Magnetic Resonance Imaging Study Of Hypertension-related Cerebrovascular Disease At Different Blood Pressure Control Levels

Objective:To explore the differences in imaging data of acute ischemic stroke（AIS）and lacune at different blood pressure control levels.Arterial spin labeling（ASL）perfusion imaging was used to detect changes in cerebral blood flow（CBF）in patients with hypertension,and to explore the effects of different blood pressure control levels on the onset of AIS.Materials and Methods:Part one.A total of 1651 patients with hypertension who were repeatedly admitted to Tianjin union medical center from July 2016 to July 2019 were collected.All patients underwent brain MRI at the first and last admission.Baseline clinical data were collected,including demographic characteristics,lifestyle,physical measurements and history of disease.The patients were divided into poor blood pressure control group（admitted with high blood pressure and blood pressure control level was not up to standard）and ideal blood pressure control group（admitted with other diseases other than hypertension and blood pressure control level was up to standard）.The distribution,number and size of AIS and lacune were evaluated in MRI.Differences in baseline clinical data,AIS and lacune between the two groups were compared.Part two.Seventy-eight patients with hypertension who were first admitted to Tianjin union medical center from August 2019 to January 2020 were collected.All patients underwent routine sequence and ASL examination.The general clinical data and grouping basis of the patients were collected as in the first part.CBF of frontal lobe,parietal lobe,temporal lobe,insula,occipital lobe,putamen,thalamus,pons and cerebellum were measured（TI was 1.5,2.0 and 2.5s,respectively）.Differences in general clinical data and regional CBF were compared between the two groups.The differences in CBF of different TI were compared in the same area of poor blood pressure control group and ideal blood pressure control group.Result:Part one.Finally,626 patients were enrolled,including 513 patients in the poor blood pressure control group and 113 patients in the ideal blood pressure control group.（1）The systolic and diastolic blood pressure,the proportion of co-diabetes and the prevalence of AIS in the poor blood pressure control group were higher than those in the ideal blood pressure control group（P<0.05）,the proportion of oral antihypertensive drugs（≥2 types）was lower than that in the ideal blood pressure control group（P<0.001）.The proportion of hypertension grade 3（62.38%vs 50.44%）in the poor control group was higher than that in the ideal control group,while the proportion of hypertension grade 1（10.53%vs 18.58%）and grade 2（27.10%vs30.97%）were lower,and the difference was statistically significant（P=0.021）.（2）At the first MRI examination,AIS occurred in 169 patients.There were 161patients in the poor blood pressure control group,including 77 patients with single infarction,84 patients with multiple infarction,126 patients with small infarction and35 patients with large infarction,AIS was more common in the frontal lobe（41.61%）,basal ganglia（32.92%）and parietal lobe（29.81%）.There were 8 patients in the ideal blood pressure control group,including 6 patients with single infarction,2 patients with multiple infarction,7 patients with small infarction and 1 patient with large infarction,AIS was most common in basal ganglia（37.50%）.Lacune were found in503 patients.There were 424 patients in the poor blood pressure control group,including 30 patients with single lacune and 394 patients with multiple lacune,lacune was more common in basal ganglia（89.62%）,frontal lobe（62.03%）and brainstem（53.30%）.There were 79 patients in the ideal blood pressure control group,including10 patients with single lacune and 69 patients with multiple lacune,lacune was most common in basal ganglia（79.75%）.AIS and lacune in the poor blood pressure control group were more than those in the ideal blood pressure control group（P<0.05）.（3）During follow-up,AIS occurred in 138 patients.There were 130 patients in the poor blood pressure control group,including 53 patients with single infarction,77patients with multiple infarction,95 patients with small infarction and 35 patients with large infarction,AIS was more common the frontal lobe（33.08%）,basal ganglia（31.54%）and parietal lobe（29.23%）.There were 8 patients in the ideal blood pressure control group,including 5 patients with single infarction,3 patients with multiple infarction,7 patients with small infarction and 1 patient with large infarction,AIS was most common in the frontal lobe（37.50%）.Increased lacune were found in246 patients.There were 226 patients in the poor blood pressure control group,including 71 patients with single lacune and 155 patients with multiple lacune,increased lacune were more common in basal ganglia（46.46%）,frontal lobe（40.27%）and brainstem（19.91%）.There were 20 patients in the ideal blood pressure control group,including 9 patients with single lacune and 11 patients with multiple lacune.Increased lacune was most common in basal ganglia（45.00%）.AIS and increased lacune were more common in the poor blood pressure control group than those in the ideal blood pressure control group（P<0.001）.Part two.Finally,65 patients were enrolled,including 39 patients in the poor blood pressure control group and 26 patients in the ideal blood pressure control group.（1）Systolic and diastolic blood pressure in the poor blood pressure control group were higher than those in the ideal blood pressure control group（P<0.05）,oral antihypertensive drugs（≥2 types）were lower than ideal blood pressure control group（P=0.005）,The proportion of hypertension grade 3（69.23%vs 38.46%）in the poor control group was higher than that in the ideal control group,while the proportion of hypertension grade 1（5.13%vs 19.23%）and grade 2（25.64%vs42.31%）were lower,and the difference was statistically significant（P=0.033）.（2）The CBF_1.5,CBF_2.0 and CBF_2.5 of frontal lobe,parietal lobe,temporal lobe,insula,occipital lobe,putamen,and cerebellum in the poor blood pressure control group were all lower than those in the ideal blood pressure control group（P<0.05）.The CBF_2.5 of thalamus and pons in the poor blood pressure control group were lower than those in ideal blood pressure control（P values were 0.017 and 0.006,respectively）.However,there was no significant difference between CBF_1.5 and CBF_2.0（P>0.05）.The CBF_2.5 and CBF_2.0 of frontal lobe,parietal lobe,temporal lobe,insula,occipital lobe,putamen,and cerebellum were all higher than CBF_1.5 in the poor blood pressure control group（P<0.001）.However,there was no significant difference between CBF_2.5 and CBF_2.0（P>0.05）.The CBF_2.5 and CBF_2.0 of frontal lobe,parietal lobe,temporal lobe,insula,occipital lobe,putamen,and cerebellum were all higher than CBF_1.5（P<0.001）,and CBF_2.5 was higher than CBF_2.0 in the ideal blood pressure control group（P<0.05）.Conclusion:（1）AIS in patients with hypertension was more common with small infarcts,suggesting that hypertension was mainly caused by cerebral small vascular damage.（2）The risk of AIS and lacune increased in the poor blood pressure control group compared with the ideal blood pressure control group.In the poor blood pressure control group,AIS tended to occur in the frontal lobe,parietal lobe and basal ganglia,and lacune tended to occur in basal ganglia,frontal lobe and brainstem.In the ideal blood pressure control group,AIS tended to occur in the basal ganglia and frontal lobe,and lacune tended to occur in basal ganglia.（3）Compared with the ideal blood pressure control group,the decrease of CBF in the poor blood pressure control group was an important hemodynamic mechanism for the increased risk of AIS.（4）The disappearance of delayed cerebral blood flow perfusion effect in the poor blood pressure control group was another important cause of AIS.