T 1D ‐weighted ihMT imaging – Part I. Isolation of long‐ and short‐T 1D components by T 1D ‐filtering

Andreea Hertanu (1) , Lucas Soustelle (1) , Arnaud Le Troter (1) , Julie Buron (1, 2) , Julie Le Priellec (2) , Victor N D Carvalho (1, 3) , Myriam Cayre (2) , Pascale Durbec (2) , Gopal Varma (4) , David C Alsop (4) , 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 ICR - Institut de Chimie Radicalaire
4 BIDMC - Beth Israel Deaconess Medical Center [Boston]

Purpose To identify T1D-filtering methods, which can specifically isolate various ranges of T1D components as they may be sensitive to different microstructural properties. Methods Modified Bloch-Provotorov equations describing a bi-T1D component biophysical model were used to simulate the inhomogeneous magnetization transfer (ihMT) signal from ihMTRAGE sequences at high RF power and low duty-cycle with different switching time values for the dual saturation experiment: Δt = 0.0, 0.8, 1.6, and 3.2 ms. Simulations were compared with experimental signals on the brain gray and white matter tissues of healthy mice at 7T. Results The lengthening of Δt created ihMT high-pass T1D-filters, which efficiently eliminated the signal from T1D components shorter than 1 ms, while partially attenuating that of longer components (≥ 1 ms). Subtraction of ihMTR images obtained with Δt = 0.0 ms and Δt = 0.8 ms generated a new ihMT band-pass T1D-filter isolating short-T1D components in the 100-µs to 1-ms range. Simulated ihMTR values in central nervous system tissues were confirmed experimentally. Conclusion Long- and short-T1D components were successfully isolated with high RF power and low duty-cycle ihMT filters in the healthy mouse brain. Future studies should investigate the various T1D-range microstructural correlations in in vivo tissues.

Domaines: Imagerie

Andreea Hertanu, Lucas Soustelle, Arnaud Le Troter, Julie Buron, Julie Le Priellec, et al.. T 1D ‐weighted ihMT imaging – Part I. Isolation of long‐ and short‐T 1D components by T 1D ‐filtering. Magnetic Resonance in Medicine, 2022, ⟨10.1002/mrm.29139⟩. ⟨hal-03529187⟩