Dynamic enhancement of upper abdominal organs in normal volunteers with MRI and effects of contrast dose reduction

To quantify enhancement parameters of the upper abdominal organs over time during magnetic resonance (MR) examinations and to evaluate the effect of a dose reduction of contrast medium on these parameters. Ten volunteers underwent two separate dynamic enhanced MR examinations with 0.1 and 0.075 mmol/kg of contrast medium, respectively. Breath-hold gradient-echo T1-weighted images were acquired every second for 118 s followed by delayed images. The percentages of enhancement, the time to maximum enhancement, and the area under the time-versus-enhancement curve were calculated for each organ. The mean times to maximum percentage of enhancement were less than 25 s for the pancreas, kidneys, and spleen and 50 s for the liver. The mean values of maximum percentage of enhancement for the standard/reduced doses were 72%/62% (pancreas), 165%/155% (kidneys), 114%/87% (spleen), and 67%/53% (liver). This difference was significant when liver enhancement was considered (p = 0.02). In addition, when the areas under the time-versus-enhancement curves were compared, the difference between the standard dose and reduced dose was significant for all organs tested (p < 0.05). Dynamic scanning of the upper abdomen should start early after contrast injection. Injection parameters should be standardized to capture arterial and venous enhancements in liver examinations. A 25% dose reduction did not significantly affect peak enhancement (except for the liver) but did significantly reduce overall enhancement.