A Clinical Study Of MSCT Perfusion Imaging And CT Angiography In Cerebral Pre-infarction Period

Background and objective: Cerebral infarction was the most common brain vessel disease which had a significant deformity and mortality. It is the concerned problem for people all the while in medical territory.At present, the study of acute ischemic cerebral vasscular disease imaging diagnosis concentrate on acute infarction period and hyperacute infarction period mostly in the world, the imaging examination techniques include diffusion weighted imaging (DWI),perfusion weighted imaging (PWI),CT perfusion imaging (CTPI),Xe-CT,ECT and so on. In recent years, with the development of multi-slice CT technology, multi-slice spiral CT cerebral perfusion imaging (MSCTPI) arise the pepole' attention beacause MSCTPI could not only discover the position, range of hyperacute ischemic cerebrovascular disease ( < 6h ) and assessed ischemic brain tissue's blood perfusion information but also confirm ischemic penumbra (IP) from imageology.The combination of MSCTPI and CT angiography (CTA) could show corresponding blood-supply artery information directly. It have great significance to introduce and apply the peri-infarction period theory in cerebral infarction. The theory consider that the process of acute cerebral infarction can be divided into 3 stages: first, somehow the regional cerebral haemodynamic changed occur; then the functions of the neurons caused by regional uncompensated low perfusion were changed; finally the irreversible morphological changed of the neurons occur, which was cerebral infarction. The first two stages are called cerebral pre-infarction period. Therefore TIA can be regarded as a recoverable ischemic penumbra in pathobiology. TIA and IP are all in pre-infarction period.The purpose of this study is to evaluate the clinical application value of MSCTPI and CTA on pre-infarction period.Materials and methods: From November 2004 to August 2006, Brain MSCTPI and CTA of 16-slice spiral CT were performed in the 78 consecutive patients ( 51 male,27 female, range 34 to 78 years old, mean age 61 years old ) with clinically diagnosed acute ischemic cerebral vasscular disease . They were divided into TIA group(n=43) and acute cerebral infarction group(n=35). TIA group: Time to peak (TTP), cerebral blood flow (CBF) , cerebral blood volume (CBV) and mean transit time (MTT) were measured within region of interest ( ROI ) of the brain after MSCTPI. The stages of pre-infarction period were made as the following: I₁ ,TTPwas delayed, MTT, rCBF and rCBV were normal; I₂ ,TTP and MTT were delayed , rCBF was normal , and rCBV was normal or slightly increased ; II₁,TTP and MTT were delayed , rCBF was decreased , and rCBV was normal or slightly decreased ; II₂, TTP and MTT were delayed , rCBF and rCBV were decreased. Acute cerebral infarction group: 26-68 hours stroke onset, to combine with the CT source imaging, two ROI were defined, region 1: infarct core - infarcted tissue with decreased regional cerebral blood volume(rCBV) and regional cerebral blood flow(rCBF); region2: penumbra: with normal regional cerebral blood volume but decreased regional cerebral blood flow. Quantitative assessment ( absolute value and relative value ) was performed on ROI. All patient's data was send to ADW4.2 workstation. We evaluated the vessel wall's plaque with the axial imaging. CTA was postprocessed using CPR, MIP and VR ( anterior cerebral artery, middle cerebral artery and posterior cerebral artery's 3～4 branch level were reconstructed ), and caculated stenosis ratio according to North American Symptomatic Carotid Endarterectomy Trial (NASCET). Statistical analysis was executed by SPSS12.0 software packages. Significant level was set asα=0.01.Results: TIA group:â‘ Persisting abnormal perfusion changes corresponding to clinical symptoms were found in 33 of 43 cases TIA onset with prolonged TTP, 27 cases with prolonged MTT, 18 cases with decreased rCBF, and 19 cases with decreased rCBV. Other 10 cases showed normal perfusion results.There were 6 cases in stage I₁, 9 cases in stage I₂ ,7 cases in stage II₁ and 11 cases in stage II₂. The TTP (12.83±4.30s) of affected side compared with that (10.48±2.47s)of the contralateral side was significantly prolonged (t = 1.642, P =0.009). The rCBF,rCBV and MTT was not statistically significantly between affectal and contralateral sides.â‘¡Extracalvarial internal caroid artery stenosis was found 57 of 86 branches in 43 case of TIA. Intracalvarial artery stenosis was 25 case.â‘¢Different degree stenosis were detected in extracranial artery in the abnormal perfusion results. Internal carotid artery's initial segment middle degree stenosis and atheromatous was 1 case.Acute cerebral infarction group:â‘ 3 cases appearanced hypertransfusion, 30 case appearanced variant hypoperfusion. Another 2 case of MSCTP1 had negative results within the acute cerebral infarction group.There was a highly significant difference of rCBV and rCBF ratios and absolute values for region1 versus region2 (p<0.01) in the 35 patient. All ROI with a mean CBF ratio<0.23 demonstrated infarction, mean CBF ratio > 0.29 demonstrated IP, whereas all ROI with a mean CBF ratio>0.39 appeared normal. 21 cases with large or moderate cerebral infarction volume(5cm³ï½ž8cm³) were confirmed by MSCTPI as having ischemic hypoperfusion lesions. In 2 cases with small cerebral infarction volume, MSCTPI all revealed normal perfusion (3cm³ï½ž4cm³).â‘¡Extracalvarial internal carotid antery stenosis was 51 of 70 branches in 35 case. Arteria vertebralis light stenosis was 13 cases. Intracalvarial artery stenosis was 18 cases in 35 cases.Conclusion: CD MSCTPI could provides valuable cerebral hemodynamic information, shows the exent of perfusion disturbances for patients with TIA. CTA could demonstrate the stenosis of the affected cerebral arteries and carotid arteries. (2) The TTP is the most sensitive perfusion parameter to find TIA.â‘¢The combination of MSCTPI and CT angiography could differentiate infarction core from IP effectively and haemodynamic information of brain and the affected vessels were evaluated for TIA and acute cerebral infarction exactly.â‘£It had great clinical significance and application perspective for research of cerebral infarction to advance the study of acute ischemic cerebral vasscular disease imaging to pre-infarction period.