Which Iodine concentration in chest CT?--a prospective study in 300 patients

In computed tomography (CT) several contrast media with different iodine concentrations are available. The aim of this study is to prospectively compare contrast media with iodine concentrations of 300, 370 and 400 mg iodine/ml for chest- CT. 300 consecutive patients were prospectively enrolled, under a waiver of the local ethics committee. The first (second, third) 100 patients, received contrast medium with 300 (370, 400) mg iodine/ml. Injection protocols were adapted for an identical iodine delivery rate (1.3 mg/s) and total iodine load (33 g) for all three groups. Standardized MDCT of the chest (16 x 0.75 mm, 120 kVp, 100 mAseff.) was performed. Intravascular attenuation values were measured in the pulmonary trunk and the ascending aorta; subjective image quality was rated on a 3-point-scale. Discomfort during and after injection was evaluated. There were no statistically significant differences in contrast enhancement comparing the three contrast media at the pulmonary trunk (p = 0.3198) and at the ascending aorta (p = 0.0840). Image quality (p = 0.0176) and discomfort during injection (p = 0.7034) were comparable for all groups. General discomfort after injection of contrast media with 300 mg iodine/ml was statistically significant higher compared to 370 mg iodine/ml (p = 0.00019). Given identical iodine delivery rates of 1.3 g/s and iodine loads of 33 g, contrast media with concentrations of 300, 370 and 400 mg iodine/ml do not result in different intravascular enhancement in chest-CT.