A Comparative Study Of Structural And Functional Changes Of The Parahippocampal Gyrus In Alzheimer’s Disease Based On Multimodal MRI And PET/CT

Objective:To study the correlation between parameters of parahippocampal gyrus in multimodal MRI and PET/CT and the severity of Alzheimer’s Disease（AD）,and to explore its value in the evaluation of structural and functional changes of parahippocampal gyrus in AD patients.Methods:From October 2020 to December 2022,eligible AD patients and control group without neuropsychiatric diseases in the First Hospital of Hebei Medical University were collected for ¹⁸F-FDG PET/CT and MRI scanning.A total of 8 subjects were included,including 4 cases in the AD group and 4 cases in the control group.Each participant was tested with Mini-Mental State Examination（MMSE）and Montreal Cognitive Assessment（MoCA）.The volume,apparent diffusion coefficient（ADC）value,cerebral blood flow and standardized uptake value ratio（SUVR）of parahippocampal gyrus were measured.The visual assessment scale of medial temporal lobe atrophy and Fazekas grading were evaluated.To study the correlation between the above MRI and PET/CT parameters and MMSE and MoCA scores.Results:Compared with the control group,AD patients had lower MMSE and MoCA scores,higher ADC values of bilateral parahippocampal gyrus and Fazekas grading and lower volume and SUVR of bilateral parahippocampal gyrus.MMSE score and MoCA score were negatively correlated with ADC value of left parahippocampal gyrus and Fazekas grade,and positively correlated with volume and SUVR of left parahippocampal gyrus.MMSE score and MoCA score were negatively correlated with ADC value of right parahippocampal gyrus and Fazekas grade,positively correlated with SUVR of right parahippocampal gyrus,and MMSE score was positively correlated with volume of right parahippocampal gyrus.Conclusions:The change in volume,ADC value and SUVR of the parahippocampal gyrus can be used as quantitative imaging indicators to assess the course of AD,and Fazekas grading can be used as an auxiliary diagnostic indicator of AD.The application of multimodal MRI and PET/CT to evaluate the correlation between the structural and functional changes of the parahippocampal gyrus can more accurately assess the course of AD,in order to detect AD patients as soon as possible and prompt clinical intervention.