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

Madalsa Joshi, Jonathan R. Dillman, Alexander J. Towbin, Suraj D. Serai, Andrew T. Trout

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 ≤18 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.