CO₂ Stimulates ASL To Evaluate Cerebrovascular Reserve In Patients With Hypertension And Its Application In TCM Syndromes

Objects:1.To explore the feasibility of evaluating cerebrovascular reserve function by stimulating the MR arterial spin labeling with CO2 inhalation test.2.Using CO2 inhalation test to stimulate arterial spin labeling to explore hyperactivity of liver-fire syndrome and excessive phlegm-dampness syndrome of essential hypertension,and to explore the relationship between TCM syndrome differentiation and cerebral blood flow,so as to provide certain reference for syndrome differentiation and clinical treatment of essential hypertension.Materials and Methods:In the outpatient and hospitalized patients with essential hypertension in the Cardiovascular Department of the Third Affiliated Hospital of Beijing University of Traditional Chinese Medicine,10 patients with hyperactivity of liver-fire syndrome,10 patients with phlegm-dampness syndrome and 10 healthy persons were divided into hypertension group and control group.Using GE discovery.750 3.0T MR scanner,the two groups were scanned by magnetic resonance artery spin labeling in resting state and CO2 load state respectively.After the scanning,the ASL-CBF pseudocolor image was automatically generated by ADW4.6 post-processing workstation and Functool software.The following regions were selected as regions of interest(ROI):bilateral caudate nucleus head,thalamus,superior frontal gyrus and superior frontal gyrus.In the superior temporal gyrus,cerebral blood flow(CBF)was measured in each region,and CBF was measured before and after inhalation of CO2.Then SPSS23.0 software was used for statistical analysis.To judge the cerebrovascular reserve of hypertension patients,and to compare the correlation of cerebral perfusion parameters between hyperactivity of liver-fire syndrome group and hyperactivity of phlegm-dampness syndrome group.Results:1.The CBF and CRC values of each ROI in the bilateral brain of the control group were not significantly different(P>0.05).The CBF values of each ROI after CO2 loading were significantly higher than those before CO2 loading(P<0.05).The CBF values of each ROI in female subjects were significantly higher than those in male subjects(P<0.05).2.The CBF and CRC values of each ROI in the bilateral brains of the hypertensive group had no significant difference(P>0.05).The CBF values of each ROI after CO2 loading were significantly higher than those before CO2 loading(P<0.05).There was no significant difference in the CBF values of each ROI between the sexes(P>0.05).3.The CBF and CRC values of ROI in hypertension group before and after CO2 loading were significantly lower than those in control group(P<0.05).4.There was no significant difference in CBF values of ROI between phlegm-dampness congestion group and liver-fire hyperactivity group before CO2 load(P>0.05);after CO2 load,CBF values of superior temporal gyrus in liver-fire hyperactivity group were significantly higher than those in phlegm-dampness congestion group(P<0.05),and there was no significant difference in CBF values of other ROI between the two groups(P>0.05);the CRC values of each ROI in the two groups were unified.There was no significant difference in statistics(P>0.05).Conclusion:1.Cerebral blood flow was measured by arterial spin labeling combined with CO2 inhalation test to evaluate cerebrovascular reserve function,and to observe the difference of cerebrovascular reactivity between hypertensive subjects and healthy subjects.2.Brain reserve function of hypertensive subjects was significantly lower than that of healthy subjects3.There was no significant difference in brain reserve function between the two groups.4.The cerebral blood flow in the superior temporal gyrus of the subjects with hyperactivity of liver-fire syndrome was higher than that of the subjects with phlegm-dampness stagnation syndrome.There was no significant difference in the brain reserve function between the two groups on the other ROI.5.The brain reserve function of healthy subjects is much higher than that of male subjects,but there is no significant difference between male subjects and female subjects with hypertension.