Application Of Cerebral MRI Perfusion Imaging In Ischemic Stroke

Part I: Application value of DSC-PWI in prognosis assessment of subacute ischemic strokeObjective To explore the application value of DSC-PWI technology in the prognosis evaluation of patients with subacute ischemic stroke,and to evaluate the collateral circulation of subacute infarction and the clinical prognosis of patients without thrombolytic therapy.Methods A total of 23 ischemic stroke patients without thrombolytic therapy admitted to our hospital from January 2019 to January 2020 were collected.All enrolled patients underwent perfusion weighted imaging(PWI)and diffusion weighted imaging(DWI)at the subacute stage of cerebral infarction,and the obtained images were transferred to the corresponding post-processing workstation.Clinical MRS score was obtained by telephone follow-up 90 days later.To evaluate cerebral hemodynamic status,perfusion parameters in subacute ischemic stroke patients without thrombolytic therapy were analyzed.The low perfusion areas in DSC-PWI images were scored by the ASPECTS scoring system to obtain the PWI-aspects.The area of the maximum layer of the infarct area was measured in the DWI image,while the area of the low perfusion area was measured in the corresponding layer of DSC-PWI image,and the percentage of the mismatched area in DWI-PWI was calculated.Spearman correlation coefficient was used to analyze the correlation between PWI-Aspects score,the percentage of DWI-PWI mismatch area and clinical prognosis MRS.Result In the subacute ischemic stroke patients without thrombolytic therapy,the perfusion parameter values of CBF and CBV in the cerebral infarction area were significantly decreased compared with those in the healthy side,while MTT and TTP were increased to varying degrees compared with those in the healthy side,and the differences were statistically significant(P<0.05);There was no significant correlation between PWI-Aspects alone and clinical prognosis MRS score(P>0.05);There was a significant correlation between the proportion of mismatched area between DWI and PWI and the clinical prognosis(P<0.05).Conclusion DSC-PWI can provide the information of blood perfusion in the subacute stage of cerebral infarction.There is no significant correlation between the single PWI-aspects and the clinical prognosis MRS score,which may be related to the site and volume of the initial limited diffusion.The proportion of mismatch area between DWI and PWI was significantly correlated with clinical prognosis MRS score,which was helpful for clinicians to evaluate the therapeutic effect of non-thrombolytic therapy,and provided an important basis for clinical selection of appropriate intervention measures in the subacute stage of stroke.Part II: The application value of 3D-ASL in the diagnosis of ischemic cerebrovascular diseasesObjective To explore the application value of 3D arterial spin labeling(3D-ASL)in the diagnosis of ischemic cerebrovascular diseases.Methods Forty-seven patients with ischemic cerebrovascular disease who met the inclusion and exclusion criteria admitted to our hospital from June 2020 to December 2020 were selected.All patients underwent CT angiography(CTA)and MRI,including DWI and arterial spin labeling(ASL).The original CTA images were analyzed using various post-processing techniques,and the degree of head Carotid artery stenosis was evaluated according to the North American Symptomatic Carotid Enarterectomy Trial(NASCEET).The cerebral blood flow(CBF)was obtained from 3D-ASL images by post-processing workstation.The cerebral blood flow(CBF)was evaluated by qualitative and quantitative analysis to determine the consistency of 3D-ASL and CTA in the diagnosis of ischemic cerebrovascular diseases.Results CTA results showed that among the 47 patients,there were 26 cases with mild stenosis,10 cases with moderate stenosis,5 cases with severe stenosis,and 6 cases with occlusion.The r CBF value of the lesion side was 39.56±13.42 m L/(100g·min)、27.43±13.27 m L/(100g·min)、32.71±12.36 m L/(100g·min)、24.56±17.75 m L/(100g·min).Qualitative analysis of 3D-ASL images showed that among the CBF images of 47 enrolled patients,when PLD = 1.5s,25 patients had low perfusion area,and 22 patients had bilateral cerebral tissue perfusion symmetry.When PLD=2.5s,only 9 patients had reduced perfusion,and 38 patients had symmetrical perfusion in bilateral brain tissue.Quantitative analysis showed that when PLD=1.5s,the r CBF of the affected side ROI of 25 patients was34.34±14.78 m L/(100g·min),which was significantly lower than that of the contralateral mirror area 40.28±13.88 m L/(100g·min),and the difference was statistically significant(t=-2.009,P<0.05).When the degree of vascular stenosis was mild,the diagnosis was consistent in 15 cases and inconsistent in 11 cases.In the case of moderate stenosis,9 cases were consistent and 1 case was inconsistent.When the degree of vascular stenosis was severe or occlusion,the two tests were consistent,and the difference was statistically significant(P<0.05).Conclusion In the diagnosis and treatment of ischemic cerebrovascular diseases,3D-ASL is more sensitive to the ischemic state of brain tissue,and can be used to qualitatively and quantitatively analyze the blood perfusion state of brain tissue in patients with ischemic cerebrovascular diseases,and can directly reflect the hemodynamic changes of brain tissue in the ischemic area.