Yon Maxime, Narvaez Omar, Topgaard Daniel, Sierra Alejandra
A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
Department of Chemistry, Lund University, Lund, Sweden.
NMR Biomed. 2025 Jan;38(1):e5286. doi: 10.1002/nbm.5286. Epub 2024 Nov 24.
Massively multidimensional diffusion magnetic resonance imaging combines tensor-valued encoding, oscillating gradients, and diffusion-relaxation correlation to provide multicomponent subvoxel parameters depicting some tissue microstructural features. This method was successfully implemented ex vivo in microimaging systems and clinical conditions with tensor-valued gradient waveform of variable duration giving access to a narrow diffusion frequency (ω) range. We demonstrate here its preclinical in vivo implementation with a protocol of 389 contrast images probing a wide diffusion frequency range of 18 to 92 Hz at b-values up to 2.1 ms/μm enabled by the use of modulated gradient waveforms and combined with multislice high-resolution and low-distortion echo planar imaging acquisition with segmented and full reversed phase-encode acquisition. This framework allows the identification of diffusion ω-dependence in the rat cerebellum and olfactory bulb gray matter (GM), and the parameter distributions are shown to resolve two water pools in the cerebellum GM with different diffusion coefficients, shapes, ω-dependence, relaxation rates, and spatial repartition whose attribution to specific microstructure could modify the current understanding of the origin of restriction in GM.
大规模多维度扩散磁共振成像结合张量值编码、振荡梯度和扩散-弛豫相关性，以提供描绘某些组织微观结构特征的多组分亚体素参数。该方法已在微观成像系统和临床条件下成功地在体外实施，采用可变持续时间的张量值梯度波形，可获得较窄的扩散频率（ω）范围。我们在此展示其临床前体内实施情况，通过389幅对比图像的方案，利用调制梯度波形，在高达2.1 ms/μm的b值下探测18至92 Hz的宽扩散频率范围，并结合多层高分辨率和低失真回波平面成像采集以及分段和全反转相位编码采集。该框架能够识别大鼠小脑和嗅球灰质（GM）中的扩散ω依赖性，并且参数分布显示可解析小脑GM中具有不同扩散系数、形状、ω依赖性、弛豫率和空间分布的两个水池，其对特定微观结构的归因可能会改变目前对GM中限制起源的理解。
