The Application Of High-resolution MRI In The Middle Cerebral Artery Stenosis

BackgroundIschemic cerebrovascular disease, including cerebral infarction and transientischemic attack (TIA), has high morbidity and disability. Early detection andtreatment and is of great importance to the progression of the disease and prognosis ofthe patients. Commonly used clinical imaging modalities to evaluate the degree ofcerebral vascular stenosis such as digital subtraction angiography(DSA), CTangiography(CTA), magnetic resonance angiography(MRA) and transcranial Dopplerultrasound(TCD) all have some certain deficiencies. High-resolution magneticresonance imaging (HRMRI) emerges as a new imaging modality, both able to depictthe lumen and the wall. It has been successfully applied to the extracranial carotidmature and can accurately assess the carotid artery stenosis. In recent years, with therapid development of high-field MRI scanner, HRMRI has been gradually applied forintracranial artery. Middle cerebral artery (MCA) is the direct continuation of theinternal carotid artery in the brain, and is most likely to be involved by diseases suchas atherosclerosis. According to reports, MCA atherosclerotic stenosis is the mostcommon cause of ischemic cerebrovascular disease. How well is HRMRI in evaluatethe major intracranial artery stenosis? Why some patients suffered cerebral infarction while others performed TIA when they have the same severity of cerebral arterystenosis? Are there any differences in vascular stenosis between patients with cerebralinfarction and TIA?The aim of this study included two aspects: to investigate the value of HRMRIin evaluating the middle cerebral artery stenosis and to confirm that wether there aredifferences in atherosclerotic stenosis rate of MCAs between patients with cerebralinfarction and TIA caused by MCA stenosis.Part ⅠStudy of HRMRI value in assessing MCA stenosisObjectiveTo explore the diagnostic value of high-resolution MRI (HRMRI) in theevaluation of middle cerebral artery (MCA) stenosis or occlusion using MRA andDSA.Materials and MethodsWithin a1-year study from October2012to October2013,55(33males and22females, aged from17to68years old, mean age44.8±11.2, recently symptomaticpatients with MCA territory symptoms adimtted to the Intervention Department of theFirst Affiliated Hospital of Zhengzhou University underwent preliminary MRA orCTA. MRA or CTA was performed as a screening test to confirm that there existedipsilateral MCA stenosis in those patients. All the patients underwent MRA, HRMRIand DSA, and the average time interval was3.4days. Based on the results of DSA,the gold standard, and compared with MRA, we analyzed the diagnostic value ofHRMRI for measuring the degree of MCA stenosis.Results55segments were diagnosed consistently by MRA, HRMRI and DSA. The rateof coincidence between HRMRI and DSA was83.6%（46/55）. The overestimationrate of MRA was61.8%(34/55). The MCA stenosis rates were (70±17)%,(68±19)%and (85±20)%on HRMRI, DSA and MRA, respectively. There was no statistical difference observed to evaluate the degree of stenosis by HRMRI and DSA (Z=-1.192,p=0.233), whereas observed significant statistical difference between HRMRI andMRA (t=-6.604, P=0.000). HRMRI-derived value correlated more significantly rwith DSA (Pearson’s r=0.893, P=0.000) than with MRA (Spearman’s r=0.602,P=0.000). HRMRI and DSA conformed well in evaluation of the stenosis rate(Kappa=0.773), meanwhile,0.355between HRMRI and MRA.ConclusionFor evaluating MCA stenosis or occlusion, HRMRI consists with DSA betterthan MRA does. HRMRI. ObjectiveTo investigate the stenosis rate differences of atherosclerotic middle cerebralartery (MCA) between TIA and cerebral infarct patients caused by MCA stenosisusing high-resolution magnetic resonance imaging (HRMRI).MethodsNinety-one consecutive patients with symptomatic atherosclerotic stenosis at M1segment of MCA on MRA or DSA were enrolled from April2012to September2013.HRMRI was performed on the target segment by using a3.0T MR scanner.Stenosis rate was calculated as vessel area at maximal lumen narrowing/referencevessel area. Diffusion weighted imaging (DWI), T2WI and dark-fluid sequences wereperformed to make sure if infarct occurred. ResultsSeventy-eight patients were included in the final analysis, including46patientswith infarct, the stenosis of which is0.72±0.21, and32patients with TIA, the stenosisrate0.72±0.20. The rate difference between patients with infarct and TIA was notstatistically significant(t=-0.10,P=0.92>0.05).ConclusionsThe stenosis rates of M1segment of MCA in patients with infarct and TIA haveno statistical difference, suggesting that the stenosis rate of M1segment of MCA isnot the determining factor of infarction.