T 1D ‐weighted ihMT imaging – Part II. Investigating the long‐ and short‐T 1D components correlation with myelin content. Comparison with R 1 and the macromolecular proton fraction

Andreea Hertanu (1) , Lucas Soustelle (1) , Julie Buron (1, 2) , Julie Le Priellec (2) , Myriam Cayre (2) , Arnaud Le Troter (1) , Gopal Varma (3) , David C Alsop (3) , Pascale Durbec (2) , Olivier Girard (1) , Guillaume Duhamel (1)

1 CRMBM - Centre de résonance magnétique biologique et médicale
2 IBDM - Institut de Biologie du Développement de Marseille
3 BIDMC - Beth Israel Deaconess Medical Center [Boston]

Purpose To investigate the long- and short-T1D components correlation with myelin content using inhomogeneous magnetization transfer (ihMT) high-pass and band-pass T1D-filters and to compare ihMT, R1, and the macromolecular proton fraction (MPF) for myelin specific imaging. Methods The 3D ihMT rapid gradient echo (ihMTRAGE) sequences with increasing switching times (Δt) were used to derive ihMT high-pass T1D-filters with increasing T1D cutoff values and an ihMT band-pass T1D-filter for components in the 100 µs to 1 ms range. 3D spoiled gradient echo quantitative MT (SPGR-qMT) protocols were used to derive R1 and MPF maps. The specificity of R1, MPF, and ihMT T1D-filters was evaluated by comparison with two histological reference techniques for myelin imaging. Results The higher contribution of long-T1Ds as compared to the short components as Δt got longer led to an increase in the specificity to myelination. In contrast, focusing on the signal originating from a narrow range of short-T1Ds (< 1 ms) as isolated by the band-pass T1D-filter led to lower specificity. In addition, the significantly lower r2 correlation coefficient of the band-pass T1D-filter suggests that the origin of short-T1D components is mostly associated with non-myelin protons. Also, the important contribution of short-T1Ds to the estimated MPF, explains its low specificity to myelination as compared to the ihMT high-pass T1D-filters. Conclusion Long-T1D components imaging by means of ihMT high-pass T1D-filters is proposed as an MRI biomarker for myelin content. Future studies should enable the investigation of the sensitivity of ihMT T1D-filters for demyelinating processes.

Domaines: Imagerie

Andreea Hertanu, Lucas Soustelle, Julie Buron, Julie Le Priellec, Myriam Cayre, et al.. T 1D ‐weighted ihMT imaging – Part II. Investigating the long‐ and short‐T 1D components correlation with myelin content. Comparison with R 1 and the macromolecular proton fraction. Magnetic Resonance in Medicine, 2022, ⟨10.1002/mrm.29140⟩. ⟨hal-03529600⟩