title: Inversion recovery prepared turbo spin echo sequences with reduced SAR using smooth transitions between pseudo steady states.
abstract: This study investigates the contrast behavior of 2D inversion recovery (IR) prepared turbo spin echo (TSE) sequences that use RF pulse schemes with variable low flip angles (hyperTSE) to reduce RF power deposition. A framework of equations and calculations for adapting the sequence parameters is presented by which equivalent image contrast is achieved compared to conventional IR-TSE imaging. Although the inversion time (TI) and repetition time (TR) do not need to be changed, the echo time (TE) has to be prolonged such that the effective TE (TE(eff)) is preserved. Measurements in healthy volunteers confirmed this finding for IR-TSE sequences using different TIs: fluid attenuated inversion recovery (FLAIR), gray matter (GM)-white matter (WM)-IR, and short tau IR (STIR). The results demonstrate that hyperTSE sequences enable high-quality IR-prepared imaging with a considerably reduced specific absorption rate (SAR).
authors.affiliation: Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany. Matthias.Weigel@uniklinik-freiburg.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Weigel
authors.forename: Maxim
authors.initials: M
authors.lastname: Zaitsev
authors.forename: Juergen
authors.initials: J
authors.lastname: Hennig
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male