The Study Of Diffusion Tensor Imaging In Ischemic Cerebral Infarction

Objective:To study the changes of average diffusion coefficient(DCavg) and Fractional anisotropy(FA) of DTI in the course of ischemic cerebral infarction by using MR diffusion tensor imaging(DTI);To analyse and classify the signal characteristics of DCavg maps and FA maps in different clinical stages;To investigate the correlation between the types of DTI and the clinical stages.Materials and Methods:79patients in different clinical stages of ischemic cerebral infarction were underwent routine MRI and DTI.DCavg values and FA values of the infarcted areas and contralateral normal areas in different clinical stages were measured and the rDCavg values and the rFA values aslo were calculated. Compared values of the infarcted areas with the contralateral normal areas in the same clinical stage. Analysed the variation trend of the rDCavg values and the rFA values among different clinical stages.②79patients’ signal characteristics of DCavg maps and FA maps were observed and classified with double-blind method. Compared the DCavg values and FA values of the infarcted areas with the values of the contralateral normal areas in the same type. Analysed the variation trend of the rDCavg values and the rFA values among different types.③Investigated the correlation between the types of DTI and the clinical stages. Results:1The performances of different clinical stages1.1The changes of the signal of DCavg maps, DCavg values and rDCavg values in infarcted areasThe cases of hyperacute, acute and subacute mainly showed hypo-intensity in varying degrees, while the DCavg values were decreased in varying degrees (P <0.05).Most of the early chronic cases and late chronic cases showed hyper-intensity in varying degrees, while the DCavg values were increased in varying degrees (P<0.05).The differences of the rDCavg values among the superacute, acute and subacute were not statistically significant (P>0.05),while that of the rDCavg values among the rest stages were statistically significant (P<0.05).1.2The changes of the signal of FA maps, FA values and rFA values in infarcted areasThe signal performance of the superacute stage was relatively complex. It might manifest as iso-intensity, inhomogeneous hyper-intensity or hypo-intensity. In our study, it mainly manifested as hyper-intensity, but there was no statistical difference(P=0.436). Most of the rest clinical stages’cases showed various degrees of hypo-intensity, and the FA values were decreased in varying degrees (P<0.05). The rFA values between superacute and acute, acute and subacute were not statistically different (P>0.05).The comparisons of the rFA values of the rest stages were statistically differenct(P<0.05).2The performances of different DTI types Four types of the signal characteristics of DTI were classified as follows. Type I:the infraction lesion showed iso-intensity or slight hypo-intensity on DCavg maps and iso-intensity or slight hyper-intensity or hyper-intensity on FA maps, where the DCavg values decreased and FA values increased; Type II:the infraction lesion showed hypo-intensity on DCavg maps and slight hypo-intensity on FA maps, where the DCavg values decreased and FA values decreased slightly; TypeⅢ:the infraction lesions showed slight hyper-intensity on DCavg maps and hypo-intensity on FA maps, where the DCavg values increased slightly and FA values decreased; TypeⅣ:the infraction lesions showed obvious hyper-intensity on DCavg maps and obvious hypo-intensity on FA maps,where the DCavg values increased significantly and FA values decreased significantly.The difference of the rDCavg values between type I and II was not statistically significant (P=1.000); The differences of the rest comparisons among tpyes were statistically significant (P<0.05).3The correlation between DTI types and the clinical stagesThere was a positive correlation between the types of DTI and clinical stages.The higher of the types were, the longer of the onset time were.Conclusions:①In different clinical stages of cerebral infarction, there were some rules about the evolution of the DCavg values and the FA values. As such, it might reveal the neuropathology physiological processes of cerebral infarction and estimate the clinical stage.②The DTI types might reveal the pathophysiological procedure of cerebral infarction and estimate the clinical stage more directly and simply. It was expected to provide a new imaging staging methods of cerebral infarction for clinic.③There was a positive correlation between the types of DTI and clinical stages.The higher of the types were,the longer of the onset time were.