The clinical value of olfactory functional magnetic resonance imaging in early diagnosis of Alzheimer's disease

Abstract

Objective To investigate the clinical value of olfactory functional magnetic resonance imaging in early diagnosis of Alzheimer's disease (AD). Methods 43 patients with mild cognitive impairment were selected, in the same period, 49 cases of patients with AD were selected as the AD patients group, and 53 normal populations were selected as the control group.The neuropsychological of all cases were assessed by using MMSE scale, MoCA scale and CDR Scale.Siemens 3.0T MRI machines were used according to event-related design approach for olfactory cortex conducted fMRI scans.The matlab7.0 and SPM8 data preprocessing tools were used to image analysis.The primary olfactory cortex volumes and activation voxels numbers of the three groups were compared.The correlations of activation voxels numbers and primary olfactory cortex volumes and neuropsychological scores were analyzed. Results The primary olfactory cortex volumes of the control group, patients with mild cognitive impairment and AD patients were (3 846±517)mm3, (2 863±367)mm3 and (2 214±283)mm3, respectively, pairwise comparison, the control group>mild cognitive impairment>AD patients, the differences were statistically significant (compared with the control group, t=16.835 and 34.716, compared with mild cognitive impairment group, t=19.753, P mild cognitive impairment>AD patients, the differences were statistically significant (compared with the control group, t=47.916 and 72.954, compared with mild cognitive impairment group, t=37.382, P<0.05). Partial correlation analysis showed that the activation voxels numbers of the three groups were positively correlated with primary olfactory cortex volume, MMSE score and MOCA score (r=0.397, 0.462 and 0.494, all P<0.05). Conclusion Olfactory fMRI in patients with AD might reflect the changes in the entorhinal cortex caused by pathological changes.It could provide clues and information for the early diagnosis of AD. Key words: Alzheimer's disease; Olfactory functional magnetic resonance imaging; Entorhinal cortex; Diagnosis