Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
MS Center Amsterdam, Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Location VUmc, Amsterdam, The Netherlands.
Ann Clin Transl Neurol. 2024 Jun;11(6):1405-1419. doi: 10.1002/acn3.52026. Epub 2024 May 9.
To evaluate the intrinsic and extrinsic microstructural factors contributing to atrophy within individual thalamic subregions in multiple sclerosis using in vivo high-gradient diffusion MRI.
In this cross-sectional study, 41 people with multiple sclerosis and 34 age and sex-matched healthy controls underwent 3T MRI with up to 300 mT/m gradients using a multi-shell diffusion protocol consisting of eight b-values and diffusion time of 19 ms. Each thalamus was parcellated into 25 subregions for volume determination and diffusion metric estimation. The soma and neurite density imaging model was applied to obtain estimates of intra-neurite, intra-soma, and extra-cellular signal fractions for each subregion and within structurally connected white matter trajectories and cortex.
Multiple sclerosis-related volume loss was more pronounced in posterior/medial subregions than anterior/ventral subregions. Intra-soma signal fraction was lower in multiple sclerosis, reflecting reduced cell body density, while the extra-cellular signal fraction was higher, reflecting greater extra-cellular space, both of which were observed more in posterior/medial subregions than anterior/ventral subregions. Lower intra-neurite signal fraction in connected normal-appearing white matter and lower intra-soma signal fraction of structurally connected cortex were associated with reduced subregional thalamic volumes. Intrinsic and extrinsic microstructural measures independently related to subregional volume with heterogeneity across atrophy-prone thalamic nuclei. Extrinsic microstructural alterations predicted left anteroventral, intrinsic microstructural alterations predicted bilateral medial pulvinar, and both intrinsic and extrinsic factors predicted lateral geniculate and medial mediodorsal volumes.
Our results might be reflective of the involvement of anterograde and retrograde degeneration from white matter demyelination and cerebrospinal fluid-mediated damage in subregional thalamic volume loss.
使用活体高梯度扩散 MRI 评估多发性硬化症中单个丘脑亚区萎缩的内在和外在微观结构因素。
在这项横断面研究中，41 名多发性硬化症患者和 34 名年龄和性别匹配的健康对照者接受了 3T MRI 检查，使用包含 8 个 b 值和 19 ms 扩散时间的多壳扩散方案进行检查，梯度可达 300 mT/m。每个丘脑被分割成 25 个亚区，用于体积确定和扩散度量估计。应用神经元内和神经元外信号分数成像模型，以获得每个亚区以及结构连接的白质轨迹和皮质内的神经元内、神经元内和细胞外信号分数的估计值。
与前/腹侧亚区相比，多发性硬化症相关的体积损失在后/内侧亚区更为明显。多发性硬化症患者的神经元内信号分数较低，反映了细胞体密度降低，而细胞外信号分数较高，反映了细胞外空间增大，这两种情况在后/内侧亚区比前/腹侧亚区更为明显。连接的正常表现白质中的神经元内信号分数较低，结构连接的皮质中的神经元内信号分数较低，与丘脑亚区体积减小有关。内在和外在微观结构测量与亚区体积独立相关，且在易萎缩的丘脑核之间存在异质性。外在微观结构改变预测左侧前腹侧，内在微观结构改变预测双侧内侧丘脑枕，内在和外在因素都预测外侧膝状体和内侧mediodorsal 体积。
我们的结果可能反映了白质脱髓鞘和脑脊液介导的损伤引起的顺行和逆行变性累及丘脑亚区体积减少。
