title: Comparison of dual-source parallel radio frequency transmission liver MRI at 3.0 T with conventional MRI.
abstract: OBJECTIVE
  Aim of the present study was to investigate the role of dual-source parallel Radio frequency (RF) and single-source excitation in liver imaging at 3.0 T MR.
  
  
  METHODS
  This study was a retrospective analysis. One hundred and seven subjects underwent a 3.0 T TX MR scanning including axial spectrally selective attenuated inversion recovery (SPAIR) T2WI, axial DWI and coronal balanced-fast field echo (Balanced FFE). Each sequence was carried out with both single-source and dual-source RF excitation. Student's t test was used to compare whether there was difference between single-source and dual-source RF excitation in the image uniformity, single-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Wilcoxon signed rank test was used to determine whether there was difference between conventional and parallel transmission in the score of image quality. Reader agreement was assessed using the Cohen's Kappa test.
  
  
  RESULTS
  For the image uniformity, there was significant difference between single-source and dual-source excitation (418.40±66.75 for single-source vs. 416.26±50.61 for dual-source, t=2.524, P<0.05). There also existed significant difference between single-source and dual-source excitation in SNR and CNR, respectively. The SNR and CNR of parallel transmission (22.03±12.16 and 18.33±10.01, respectively) were both higher than those of single transmission (20.36±11.21 and 15.22±8.95, respectively) (t=-2.630, P<0.05 for SNR and t=-4.238, P<0.05 for CNR). Image quality comparisons revealed significantly better results with dual-source than single-source RF excitation at SPAIR T2WI (1.4±0.42 vs. 1.81±0.27), DWI (1.08±0.46 vs. 1.63±0.36) and balanced FFE sequence (0.95±0.45 vs. 1.65±0.37, Z=-5.894, -5.801 and -6.985, respectively, P<0.01). In the comparison of image quality, the agreement between the two readers was very good (Kappa>0.8, P<0.05).
  
  
  CONCLUSIONS
  Dual-source parallel RF excitation MR imaging in liver enables reducing dielectric shading, improving homogeneity of the RF magnetic induction field, and increasing SNR and CNR at 3.0 T.
authors: Department of Radiology The First Affiliated Hospital Xiamen University, Xiamen, China - shenbaozhong2009@163.com.
authors: Z R
authors: ZR
authors: Luo
authors: D
authors: D
authors: Wang
authors: X L
authors: XL
authors: Sun
authors: G K
authors: GK
authors: Wang
authors: X J
authors: XJ
authors: Zhuang
authors: B Z
authors: BZ
authors: Shen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008099:Liver / Q000033:anatomy & histology*; D008107:Liver Diseases / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D018709:Statistics, Nonparametric