Pediatric Neuroimaging Research Consortium, Division of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
Mil Med. 2021 Nov 2;186(11-12):1183-1190. doi: 10.1093/milmed/usab168.
Special Weapons and Tactics (SWAT) personnel who practice breaching with blast exposure are at risk for blast-related head trauma. We aimed to investigate the impact of low-level blast exposure on underlying white matter (WM) microstructure based on diffusion tensor imaging (DTI) and neurite orientation and density imaging (NODDI) in SWAT personnel before and after breacher training. Diffusion tensor imaging is an advanced MRI technique sensitive to underlying WM alterations. NODDI is a novel MRI technique emerged recently that acquires diffusion weighted data from multiple shells modeling for different compartments in the microstructural environment in the brain. We also aimed to evaluate the effect of a jugular vein compression collar device in mitigating the alteration of the diffusion properties in the WM as well as its role as a moderator on the association between the diffusion property changes and the blast exposure.
Twenty-one SWAT personnel (10 non-collar and 11 collar) completed the breacher training and underwent MRI at both baseline and after blast exposure. Diffusion weighted data were acquired with two shells (b = 1,000, 2,000 s/mm2) on 3T Phillips scanners. Diffusion tensor imaging metrices, including fractional anisotropy, mean, axial, and radial diffusivity, and NODDI metrics, including neurite density index (NDI), isotropic volume fraction (fiso), and orientation dispersion index, were calculated. Tract-based spatial statistics was used in the voxel-wise statistical analysis. Post hoc analyses were performed for the quantification of the pre- to post-blast exposure diffusion percentage change in the WM regions with significant group difference and for the assessment of the interaction of the relationship between blast exposure and diffusion alteration.
The non-collar group exhibited significant pre- to post-blast increase in NDI (corrected P < .05) in the WM involving the right internal capsule, the right posterior corona radiation, the right posterior thalamic radiation, and the right sagittal stratum. A subset of these regions showed significantly greater alteration in NDI and fiso in the non-collar group when compared with those in the collar group (corrected P < .05). In addition, collar wearing exhibited a significant moderating effect for the alteration of fiso for its association with average peak pulse pressure.
Our data provided initial evidence of the impact of blast exposure on WM diffusion alteration based on both DTI and NODDI. The mitigating effect of WM diffusivity changes and the moderating effect of collar wearing suggest that the device may serve as a promising solution to protect WM against blast exposure.
进行爆炸物破拆训练并接触爆炸冲击波的特警人员可能会因爆炸相关的头部外伤而面临风险。我们旨在通过扩散张量成像（DTI）和神经丝取向和密度成像（NODDI）研究低水平爆炸暴露对特警人员破拆训练前后的白质（WM）微观结构的影响。扩散张量成像（DTI）是一种敏感的磁共振成像（MRI）技术，可用于检测 WM 的变化。NODDI 是一种新出现的 MRI 技术，它可以从多个壳层获取扩散加权数据，用于建模脑内微观结构环境的不同隔室。我们还旨在评估颈静脉压迫套装置在减轻 WM 扩散特性变化方面的作用，以及其作为 moderator 在扩散特性变化与爆炸暴露之间的关联中的作用。
21 名特警人员（10 名无套人员和 11 名带套人员）完成了破拆训练，并在基线和爆炸暴露后进行了 MRI 检查。在 3T 飞利浦扫描仪上采集两个壳层（b=1000、2000 s/mm2）的扩散加权数据。计算扩散张量成像的各向异性分数（FA）、平均值、轴向和径向扩散系数以及 NODDI 指标，包括神经丝密度指数（NDI）、各向同性体积分数（fiso）和取向弥散指数。使用基于体素的空间统计学进行了基于 voxel 的统计分析。对于有显著组间差异的 WM 区域，进行了从基线到爆后扩散百分比变化的定量分析，以及评估了爆后扩散百分比变化与扩散改变之间关系的交互作用。
无套组在 WM 内的右侧内囊、右侧后冠状辐射、右侧后丘脑辐射和右侧矢状层出现了显著的 NDI（校正后 P<.05）从基线到爆后增加。在无套组中，这些区域中的一部分 NDI 和 fiso 的变化明显大于带套组（校正后 P<.05）。此外，当与平均峰值脉搏压相关联时，带套暴露显示出对 fiso 改变的显著调节作用。
我们的数据提供了基于 DTI 和 NODDI 的爆炸暴露对白质扩散改变影响的初步证据。WM 弥散改变的减轻作用和套戴的调节作用表明，该装置可能是保护 WM 免受爆炸暴露的一种有前途的解决方案。
