Accelerated 3D free‐breathing high‐resolution myocardial T1ρ mapping at 3 Tesla

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 mm 3 ) and short scan time of ∼4.5 min.