Accelerated 3D free-breathing high-resolution myocardial T 1ρ mapping at 3 Tesla
Haikun Qi, Zhenfeng Lv, Junpu Hu, Jian Xu, René Botnar, Claudia Prieto, Peng Hu
Abstract
Purpose
To develop a fast free-breathing whole-heart high-resolution myocardial T 1ρ 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 T 1ρ preparation. Multiple T 1ρ-weighted images were acquired with T 1ρ 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 T 1ρ mapping technique was investigated in phantoms and in vivo in 10 healthy subjects compared with the 2D T 1ρ mapping.
Results
The 3D T 1ρ mapping technique provided similar phantom T 1ρ measurements in the range of 25–120 ms to the 2D T 1ρ 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 T 1ρ-weighted images and T 1ρ maps were obtained. Myocardial T 1ρ values with the 3D T 1ρ mapping were slightly longer than 2D breath-hold measurements (septal T 1ρ: 52.7 ± 1.4 ms vs. 50.2 ± 1.8 ms, P < 0.01).
Conclusion
A fast 3D free-breathing whole-heart T 1ρ mapping technique was proposed for T 1ρ quantification at 3 T with isotropic spatial resolution (2 mm3) and short scan time of ∼4.5 min.