Intracranial Effects of Microgravity: A Prospective Longitudinal MRI Study
Intracranial Effects of Microgravity: A Prospective Longitudinal MRI Study
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DOI：
10.1148/radiol.2020191413
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发表时间：
2020-06-01
期刊：
影响因子：
19.7
通讯作者：
Macias, Brandon R.
中科院分区：
文献类型：
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作者：
Kramer, Larry A.;Hasan, Khader M.;Macias, Brandon R.
背景资料：长期太空飞行任务的宇航员可能会发生眼部结构和功能的变化，这种变化在恢复正常重力后可能持续数年。在航天飞行期间长期暴露于颅内压升高被假设为一个促成因素，然而，病因仍然未知。目的：通过测量颅内体积参数、垂体形态结构、和导水管脑脊液（CSF）与航天相关的流体动力学并建立返回地球后恢复的综合模型。材料和方法：这项前瞻性纵向MRI研究招募了计划进行长期太空飞行的宇航员。在航天飞行前进行测量，然后在着陆后1天、30天、90天、180天和360天进行测量。对每个阶段的颅内容量和导水管CSF流体动力学（CSF峰-峰速度幅度和导水管每搏输出量）进行定量。定性和定量的变化前飞行后（第1天）垂体形态结构进行了测定。统计分析包括每个因变量单独的混合效应模型，并随着时间的推移进行重复观察。（平均年龄，45岁+/- 5 [标准差]; 10名男性）显示大脑平均体积增加（28 mL; P < .001），白色物质（26 mL; P < .001），平均侧脑室（2.2 mL; P < .001），以及平均脑和CSF总和（33 mL; P <0.001），平均导水管每搏输出量（14.6 μ L; P = 0.045）和平均CSF峰-峰流速幅度（2.2 cm/sec; P = 0.01）相应增加。在航天飞行后360天，脑和脑脊液的总平均体积仍在增加（28 mL; P < .001）。与此同时，11名宇航员中有6名（55%）与基线相比出现或表现出恶化的垂体圆顶抑郁症。平均中线垂体高度从5.9 mm降至5.3 mm（P < .001）。结论：长时间航天飞行与垂体变形增加、导水管脑脊液（CSF）流体动力学增强以及脑和CSF总体积的扩大有关。恢复期脑和CSF体积扩张总和持续长达1年，表明发生永久性改变。(C)RSNA，2020年
Background: Astronauts on long-duration spaceflight missions may develop changes in ocular structure and function, which can persist for years after the return to normal gravity. Chronic exposure to elevated intracranial pressure during spaceflight is hypothesized to be a contributing factor, however, the etiologic causes remain unknown.Purpose: To investigate the intracranial effects of microgravity by measuring combined changes in intracranial volumetric parameters, pituitary morphologic structure, and aqueductal cerebrospinal fluid (CSF) hydrodynamics relative to spaceflight and to establisha comprehensive model of recovery after return to Earth.Materials and Methods: This prospective longitudinal MRI study enrolled astronauts with planned long-duration spaceflight. Measures were conducted before spaceflight followed by 1, 30, 90, 180, and 360 days after landing. Intracranial volumetry and aqueductal CSF hydrodynamics (CSF peak-to-peak velocity amplitude and aqueductal stroke volume) were quantified for each phase. Qualitative and quantitative changes in pre- to postflight (day 1) pituitary morphologic structure were determined. Statistical analysis included separate mixed-effects models per dependent variable with repeated observations over time.Results: Eleven astronauts (mean age, 45 years +/- 5 [standard deviation]; 10 men) showed increased mean volumes in the brain (28 mL; P < .001), white matter (26 mL; P < .001), mean lateral ventricles (2.2 mL; P < .001), and mean summated brain and CSF (33 mL; P < .001) at postflight day 1 with corresponding increases in mean aqueductal stroke volume (14.6 mu L; P =.045) and mean CSF peak-to-peak velocity magnitude (2.2 cm/sec; P =.01). Summated mean brain and CSF volumes remained increased at 360 days after spaceflight (28 mL; P < .001). Qualitatively, six of 11 (55%) astronauts developed or showed exacerbated pituitary dome depression compared with baseline. Average midline pituitary height decreased from 5.9 to 5.3 mm (P < .001).Conclusion: Long-duration spaceflight was associated with increased pituitary deformation, augmented aqueductal cerebrospinal fluid (CSF) hydrodynamics, and expansion of summated brain and CSF volumes. Summated brain and CSF volumetric expansion persisted up to 1 year into recovery, suggesting permanent alteration.(C) RSNA, 2020