A Dsc-pwi Study Of Corrilation Between MCA Stenosis/Oclusion And Different Types Of Cerebral Infarction

PurposeTo explore values of clinical applications of DSC-PWI by analyzingperfusion changes and characters of different types of cerebral infarctions inpatients with varying degrees of MCA stenosisMaterials and methodsThirty-six patients, including28males and8females, with varying degreesof cerebral artery stenosis or occlusion were involved in this study, they werecollected from Linyi People’s Hospital affiliated to Shandong University fromJune2011to March2013. All the patients were diagnosed as transient ischemicattack (TIA) or cerebral infarction and accepted residential treatment. Unilateralmiddle cerebral artery stenosis or occlusion were diagnosed and confirmed byusing “Philips Allura FD20” DSA system. Degrees of MCA stenosis weremeasured following “the north American symptomatic carotid endarterectomytrial (NASCET)”. Measurement criteria: degree of stenosis (%)=[(arterialdiameter distal to stenosis-the narrowest arterial diameter)/arterial diameterdistal to stenosis]×100%. All the cases were divided into4groups accordingto their stenosis degree or occlusion: mild stenosis group, moderate stenosisgroup, severe stenosis group, occlusion group.Conventional MRI T1WI and T2WI series, diffusion-weighted imaging(DWI), and dynamic susceptibility contrast enhanced MR perfusion-weightedimaging (DSC-PWI) were undergone for all patients by using Siemens Verio3.0T whole body MR scanner. PWI data was transmitted to Siemens Syngoworkstation for processing, the time-intensity curve (TIC) figure was first obtained; and perfusion parameter maps of the regional cerebral blood flow(rCBF), regional cerebral blood volume (rCBV), regional mean transit time(rMTT), regional time to peak (rTTP) maps were automatically processed. Fourregions of interest (ROI) within the MCA territory were manually drawn on bothsides symmetrically, including the front watershed area, back watershed area,temporal lobe area and basal ganglia area. Quantitative analysis on the perfusionimages was performed to obtain parameters of rCBF, rCBV, rMTT, rTTP withinthe MCA region. Twenty-five cases of cerebral infarction were diagnosed fromthe36MCA stenosis or occlusion patients. By referring Lee’s grouping criteria,cerebral infarctions were divided into four groups:①lacunar infarction;②striatum internal capsule infarction;③watershed infarction;④watershedinfarction.Statistical analysis were performed by using SPSS16.0software, databasewas established by Epidata3.0, measurement data was displayed in x±s;Correlation between degrees of stenosis and perfusion parameters was analyzedby using Spearman rank correlation analysis; Comparison between the twosamples were conducted by using t-test; Multiple sample means were comparedby using analysis of variance (ANOVA)-the F-test; Comparison between any twomeans was analyzed by using LSD-t test. Chi-square test was adopted for countdata analysis. Statistically significant,(P<0.05).Results1. Thirty-six patients,28males and8females, were diagnosed as unilateralMCA stenosis/occlusion and confirmed by DSA,23right vessels and13leftvessels were involved. There were6cases in mild stenosis group (Ⅰ),10casesin moderate stenosis group (Ⅱ),15cases in severe stenosis group (Ⅲ),5casesin occlusion group (Ⅳ).2. There was no correlation between the degree of MCA stenosis and therCBV ratio of ipsilateral/contralateral (γ=0.070, P=0.520); There wasnegative correlation between the degree of MCA stenosis and the rCBF ratio ofipsilateral/contralateral (γ=-0.539, P=0.003); There was positive correlationbetween the degree of MCA stenosis and the rMTT, rTTPipsilateral/contralateral ratios (rMTT: γ=0.819, P=0.0001; rTTP: γ=0.614, P=0.0001） 3. Ipsilateral/contralateral ratio differences of rCBF, rCBV in differentROIs were not statistically significant (rCBF: F=1.048, P=0.375; rCBV: F=0.225, P=0.879); Ipsilateral/contralateral ratio differences of rMTT, rTTP indifferent ROIs were statistically significant (rMTT: F=4.030, P=0.010; rTTP=3.258, P=0.025); Comparison between any two means ofipsilateral/contralateral ratios of rMTT, rTTP was conducted by using LSD-t test.There were statistically significant differences between the front and rearwatershed area (rMTT: P=0.036, rTTP: P=0.042).4. Among36cases of MCA stenosis/occlusion patients,25cases werediagnosed as cerebral infarctions, including13cases of lacunar infarction (LI),9cases of cerebral watershed infarction (CWSI),2cases of internal capsulestriatal infarction (SCI),1case of watershed infarction (TI). Various types ofcerebral infarctions distributed in MCA stenosis groups as follows, Group I:1LI; GroupⅡ:6LIs,1CWSI; Group Ⅲ:6LIs,1SCI,5CWSIs; Group Ⅳ:1LI,3CWSIs,1TI.Conclusion1. Hemodynamic changes in MCA blood supply brain tissues may not besensitively and correctly reflected by DSC-PWI perfusion parameters in mildand moderate MCA stenosis patients; Hemodynamic changes in MCA bloodsupply brain tissues can be properly reflected by DSC-PWI perfusion parametersin severe MCA stenosis or MCA occlusion patients, thus indicating DSC-PWIcan help us understand the corresponding brain tissue blood circulationcompensatory mechanisms and assess cerebral metabolic reserve capacity, andprovide with an objective fact for clinical intervention.2. Back watershed area is most sensitive to reperfusion injury, perfusionabnormalities in the area can be accurately revealed by changes of rMTT andrTTP of DSC-PWI at an early stage.3. There was correlation between degrees of MCA stenosis and SCI, andDSC-PWI could provide valuable objective fact for clinical assessment. Therewere limitations for the clinical assessment on LI by using DSC-PWI parametersonly.4. DSC-PWI examination can provide different perfusion parameters in TIpatients. It is helpful in the indirect assessment of collateral circulationdevelopment around the lesion, and is valuable to provide important objective facts for proper clinical interventions.