Regional cerebral blood flow in natives at high altitude: An arterial spin labeled MRI study.

Background: It is known that a neurologic sequence occurs at high altitudes (HA); hence, cerebral blood flow (CBF) might vary by altitude. Purpose: To use arterial spin labeled (ASL) MRI to evaluate absolute CBF differences between subjects who live at HA and lowlands. Study Type: Cohort prospective trial. Population: In all, 64 HA Tibetans, 19 lowland Tibetans, and 25 lowland Han subjects. Field Strength/Sequence: CBF was measured with the pulsed ASL sequence at 3T. Assessment: CBF was correlated with abode altitude in HA Tibetans; CBF differences among HA Tibetans, lowland Tibetans, and lowland Han subjects was assessed. Statistical Tests: Pearson correlation assessed the correlation. Independent t-tests analyzed group differences. Results: In HA Tibetans, CBF decreased with altitude in the bilateral anterior and posterior cingulate gyri, fusiform gyrus, cerebellar tonsil and cortices, and thalamus as well as left middle and inferior temporal gyri and right insula (P< 0.05); HA Tibetans (vs. lowland Tibetans) had lower CBF in the left hemisphere (precuneus, anterior cingulate gyrus, fusiform gyrus, and lingual gyrus) and right hemisphere (superior parietal lobule, precuneus, posterior cingulate gyrus, and cerebellar tonsil), while they had higher CBF in the left inferior parietal lobule, lentiform nucleus, and inferior frontal gyrus (P< 0.05). The overlapping regions, in which CBF in HA Tibetans correlated with altitude and decreased (vs. lowland Tibetans), were selected for region of interest analysis, and the results showed lower CBF in HA Tibetans than lowland Han subjects (P< 0.05). Data Conclusion: HA adaptation in Tibetans is associated with a decrease of regional CBF. Level of Evidence: 2 Technical Efficacy: Stage 4