The Study Of DKI And Blood Inflow State In Acute Ischemic Stroke

OBJECTIVE: To observe the changes of diffusion kurtosis imaging(DKI)in the acute phase of ischemic stroke and compare the ability of evaluating the infarct core area by DKI and DWI.And to investigate the performance of blood perfusion in different regions of DKI and DWI,thus revealing the valueof DKI in patients with acute cerebral infarction in the early diagnosis and evaluation of the prognosis,and explaining the possible mechanism.Subjects and Methods:(1)A total of 60 patients with acute cerebral infarction were enrolled.All patients were examined by routine sequences,DWI,DKI,MRA and DSC-PWI(dynamic susceptibility contrast enhanced perfusion weighted imaging,DSC-PWI).The parameters of ADC,MD,MK,AK and RK were obtained,all parameters of ipsilateral and contralateral were measured,and then the rate of change were calculate.(2)37 patients with acute cerebral infarction completed a longitudinal follow-up study,MRI examination time were 24 hours,5-7 days,30 days later,all the lesions were divided into small lesions(Dmax <1cm)and large lesions(Dmax?1)according to the lesion size,the small lesion group was counted,the large lesion group was measured.(3)25 patients included 32 large lesions,which divided into MD / MK matched and MD / MK mismatch two groups.For the mismatch group,the lesion divided into the central area,the mismatch area and the marginal area from inside to outside,while the matched group had no mismatch area.We mesured the hemodynamics parameters(MTT,TTP,CBF,CBV)of different areas,respectively.The contralateral brain tissue defined as the control area.Statistical analysis:We analyzed the difference of the diffusion and kurtosis parameters in the acute phase,and compared the rate of these parameters.We analyzed the difference of the lesion volume of each parameter maps in the acute phase and compared the relationship between the lesion volume in acute phase and the final volume.We analyzed the difference of perfusion hemodynamics parameters between different regions of MD / MK matched and mismatched patients in acute cerebral infarction,and to compare the differences between the different regions of each group.Results:(1)In acute cerebral infarction,the ADC and MD values were decreased,andthe MK,AK and RK were increased(P <0.001),and the rate of kurtosis parameter was greater than that of diffusion parameter(P <0.005).There was no significant difference between the rate of ADC and MD value.,and there were no significant difference between the parameters of the kurtosis except for the difference between AK and RK(P <0.005).(2)The lesion volume of the diffusion and kurtosis in the acute phase showed no statistically significant(H = 8.506,P> 0.05).The final T2 WI volume showed moderately correlated with the baseline the ADC,MD volume,the correlation coefficiects.r was 0.761 and 0.775,respectively,but which showed highly correlated with the baseline MK,AK and RK volume,r were 0.880,0.869,0.870 respectively.For small lesion group,the number of positive lesions in kurtosis maps in acute phase had better agreement with the final T2 WI map(P >0.05).(3)There was a significant difference in CBF between the central area and the mismatch area,which was lower than the latter(P <0.05).There was a significant difference in the values of TTP,CBF and CBV between the center and the marginal area,which showed that the former had longer,decreased and decreased than the latter(P <0.05).There was a significant difference in CBV between the mismatch area and the marginal area,which was lower than the latter(P <0.05).Conclusions: DKI in patients with acute cerebral infarction can provide richer information than DWI,and contribute to early diagnosis,especially the MK parameter map;For stoke patients in acute phase the kurtosis parameters can define the core area and predict the final changes more accurately than diffusion parameters;When the MD / MK abnormal range was mismatched in patients with acute cerebral infarction,the central region of MK abnormalities had lower CBF values than MK normal mismatche region,suggesting that MK could grade the histological changes of MD in different metabolic states,providing a possible explanation for the DKI closer to the core area,and also complementing the precise definition of IP.