Optimal T2-weighted MR Cholangiopancreatographic Images Can Be Obtained after Administration of Gadoxetic Acid

Abstract

To compare the image quality and diagnostic performance with T2-weighted magnetic resonance (MR) cholangiopancreatographic images obtained before and after dynamic MR imaging performed with gadoxetic acid. This retrospective study was approved by the institutional review board, and informed consent was waived. Fifty-six patients suspected of having pancreatic or biliary disease underwent two-dimensional (2D) single-section and three-dimensional (3D) multisection MR cholangiopancreatography before and after dynamic imaging with gadoxetic acid. One radiologist measured the mean signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the common bile duct on precontrast and postcontrast images. Two radiologists independently reviewed the 2D and 3D MR cholangiopancreatographic images in random order. The depiction of each segment of the pancreaticobiliary duct, the presence of artifacts, background suppression, and overall image quality were assessed according to a four-point scale. Paired t, McNemar, and Wilcoxon signed rank tests were performed with a power analysis. Interobserver agreement was assessed by using the kappa statistic. Mean SNRs at precontrast MR imaging (2D, 50.8 +/- 45.1 [standard deviation]; 3D, 54.7 +/- 25.5) were similar to those at postcontrast MR imaging (2D, 48.5 +/- 45.7; 3D, 51.5 +/- 21.6). Mean CNRs were also similar between precontrast and postcontrast MR imaging (2D, 45.5 +/- 43.0 vs 44.2 +/- 45.2; 3D, 51.4 +/- 24.3 vs 48.7 +/- 21.0). Depiction scores for each segment of the pancreaticobiliary duct were also similar between 2D and 3D precontrast and postcontrast images. Both radiologists found that scores for background suppression were improved on postcontrast 2D MR images (3.79 and 3.84) compared with precontrast images (3.25 and 3.64). One of the two radiologists found that scores for artifacts (precontrast, 1.23; postcontrast, 1.09) and for overall image quality (precontrast, 3.54; postcontrast, 3.71) were improved at 2D postcontrast MR cholangiopancreatography. Both 2D and 3D MR cholangiopancreatography can be effectively performed immediately after gadoxetic acid-enhanced dynamic MR imaging in patients suspected of having biliary or pancreatic disease.