Blood Perfusion Analysis Of Cerebral Gray Matter And Deep White Matter In Supply Region Of Chronic Cerebral Artery Occlusion

Objective To study the different ischemic characteristics of cerebral cortical gray matter and deep white matter in patient with chronic cerebral artery severe stenosis or occlusion.Method A retrospective study was conducted on 30 patients with chronic unilateral cerebral artery severe stenosis(CTA,DSA or MRA≥ 75%)or occlusion and there was no abnormality in contralateral cerebral artery,bilateral common carotid artery and internal carotid artery and no other brain diseases proved by conventional CT or MRI from April 2014 to April 2018 in Qilu Hospital of Shandong University.And a total of 68 cerebral cortex gray matter and deep white matter with chronic severe stenosis or occlusion of cerebral arteries were included in the study.Using the Siemens SOMATOM Definition Flash CT,the patient took supine position,scanning range included whole brain,using low-dose dynamic volume CT perfusion scanning,all patients were injected with contrast agent(iodopramine,containing iodine 300 mg/ml,Bayer company)through the right elbow median vein using a double barrel high-pressure syringe.The total injection volume was calculated as 0.6 ml/kg body weight,and 40 ml normal saline was injected later.The injection flow rate of contrast agent and normal saline was 5.0 ml/s.The scanning was started after 5 seconds of injection,and the data was processed by the equipment’s own workstation.For the region of interest,select the cortical gray matter and deep white matter in blood supply area of anterior cerebral artery,middle cerebral artery,and posterior cerebral artery in the top layer of the lateral ventricle as the measurement site.Using mirror image method to measure CBF,CBV,MTT,TTP and TTD values symmetrically in the deep white matter of the affected and healthy sides.The gray matter of the cerebral cortex of the affected side and the healthy side was selected by hand animation method to measure the substantially symmetrical position of CBF,CBV,MTT,TTP and TTD valuesStatistical analysis of the perfusion parameters of cerebral cortex gray matter and deep white matter in the affected side and contralateral side were performed using SPSS13.0 software package.T test was used for variance homogeneity,and t’test was used for variance discrepancy,and P<0.05 was considered statistically significant.Results Comparison of perfusion parameters between the affected and healthy cerebral cortex gray matter show that the average values of CBF and CBV in gray matter of the affected side and the healthy side of the cerebral cortex were greater than that of the ipsilateral deep white matter(P<0.01),the average values of MTT,TTP and TTD in the gray matter of the affected and healthy cerebral cortex were less than that of the deep white matter on the same side(P<0.01).Comparison of perfusion parameters of gray matter and deep white matter in the affected side cerebral cortex and healthy side mirror area show that there was no statistically significant difference of the CBF average value between the affected side and the healthy side of the gray matter,and the average value of CBF in the deep white matter of the affected side decreased compared with the healthy side(P<0.01),and the average value of CBV in the gray matter of the affected side cerebral cortex was greater than that of the healthy side(P<0.01).The average value of CBV in deep white matter was not statistically different from that of healthy side,and the average values of MTT,TTP and TTD in the gray matter and the deep white matter in the affected side were longer than those in the healthy side(P<0.01).Conclusion 1.The perfusion of cerebral cortex gray matter is higher than deep white matter in the same blood supply area.2.The perfusion changes of cerebral cortex gray matter and deep white matter in the chronic severe stenosis or occlusion cerebral artery blood supply area were not completely consistent,and cerebral cortical gray matter perfusion decreases slightly less than deep cerebral white matter.CTP can quantitatively evaluate the degree of chronic cerebral ischemia,and provide a quantitative diagnosis basis for clinical treatment and therapeutic effect evaluation.