Magnetic resonance in medicine · 2025
Interpretation of inhomogeneous magnetization transfer in myelin water using a four-pool model with dipolar reservoirs.
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Lam Michelle H, Novoselova Masha, Yung Andrew, Prevost Valentin H, Manning Alan P, Liu Jie, Tetzlaff Wolfram, Kozlowski Piotr
Аннотация
PURPOSE: To confirm ihMT's specificity to myelin, an ihMT presaturation module was combined with a Poon-Henkelman multi-echo spin-echo readout to separate the ihMT signal in myelin water from intra-/extra-cellular water. This study explored the relationship between two quantitative myelin imaging techniques and measured the ihMT signal of myelin water.
METHODS: Six rats were injured; three were sacrificed three weeks post-injury, and three were sacrificed eight weeks post-injury, and three healthy control rats were also sacrificed. The nine formalin-fixed rat spinal cords were imaged using a Poon-Henkelman multi-echo spin-echo readout with an ihMT prepulse at different strengths of T 1 D $$ {T}_{1D} $$ filtering at 7T.
RESULTS: The proposed model was able to characterize the ihMT decay signal in myelin water and intra-/extra-cellular water pool. From this proposed four-pool model with dipolar order reservoirs, we see a drop in the T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ fit parameter in the fasciculus gracilis white matter region of the three-week post-injury cord. T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ and T 1 D $$ {T}_{1D} $$ (non-myelin) were estimated to be approx. 8 and 1.5 ms, respectively.
CONCLUSION: The drop in T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ in the three-week post-injury cords suggests that T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ could potentially distinguish between functional myelin and myelin debris; however, more studies are needed to confirm this.
METHODS: Six rats were injured; three were sacrificed three weeks post-injury, and three were sacrificed eight weeks post-injury, and three healthy control rats were also sacrificed. The nine formalin-fixed rat spinal cords were imaged using a Poon-Henkelman multi-echo spin-echo readout with an ihMT prepulse at different strengths of T 1 D $$ {T}_{1D} $$ filtering at 7T.
RESULTS: The proposed model was able to characterize the ihMT decay signal in myelin water and intra-/extra-cellular water pool. From this proposed four-pool model with dipolar order reservoirs, we see a drop in the T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ fit parameter in the fasciculus gracilis white matter region of the three-week post-injury cord. T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ and T 1 D $$ {T}_{1D} $$ (non-myelin) were estimated to be approx. 8 and 1.5 ms, respectively.
CONCLUSION: The drop in T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ in the three-week post-injury cords suggests that T 1 D ( myelin ) $$ {T}_{1D}\left(\mathrm{myelin}\right) $$ could potentially distinguish between functional myelin and myelin debris; however, more studies are needed to confirm this.