Department of Diagnostic and Intervention Imaging, University of Texas Health Science Center, Houston, TX.
Memorial Sloan Kettering Cancer Center, New York City, NY.
J Neuroimaging. 2019 May;29(3):323-330. doi: 10.1111/jon.12609. Epub 2019 Feb 19.
Assessment of the effects of microgravity on astronauts' brains using microstructural measures by utilizing quantitative MRI, before and after spaceflight would help understand the structural changes.
Quantitative MRI data sets in 19 astronauts were acquired before and after space missions. Both diffusion tensor metrics and volumetric measures were analyzed in the brain regions involved in the visual function.
The fractional anisotropy was reduced in the right posterior thalamic radiations (P = .0009) and remained significant after a false discovery rate (FDR) correction (P = .03). A trend of increase in the mean diffusivities of different subregions of the occipital cortex on the right side, including calcarine, middle occipital, inferior occipital, and fusiform gyri, was noted and became insignificant after FDR correction. Similarly, there was a trend of cortical thinning involving the right occipital lobe and bilateral fusiform gyri, volume reduction of the left thalamus, and increase in lateral ventricular volume in the postflight scans.
Gray and white matter alterations are detected by quantitative MRI before and after space flight. Our findings may be used to understand the neuroanatomical mechanisms of possible brain dysfunction or neuroplasticity in microgravity condition in the future studies.
利用定量磁共振成像（quantitative MRI），在航天飞行前后评估微重力对宇航员大脑的影响，有助于了解结构变化。
对 19 名宇航员在航天任务前后的定量 MRI 数据集进行了分析。对与视觉功能相关的脑区的弥散张量指标和体积测量进行了分析。
右侧丘脑后辐射的各向异性分数降低（P=.0009），在经过假发现率（FDR）校正后仍有统计学意义（P=.03）。右侧枕叶皮质不同亚区（包括舌回、中回、下回和梭状回）的平均弥散度有增加的趋势，右侧枕叶和双侧梭状回的皮质变薄，左侧丘脑体积减小，侧脑室体积增大，这些在 FDR 校正后变得不显著。
在航天飞行前后，通过定量 MRI 检测到灰质和白质的改变。我们的研究结果可能有助于在未来的研究中了解微重力环境下可能的大脑功能障碍或神经可塑性的神经解剖学机制。
