title: [Analysis of MR image quality of echo planar diffusion-weighted imaging: investigations at 1.5 Tesla with higher gradient field strength].
abstract: OBJECTIVE
  Single-shot echo planar Diffusion-weighted-Imaging (EPI DWI) requires extended gradient facilities with strong, fast switching gradients. Up to now the image quality of EPI DWI is enormously influenced by some kinds of artifacts. Therefore we evaluated the image quality of EPI DWI in demonstrating anatomical structures using a 1.5 T MR scanner with a higher gradient field strength of 40 mt/m, a risetime of 200 micros and a slewrate of 200T/m/s.
  
  
  METHODS
  Using an evaluation scale with four categories two independent readers evaluated 12 different infra- and supratentorial anatomic regions of the brain on 50 DWI images and compared them with the corresponding T2 turbospin echo image.
  
  
  RESULTS
  No region was judged to be undistinguishable. On axial DWI images the assessment of the brain stem was poor. In the level of the putamen and thalamus the image quality of DWI was judged to be from adequate to excellent. The central sulcus and the boundary of the white and grey matter was assessed to be adequately visible. The interobserver variability showed a good agreement between the two readers.
  
  
  CONCLUSIONS
  The image quality of EPI DWI improves from a higher gradient field strength. The shortening rise time of 200 micros and the slewrate of 200 T/m/s will lead to a faster gradient switching. Single shot EPI DWI is less influenced by image artefacts and the presentation of different anatomical structures profits when a MR scanner with higher gradient field strength is used.
authors.affiliation: Radiologische Klinik, FE Neuroradiologie, Universitätsklinik Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. ulrich.dorenbeck@ukb.uni-bonn.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dorenbeck
authors.forename: Nils
authors.initials: N
authors.lastname: Zorger
authors.forename: Stefan
authors.initials: S
authors.lastname: Feuerbach
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology*; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011785:Quality Assurance, Health Care / Q000379:methods; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity