Accelerated DESPOT1 with variable parameters for 3D T1 brain mapping

Driven equilibrium single pulse observation of T1 (DESPOT1) is a reliable technique for clinical 3D T1 brain mapping. However, its fixed repetition time (TR) and bandwidth (BW) and its linear modeling to estimate T1 conveys to an inefficient imaging protocol. We propose a variable DESPOT1 (vDESPOT1) acquisition and modeling strategy to improve scan efficiency and to accelerate image acquisition.

vDESPOT1 uses SPGR acquisitions with optimized combinations of TRs, BWs, and FAs, coupled with dictionary-based reconstruction to achieve faster acquisition and more efficient T1 mapping. The proposed vDESPOT1 method was compared to DESPOT1 and inversion recovery spin echo (IR-SE) in phantom and in ten brain healthy subjects.

Results demonstrate a reduction in scan time of approximately 40 %, allowing faster 3D brain T1 mapping while maintaining accuracy and T1NR in comparison to conventional DESPOT1. Also, the computational efficiency of a pre-computed dictionary of vDESPOT1 reduces the reconstruction time by ∼50× in comparison linear regression of conventional DESPOT1. Variable BW can enhance scan efficiency without significantly affecting the SNR for T1 when using vDESPOT1.

These time improvements make vDESPOT1 particularly valuable for dynamic and high-field MRI applications, such as thermal therapy monitoring, pharmacokinetic analysis in DCE-MRI, and imaging in anatomies prone to motion, including the heart, liver, and lungs.