Rapid and accurate T 2 mapping from multi–spin‐echo data using Bloch‐simulation‐based reconstruction

Purpose Quantitative T 2 ‐relaxation‐based contrast has the potential to provide valuable clinical information. Practical T 2 ‐mapping, however, is impaired either by prohibitively long acquisition times or by contamination of fast multiecho protocols by stimulated and indirect echoes. This work presents a novel postprocessing approach aiming to overcome the common penalties associated with multiecho protocols, and enabling rapid and accurate mapping of T 2 relaxation values. Methods Bloch simulations are used to estimate the actual echo‐modulation curve (EMC) in a multi–spin‐echo experiment. Simulations are repeated for a range of T 2 values and transmit field scales, yielding a database of simulated EMCs, which is then used to identify the T 2 value whose EMC most closely matches the experimentally measured data at each voxel. Results T 2 maps of both phantom and in vivo scans were successfully reconstructed, closely matching maps produced from single spin‐echo data. Results were consistent over the physiological range of T 2 values and across different experimental settings. Conclusion The proposed technique allows accurate T 2 mapping in clinically feasible scan times, free of user‐ and scanner‐dependent variations, while providing a comprehensive framework that can be extended to model other parameters (e.g., T 1 , B 1 + , B 0 , diffusion) and support arbitrary acquisition schemes. Magn Reson Med 73:809–817, 2015. © 2014 Wiley Periodicals, Inc.