title: Improvements in lumbar spine MRI at 3 T using parallel transmission.
abstract: OBJECTIVE
  Parallel transmission MRI at 3 T improves image quality by reducing dielectric effects with radiofrequency shimming. The purpose of this study was to determine whether parallel transmission MRI improves signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in lumbar spine MRI at 3 T.
  
  
  METHODS
  Ten healthy volunteers underwent T1-weighted MRI and nine healthy volunteers underwent T2-weighted MRI of the lumbar spine. Sagittal and axial T1- and T2-weighted images were acquired using parallel transmission MRI and conventional MRI. The percentage improvements in SNR and CNR were calculated, and statistical significance was determined using a two-tailed Student t test with p < 0.05 for significance.
  
  
  RESULTS
  The CNR and SNR showed statistically significant improvements at all levels of the lumbar spine except SNR at T11 on axial T2-weighted imaging. For sagittal T1-weighted imaging, the average improvement with parallel transmission MRI was 53% in CNR and 19% in SNR. For axial T1-weighted imaging, the average improvement was 48% in CNR and 23% in SNR. For sagittal T2-weighted imaging, the average CNR improvement was 38% and the average SNR improvement, 20%. For axial T2-weighted scans, the average percentage improvement in CNR was greater than 100% and the average SNR improvement was 18% with parallel transmission MRI.
  
  
  CONCLUSIONS
  The parallel transmission sequence improves image quality of lumbar spine MRI at 3 T, which is quantitatively supported by statistically significant improvements in SNR and CNR.
authors.affiliation: Department of Radiology, Fletcher Allen Health Care-University of Vermont School of Medicine, 111 Colchester Ave, Patrick One, Burlington, VT 05401, USA. christopher.filippi@vtmednet.org
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Filippi
authors.forename: Morgan
authors.initials: M
authors.lastname: Carlson
authors.forename: Jason M
authors.initials: JM
authors.lastname: Johnson
authors.forename: Heather N
authors.initials: HN
authors.lastname: Burbank
authors.forename: Gary F
authors.initials: GF
authors.lastname: Alsofrom
authors.forename: Trevor
authors.initials: T
authors.lastname: Andrews
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055815:Young Adult