Olfactory Fmri Optimization And Application In Different Types Of Dementia

Objective: Optimize the odor simulation, sequence acquisition time interval, image processing time, to explore the olfactory fMRI application in clinical diagnosis and differential diagnosis of different types of dementia patients.Subjects and Methods:Olfactory fMRI optimization: normal young volunteers were recruited. Olfactory fMRI were conducted and compared three aspects:(1)two different odor stimulation included respiratory gating and breathe freely given;(2)used Multiband(MB) EPI sequence to compare three different repetition time(TR).;(3) stimulation time correction method were used for post-processing. Evaluation included the following: observed the activation of all brain regions; selected the bilateral primary olfactory cortex(POC) as the region of interest(ROI) to calculate the number of activated voxels; extracted BOLD time-signal intensity curve of ROI. Finally, analyzed the results statistically and compared the three means of stimulating-acquisition-image processing synchrony time, to improve the reliability of the olfactory fMRI.Alzheimer’s disease(AD), Parkinson’s disease dementia(PDD), frontotemporal dementia(FTD), vascular dementia(VaD) were recruited. Related neuropsychological ratings, and ApoE ε4 allele and AD7c-NTP were tested. T&T olfactometer were used to receive subjective olfactory score. Olfactory fMRI were conducted. Selected the POC as ROI to calculate the activation. Finally, compared the differences of different dementia patients and evaluated the diagnostic efficacy of subjective and objective olfactory functional examination.Result:Olfactory fMRI optimization:(1)respiratory gating and breathe freely showed no different results;(2)decreases the TR, the activated voxels of POC and information obtained increased significantly;(3)MB-EPI breathe freely after the corrected time was better than before.Application of olfactory fMRI: for AD and PDD two olfactory fMRI showed the adaptation of the vast majority of patients were disappeared, the olfactory dysfunction. for FTD and VaD, most patients olfactory function properly, olfactory fMRI were significantly higher sensitivity and specificity than subjective olfactory scores; for the three atypical AD, the results in patients with PCA showed olfactory function properly, the lvPPA and fv-AD patients showed olfactory dysfunction, which means different types AD may have different pathogenesis and process;Conclusion:Olfactory fMRI optimization: Breathing may not affect the results obviously; decreases TR and correction during data processing could improve the temporal synchronization and get more reliable result.Olfactory fMRI could find AD and PDD olfactory fMRI showed the adaptation of the vast majority of patients were disappeared, the olfactory dysfunction, which were consistent with the pathlogical studies confirmed POC were affected early in the disease, for FTD and VaD, most patients olfactory function properly, suggesting that the olfactory cortex were not involved early, olfactory fMRI were significantly higher sensitivity and specificity than subjective olfactory scores;For the atypical AD, the lvPPA and fv-AD patients showed olfactory dysfunction, the results in patients with PCA showed olfactory function properly, suggesting that atypical AD may have different pathogenesis and process.