T 1D ‐weighted ihMT imaging – Part I. Isolation of long‐ and short‐T 1D components by T 1D ‐filtering
Résumé
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| Origine | Fichiers produits par l'(les) auteur(s) |
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