新しいMRI手法が脳生理学への理解を深める(New MRI Method Offers Deeper Insight into Brain Physiology)

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2025-05-29 カリフォルニア大学バークレー校(UCB)

カリフォルニア大学バークレー校の研究チームは、新たなMRI技術「DiSpect(Displacement Spectrum MRI)」を開発し、脳の血流を逆方向に追跡することで、脳機能や疾患の理解を深める手法を提案しました。この技術は、血液中の水分子のスピン情報をタグ付けし、数秒後に大静脈でその情報を読み取ることで、血流の起点を特定します。従来のfMRIでは困難だった局所的な血流変化の観察が可能となり、神経活動に伴う血流の再分配(arterial blood stealing)などの現象を直接可視化できます。DiSpectは、非侵襲的かつ造影剤不要で、脳の血管構造や動態の変化を詳細に捉えることができ、将来的には脳動静脈奇形などの診断にも応用が期待されています。

<関連情報>

MR灌流源マッピングにより静脈領域が描出され、神経活性化時の灌流調節が明らかになる MR perfusion source mapping depicts venous territories and reveals perfusion modulation during neural activation

Ekin Karasan,Jingjia Chen,Julian Maravilla,Zhiyong Zhang,Chunlei Liu & Michael Lustig
Nature Communications  Published:24 April 2025
DOI:https://doi.org/10.1038/s41467-025-59108-3

figure 1

Abstract

The cerebral venous system plays a crucial role in neurological and vascular conditions, yet its hemodynamics remain underexplored due to its complexity and variability across individuals. To address this, we develop a venous perfusion source mapping method using Displacement Spectrum MRI, a non-contrast technique that leverages blood water as an endogenous tracer. Our technique encodes spatial information into the magnetization of blood water spins during tagging and detects it once the tagged blood reaches the brain’s surface, where the signal-to-noise ratio is 3–4 times higher. We resolve the sources of blood entering the imaging slice across short (10 ms) to long (3 s) evolution times, effectively capturing perfusion sources in reverse. This approach enables the measurement of slow venous blood flow, including potential contributions from capillary beds and surrounding tissue. We demonstrate perfusion source mapping in the superior cerebral veins, verify its sensitivity to global perfusion modulation induced by caffeine, and establish its specificity by showing repeatable local perfusion modulation during neural activation. From all blood within the imaging slice, our method localizes the portion originating from an activated region upstream.

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