title: B1-insensitive T2 mapping of healthy thigh muscles using a T2-prepared 3D TSE sequence.
abstract: OBJECTIVE
  To propose a T2-prepared 3D turbo spin echo (T2prep 3D TSE) sequence for B1-insensitive skeletal muscle T2 mapping and compare its performance with 2D and 3D multi-echo spin echo (MESE) for T2 mapping in thigh muscles of healthy subjects.
  
  
  METHODS
  The performance of 2D MESE, 3D MESE and the proposed T2prep 3D TSE in the presence of transmit B1 and B0 inhomogeneities was first simulated. The thigh muscles of ten young and healthy subjects were then scanned on a 3 T system and T2 mapping was performed using the three sequences. Transmit B1-maps and proton density fat fraction (PDFF) maps were also acquired. The subjects were scanned three times to assess reproducibility. T2 values were compared among sequences and their sensitivity to B1 inhomogeneities was compared to simulation results. Correlations were also determined between T2 values, PDFF and B1.
  
  
  RESULTS
  The left rectus femoris muscle showed the largest B1 deviations from the nominal value (from 54.2% to 92.9%). Significant negative correlations between T2 values and B1 values were found in the left rectus femoris muscle for 3D MESE (r = -0.72, p<0.001) and 2D MESE (r = -0.71, p<0.001), but not for T2prep 3D TSE (r = -0.32, p = 0.09). Reproducibility of T2 expressed by root mean square coefficients of variation (RMSCVs) were equal to 3.5% in T2prep 3D TSE, 2.6% in 3D MESE and 2.4% in 2D MESE. Significant differences between T2 values of 3D sequences (T2prep 3D TSE and 3D MESE) and 2D MESE were found in all muscles with the highest values for 2D MESE (p<0.05). No significant correlations were found between PDFF and T2 values.
  
  
  CONCLUSIONS
  A strong influence of an inhomogeneous B1 field on the T2 values of 3D MESE and 2D MESE was shown, whereas the proposed T2prep 3D TSE gives B1-insensitive and reproducible thigh muscle T2 mapping.
authors.affiliation: Institut für Diagnostische und Interventionelle Neuroradiologie, Technische Universität München, Munich, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Klupp
authors.affiliation: Institut für Diagnostische und Interventionelle Radiologie, Technische Universität München, Munich, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Weidlich
authors.affiliation: Institut für Diagnostische und Interventionelle Neuroradiologie, Technische Universität München, Munich, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Schlaeger
authors.affiliation: Institut für Diagnostische und Interventionelle Radiologie, Technische Universität München, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.affiliation: Institut für Diagnostische und Interventionelle Radiologie, Technische Universität München, Munich, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cervantes
authors.affiliation: Neurologische Klinik und Poliklinik, Technische Universität München, Munich, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Deschauer
authors.affiliation: Philips Healthcare, Hamburg, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Kooijman
authors.affiliation: Institut für Diagnostische und Interventionelle Radiologie, Technische Universität München, Munich, Germany.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.affiliation: Institut für Diagnostische und Interventionelle Neuroradiologie, Technische Universität München, Munich, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Zimmer
authors.affiliation: Institut für Diagnostische und Interventionelle Neuroradiologie, Technische Universität München, Munich, Germany.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Kirschke
authors.affiliation: Institut für Diagnostische und Interventionelle Radiologie, Technische Universität München, Munich, Germany.
authors.forename: Dimitrios C
authors.initials: DC
authors.lastname: Karampinos
mesh_terms: D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D013848:Thigh / Q000000981:diagnostic imaging*