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Inversion recovery at 7 T in the human myocardium: Measurement of T 1 , inversion efficiency and B 1 +
Author(s) -
Rodgers Christopher T.,
Piechnik Stefan K.,
DelaBarre Lance J.,
Moortele PierreFrançois,
Snyder Carl J.,
Neubauer Stefan,
Robson Matthew D.,
Vaughan J. Thomas
Publication year - 2013
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24548
Subject(s) - inversion (geology) , heartbeat , nuclear magnetic resonance , magnetization , physics , magnetic field , computer science , mathematics , nuclear medicine , medicine , geology , quantum mechanics , paleontology , computer security , structural basin
At clinical MRI field strengths (1.5 and 3 T), quantitative maps of the longitudinal relaxation time T 1 of the myocardium reveal diseased tissue without requiring contrast agents. Cardiac T 1 maps can be measured by Look‐Locker inversion recovery sequences such as ShMOLLI at 1.5 and 3 T. Cardiovascular MRI at a field strength of 7 T has recently become feasible, but doubts have remained as to whether magnetization inversion is possible in the heart due to subject heating and technical limitations. This work extends the repertoire of 7 T cardiovascular MRI by implementing an adiabatic inversion pulse optimized for use in the heart at 7 T. A “ShMOLLI+IE” adaptation of the ShMOLLI pulse sequence has been introduced together with new postprocessing that accounts for the possibility of incomplete magnetization inversion. These methods were validated in phantoms and then used in a study of six healthy volunteers to determine the degree of magnetization inversion and the T 1 of normal myocardium at 7 T within a 22‐heartbeat breathhold. Using a scanner with 16 × 1 kW radiofrequency outputs, inversion efficiencies ranging from −0.79 to −0.83 (intrasegment means; perfect 180° would give −1) were attainable across the myocardium. The myocardial T 1 was 1925 ± 48 ms (mean ± standard deviation). Magn Reson Med, 70:1038–1046, 2013. © 2012 Wiley Periodicals, Inc.