ABSTRACT
Objective:To investigate the differences in cerebral oxygen metabolism in healthy volunteers at three altitude areas by MR quantitative magnetic susceptibility imaging (QSM) combined with three-dimensional arterial spin labeling (3D-ASL).Methods:From March 2019 to October 2020, Zhengzhou Han Chinese volunteers recruited from the First Affiliated Hospital of Zhengzhou University, Xining Han Chinese volunteers recruited from the Fifth People′s Hospital of Qinghai Province, Lhasa Han Chinese volunteers and Tibetan volunteers recruited from Lhasa People′s Hospital were collected. They were divided into 21-30 age group, 31-40 age group, and 41-50 age group. All the volunteers underwent MR QSM combined with 3D-ASL sequence imaging, and oxygen extraction fraction (OEF) and cerebral blood flow (CBF) images of gray matter, and white matter were collected, OEF and CBF values were obtained, and cerebral metabolic rate of oxygen (CMRO 2) values were calculated. The comparison of various indicators among multiple groups was conducted using one-way ANOVA, and pairwise comparisons were conducted using LSD- t test. Results:A total of 132 volunteers were included, including 38 Han Chinese volunteers in Zhengzhou, 9 in the 21-30 age group, 13 in the 31-40 age group and 16 in the 41-50 age group; 27 Han Chinese volunteers in Xining, including 9 in the 21-30 age group, 8 in the 31-40 age group and 10 in the 41-50 age group; 34 Han Chinese volunteers in Lhasa, including 13 in the 21-30 age group, 11 in the 31-40 age group and 10 in the 41-50 age group; and 33 Tibetan volunteers in Lhasa, including 10 in the 21-30 age group, 10 in the 31-40 age group and 13 in the 41-50 age group. In the group aged 21-30 years, the overall difference in brain gray matter OEF values among volunteers from different altitudes was statistically significant ( P<0.05), with statistically significant differences in OEF values between Tibetans in Lhasa and Han Chinese in Xining, Han Chinese in Lhasa ( P<0.05). The overall difference in CMRO 2 values in the gray matter of volunteers at different altitudes was statistically significant ( P<0.05), with significant differences in CMRO 2 values between Lhasa Tibetan and Han Chinese in Zhengzhou, Han Chinese in Xining, Han Chinese in Lhasa ( P<0.05). In the 31-40 age group, there were statistically significant differences in the overall CBF values of gray and white matter among volunteers from different altitudes ( P<0.05). Among them, there were statistically significant differences in the CBF values of gray and white matter between Han Chinese in Zhengzhou and Han in Xining, Han Chinese in Lhasa, Lhasa Tibetan ( P<0.05). The overall differences in OEF values of gray matter and white matter among volunteers at different altitudes were statistically significant ( P<0.05). Among them, there were statistically significant differences in OEF values of gray matter and white matter between the Han Chinese in Zhengzhou and the Han Chinese in Xining, the Han Chinese in Lhasa ( P<0.05). There was also a statistically significant difference in OEF values of gray matter and white matter between the Han Chinese in Lhasa and the Tibetan in Lhasa ( P<0.05). The overall difference in CMRO 2 values in gray and white matter among volunteers from different altitudes was statistically significant ( P<0.05). Among them, there was a statistically significant difference in CMRO 2 values of cerebral gray matter between Lhasa Tibetans and Zhengzhou Han, Xining Han, Lhasa Han ( P<0.05), and there was a statistically significant difference in CMRO 2 values of cerebral white matter between Lhasa Tibetans and Zhengzhou Han, Lhasa Han ( P<0.05). Conclusions:The cerebral oxygen metabolism of Tibetan living in the plateau is characterized by low oxygen consumption, low blood oxygen dependence and high tissue oxygen utilization. The CMRO 2 of the Han people who migrated to the plateau for a long time is maintained at a certain level, similar to that in the plain area. The effects of age factors on CBF, OEF and CMRO 2 are small.