Diffusion Tensor Imaging And ~1HMR Spectroscopy Studies In Patients With Diabetes Mellitus

Objective: To investigate the change and the correlation among FA, ADC values, metabolic index and the cognitive impairment in patients with diabetes mellitus (DM) by using the diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS).Materials and Methods:Forty-one patients (age 45-70y) with metabolic syndrome were studied and divided into two groups in which twenty-three patients with diabetes mellitus and eighteen patients without diabetes mellitus but with hypertension and lipid metabolism disorders. Ten healthy control subjects were included in the study. All subjects were studied with conventional MR imaging, MRS and DTI by using the same imaging parameters. Choline(Cho), creatine(Cr), N-acetylaspartate(NAA), FA and ADC values were detected in the centrum semiovale. To compare 1 H-MRS and DTI findings, a supraventricular volume of interest of 8×8×2 cm~3 (64 voxels) MRS peak areas were matched to the results of DTI for the corresponding volume. Statistical analysis was performed by SPSS 11.5 software.Result:1. The assessment of cognitive function: The mini-mental state examination (MMSE) in diabetic group and non-diabetic group were both lower than that in control group (P < 0.01,both). The difference of MMSE in diabetic and non-diabetic group was no statistically significant (P>0.05). The difference of incidence rates of cognitive impairment in diabetic group and in non-diabetic group was statistically significant (χ~2= 3.903,P = 0.048<0.05).2. The conventional MR imaging of brain: The study population consisted of 41 patients (23 with DM, 18 without DM) and 10 healthy controls. Patients in DM group showed lacunar infarct(n=16), brain atrophy (n=13),leukoaraiosis(n=12)and no brain MRI abnormalities(n=6). Patients in non-DM group showed lacunar infarct(n=8), brain atrophy (n=3),leukoaraiosis(n=3)and no brain MRI abnormalities(n=7). The number of patients with brain atrophy and leukoareosis in diabetic group were obviously higher than those in non-diabetic group (P<0.01,both), and the difference of incidence rates of lacunar infarct between two groups was not statistically significant(P >0.05).3. DTI and MRS in diabetic group, nondiabetic group and control group: Compared with control group, mean FA values, NAA/Cr and NAA/Cho values in centrum semiovale decreased, and mean ADC values increased in both diabetic group and nondiabetic group.(P<0.01,all) .Cho/Cr values increased than that in control group, but the difference were not statistically significant (P>0.05). Mean FA values in centrum semiovale in diabetic group decreased than that in non-diabetic group (P<0.01); Mean ADC values,Cho/Cr increased ,and NAA/Cr , NAA/Cho decreased than that in nondiabetic group, but the difference were not statistically significant (P>0.05, all). There are 5 patients had mild cognitive impairment in 13 patients whose brain MRI had no abnormalities,and DTI showed the FA values were reduced compared to the heavy controls.4. The relationships of DTI and MRS in centrum semiovale both in diabetic group and non-diabetic group: In diabetic group, the ADC values in centrum semiovale was correlated to NAA/Cho and Cho/Cr (r=-0.499 and r=0.499; P<0.01, both), but the FA was not correlated to NAA/Cr, NAA/Cho and Cho/Cr (P>0.05, all). In non-diabetic group, however, the FA values was correlated to NAA/Cho and Cho/Cr (r=0.603 and r=-0.646; P<0.01, both) ,but the ADC was not correlated to NAA/Cr,NAA/Cho and Cho/C (P>0.05, all).5. The relationships between MMSE and DTI and MRS in diabetic group: MMSE were correlated to FA values (r=0.701; P<0.01), but not correlated to ADC values, NAA/Cr values and Cho/Cr values in diabetic group.Conclusion:1. The MMSE in patients with metabolic syndrome was lower than the heathy control,however, there no significant difference between patients with and without DM. The difference of incidence rates of cognitive impairment in diabetic group were significantly higher than in non-diabetic group .2. Patients with DM had more cerebrovascular disease, such as lacunar infarct, brain atrophy and leukoaraiosis.3. The difference of DTI and MRS between diabetic and controls indicated that there are variation of cerebral white matter fiber bundles and cerebral metabolite in diabetics.4.The DTI/MRS United Technology used in our study showed NAA/Cho and Cho/Cr were correlated with FA and ADC values respectively in different groups, which indicated axonal loss or dysfunction, or both, accounting for at least part of the DTI abnormalities found in patients.5. MMSE showed strong correlation to DTI in diabetic brains. It provides evidence that DTI identifies axonal disruption in white matter tracts and detects cognitive impairment in DM patients even with no abnormalities brain MRI.