MR elastography: high rate of technical success in pediatric and young adult patients

Magnetic resonance (MR) elastography allows the noninvasive assessment of liver stiffness, which is a surrogate for fibrosis. The purpose of this study was to describe our experience using liver MR elastography in a large pediatric population with attention to the frequency and causes of exam failure. Imaging records were searched for patients a18 years of age who underwent 2-D gradient recalled echo (GRE) MR elastography of the liver between September 2011 and August 2015 on one of two 1.5-T MRI platforms. Imaging reports and clinical records were reviewed for failed MR elastography acquisitions, factor(s) resulting in failure and whether a subsequent successful examination had been performed. Four hundred sixty-eight MR elastography examinations were performed in 372 patients between 1.5 months and 18 years of age during the study period. Ninety-six percent (450/468) of the examinations were successful. There was no significant difference in mean age (12.6 +/- 3.6 vs. 11.2 +/- 4.1 years, P=0.12) or body mass index (BMI) (28.2 +/- 12.4 vs. 29.5 +/- 10 kg/m(2), P=0.6) between patients with and without successful examinations. MR elastography failures were due to poor paddle positioning resulting in inadequate generation of hepatic shear waves (n=5), iron overload (n=4), patient inability to tolerate MRI (n=3), patient breathing/motion (n=3), artifact from implanted hardware (n=1) and technical malfunction (n=2). Seven of nine (78%) repeat examinations were successful (78%). Hepatic 2-D GRE MR elastography at 1.5 T is technically robust in children. Exam failure is infrequent and largely reflects patient specific factors, some of which can be mitigated with careful technique.