title: Whole-heart coronary magnetic resonance angiography at 3.0T using short-TR steady-state free precession, vastly undersampled isotropic projection reconstruction.
abstract: OBJECTIVE
  To evaluate the feasibility of improving 3.0T steady-state free precession (SSFP) whole-heart coronary magnetic resonance angiography (MRA) using short-TR (repetition time) VIPR (vastly undersampled isotropic projection reconstruction).
  
  
  METHODS
  SSFP is highly sensitive to field inhomogeneity. VIPR imaging uses nonselective radiofrequency pulses, allowing short TR and reduced banding artifacts, while achieving isotropic 3D resolution. Coronary artery imaging was performed in nine healthy volunteers using SSFP VIPR. TR was reduced to 3.0 msec with an isotropic spatial resolution of 1.3 x 1.3 x 1.3 mm(3). Image quality, vessel sharpness, and lengths of major coronary arteries were measured. Comparison between SSFP using Cartesian trajectory and SSFP using VIPR trajectory was performed in all volunteers.
  
  
  RESULTS
  Short-TR SSFP VIPR resulted in whole-heart images without any banding artifacts, leading to excellent coronary artery visualization. The average image quality score for VIPR-SSFP was 3.12 +/- 0.42 out of four while that for Cartesian SSFP was 0.92 +/- 0.61. A significant improvement (P < 0.05) in image quality was shown by Wilcoxon comparison. The visualized coronary artery lengths for VIPR-SSFP were: 10.13 +/- 0.79 cm for the left anterior descending artery (LAD), 7.90 +/- 0.91 cm for the left circumflex artery (LCX), 7.50 +/- 1.65 cm for the right coronary artery (RCA), and 1.84 +/- 0.23 cm for the left main artery (LM). The lengths statistics for Cartesian SSFP were 1.57 +/- 2.02 cm, 1.54 +/- 1.93 cm, 0.94 +/- 1.17 cm, 0.46 +/- 0.53 cm, respectively. The image sharpness was also increased from 0.61 +/- 0.13 (mm(-1)) in Cartesian-SSFP to 0.81 +/- 0.11 (mm(-1)) in VIPR-SSFP.
  
  
  CONCLUSIONS
  With VIPR trajectory the TR is substantially decreased, reducing the sensitivity of SSFP to field inhomogeneity and resulting in whole-heart images without banding artifacts at 3.0T. Image quality improved significantly over Cartesian sampling.
authors.affiliation: Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, Illinois, USA.
authors.forename: Jingsi
authors.initials: J
authors.lastname: Xie
authors.forename: Peng
authors.initials: P
authors.lastname: Lai
authors.forename: Himanshu
authors.initials: H
authors.lastname: Bhat
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
mesh_terms: D000328:Adult; D000465:Algorithms; D016880:Anisotropy; D003331:Coronary Vessels / Q000033:anatomy & histology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D055815:Young Adult