title: Dual-source parallel RF transmission for clinical MR imaging of the spine at 3.0 T: intraindividual comparison with conventional single-source transmission.
abstract: OBJECTIVE
  To prospectively and intraindividually compare single-source radiofrequency (RF) excitation and dual-source parallel RF excitation in 3.0-T magnetic resonance (MR) imaging of the spine.
  
  
  METHODS
  Institutional review board approval and written informed patient consent were obtained. The RF power of a 3.0-T MR imaging system was distributed to two ports of the body coil of the system by using independent RF transmit channels. The maximum B(1) field strength for dual-source parallel RF excitation was maintained, as compared with single-source RF excitation. The repetition time was reduced according to the revised RF setup with dual-source parallel RF excitation while maintaining specific energy absorption limitations. Thirty patients were examined with and without dual-source parallel RF excitation. Diagnostic quality was assessed independently by two radiologists according to a four-point grading system. Image contrast ratios (CRs) were calculated between reference tissues and vertebrae for single-source RF excitation and dual-source parallel RF excitation.
  
  
  RESULTS
  The mean acceleration achieved with dual-source parallel RF excitation was 36% (range, 18%-50%). The total imaging duration of a three-station total spinal examination was reduced by one-third by using dual-source parallel RF transmission. For all cases investigated, diagnostic image quality without significant differences between the two methods and with a good interobserver agreement was achieved (Kendall tau-b, 0.50-0.84). The observed image contrast changes were predominantly small (<0.10 in 15 of 24 CRs), though they were significantly different (P < .05).
  
  
  CONCLUSIONS
  While shortening examination times by approximately one-third, the dual-source parallel RF transmission mode in MR imaging of the spine yielded diagnostic image quality comparable to that with the conventional single-source RF transmission mode.
authors.affiliation: Department of Radiology, University of Bonn Hospital and Medical School, Sigmund Freud Strasse 25, D-53105 Bonn, Germany. michael.nelles@ukb.uni-bonn.de
authors.forename: Michael
authors.initials: M
authors.lastname: Nelles
authors.forename: Roy S
authors.initials: RS
authors.lastname: König
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Marjolijn M
authors.initials: MM
authors.lastname: Guerand-van Battum
authors.forename: Guido M
authors.initials: GM
authors.lastname: Kukuk
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds; D011446:Prospective Studies; D011846:Radio Waves; D013122:Spinal Diseases / Q000473:pathology*
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol