Study Of Key Parts In Patients With Vascular Cognitive Impairment No Dementia Based On MRS And DTI

Objective The functional magnetic resonance imaging technologies,including magnetic resonance spectroscopy(MRS)and diffusion tensor imaging(DTI),are used to compare the difference in metabolic parameters and molecular diffusion parameters of key parts in brain between patients with vascular cognitive impairment no dementia(VCIND)and healthy volunteers,quantitatively analyze the correlation between DTI and MRS parameters and MoCA in patients with VCIND,and explore the key parts that are changed in early stage of cognitive impairment caused by cerebral small vessel diseases and summarize the early imaging manifestations.Method This study included 38 VCIND patients who were selected from the our hospital from November,2015 to December,2017 and 44 healthy volunteers.The patients of VCIND group had a medical history of mild cognitive decline in different degrees and were definitely diagnosed with cognitive impairment through neuropsychological test.The diagnosis of VCIND was made by experienced neurologists based on related neuropsychological assessment scale and diagnostic criteria.All subjects included in groups,including the normal control group,not only received a variety of neuropsychological assessments,such as Montreal Cognitive Assessment(MoCA)and Clinical Dementia Rating(CDR),but also received routine MRI examination and functional sequence examination of MRS and DTI.The blind tests were used to measure the MRS and DTI parameters in bilateral frontal lobe,temporal lobe,thalamus,hippocampus and basal ganglia,with the measurement indexes including N-acetyl aspositionate(NAA)value,choline(Cho)value,creatine(Cr)value and NAA/Cr and Cho/Cr ratios in MRS and FA value and ADC value in DTI.The parameter values of dominant hemisphere were compared between groups,and the correlation between NAA,Cho,NAA/Cr,Cho/Cr,FA,ADC of the dominant side of VCIND patients and MoCA score was analyzed as well.Results2.1 There were 38 patients in VCIND group,including 18 females and 20 males,with an average age of(67.4±7.4).In the normal control group,there were 44 subjects,including 20 females and 24 males,with an average age of(61.6±6.6).The average MoCA scores of VCIND group(20.5±2.6)were lower than those of normal control group(28.4±1.7),which indicated that the difference between groups had statistical significance(P<0.05).2.2 Compared with normal control group,the NAA value of temporal lobe,hippocampus and thalamus and the NAA/Cr ratio of frontal lobe,hippocampus,thalamus in dominant hemisphere reduced in VCIND group,which indicated that the difference had statistical significance(P<0.05).There was no statistical difference in Cho value and Cho/Cr ratio of dominant hemisphere between two groups(P>0.05);and there was no statistical difference in metabolic parameter values of all parts between dominant and nondominant hemispheres in VCIND group(P>0.05).2.3 Compared with normal control group,the FA value of frontal lobe,hippocampus,temporal lobe and basal ganglia in dominant hemisphere reduced and the ADC value of frontal lobe,hippocampus,temporal lobe,basal ganglia and thalamus increased in VCIND group,which indicated that the difference had statistical significance(P<0.05).There was no statistical difference in FA value of dominant and nondominant hemispheres between two groups in thalamus(P>0.05);and there was no statistical difference in metabolic parameter values of all parts between dominant and nondominant hemispheres in VCIND group(P>0.05).2.4 In VCIND group,FA value in the dominant frontal lobe was positively correlated with MoCA score(r=0.763),while ADC value was negatively correlated with MoCA score(r=-0.706),with statistically significant difference(P<0.05).Conclusion1.Based on MRS,the extensive cerebreal metabolic abnormality was observed in VCIND patients,but VCIND was closely related to the metabolic changes of frontal lobe,temporal lobe,hippocampus,and thalamus in dominant hemisphere.NAA and NAA/Cr were sensitive indexes to detect VCIND and the latter was more stable.2.Based on DTI,VCIND patients had the structural lesion of cognitive structure-related fiber in a variety of key parts in frontal lobe,temporal lobe,hippocampus,and basal ganglia with significant changes in FA and ADC,of which the lesion was the most obvious in frontal lobe.3.MRS and DTI combined with routine brain scanning could provide semiquantitative imaging value for the early diagnosis of VCIND.