title: MR elastography: high rate of technical success in pediatric and young adult patients.
abstract: BACKGROUND
  Magnetic resonance (MR) elastography allows the noninvasive assessment of liver stiffness, which is a surrogate for fibrosis.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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/m2, 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%).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiology, British Columbia Children's Hospital, Vancouver, BC, Canada.
authors.forename: Madalsa
authors.initials: M
authors.lastname: Joshi
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229-3026, USA.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Dillman
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229-3026, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Towbin
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229-3026, USA.
authors.forename: Suraj D
authors.initials: SD
authors.lastname: Serai
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229-3026, USA. andrew.trout@cchmc.org.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Trout
mesh_terms: D000293:Adolescent; D016477:Artifacts; D002648:Child; D002675:Child, Preschool; D054459:Elasticity Imaging Techniques / Q000379:methods; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012189:Retrospective Studies
keywords: Children; Fibrosis; Liver; Magnetic resonance elastography; Stiffness