title: Dual-source radiofrequency transmission with patient-adaptive local radiofrequency shimming for 3.0-T cardiac MR imaging: initial experience.
abstract: OBJECTIVE
  To evaluate the effect of dual-source parallel radiofrequency (RF) transmission with patient-adaptive local RF shimming on image quality, image contrast, and diagnostic confidence at routine clinical cardiac magnetic resonance (MR) imaging with use of a 3.0-T dual-channel transmit whole-body MR system.
  
  
  METHODS
  Written informed consent was obtained from all patients, and the study protocol was approved by the local institutional review board. Cardiac MR imaging was performed in 28 patients by using a 3.0-T MR unit equipped with a dual-source RF transmission system. The effect of conventional versus dual-source RF transmission on steady-state free precession (SSFP) cine sequences and turbo spin-echo (TSE) black-blood (BB) sequences was evaluated. The homogeneity of the B1 field and contrast-to-noise ratios (CNRs) were measured and tested for statistical significance with the paired t test. Images were analyzed qualitatively for homogeneity, the presence of off-resonance artifacts, and diagnostic confidence independently by two readers. Statistical significance was assessed with the Wilcoxon signed rank test. Inter- and intraobserver agreement was assessed with κ statistics.
  
  
  RESULTS
  Quantitative image analysis revealed that B1 homogeneity and CNR were significantly improved for images acquired with dual-source RF transmission compared with conventional RF transmission (P = .005). The quality of SSFP and TSE BB images of the left and the right ventricles showed a significant improvement with respect to image homogeneity and diagnostic confidence as evaluated by the readers (P = .0001, κ > 0.74). As a side effect, off-resonance artifacts were significantly reduced on SSFP images (P = .0001, κ > 0.76).
  
  
  CONCLUSIONS
  Dual-source parallel RF transmission significantly improves image homogeneity, image contrast, and diagnostic confidence compared with conventional RF transmission of cardiac SSFP and TSE BB sequences.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Str 25, 53105 Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Mueller
authors.forename: Marc
authors.initials: M
authors.lastname: Kouwenhoven
authors.forename: Claas P
authors.initials: CP
authors.lastname: Naehle
authors.forename: Juergen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Katharina
authors.initials: K
authors.lastname: Strach
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Daniel
authors.initials: D
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016477:Artifacts; D009202:Cardiomyopathies / Q000175:diagnosis*; D003327:Coronary Disease / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011846:Radio Waves; D018709:Statistics, Nonparametric