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

Background: To quantify enhancement parameters of the upper abdominal organ s over time during magnetic resonance (MR) examinations and to evaluate the effect of a dose reduction of contrast medium on these parameters. Methods: Ten volunteers underwent two separate dynamic enhanced MR examinat ions with 0.1 and 0.075 mmol/kg of contrast medium, respectively. Breath-ho ld gradient-echo T1-weighted images were acquired every second for 118 s fo llowed by delayed images. The percentages of enhancement, the time to maxim um enhancement, and the area under the time-versus-enhancement curve were c alculated for each organ. Results: 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 mea n values of maximum percentage of enhancement for the standard/reduced dose s were 72%/62% (pancreas), 165%/155% (kidneys), 114%/87% (spleen), and 67%/ 53% (liver). This difference was significant when liver enhancement was con sidered (p = 0.02). In addition, when the areas under the time-versus-enhan cement curves were compared, the difference between the standard dose and r educed dose was significant for all organs tested (p < 0.05. Conclusions: 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 reducti on did not significantly affect peak enhancement (except for the liver) but did significantly reduce overall enhancement.