Free-breathing three-dimensional simultaneous myocardial T₁ and T₂ mapping based on multi-parametric SAturation-recovery and Variable-flip-Angle

Background: Quantitative myocardial tissue characterization with T₁ and T₂ parametric mapping can provide an accurate and complete assessment of tissue abnormalities across a broad range of cardiomyopathies. However, current clinical T₁ and T₂ mapping tools rely predominantly on two-dimensional (2D) breath-hold sequences. Clinical adoption of three-dimensional (3D) techniques is limited by long scan duration. The aim of this study is to develop and validate a time-efficient 3D free-breathing simultaneous T₁ and T₂ mapping sequence using multi-parametric SAturation-recovery and Variable-flip-Angle (mSAVA). Methods: mSAVA acquires four volumes for simultaneous whole-heart T₁ and T₂ mapping. We validated mSAVA using simulations, phantoms, and in-vivo experiments at 3T in 11 healthy subjects and 11 patients with diverse cardiomyopathies. T₁ and T₂ values by mSAVA were compared with modified Look-Locker inversion recovery (MOLLI) and gradient and spin echo (GraSE), respectively. The clinical performance of mSAVA was evaluated against late gadolinium enhancement (LGE) imaging in patients. Results: Phantom T₁ and T₂ by mSAVA showed a strong correlation to reference sequences (R² = 0.98 and 0.99). In-vivo imaging with an imaging resolution of 1.5 × 1.5 × 8 mm³ could be achieved. Myocardial T₁ and T₂ of healthy subjects by mSAVA were 1310 ± 46 and 44.6 ± 2.0 ms, respectively, with T₁ standard deviation higher than MOLLI (105 ± 12 vs 60 ± 16 ms) and T₂ standard deviation lower than GraSE (4.5 ± 0.8 vs 5.5 ± 1.0 ms). mSAVA T₁ and T₂ maps presented consistent findings in patients undergoing LGE. Myocardial T₁ and T₂ of all patients by mSAVA were 1421 ± 79 and 47.2 ± 3.3 ms, respectively. Conclusion: mSAVA is a fast 3D technique promising for clinical whole-heart T₁ and T₂ mapping.