Water molecular diffusion changes in cerebral ischemia and the study of its clinical application / 北京大学学报(医学版)

ABSTRACT

Objective： To study the changes of water molecular diffusion in the ischemic region by using MR dephase technique and discuss the potential mechanism of the diffusion changes at early stage. Methods: Totally 43 cases were studied retrospectively. There were 10 cases whose MRI examinations were performed within 6 hours，12 cases from 7－24 hours，7 cases from 2－7 days, 8 cases from 8－14 days, 6 cases from 15 days to 2 months. The apparent diffusion coefficients in the ischemic region were calculated. Results: The ADCav in the grey matter was 8.61×10－4mm2*s－1. The ADCav decreased to (4.72×10－4±1.51×10－4) mm2*s－1 in ischemic region at superacute stage, ADCav ratio to contralateral corresponding region was 0.55±0.18, and ADCav increased to (5.68×10－4±1.22×10－4) mm2*s－1 during the time range of 2-7 days, （9.22×10－4±2.07×10－4） during the time range of 8－14 days, and approaching （26.42×10－4+9.65×10－4） mm2*s－1 during the time range of 2 months. The pearson product- moment correlation between the changes of diffusion value and time was sighificent (r=0.95, P<0.001). ADCv increased at superacute stage and decreased over time. Conclusion: The diffusion of water molecules in ischemic region decreased at superacute stage, and the ADC increased over time. The anisotropy increased at superacute stage and decreased as the course developed. DWI could detect ischemic lesion much earlier than CT and routine MR examination. DWI has great value in the diagnosis of superacute stroke. The mechanism of the diffusion changes at early stage may be the intracellular toxicity edema.