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SUPER: A blockwise curve‐fitting method for accelerating MR parametric mapping with fast reconstruction
Author(s) -
Hu Chenxi,
Peters Dana C.
Publication year - 2019
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.27662
Subject(s) - undersampling , imaging phantom , mathematics , voxel , algorithm , parametric statistics , computer science , nuclear medicine , artificial intelligence , statistics , medicine
Purpose To investigate Shift Undersampling improves Parametric mapping Efficiency and Resolution (SUPER), a novel blockwise curve‐fitting method for accelerating parametric mapping with very fast reconstruction. Methods SUPER uses interleaved k‐space undersampling, which enables a blockwise decomposition of the otherwise large‐scale cost function to improve the reconstruction efficiency. SUPER can be readily combined with SENSE to achieve at least 4‐fold acceleration. D‐factor, a parametric‐mapping counterpart of g‐factor, was proposed and formulated to compare spatially heterogeneous noise amplification because of different acceleration methods. As a proof‐of‐concept, SUPER/SUPER‐SENSE was validated using T 1 mapping, by comparing them to alternative model‐based methods, including MARTINI and GRAPPATINI, via simulations, phantom imaging, and in vivo brain imaging ( N = 5), over criteria of normalized root‐mean‐squares error (NRMSE), average d‐factor, and computational time per voxel (TPV). A novel SUPER‐SENSE MOLLI cardiac T 1 ‐mapping sequence with improved resolution (1.4 mm × 1.4 mm) was compared to standard MOLLI (1.9 mm × 2.5 mm) in 8 healthy subjects. Results In brain imaging, 2‐fold SUPER achieved lower NRMSE (0.04 ± 0.02 vs. 0.11 ± 0.02, P < 0.01), lower average d‐factor (1.01 ± 0.002 vs. 1.12 ± 0.004, P < 0.001), and lower TPV (4.6 ms ± 0.2 ms vs. 79 ms ± 3 ms, P < 0.001) than 2‐fold MARTINI. Similarly, 4‐fold SUPER‐SENSE achieved lower NRMSE (0.07 ± 0.01 vs. 0.13 ± 0.03, P = 0.02), lower average d‐factor (1.15 ± 0.01 vs. 1.20 ± 0.01, P < 0.001), and lower TPV (4.0 ms ± 0.1 ms vs. 72 ms ± 3 ms, P < 0.001) than 4‐fold GRAPPATINI. In cardiac T 1 mapping, SUPER‐SENSE MOLLI yielded similar myocardial T 1 (1151 ms ± 63 ms vs. 1159 ms ± 32 ms, P = 0.6), slightly lower blood T 1 (1643 ms ± 86 ms vs. 1680 ms ± 79 ms, P = 0.004), but improved spatial resolution compared with standard MOLLI in the same imaging time. Conclusion SUPER and SUPER‐SENSE provide fast model‐based reconstruction methods for accelerating parametric mapping and improving its clinical appeal.