title: Enhancing gray-to-white matter contrast in 3T T1 spin-echo brain scans by optimizing flip angle.
abstract: OBJECTIVE
  Compared with MR imaging at 1.5T T1-weighted spin-echo imaging at 3T shows up with reduced gray-to-white matter contrast. The purpose of the present study was to show the effects of alterations of different flip angles as an easily accessible parameter to increase gray-to-white matter contrast.
  
  
  METHODS
  Spin-echo T1 sequences of 6 healthy volunteers were acquired in a 3T head scanner with 5 different flip angles. Observer-independent contrast-to-noise ratios for gray versus white matter from different flip angles, as well as subjective ratings of image quality from 2 blinded neuroradiologists, were compared statistically.
  
  
  RESULTS
  Gray-to-white matter contrast increased significantly with decreasing flip angle. No artifacts were introduced by decreasing flip angles, and T1 contrast characteristics were robust and stable at lowered flip angles. Also, specific absorption ratios significantly decreased with decreasing flip angles.
  
  
  CONCLUSIONS
  Using a flip angle of 50 degrees significantly increases gray-to-white matter contrast in T1 spin-echo brain scans at 3T B0 field strength.
authors.affiliation: Department of Radiology, University Hospitals, Ulm, Germany.
authors.forename: Bernd L
authors.initials: BL
authors.lastname: Schmitz
authors.forename: Georg
authors.initials: G
authors.lastname: Grön
authors.forename: Florian
authors.initials: F
authors.lastname: Brausewetter
authors.forename: Martin H K
authors.initials: MH
authors.lastname: Hoffmann
authors.forename: Andrik J
authors.initials: AJ
authors.lastname: Aschoff
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D010487:Periaqueductal Gray / Q000033:anatomy & histology*; D012016:Reference Values