Application Of MRI Diffusion Kurtosis Imaging In Mild Cognitive Impairment And Alzheimer’s Disease

ObjectiveAlzheimer’s disease(AD)is a common neurodegenerative disease with insidious onset and slow progression.Its clinical symptoms are mainly manifested as progressive cognitive impairment and behavioral impairment.The early symptoms of the disease are not significant and easy to be confused.Mild Cognitive Impairment(MCI)is considered to be a transitional stage between normal aging and AD.There is only mild cognitive impairment,which has not yet reached the diagnostic criteria for AD.Early recognition of MCI,AD and monitoring of the disease are critical to the treatment and prognosis of patients.Diffusion Kurtosis Imaging(DKI),as a new imaging technique based on the diffusion of non-Gaussian water molecules,has been widely used in the study of neurological diseases.But there is less research on neurodegenerative diseases.This study used DKI technology to scan the brain tissues of AD patients,MCI patients,and normal controls and quantitatively analyze their various parameter maps,aiming to explore the differences in the microstructure of the three groups of brains and evaluate the effects of DKI on AD patients,MCI patients,and diagnostic power of normal controls.Material and MethodsThe patients in the neurology clinic and inpatient department of the Second Affiliated Hospital of Dalian Medical University were collected,and the patients were divided into AD group,MCI group,and normal control group,with 20 patients in each group after sample size calculation.Mini-mental state examination(MMSE),Activity of Daily Living(ADL),and Clinical Demetia Rating(CDR)were used for neuropsychological assessment.Use the Siemens MAGNETOM Skyra 3.0T magnetic resonance scanner to perform magnetic resonance scanning to obtain the original DKI image.The original image is processed by the DKE software to obtain DKI and DTI related parameter maps.Use MRIcron software to measure bilateral frontal lobe subcortical white matter(WM),parietal lobe-WM,temporal lobe-WM,occipital lobe-WM,precuneus-WM,centrum semiovale,corona radiate,corpus callosum genu,corpus callosum splenium,internal capsule posterior limb,lentiform nucleus and the parameter values of the hippocampus.SPSS 23.0 statistical analysis software was used to perform statistical analysis on the measurement data.The measurement data are expressed in the form of mean ± standard deviation(x ± s),and P<0.05 indicates that the difference is statistically significant.The graph values of DKI parameters of each part of the three groups were tested for normal distribution and homogeneity of variance.Statistical analysis was performed by single factor analysis of variance,and multiple comparisons were performed by LSD method.The area under the curve(AUC)of the receiver operating curve(ROC)was used to evaluate the diagnostic efficacy of each parameter value of DKI.Results1.Compared with the normal control group,the AD group had significantly higher MD and Dr parameter values in the frontal lobe-WM,parietal lobe-WM,occipital lobe-WM,temporal lobe-WM,precuneus-WM,centrum semiovale,corpus callosum genu and hippocampus.The MD and Da parameters of the corona radiate,internal capsule posterior limb and the corpus callosum splenium were significantly increased.The Da parameters of the precuneus-WM,lentiform nucleus and hippocampus increased significantly.And the FA parameters of the temporal lobe-WM,centrum semiovale and hippocampus decreased significantly(P<0.05)Compared with the MCI group,the AD group had significantly higher MD and Dr parameter values in the parietal lobe-WM,occipital lobe-WM,temporal lobe-WM,precuneus-WM,centrum semiovale,corpus callosum genu and hippocampus.The MD parameters of the frontal lobe-WM,corona radiate,internal capsule posterior limb and corpus callosum splenium are significantly increased.The values of Da parameters of the precuneus-WM,internal capsule posterior limb,corpus callosum splenium and the hippocampus increased significantly,and the FA parameter values of the centrum semiovale decreased significantly(P<0.05).Compared with the normal control group,the MD and Da parameters of the precuneus-WM were significantly increased in the MCI group,the Da parameters of the corpus callosum genu was significantly increased,the hippocampus Dr parameters were significantly increased,and the temporal lobe-WM FA parameters was significantly decreased(P<0.05).2.Compared with the control group,the AD group had significantly lower MK and Kr parameter values in frontal lobe-WM,temporal lobe-WM,precuneus-WM,corpus callosum genu and hippocampus.And MK parameter values in centrum semiovale,corona radiate,internal capsule posterior limb,and corpus callosum splenium significantly reduced.The precuneus-WM,corona radiate and hippocampus Ka parameter values were significantly reduced,and the parietal lobe-WM,temporal lobe-WM,centrum semiovale and hippocampus FAK parameter values were significantly reduced(P<0.05).Compared with the MCI group,the AD group had significantly lower MK and Kr parameter values in the temporal lobe-WM,precuneus-WM,corpus callosum genu and hippocampus.The MK parameter values of frontal lobe-WM,centrum semiovale,corona radiate,internal capsule posterior limb and corpus callosum splenium are significantly reduced.The Ka parameters of the precuneus-WM and hippocampus were significantly reduced,and the FAK parameters of the hippocampus were significantly reduced(P<0.05).Compared with the normal control group,in the MCI group,the temporal lobe-WM and hippocampus MK,Kr and FAK parameters were significantly reduced,and the corpus callosum genu and corpus callosum splenium MK parameter values were significantly reduced(P<0.05).3.ROC analysis showed that the hippocampus MK parameter map was the best distinguishing parameter map between the AD group and the control group,and the AUC was 0.97.The MK parameter maps of the hippocampus and temporal lobe-WM are the best parameter maps for distinguishing the AD group from the MCI group,and their AUC are 0.91 and 0.90,respectively.The best distinguishing parameter map between MCI and normal control group is the hippocampus MK parameter map,with AUC of 0.82.ConclusionsThe hippocampus MK parameter map helps to distinguish AD patients,MCI patients and normal controls.As an emerging imaging technology based on the diffusion of non-Gaussian water molecules,DKI can assess the true microstructure changes of brain tissue to a certain extent,and contribute to the development of AD and MCI imaging markers.