Evaluation By Apparent Diffusion Coefficien Of The Secondary Change In The Distant Parts Of Unilateral Supratentorial Cerebral Infarction

Part I Changes of apparent diffusion coefficient at distant parts in rats after MCAOBackground and Purpose:Ischemic cerebrovascular disease (ICVD) has been seriously threatening human health and quality of life. According to the latest epidemiological survey, the incidence rate of ICVD was 116/10 million,81/10 million for the mortality rate,3%o million for the prevalence rate, and has showed an obvious upward trend in our country. ICVD has been seriously threatening human health and quality of life, so it is important to diagnose and treat this disease earlier. ICVD could cause inhibition of distant areas (such as the thalamus and cerebellum), whose mechanism is still unclear, but may be relevant to diaschisis. In recent years, with the development of the magnetic resonance imaging (MRI) new techniques, especially the diffusion weighted imaging (DWI) techniques, MRI has become more and more sensitive and differential to diagnose ICVD. However, previous scholars put particular emphasis on the evaluation by apparent diffusion coefficient (ADC) values of ICVD lesions itself and ischemic penumbra (IP). For the research of secondary changes in distant regions after supratentorial ischemic stroke, there has not yet related reports at home and abroad. In order to study human cerebral infarction better, it is important to establish a cerebral ischemic model in rats with reproducible, strong stability and cerebrovascular characteristics similar to human. Intraluminal suture method is widely used to establish a middle cerebral artery occlusion (MCAO) model in clinical, and the traditional approach is Longa suture method. In this study, remote undamaged regions of rats brain after MCAO were detected continuously by MRI ADC at 1h,3h, 9h and 24h for different time points, compared with TTC staining, optical microscopy and immunohistochemical identification of apoptotic cells, to evaluate the evaluation by ADC values after MCAO at different time points in the remote regions, providing experimental and theoretical basis on the evaluation of diaschisis by ADC values.Materials and Methods:The MCAO model of rats was established based on Lon-ga method, having been modified. The experimental group of rats were dynamically examined by magnetic resonance imaging (MRI) at 1h,3h,9h, and24h after MCAO. With high-field 3.0 T superconducting magnetic resonance scanner of GE in U.S., the line cross-sectional T1-weighted imaging (TIWI), T2-weighted imaging (T2WI) and DWI imaging sequence were performed. For the sake of 2,3,5-triphengltetrazolium chloride (TTC) staining, the brain of two rats in each group were cut into slices every 3 mm, obtained correspondently to MRI scans, to observe that whether brain tissue samples were dyeing or not.2 specimens in each time point which were obtained correspondently to MRI scans, were taken into cut brain tissue, to be observed by microscopy after HE staining and identified apoptotic cells by immunohistochemical respectively.Results:1. With the time coursing, the infarct core size and signal intensity became larger, involving the adjacent cortex gradually during 1h-24h after MCAO in the image of DWI, and the signal change became gradually stable during at 24h after MCAO. The infarct area and the signal were gradually changed with time in the map of ADC. The decreased levels of ADC values in the core of infarction were not consistent with each inspection time after MCAO. ADC values decreased significantly at 1h compared with normal control group, and increased gradually with time, but had not yet resumed normal levels. Paired sample t test showed that, ADC values of the infarction core at each inspection time were significantly lower after MCAO compared with the corresponding parts of the control group (P?0.01).2. After MCAO, ADC values varied similarly on bilateral hypothalamus, it decreased the most obviously at 1h after MCAO, on the left and right thalamus it decreased by about 28%,24%separately compared with normal control group; During lh-3h after MCAO it rebounded, During 3h-24h after MCAO it varied more steadily, but mildly decreased at 9h after MCAO. The change of ADC values on both sides of the cerebellum and thalamus showed a similar trend after MCAO. Paired t test showed that in normal control group, the difference of ADC values between the corresponding parts was not significant (P>0.05); after MCAO on the left, compared with the normal control group, the ADC values in different parts decreased significantly (P<0.05) at different time points, in particular, the most obviously at 1h after MCAO.3. In the control group, the rat brain showed red staining on TTC. The infarct core showed on DWI in the experimental group was not stained and showed white. With the time extending after MCAO, infarct size increased gradually within 3-24h, gradually involving the adjacent cortex. But both sides of the thalamus and cerebellum showed red staining on TTC in each time point.4. In the normal control group and experimental group, by light microscope, neuronal nucleus of both sides of the thalamus and cerebellum located in the central of cells were large and round and cytoplasm was full, showing no obvious abnormalities. At 1 h after MCAO, neurons of infarct area showed no abnormality by light microscope, but individual nuclear showed anachromasis and cytoplasm showed acidophily alteration. At 3h after MCAO a small number of nucleus of neurons showed anachromasis and cytoplasm showed eosinophilic alteration in infarction area. At 9h after MCAO, the number of neurons of nuclear condensation on the left brain increased in further. At 24h after MCAO, more neurons with pyknosis and ischemic change were seen in the cerebral infarction region, and in some regions nucleus of neurons disappeared and the number of neurons reduced. However, the neurons of both sides of thalamus and cerebellum showed no abnormality by light microscope in 1h-24h experimental groups.5. With the time extending after infarction, the number of apoptotic cells in infarction core gradually increased, from 2.400±0.548 at 1h after MCAO to 61.000±7.483 at 24h after MCAO. At 24h after MCAO the largest number of apoptotic cells was largest (p<0.05), while no apoptotic cell was showed in thalamus and cerebellum at all time points.Conclusion:1. Modified MCAO model is operated simply with low mortality in 24h and good repeatability, and is the ideal model to quantify ADC value effectively.2. Compared with the normal control group, the ADC values of ipsilateral and contralateral remote regions (thalamus and cerebellum) of infarction after MCAO are significantly different. It explains that the phenomenon of diaschisis exists on both sides of the distant parts.3. ADC values of remote regions (thalamus and cerebellum) varies along with the change of the supratentorial infarction core, to a certain extent, it is illustrated indirectly that the phenomenon of diaschisis and neural pathways are closely related. Part II The secondary changes by apparent diffusion coefficient in the distant parts of hyperacute unilateral supratentorial cerebral infarctionBackground and Purpose:Secondary changes in the remote region of ischemic stroke are explained by diaschisis. Diaschisis is the phenomenon that the focal damage of brain tissue could lead to a brief inhibition in remote regions of normal structure, and the primary damage site and the remote regions are contacted with fiber anatomically. Diaschisis played a role in the recovery of cerebral infarction, so it is very necessary to realize the phenomenon correctly and to understand the role it played in the functional recovery of cerebral infarction. Most previous scholars utilized single photon emission computed tomography (SPECT) and positron emission tomography (PET) to study this phenomenon, but the factors such as expensive equipment, scanning with radiation, more costly, inconvenient to operate made its application limited.Dynamic susceptibility contrast-enhanced magnetic resonance perfusion weighted imaging (DSC-PWI), a noninvasive technique making evaluation of abnormal perfusion lesions, can be used to evaluate the phenomenon of crossed cerebral-cerebellar diaschisis (CCD) after supratentorial cerebral infarction. In this study, MRI datas of 17 patients of hyperacute cerebral infarction (?6h) are retrospectively analyzed, who are from our hospital in the "Project supported by National Eleventh Five-Year Plan". Combined with the ADC values study in first part of this group, ADC value is utilized to quantify the change in the remote parts of hyperacute unilateral supratentorial cerebral infarction, and the consistency analysis of it and DSC-PWI perfusion parameters is made simultaneously. The signal change in the remote regions of unilateral supratentorial cerebral infarction is observed from the ADC map perspective, and is compared with DSC-PWI parameter map, thereby a new evaluation method for clinical assessment of diaschisis secondary to hyperacute cerebral infarction was provided. Materials and Methods:From December 2007 to September 2010, all data of 17 patients of hyperacute cerebral infarction (?6h) diagnosed by our hospital emergency room were continuously selected.17 patients were from our hospital in the "Project supported by National Eleventh Five-Year Plan". All of the subjects were undertaken head scan using the 3.0 T superconducting MR unit (GE Medical System),8-channel coil, DWI and DSC-PWI examination. DSC-PWI were delivered to the workstation (ADW 4.3), contrast time intensity curve was got after the handle of special perfusion software of GE.Results:1. In the same age group, ADC values varied in different parts of brain tissue in normal adult, among which the frontal gray matter valued the highest, followed by the frontal white matter and thalamus. In the same part, ADC values increased along with age increasing except the cerebellum. Paired t test showed that there was no significant statistical difference for ADC values of both sides of the brain tissue in different parts (p>0.05). In patients with hyperacute cerebral infarction, ADC values of the both sides of the thalamus were compared, and there was significantly different (p=0.032), however, in other region the different of ADC values were not significantly (p>0.05). ADC values of both sides of the cerebellum in patients with hyperacute cerebral infarction were decreased to different levels and paired sample test showed no difference (p>0.05). Compared with the normal group, ADC values of cerebellum contralateral to infarction were statistically significant different in independent samples t test (P<0.05). Compared with the normal group, ADC values of cerebellum ipsilateral to infarction were not significantly different (p>0.05).2.10 cases of hyperacute cerebral infarction were undertaken DSC-PWI and DWI MRI examination in distant cerebellum. On NEI map,4 patients showed significant perfusion defects,2 patients showed mild perfusion defect, and 4 patients showed no perfusion defects. On MTE Fig,2 patients showed significant perfusion differences in pseudo-color, 2 patients showed mild perfusion differences in pseudo-color,2 patients showed no perfusion pseudo color difference. On ADC map,3 patients showed significant differences in pseudo-color,3 patients showed slight differences in pseudo-color,4 patients showed no pseudo color difference.3. In 10 cases of hyperacute cerebral infarction, there was significantly different (p<0.05) in NEI measured values between ipsilateral and contralateral cerebellum of infarction, while there was no statistical difference (p> 0.05) in MTE measured values between bilateral cerebellum.Conclusion:1. ADC values can quantify diaschisis in the distant parts of hyperacute (?6h) unilateral supratentorial cerebral infarction.2. ADC maps can get a good consistency with enhanced magnetic resonance perfusion negative points (NEI) parametric maps.3. The infarction itself should be paid attention, and its distant part should also be concern about.