| Objective This study observed the diffusion of early cerebral infarction and analyzed the characteristics of the temporal evolution in early cerebral infarction patients by using diffusion kurtosis imaging(DKI),the ability of DKI in showing the final lesion of cerebral infarction was also evaluated,aimed to explore the application value of new diffusion magnetic resonance imaging(d MRI)in early cerebral infarction.Materials and Methods 1.Materials: This study collected 35 patients with early cerebral infarction admitted by neurology department of Second Hospital of Dalian Medical university from December 2016 to December 2017,the oldest was 92 and the youngest was 48,the average age was 70 years.There were 19 males and 16 females among them.All the patients were examined head MRI within seven days.They were divided into four groups according to literatures and the time of cerebral infarction: hyperacute phase(n=5),acute phase(n=7),early subacute phase(n=14)and late subacute phase(n=9).10 patients of them were rechecked the MRI routine sequence in a month(recovery period)after cerebral infarction.2.Equipment and Post-processing software : MRI scan was used Siemens 3.0 T Magnetom Verio superconducting magnetic resonance scanner and Standard 8 channel head coil.The scan sequences included axial FLAIR T1 WI,axial and sagittal FSE T2 WI,DWI and DKI.Using DKE software to read and post-processing DKI original image,DKI and corrected DTI data information were interpreted,and the corresponding NIf TI images were also created.3.Date measurement and Statistical: Using Image J software to read,measure and record data.Three region of interest(ROI)were placed in the infarcted area and in the symmetry of normal brain tissue in the side of mirror area,measuring the MK,AK,RK,MD,AD,RD,FA values of each ROI respectively and calculating the percentage change rate of each parameter in the infarct area.Delineating the areas of lesions(mm2)manually on the maximum lesion level of MK and MD maps,and the average was measured three times before recorded.The area of lesion on T2 WI was measured by the same method.Using SPSS statistical software to analysis the changes of DKI and DTI in patients with early cerebral infarction.The temporal evolution of MK,AK,RK,MD,AD,RD,FA between the lesion side and control side,the lesion area on MK and MD maps were compared with the paired sample t test.Spearman correlation analysis was used to analyze the correlation between MK,AK,RK,MD,AD,RD,FA value and time of onset in infarction area,the correlation between the final infarct area of T2 WI and the lesion area of the first MK and MD maps were also analyzed.Results 1.In the early cerebral infarction area,the region of MK,AK and RK showed uneven high signal,while the MD,AD and RD images showed uniform and low signal.MK,AK,RK value increased after infarction,the peak values of each value in the acute phase were 1.86±0.28,1.79±0.16 and 1.90±0.26,then this three parameters decreased gradually,the maximum increase of each value in the acute phase was 89.82%,92.47% and 79.25% respectively;MD,AD,RD value decreased after infarction,the lowest value of each value in the acute phase were 0.38±0.03??/ms,0.49±0.08??/ms and 0.33±0.07??/ms,then they increased gradually,the largest reduction rate of each value in acute phase were 62.75%,63.70% and 59.76% respectively;The FA value of the lesion was slightly higher than that in the hyperacute phase(0.48±0.07),after that,it gradually decreased(0.30±0.07,0.28±0.04 and 0.29±0.09).2.The rate of change of the diffusion kurtosis parameters(MK,AK,RK)in the infarction area were higher than those of the diffusion tensor parameters(MD,AD,RD),and the rate of change of axial diffusion parameters(AK,AD)were larger than those of radial parameters(RK,RD).3.The values of MK,AK,RK and FA in infarction area were significantly negatively correlated with the time of onset(r =-0.348,-0.400,-0.337,-0.369,and P<0.05);The values of MD,AD,RD and onset time showed significant positive correlation(r = 0.650,0.713,0.684,and P < 0.05).4.The lesion area in the hyperacute phase,acute phase and early subacute phase was not matched on MK and MD maps,unmatched occurrence rate: 80%(4/5)in the hyperacute phase group,71.4%(5/7)in the acute phase group,and 71.4%(10/14)in the early subacute group;Most of the lesion area on MK maps was less than that of MD maps and the difference was statistically significant(P<0.05);There was no significant difference in lesion area of MK and MD maps in late subacute phase.5.Ten patients were followed up with T2 WI,the final infarction area of T2 WI was significantly positively correlated with the area of the first MK and MD maps(r =0.979,0.869,and P<0.01),however,the correlation between T2 WI and MK map lesions was more significant than that of T2 WI and MD.The final infarction of 6 patients with T2 WI was basically consistent with the lesion area shown in the first MK map,among them,4 lesion areas of T2 WI were smaller than that of MD,and two were similar to MD maps,it indicated that the infarct areas were not enlarged and had good curative effect;4 patients' lesion areas of T2 WI were larger than that of MK map,1 of which was smaller than that of MD maps,and 3 cases were similar to MD maps,it indicated that the infarction areas were enlarged but not larger than the ischemic areas and the curative effect was stable.Conclusions The parameters of DKI in the early cerebral infarction have the characteristic evolution.The range of each parameter was the largest in the acute phase,indicated that the pathological change of this period is the most serious,it is suggested that DKI can provide more detailed diffusion information related to pathological changes.The changes of diffusion kurtosis parameters were more significant than that of diffusion tensor parameters in various periods,it is shown that DKI is more sensitive and accurate than DTI to describe the changes of microstructure caused by ischemic brain injury.MK can help predict the final infarction and prognosis in addition,therefore,the application of DKI in the process of cerebral infarction has great potential. |
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