title: Rapid phase-modulated water excitation steady-state free precession for fat suppressed cine cardiovascular MR.
abstract: BACKGROUND
  The purpose of this article is to describe a steady-state free precession (SSFP) sequence for fat suppressed cine cardiovascular magnetic resonance (CMR). A rapid phase-modulated binomial water excitation (WE) pulse is utilized to minimize repetition time and acquisition time.
  
  
  METHODS
  Three different water-excitation pulses were combined with cine-SSFP for evaluation. The frequency response of each sequence was simulated and examined in phantom imaging studies. The ratio of fat to water signal amplitude was measured in phantoms to evaluate the fat suppression capabilities of each method. Six volunteers underwent CMR of the heart at 1.5T to compare retrospectively-gated cine-SSFP with and without water excitation. The ratio of fat to myocardium signal amplitude was measured for conventional cine-SSFP and phase-modulated WE-SSFP. The proposed WE-SSFP method was tested in one patient referred for CMR to characterize a cardiac mass.
  
  
  CONCLUSIONS
  The measured frequency response in a phantom corresponded to the numerical Bloch equation simulation demonstrating the widened stop-band around the fat resonant frequency for all water-excitation pulses tested. In vivo measurements demonstrated that a rapid, phase-modulated water excitation pulse significantly reduced the signal amplitude ratio of fat to myocardium from 6.92 +/- 2.9 to 0.8 +/- 0.13 (mean +/- SD) without inducing any perceptible artifacts in SSFP cine CMR.
  
  
  CONCLUSIONS
  Fat suppression can be achieved in SSFP cine CMR while maintaining steady-state equilibrium using rapid, phase modulated, binomial water-excitation pulses.
authors.affiliation: Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA. hung-yu.lin@osumc.edu
authors.forename: Hung-Yu
authors.initials: HY
authors.lastname: Lin
authors.forename: Subha V
authors.initials: SV
authors.lastname: Raman
authors.forename: Yiu-Cho
authors.initials: YC
authors.lastname: Chung
authors.forename: Orlando P
authors.initials: OP
authors.lastname: Simonetti
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D001834:Body Water; D005260:Female; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009206:Myocardium; D009929:Organ Size; D019047:Phantoms, Imaging; D012189:Retrospective Studies; D013997:Time Factors