Diffusion Weighted Imagin Findings Of Pathological Evolution Process Of Cerebral Infarcts

ObjectiveTo analyze the changes and the evolution in the signal intensity of cerebral infarcts ondiffusion-weighted imaging (DWI), and determine the time of acute and subacute phases ofthe cerebral infraction lesions.MethodsOne hundred and thirty-three patients with cerebral infraction from DongpingPepeople，s hospital were retrospectively analyzed. The patients included74male and59female, the age was30-85years old and the average age was62.3years old, the diseasecourse from onset of infraction to MR examination was from1to15days. All patientswere used conventional MRI examination and diffusion-weighted imaging （DWI）scan.GE signa HDe1.5T MR system was used for the examination. DWI sequence wasecho planar imaging with b value of1000s/mm2. GE aw4.4workstation was used for theafter processing and analysis images.The DWI data was treated with functool tools of theworkstation for the apparent diffusion coefficient（ADC)map. the region of interest(ROI)were placed on the lesions in the slice of ADC map with biggest area of the lesions. ROIwas circle and contained25-40pixels with36±2mm2. The unit of ADC value was10-3mm/s. ROI should be completely located with in the lesion and avoid vessel, sulcusand ventricle. ADC value was measured for the quantitative analysis of infarction lesions.Results1．This experiment in the examination of194,the results showed that the infarctionlesion presented high signal on DWI and low signal on ADC map in136patients, and highsigna on DWI and low signal on ADC map in58patients. In the patients with﹤10daysof disease course, there were131patients with high signal on DWI and low signal on ADCmap and4patients with low signal on DWI and high signal on ADC map. In the patients with≥10days of disease course, there were5patients with high signal on DWI and lowsignal on ADC map and54patients with low signal on DWI and high signal on ADC map2．The results showed that ADC value decreased in the early period and increased inthe late period in133patients with the infarction. ADC value started to decrease at thesuperacute phase of infarction, reached the lowest point at the acute phase, then began toincrease slightly and was still obviously lower than the normal at the sub-acute phase andwent to the normal or higher than the normal at the chronic phase. According to signalchange The period from1to3days after the onset of the infarction could be defined as anacute phase, from3to9days as a sub-acute phase and from10to15days as a chronicphase. The high signal of the lesion of the infarction on DWI changed to low signal and thelow signal on ADC map changed to high signal on the tenth day after the onset of theinfarction.3．The results showed that they have lots of relation in133patients with the infarctionsite and the supplying area of blood.one of middle cerebral artery of62.3%,posteriorcerebral artery18.8%,cerebellar artery11.2%,anterior cerebral artery6.7%.Conclusions1．The combination of DWI, ADC map and quantitative analysis of ADC value canhave a high accuracy in the evolution stage of the cerebral infarction..2．The lesion of the acute cerebral infarction presents high signal on DWI and lowsignal on ADC map within9days after the onset of the infarction. There is similar days tothe duration of acute and sub-acute phases of clinical stage. Therefore, the cerebralinfarction can be staged by means of imaging, which provides a basis for clinicaltreatment.3．The most possible site of the cerebral infarction is the supplying area of middlecerebral artery, which is followed by posterior cerebral artery and cerebellar artery.