Computed tomography with iodine-free contrast media.

The purpose of this work was to evaluate the enhancement of different concentrations of gadolinium (Gd), ytterbium (Yb) and iodine in vitro and in vivo. Comparisons were made of the enhancement (HU) of Gd, Yb and iodine in concentrations ranging from 0.1 to 30 mg/ml. In vivo dynamic CT studies were performed in ten dogs with 0.5 M Gd, Yb and iodine. Time-density curves were achieved in aorta and liver. The in vitro studies confirmed a decrease in the enhancement in this order: Gd (120 kV) > Gd (137 kV) > Yb (120 kV) > Yb (137 kV) > iodine (120 kV) > iodine (137 kV). The specific enhancement of Gd was 40.8 (120 kV), of Yb 34.2 and of iodine 29.6 HU. The enhancement of the liver decreases from 21 HU (Gd) to 19 HU (Yb) and 12 HU (iodine). Gd and Yb achieved a higher aortal enhancement than iodine (190 vs 157 HU) All contrast media were well tolerated. Equimolar concentrations of Gd and Yb show a higher in vitro contrast and enhancement than iodine.