title: Comparison of readout-segmented echo-planar imaging (EPI) and single-shot EPI in clinical application of diffusion-weighted imaging of the pediatric brain.
abstract: OBJECTIVE
  Readout-segmented echo-planar imaging (EPI) has been suggested as an alternative to single-shot EPI for diffusion-weighted imaging (DWI) with reduced distortion. However, clinical comparisons of readout-segmented EPI and EPI DWI are limited by unmatched imaging parameters and reconstruction procedures. Our goal was to compare the clinical utility of generalized autocalibrating partial parallel acquisition (GRAPPA)-accelerated readout-segmented EPI DWI with GRAPPA-accelerated EPI DWI for visualization of the pediatric brain in regions prone to distortion, such as the orbit, skull base, and posterior fossa.
  
  
  METHODS
  Thirty consecutive patients (mean age, 7.8 years) presenting with orbital, skull base, and posterior fossa neuropathologic abnormalities were scanned at 3 T. Images were obtained using GRAPPA-accelerated readout-segmented EPI and GRAPPA-accelerated EPI with an identical scanning time, acceleration factor, target resolution, and image postprocessing procedure. The two datasets were independently reviewed by two blinded neuroradiologists. Imaging studies were evaluated for resolution, signal-to-noise ratio (SNR), contrast, distortion, lesion conspicuity, and diagnostic confidence and graded using a 7-point Likert scale (1, nondiagnostic; 7, outstanding).
  
  
  RESULTS
  There was good reader agreement in the scores (κ = 0.66; 95% CI, 0.54-0.78). The mean scores for EPI and readout-segmented EPI, respectively, were as follows: resolution, 5.0 and 6.0; SNR, 5.5 and 3.0; contrast, 3.7 and 3.2; distortion, 4.8 and 6.0; lesion conspicuity, 4.6 and 5.1; and diagnostic confidence, 4.7 and 5.4. Readout-segmented EPI was superior in resolution, distortion reduction, lesion conspicuity, and diagnostic confidence, whereas EPI scored better in SNR and contrast. Readout-segmented EPI was considered the better sequence overall in 85% of the cases.
  
  
  CONCLUSIONS
  This study shows the benefits of improved resolution and reduced distortion of readout-segmented EPI in evaluating the orbit, skull base, and posterior fossa, sites of common neuropathologic abnormalities in children.
authors.affiliation: Department of Radiology, Stanford University, Palo Alto, CA 94304, USA. kyeom@stanford.edu
authors.forename: Kristen W
authors.initials: KW
authors.lastname: Yeom
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Holdsworth
authors.forename: Anh T
authors.initials: AT
authors.lastname: Van
authors.forename: Michael
authors.initials: M
authors.lastname: Iv
authors.forename: Stefan
authors.initials: S
authors.lastname: Skare
authors.forename: Robert M
authors.initials: RM
authors.lastname: Lober
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
mesh_terms: D000293:Adolescent; D001921:Brain / Q000473:pathology*; D001927:Brain Diseases / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult