title: Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition.
abstract: The dual echo steady-state (DESS) sequence has been shown successful in achieving fast T2 mapping with good precision. Under-estimation of T2, however, becomes increasingly prominent as the flip angle decreases. In 3D DESS imaging, therefore, the derived T2 values would become a function of the slice location in the presence of non-ideal slice profile of the excitation RF pulse. Furthermore, the pattern of slice-dependent variation in T2 estimates is dependent on the RF pulse waveform. Multi-slice 2D DESS imaging provides better inter-slice consistency, but the signal intensity is subject to integrated effects of within-slice distribution of the actual flip angle. Consequently, T2 measured using 2D DESS is prone to inaccuracy even at the designated flip angle of 90°. In this study, both phantom and human experiments demonstrate the above phenomena in good agreement with model prediction.
authors.affiliation: Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Pei-Hsin
authors.initials: PH
authors.lastname: Wu
authors.forename: Cheng-Chieh
authors.initials: CC
authors.lastname: Cheng
authors.forename: Ming-Long
authors.initials: ML
authors.lastname: Wu
authors.forename: Tzu-Cheng
authors.initials: TC
authors.lastname: Chao
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Chung
authors.forename: Teng-Yi
authors.initials: TY
authors.lastname: Huang
mesh_terms: D001921:Brain / Q000473:pathology; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
keywords: 2D and 3D imaging; Dual-echo steady-state imaging; Flip angle dependency; Slice profile; T2 quantification