脑血流在平原及高海拔地区动态变化的动脉自旋标记灌注成像研究

Three-dimensional Arterial Spin-labeling Perfusion Imaging in Measuring the Dynamic Changes of Cerebral Blood Flow Between Plain and High Altitude Areas

目的平原人口在急进高原时因低压缺氧会发生脑血流量改变。本研究利用动脉自旋标记技术测量平原受试者在平原及高海拔地区脑血流量值,进一步了解高原低压缺氧环境下脑血流量的动态变化。资料与方法 6名平原健康受试者快速进驻高原并停留5 d,然后返回平原。扫描在平原和高原两地进行,试验仪器为2台同一机型的3.0T MR扫描仪。共进行8次MRI扫描,所有扫描参数一致,观察受试者脑血流量值的变化。结果受试者快速进驻高原后,脑血流量值较平原脑血流量值明显上升,并达到一定的峰值,进驻高原第1天全脑、灰质及白质区域的脑血流量值与平原脑血流量值相比,差异有统计学意义(P<0.05);高原停留第2天,脑血流量值有一定程度的下降,第3天稍有上升,然后脑血流量值持续下降至低于进驻高原前在平原的脑血流量值;回到平原1周后,全脑、灰质、白质区域的脑血流量值仍低于进驻高原前在平原的脑血流量值,差异有统计学意义(P<0.05)。结论平原人口快速进驻高原后,脑血流量会有一定程度的升高,随着高原习服,脑血流量逐渐降低至低于平原脑血流量水平。

Purpose It is well known hypobaric hypoxia occurs with acute exposure to high altitude, with commonly associated change of cerebral blood flow（CBF）. In this work, three-dimensional arterial spin-labeling（3D ASL） was used to monitor the change of CBF to further extend our understanding of hypobaric hypoxia. Materials and Methods Six healthy subjects were recruited for this study, they were asked to stay at high altitude areas for 5 days, and then returned to the plain. All subjects received MRI examination in both plain and high altitude areas using exactly the same 3.0T MR scanner. A total of 8 MR scans were performed, and all the parameters were kept the same, the changes of cerebral blood flow were observed. Results CBF increased obviously and reached its peak after acute exposure to high altitude, at the first day at high altitude, CBF measurements in global brain, grey matter and white matter increased significantly compared to the plain, the difference was statistically significant（P〈0.05）; after that, the CBF measurements started to gradually decrease in the second day and a small climb on the third day at high altitude, then the CBF continued to drop after returning to sea level, even below that at sea level prior to departure. After 1 week back to the plain area, CBF measurements in global brain, grey matter and white matter were still lower than those before departure for high altitude areas, with a statistically significant difference（P〈0.05）. Conclusion CBF measurements had obvious increase upon initial arrival at high altitude, and then the CBF continued to drop even below that at sea level prior to departure.