A multi‐dimensional diffusion encoding (MDE) protocol for studying brain microstructure changes in neurodegeneration

作者：Erpeng Dai, Martin Schneider, Xuetong Zhou, S. Shailja, Michael Zeineh, Jennifer A. McNab · 发表于：Alzheimer s & Dementia · 年份：2025 · DOI：10.1002/alz70862_109814 · 被引用次数：1 · 研究领域：Advanced Neuroimaging Techniques and Applications、Functional Brain Connectivity Studies、MRI in cancer diagnosis

Abstract Background Diffusion MRI is a promising approach to detecting brain microstructure changes associated with neurodegeneration. Unfortunately, diffusion tensor imaging (DTI) only provides limited specificity as it relies solely on single‐dimensional diffusion encoding. Multi‐dimensional diffusion encoding (MDE) is an emerging method for more specific brain microstructure mapping with advanced diffusion‐encoding waveform design and modeling. However, MDE typically decreases the diffusion‐encoding efficiency and SNR, resulting in relatively low voxel resolution (>2 mm isotropic). We aim to develop an MDE protocol of 1.8 mm isotropic with a clinically feasible scan time using an optimized MDE waveform design and an SNR‐efficient readout, for studying brain microstructure changes in neurodegeneration. Moreover, we evaluate the scan‐rescan reproducibility of the developed MDE protocol. Methods A customized MDE sequence was developed by jointly using two different diffusion‐encoding waveforms: linear and spherical tensor‐valued diffusion encoding (LTE and STE). An SNR‐efficient multi‐band multi‐shot EPI sequence and reconstruction were used for data readout. Three cognitively normal elderly subjects (1F/2M, aged 62∼70 y/o) were scanned on a 3T GE scanner equipped with a UHP gradient coil. Detailed parameters are listed in Table 1. Quantitative diffusion metrics were calculated, including mean diffusivity (MD), microscopic fractional anisotropy (μFA), anisotropic and isotr...