Leppert Ilana R, Bontempi Pietro, Rowley Christopher D, Campbell Jennifer S W, Nelson Mark C, Schiavi Simona, Pike G Bruce, Daducci Alessandro, Tardif Christine L
McConnell Brain Imaging Centre, Montreal Neurological institute and Hospital, Montreal, Canada.
Department of Computer Science, University of Verona, Verona, Italy.
Imaging Neurosci (Camb). 2023 Sep 26;1. doi: 10.1162/imag_a_00019. eCollection 2023.
We present a novel dual-encoded magnetization transfer (MT) and diffusion-weighted sequence and demonstrate its potential to resolve distinct properties of white matter fiber tracts at the sub-voxel level. The sequence was designed and optimized for maximal MT ratio (MTR) efficiency. The resulting whole brain 2.6 mm isotropic protocol to measure tract-specific MTR has a scan time under 7 minutes. Ten healthy subjects were scanned twice to assess repeatability. Two different analysis methods were contrasted: a technique to extract tract-specific MTR using Convex Optimization Modeling for Microstructure Informed Tractography (COMMIT), a global optimization technique; and conventional MTR tractometry. The results demonstrate that the tract-specific method can reliably resolve the MT ratios of major white matter fiber pathways and is less affected by partial volume effects than conventional multi-modal tractometry. By reducing the contamination due to partial volume averaging of tracts, dual-encoded MT and diffusion may increase the sensitivity to microstructure alterations of specific tracts due to disease, aging, or learning, as well as lead to weighted structural connectomes with more anatomical specificity.
我们展示了一种新型的双编码磁化传递（MT）和扩散加权序列，并证明了其在亚体素水平解析白质纤维束不同特性的潜力。该序列是为实现最大MT比（MTR）效率而设计和优化的。由此产生的用于测量特定纤维束MTR的全脑2.6毫米各向同性方案扫描时间不到7分钟。对10名健康受试者进行了两次扫描以评估重复性。对比了两种不同的分析方法：一种使用用于微观结构信息纤维束成像的凸优化建模（COMMIT）提取特定纤维束MTR的技术，这是一种全局优化技术；以及传统的MTR纤维束测量法。结果表明，特定纤维束方法能够可靠地解析主要白质纤维通路的MTR，并且比分体素效应下的传统多模态纤维束测量法受部分容积效应的影响更小。通过减少纤维束部分容积平均造成的污染，双编码MT和扩散可能会提高对疾病、衰老或学习导致的特定纤维束微观结构改变的敏感性，以及生成具有更高解剖特异性的加权结构连接组。
