concentration group experienced below-average vascular pain.ConclusionsThe low-concentration group offered noninferior overall image quality compared to the high-concentration group among patients with cancer.