%0 Journal Article
%@ 0278-0062
%A Ramos Llordén, Gabriel
%A Vegas Sánchez-Ferrero, Gonzalo
%A Björk, Marcus
%A Vanhevel, Floris
%A Parizel, Paul M.
%A San José Estépar, Raúl
%A Dekker, Arnold J. den
%A Sijbers, Jan
%D 2018
%F upm:55074
%I IEEE
%J IEEE transactions on medical imaging
%K T1 mapping; variable flip angle; SPGR; DESPOT1; relaxometry
%N 11
%P 2414-2427
%T NOVIFAST: A Fast Algorithm for Accurate and Precise VFA MRI T1 Mapping
%U https://oa.upm.es/55074/
%V 37
%X In quantitative magnetic resonance T1 mapping, the variable flip angle (VFA) steady state spoiled gradient recalled echo (SPGR) imaging technique is popular as it provides a series of high resolution T1 weighted images in a clinically feasible time. Fast, linear methods that estimate T1 maps from these weighted images have been proposed, such as DESPOT1 and iterative re-weighted linear least squares. More accurate, non-linear least squares (NLLS) estimators are in play, but these are generally much slower and require careful initialization. In this paper, we present NOVIFAST, a novel NLLS-based algorithm specifically tailored to VFA SPGR T1 mapping. By exploiting the particular structure of the SPGR model, a computationally efficient, yet accurate and precise T1 map estimator is derived. Simulation and in vivo human brain experiments demonstrate a twenty-fold speed gain of NOVIFAST compared with conventional gradient-based NLLS estimators while maintaining a high precision and accuracy. Moreover, NOVIFAST is eight times faster than the efficient implementations of the variable projection (VARPRO) method. Furthermore, NOVIFAST is shown to be robust against initialization.