Publication Date:
2014-04-19
Description:
Purpose Fast, quantitative T 2 mapping is of value to both clinical and research environments. However, many protocols utilizing fast spin echo (FSE) pulse sequences contain acceleration-induced artifacts that are compounded when fitting parameter maps, especially in the presence of imperfect refocusing. This work presents a B 1 -corrected, model-based reconstruction and associated Cartesian FSE phase-encode ordering that provides enhanced accuracy in T 2 estimates compared with other common accelerated protocols. Theory and Methods The method, known as multiple echo, Caesar cipher acquisition and model-based reconstruction (ME-CAMBREC), directly fitted T 2 , flip angle, and proton density maps on a row-by-row basis to k-space data using the extended phase graph model. Regularization was enforced in order to minimize noise amplification effects. ME-CAMBREC was evaluated in computational and physical phantoms, as well as human brain, and compared with other FSE-based T 2 mapping protocols, DESPOT2, and parallel imaging acceleration. Results In computational, phantom, and human experiments, ME-CAMBREC provided T 2 maps with fewer artifacts and less or similar error compared with other methods tested at moderate-to-high acceleration factors. In vivo, ME-CAMBREC provided error rates approximately one-half those of other methods. Conclusion Directly fitting multi-echo data to k-space using the extended phase graph can increase fidelity of T 2 maps significantly, especially when using an appropriate phase-encode ordering. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.
Print ISSN:
0740-3194
Electronic ISSN:
1522-2594
Topics:
Medicine
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