Accelerated 3D free-breathing high-resolution myocardial T1? mapping at 3 Tesla

Abstract

Abstract
Purpose
To develop a fast free-breathing whole-heart high-resolution myocardial T1? mapping technique with robust spin-lock preparation that can be performed at 3 Tesla.

Methods
An adiabatically excited continuous-wave spin-lock module, insensitive to field inhomogeneities, was implemented with an electrocardiogram-triggered low-flip angle spoiled gradient echo sequence with variable-density 3D Cartesian undersampling at a 3?Tesla whole-body scanner. A saturation pulse was performed at the beginning of each cardiac cycle to null the magnetization before T1? preparation. Multiple T1?-weighted images were acquired with T1? preparations with different spin-lock times in an interleaved fashion. Respiratory self-gating approach was adopted along with localized autofocus to enable 3D translational motion correction of the data acquired in each heartbeat. After motion correction, multi-contrast locally low-rank reconstruction was performed to reduce undersampling artifacts. The accuracy and feasibility of the 3D T1? mapping technique was investigated in phantoms and in vivo in 10 healthy subjects compared with the 2D T1? mapping.

Results
The 3D T1? mapping technique provided similar phantom T1? measurements in the range of 25–120?ms to the 2D T1? mapping reference over a wide range of simulated heart rates. With the robust adiabatically excited continuous-wave spin-lock preparation, good quality 2D and 3D in vivo T1?-weighted images and T1? maps were obtained. Myocardial T1? values with the 3D T1? mapping were slightly longer than 2D breath-hold measurements (septal T1?: 52.7?±?1.4 ms vs. 50.2?±?1.8 ms, P?<?0.01).

Conclusion
A fast 3D free-breathing whole-heart T1? mapping technique was proposed for T1? quantification at 3 T with isotropic spatial resolution (2?mm3) and short scan time of ?4.5 min.