Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Alcohol Clin Exp Res. 2022 Jul;46(7):1204-1219. doi: 10.1111/acer.14857. Epub 2022 May 26.
Magnetic resonance imaging (MRI) studies of prenatal alcohol exposure (PAE) commonly report reduced hippocampal volumes, which animal models suggest may result from microstructural changes that include cell loss and altered myelination. Diffusion tensor imaging (DTI) is sensitive to microstructural changes but has not yet been used to study the hippocampus in PAE.
Thirty-six healthy controls (19 females; 8 to 24 years) and 19 participants with PAE (8 females; 8 to 23 years) underwent high-resolution (1 mm isotropic) DTI, anatomical T1-weighted imaging, and cognitive testing. Whole-hippocampus, head, body, and tail subregions were manually segmented to yield DTI metrics (mean, axial, and radial diffusivities-MD, AD, and RD; fractional anisotropy-FA), volumes, and qualitative assessments of hippocampal morphology and digitations. Automated segmentation of T1-weighted images was used to corroborate manual whole-hippocampus volumes.
Gross morphology and digitation counts were similar in both groups. Whole-hippocampus volumes were 18% smaller in the PAE than the control group on manually traced diffusion images, but automated T1-weighted image segmentations were not significantly different. Subregion segmentation on DTI revealed reduced volumes of the body and tail, but not the head. There were no significant differences in diffusion metrics between groups for any hippocampal region. Correlations between age and volume were not significant in either group, whereas negative correlations between age and whole-hippocampus MD/AD/RD, and head/body (but not tail) MD/AD/RD were significant in both groups. There were no significant effects of sex, group by age, or group by sex for any hippocampal metric. In controls, seven positive linear correlations were found between hippocampal volume and cognition; five of these were left lateralized and included episodic and working memory, and two were right lateralized and included working memory and processing speed. In PAE, left tail MD positively correlated with executive functioning, and right head MD negatively correlated with episodic memory.
Reductions of hippocampal volumes and altered relationships with memory suggest disrupted hippocampal development in PAE.
磁共振成像（MRI）研究产前酒精暴露（PAE）通常报告海马体积减小，动物模型表明，这可能是由于包括细胞丢失和髓鞘改变在内的微观结构变化所致。弥散张量成像（DTI）对微观结构变化敏感，但尚未用于研究 PAE 中的海马体。
36 名健康对照者（19 名女性；8 至 24 岁）和 19 名 PAE 参与者（8 名女性；8 至 23 岁）接受了高分辨率（1 毫米各向同性）DTI、解剖 T1 加权成像和认知测试。手动分割整个海马体、头部、体部和尾部亚区，以获得 DTI 指标（平均、轴向和径向扩散系数-MD、AD 和 RD；各向异性分数-FA）、体积以及海马体形态和分肢的定性评估。使用自动 T1 加权图像分割来证实手动全海马体体积。
两组的大体形态和分肢计数相似。在手动追踪的弥散图像上，PAE 组的全海马体体积比对照组小 18%，但自动 T1 加权图像分割没有显著差异。DTI 上的亚区分割显示体部和尾部体积减小，但头部没有。任何海马体区域的组间扩散指标均无显著差异。两组的年龄与体积均无显著相关性，而年龄与全海马体 MD/AD/RD 和头/体（但不包括尾）MD/AD/RD 呈负相关在两组中均具有统计学意义。任何海马体指标均无性别、年龄组与性别组之间的显著影响。在对照组中，发现海马体体积与认知之间存在 7 个正线性相关；其中 5 个为左侧偏侧化，包括情景和工作记忆，2 个为右侧偏侧化，包括工作记忆和处理速度。在 PAE 中，左尾 MD 与执行功能呈正相关，右头 MD 与情景记忆呈负相关。
海马体体积减小和与记忆的改变关系提示 PAE 中海马体发育受损。
