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Accelerating MR parameter mapping using sparsity‐promoting regularization in parametric dimension
Author(s) -
Velikina Julia V.,
Alexander Andrew L.,
Samsonov Alexey
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.24577
Subject(s) - undersampling , regularization (linguistics) , compressed sensing , computer science , parametric statistics , algorithm , nonparametric statistics , iterative reconstruction , dimension (graph theory) , signal reconstruction , artificial intelligence , mathematical optimization , mathematics , signal processing , statistics , telecommunications , radar , pure mathematics
MR parameter mapping requires sampling along additional (parametric) dimension, which often limits its clinical appeal due to a several‐fold increase in scan times compared to conventional anatomic imaging. Data undersampling combined with parallel imaging is an attractive way to reduce scan time in such applications. However, inherent SNR penalties of parallel MRI due to noise amplification often limit its utility even at moderate acceleration factors, requiring regularization by prior knowledge. In this work, we propose a novel regularization strategy, which uses smoothness of signal evolution in the parametric dimension within compressed sensing framework (p‐CS) to provide accurate and precise estimation of parametric maps from undersampled data. The performance of the method was demonstrated with variable flip angle T 1 mapping and compared favorably to two representative reconstruction approaches, image space‐based total variation regularization and an analytical model‐based reconstruction. The proposed p‐CS regularization was found to provide efficient suppression of noise amplification and preservation of parameter mapping accuracy without explicit utilization of analytical signal models. The developed method may facilitate acceleration of quantitative MRI techniques that are not suitable to model‐based reconstruction because of complex signal models or when signal deviations from the expected analytical model exist. Magn Reson Med 70:1263–1273, 2013. © 2012 Wiley Periodicals, Inc.