Effect of contrast media on single-shot echo planar imaging: Implications for abdominal diffusion imaging

Abstract

The goal of this study was to determine the effect of contrast media on the signal behavior of single-shot echo planar imaging (ssEPI) used for abdominal diffusion imaging. The signal of an ssEPI spin echo sequence in a water phantom with varying concentrations of gadolinium was modeled with Bloch equations and the predicted behavior validated on a phantom at 1.5T. Six volunteers were given gadolinium contrast and signal intensity (SI) time courses for regions of interest (ROIs) in the liver, pancreas, spleen, renal cortex, and medulla were analyzed. Student's t-test was used to compare precontrast SI to 0, 1, 4, 5, 10, and 13 minutes following contrast. The results show that following contrast ssEPI SI goes through a nadir, recovering differently for each organ. Maximal contrast-related signal losses relative to precontrast signal are 20%, 20%, 53%, and 67% for the liver, pancreas, renal cortex, and medulla, respectively. The SIs remain statistically below the precontrast values for 5, 4, and 1 minute for the pancreas, liver, and spleen, and for all times measured for the renal cortex and medulla. Abdominal diffusion imaging should be performed prior to contrast due to adverse effects on the signal in ssEPI.