Purpose: To propose a 3D quantitative high-resolution T1 mapping technique, called 3D SASHA (saturation-recovery single-shot acquisition), which combines a saturation recovery pulse with 1D-navigator-based-respiratory motion compensation to acquire the whole volume of the heart in free breathing. The sequence was tested and validated both in a T1 phantom and in healthy subjects.
Materials and methods: The 3D SASHA method was implemented on a 1.5T scanner. A diaphragmatic navigator was used to allow free-breathing acquisition and the images were acquired with a resolution of 1.4 × 1.4 × 8 mm3 . For assessment of accuracy and precision the sequence was compared with the reference gold-standard inversion-recovery spin echo (IRSE) pulse sequence in a T1 phantom, while for the in vivo studies (10 healthy volunteers) 3D SASHA was compared with the clinically used 2D MOLLI (3-3-5) and 2D SASHA protocols.
Results: There was good agreement between the T1 values measured in a T1 phantom with 3D SASHA and the reference IRSE pulse sequences (1111.6 ± 31 msec vs. 1123.6 ± 8 msec, P = 0.9947). Mean and standard deviation of the myocardial T1 values in healthy subjects measured with 2D MOLLI, 2D SASHA, and 3D SASHA sequences were 881 ± 40 msec, 1181.3 ± 32 msec, and 1153.6 ± 28 msec respectively.
Conclusion: The proposed 3D SASHA sequence allows for high-resolution free-breathing whole-heart T1 -mapping with T1 values in good agreement with the 2D SASHA and improved precision.
Level of evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:218-227.
Keywords: MRI; T1 mapping; accuracy; precision; saturation-recovery.
© 2017 International Society for Magnetic Resonance in Medicine.