| Background and perpouseThrough many years of research find atherosclerotic plaques in the middle cerebral artery(MCA) and caused by stenosis is the most common cause ischemic disease has made it clear in the worldwide, especially in China. CT angiography (CTA), magnetic resonance angiography (MRA), digital subtraction angiography (DSA) and transcranial Doppler ultrasound (TCD) are the most use ways to check the MCA. But these ways have less ability to diagnosis the reasons of stenosis.Recently, with the appearance of high-field magnetic resonance, high-resolution magnetic resonance imaging (HRMRI) in the intracranial arteries has attracted the people’s attention. HRMRI can find the MCA lumen of atherosclerotic plaques, and assess the degree of the MCA stenosis, Which can distinguish plaque stability. In recent years, with the rapid development of high-field magnetic resonance, susceptibility perfusion-weighted imaging (PWI) play an important role in evaluating regional cerebral transient ischemic attack (TIA) blood supply, especially echo planar imaging (EPI) technology, as well as the development of paramagnetic contrast agent, Magnetic resonance quantitative or semi-quantitative measure the brain tissue perfusion technology has become more mature. In the current examination methods which PWI can find cerebral hemodynamics abnormal earlier. Early detection and diagnosis of cerebral blood flow reduction, which is helpful to guid clinical work.This article aims to explore the HRMRI and PWI value in patients with TIA in the unilateral MCA stenosis.Materials and methods43patients with TIA in the unilateral MCA stenosis or occlusion were collected in the First Affiliated Hospital of Zheng zhou University neurology department by the MRA diagnosis from April2011to February2012,24males and19female,aged26-71year,mean age was54.02±11.17. The group of patients carry out HRMRI and PWI examinations. The clinical manifestations of these patients showed a transient with TIA, duration of2months to2years, TIA diagnostic criteria:caused by the brain, spinal cord or retinal focal cerebral ischemia, not associated with acute infarction, transient neurological dysfunction.The inclusion criteria wre:all cases occurred TIA, The conventional MRI scans and DWI no acute cerebral infarction and large area of old infarction,and MRA examination revealed unilateral MCA stenosis. Exclusion criteria were:MRA check has carotid artery, bilateral middle cerebral artery and anterior cerebral artery stenosis, moyamoya disease and other non-atherosclerotic stenosis disease;MRI scan has intracranial hemorrhage, intracranial tumors, brain trauma, inflammatory diseases and other neurological diseases. All patients were first found unilateral M1section stenosis of the MCA by brain MRA, then do HRMRI check to analyze atherosclerotic plaques within the lumen, distinguish plaque stability and atherosclerotic plaque AHA type, calculate the degree of stenosis,and then do PWI check, All examinations were in the incidence of intermittent period. All patients the MCA HRMRI and PWI data transport to the the Siemens syngo workstation for processing, All the process dealed with by two experienced radiologists, Agreed upon objection before making decision. First make assessment atherosclerotic plaques within the lumen and grading, then analyze atherosclerotic plaques within the lumen, distinguish plaque stability, calculate the degree of stenosis, according to the Samuel’s standards and methods measured, access for the two person’s measurement results,get the averaged measurement by multiple measurement, subdivided into mild stenosis (29%), moderate stenosis (30～69%), severe stenosis (70～99%), occlusion (100%).And then use Siemens syngo workstation process the PWI data,get time-signal intensity curve, the computer automatically rebuild and calculate the relative cerebral blood volume (rCBV), relative cerebral blood flow (rBCF), relative mean transit time (rMTT), time to peak (TTP) a series of parameters.Select the middle cerebral artery at the district level, avoid the pedestrian area of blood vessels and old infarction area, artificial delineate regions of interest (ROI), bilateral ROI to measure perfusion parameters, and finally get the rCBV、rCBF、rMTT and TTP. The10volunteers PWI parameters do as the same way.All data were analysed by SPSS11.5package in statistics, using the paired t-test between the two groups, the relationships between variables were analyzed by Pearson correlation, P＜0.05as statistically significant difference.ResultsHRMRI get positive155meet the requirements vessel section. Ⅲ type plaques in49(31.6%),lumen show diffuse thickening or eccentric small plaque;Ⅳ-Ⅴa type41(26.5%),show large lipid core, no hemorrhage; Ⅴb type4(2.5%), show calcification signal; Ⅵ type13(8.4%) of complex plaques with spotting signals; Ⅴc48(31.0%) show no significant lipid nuclear fiber components within the plaque, the lumen almost occlusion.The soft plaques (vulnerable plaque)(Ⅳ-Ⅴa type Ⅵ type)54(34.8%),hard plaques (stable plaques)(Ⅲ, Ⅴb, the Ⅴc ype)101(65.2%), Hard and soft plaques in the bilateral middle cerebral artery distribution was no significant difference (chi-square test P=0.257>0.05). HRMRI diagnosis four cases of mild stenosis,11cases of moderate stenosis,22cases of severe stenosis,6cases of occlusion.8cases and MRA diagnosis of inconsistency, MRA diagnosis of four cases of occlusion, high-resolution magnetic resonance diagnosis of severe stenosis. Control group:the bilateral hemisphere perfusion indexes was no statistically significant difference (t=-0.062,-1.876,1.825,-0.019,P>0.05).43cases of unilateral MCA stenosis in patients with TIA,42patients with bilateral hemisphere perfusion difference, lower rCBF, rMTT and TTP were delay (P <0.05), and rCBV of the difference was not significant difference (P>0.05). There was statistically significant correlation between the values of TTP and rMTT and the degree of artery Stenosis in PWI,as well as the ratio of the bilateral hemispheres’s rMTT、TTP (P＜0.05) of11cases of unilateral MCA in patients with moderate stenosis, the Pearson Correlation of rMTT、TTP ratio of the bilateral hemispheres is0.896、0.731(P<0.05), There was no statistically significant correlation between the ratio and value of the bilateral hemispheres’s rCBV、rCBF (P>0.05).There was no statistically significant correlation between the values of rCBV、rCBF、rMTT、TTP (P>0.05) and the degree of artery Stenosis in PWI, of22cases of unilateral MCA in patients with severe stenosis, the Pearson Correlation of rMTT、TTP ratio of the bilateral hemispheres is0.450、0.857(P＜0.05),There was no statistically significant correlation between the ratio of the bilateral hemispheres’s rCBV、rCBF (P>0.05)Conclusion1. HRMRI can be applied to the middle cerebral artery atherosclerotic plaque2. HRMRI can make AHA sub-type and assess stability of the atherosclerotic plaque.and can accurately diagnosis the degree of stenosis of middle cerebral artery3. MTT、TTP perfusion parameters can be found early in chemic changes of the brain, are sensitive parameters to judge TIA4. HRMRI joint PWI can evaluate the MCA and the hemodynamic changes of the blood supply... |
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