title: Accuracy of equilibrium magnetization mapping in sliced two-dimensional spoiled gradient-recalled echo pulse sequence with variable flip angle.
abstract: OBJECTIVE
  To evaluate the accuracy of an equilibrium magnetization (M0 ) map obtained using a two-dimensional (2D) spoiled gradient-recalled echo (SPGR) pulse sequence with variable flip angle (VFA).
  
  
  METHODS
  Single-slice 2D SPGR images of 4% agar gel phantoms with different gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) concentrations (0-1 mM) were obtained with a VFA (2-30°). The 2D SPGR-VFA data were acquired with different repetition times (TRs; 7.8-117.2 ms), Gaussian and sinc RF pulses, and different field strengths (4.7, 7, and 9.4 Tesla). M0 and T1 maps were calculated from the 2D SPGR-VFA data. M0 and T1 values were compared with those calculated from free-relaxed 2D gradient-recalled echo (GRE) images and inversion recovery-prepared 2D SPGR images. The M0 and T1 slice profiles were also investigated.
  
  
  RESULTS
  Consistent M0 values were obtained, regardless of the different Gd concentrations, TRs, and pulse sequences. The M0 slice profiles calculated from the sliced SPGR-VFA data quantitatively reproduced those calculated from the free-relaxed sliced GRE. In contrast, the T1 values calculated from the 2D SPGR-VFA data were underestimated at a high Gd concentration, short TR, and Gaussian RF pulse.
  
  
  CONCLUSIONS
  M0 values calculated from 2D SPGR-VFA images are highly quantitative.
authors: Varian Technologies Japan Limited, Tokyo, Japan.
authors: Hideto
authors: H
authors: Kuribayashi
authors: Masaki
authors: M
authors: Sekino
authors: Takuya
authors: T
authors: Minowa
authors: Yoshie
authors: Y
authors: Maitani
authors: Hiroyuki
authors: H
authors: Ohsaki
authors: Shohji
authors: S
authors: Tsushima
authors: Shuichiro
authors: S
authors: Hirai
authors: Masayuki
authors: M
authors: Ueda
authors: Yasuo
authors: Y
authors: Katayama
mesh_terms: D000465:Algorithms; D003287:Contrast Media / Q000008:administration & dosage; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: 2D SPGR-VFA; M0 map; T1 map; equilibrium magnetization map; quantitative imaging; slice profile