Dynamic Observation Of Magnetic Resonance Imaging In Intracerebral Hemorrhage In Rats

Background and Purpose:Cerebrovascular disease is one of the most common diseases, which is a seriousharm to human health. According to epidemiological information, the attack rate,mortality rate and disability rate of Intracerebral hemorrhage(ICH)are quite high,which is a threat to people’s health standards and quality of life. The hematoma itselfand the secondary injury are the most important pathological changes of the ICH.How to make accurate diagnosis in the early brain hemorrhage, and how to assess thesecondary changes of perihematoma have important influence on clinical treatmentand the patient’s prognosis.According to the traditional view, CT is the first choice of ICH, magneticresonance imaging(MRI) is not sensitive to bleeding. But with the continuousrenewal of MRI equipment and the development of new technology of MRI, such asenhanced T2star weighted angiography(ESWAN), diffusion weighted imaging(DWI),perfusion weighted imaging(PWI), magnetic resonance spectroscopic imaging(MRSI)and diffusion tensor imaging(DTI) have been widely used in the study of ICH.Among these techniques, the enhanced T2star weighted angiography sequence is anew one, which is particularly sensitive to magnetic susceptibility substance. It cannot only find hemorrhage early, but also can detect micro hemorrhage. All of thosehave an important value for the choice of clinical treatments. The aims of this experiment are to explore the evolution of volume and thechange of perifocal edema after cerebral hemorrhage, then comparing to histologicfindings, and analyze the correlation between image data and pathological indicators.Materials and Methods:1.64male healthy SD rats of clean grade were enrolled in the study, weighingfrom250g to300g, average(280.3±7.5)g. These experimental animals were suppliedby the animal experiment center of HeNan. The rats were divided into two groupswith the randomization principle. The experimental group of48rats used blood toestablish ICH models. The control group of16rats do the same operation as theexperimental group except inject blood. MR examinations were performed at1h,3h,12h,24h,48h,72h,1w,2w, and pathological specimens were taken at every timepoints.2. The production process of cerebral hemorrhage model: fixing rats on thestereotaxic instrument, positioning behind the anterior fontanelle0.3mm and3mm atthe left side, using skull drill to drill a hole, then pressing the needle down about6mm. Injecting40ul arterial blood of the left ventricle into the hole, retaining needleabout10minutes, then closing bone hole, and accepted MR examination.3. Using the GE3.0T superconducting MRI to do the examination. The coil isspecial coil in rats. Two groups of rats are proformed axial T1-weighted imaging,T2-weighted imaging, diffusion-weighted imaging, T2*and ESWAN sequence on1h,3h,12h,24h,48h,72h,1w,2w. According to the MR result, two rats were choosed ateach time point and the rat’s brain was cut into coronal slices, and then theimmunohistochemistry index of AQP4and MMP9of the specimen were semi-quantitative analysised.4. We observed the performance and signal changes in ESWAN sequence at thedifferent time points, and measured the hematoma volumes on T2WI, T2*WI,ESWAN sequence, then comparing with the volumes of pathology specimen to getthe magnification. The DWI changes and the apparent diffusion coefficient (ADC)value changes of perifocal region at different time points were measured. We also analyze the dry and wet weight datas at every time point. After brain slice staining werecord the change trend of AQP4and MMP9, and then analyze the correlationrelationship among the MR index(ADC value), dry and wet weight datas andpathological index (AQP4and MMP9).5. The data we obtained were analyzed using SPSS17.0statistical software.Measurement data were expressed by mean±standard deviation. The statisticalmethods used in the study were independent samples t-test, paired t-test, one-wayANOVA, correlation analysis, and P<0.05indicates statistically significantdifference.Results:1. The signal intensity of hemorrhage core on SWAN and the phase radian valuewere both decreased rapidly. Experimental group and the control group of rats atdifferent time points, the difference of SWAN signal values and phase radian valueswere statistically significant(P<0.05). And the the experimental side compared withthe mirror side, the difference of SWAN signal values and phase radian values werestatistically significant(P <0.05).2. On T2WI, T2*WI and ESWAN sequence, the hematoma volumes weregradually reduced between1h~2w. Comparing the hematoma volume on T2WI withhistopathology volume, the difference was not statistically significant(P=0.125>0.05).Comparing the hematoma volume on T2*WI, ESWAN sequence with thehistopathology volume, the difference was statistically significant(P=0.025<0.05).Therefor, T2WI showed hematoma volume more precise, T2*WI and ESWANsequence overestimated the histological volume.3. The ADC values of experimental rats surrounding hematoma had nosignificant changes on1h, but the ADC values rose on3~72h. The ADC valuesbetween experimental group and the control group on each time point, the differenceswere statistically significant(P<0.05). And the the experimental side compared withthe mirror side, the differences of ADC values were statistically significant(P<0.05).4. After the procedure, the IODMMP9gradually increased with time in3~24h, and reached the peak at48h~72h, there was still a little expression at14d. Except1h group, the rest time points of experimental group were statistically significantdifference with the control group(P<0.05).5. For the ICH group, the IOD of AQP4increased gradually by time, roserapidly in12h~72h, returned to normal in14d, and then increase slowly. Comparedthe experimental group with the control group at each time point, the differences werestatistically significant(P<0.05).6. After analysis the correlation relationship of the MR index (ADC value), wetand dry weight indicators and pathologican index (AQP4and MMP9), the resultshowed a significiently positive correlation(P<0.05).Conclusion:1. ESWAN sequence can accurately identify hemorrhage, and it can be used forearly check.2. According to the volumeson T2WI, T2*WI, ESWAN, and histopathology, wefind the T2WI and histological volumes were in close numerical agreement. Bycontrast, the T2*WI and ESWAN sequences overestimated the histological volume.3. As time went on, the expression of both AQP4and MMP9increased graduallywith time in rats with acute cerebral hemorrhage.