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Rapid combined T 1 and T 2 mapping using gradient recalled acquisition in the steady state
Author(s) -
Deoni Sean C.L.,
Rutt Brian K.,
Peters Terry M.
Publication year - 2003
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.10407
Subject(s) - steady state free precession imaging , voxel , flip angle , nuclear magnetic resonance , imaging phantom , physics , spin echo , gradient echo , isotropy , nuclear medicine , magnetic resonance imaging , optics , computer science , artificial intelligence , medicine , radiology
Abstract A novel, fully 3D, high‐resolution T 1 and T 2 relaxation time mapping method is presented. The method is based on steady‐state imaging with T 1 and T 2 information derived from either spoiling or fully refocusing the transverse magnetization following each excitation pulse. T 1 is extracted from a pair of spoiled gradient recalled echo (SPGR) images acquired at optimized flip angles. This T 1 information is combined with two refocused steady‐state free precession (SSFP) images to determine T 2 . T 1 and T 2 accuracy was evaluated against inversion recovery (IR) and spin‐echo (SE) results, respectively. Error within the T 1 and T 2 maps, determined from both phantom and in vivo measurements, is approximately 7% for T 1 between 300 and 2000 ms and 7% for T 2 between 30 and 150 ms. The efficiency of the method, defined as the signal‐to‐noise ratio (SNR) of the final map per voxel volume per square root scan time, was evaluated against alternative mapping methods. With an efficiency of three times that of multipoint IR and three times that of multiecho SE, our combined approach represents the most efficient of those examined. Acquisition time for a whole brain T 1 map (25 × 25 × 10 cm) is less than 8 min with 1 mm 3 isotropic voxels. An additional 7 min is required for an identically sized T 2 map and postprocessing time is less than 1 min on a 1 GHz PIII PC. The method therefore permits real‐time clinical acquisition and display of whole brain T 1 and T 2 maps for the first time. Magn Reson Med 49:515–526, 2003. © 2003 Wiley‐Liss, Inc.