Frequency-Dependent Relationship Between Resting-State fMRI and Glucose Metabolism in the Elderly.

Fangyang Jiao,Shenxun Shi,Hui Su,Chuantao Zuo,Jingjie Ge,Yu-Feng Zang,Zhongzhan Gao,Ping Wu,Chengfeng Jiang,Kuangyu Shi,Yihui Guan,Xize Jia

doi:10.3389/fneur.2019.00566

Abstract

Both glucose metabolism and resting-state fMRI (RS-fMRI) signal reflect hemodynamic features. The objective of this study was to investigate their relationship in the resting-state in healthy elderly participants (n = 18). For RS-fMRI signal, regional homogeneity (ReHo), amplitude of low frequency fluctuations (ALFF), fractional ALFF (fALFF), and degree of centrality (DC) maps were generated in multiple frequency bands. Glucose uptake was acquired with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). Linear correlation of each pair of the FDG-PET and RS-fMRI metrics was explored both in across-voxel way and in across-subject way. We found a significant across-voxel correlation between the FDG-PET and BOLD-fMRI metrics. However, only a small portion of voxels showed significant across-subject correlation between FDG-PET and BOLD-fMRI metrics. All these results were similar across all frequency bands of RS-fMRI data. The current findings indicate that FDG-PET and RS-fMRI metrics share similar spatial pattern (significant across-voxel correlation) but have different underlying physiological importance (non-significant across-subject correlation). Specifically, FDG-PET measures the mean glucose metabolism over tens of minutes, while RS-fMRI measures the dynamic characteristics. The combination of FDG-PET and RS-fMRI provides complementary information to reveal the underlying mechanisms of the brain activity and may enable more comprehensive interpretation of clinical PET-fMRI studies. Future studies would attempt to reduce the artifacts of RS-fMRI and to analyze the dynamic feature of PET signal.

Highlights

Blood-oxygenation-level dependent (BOLD) resting-state functional magnetic resonance imaging (RS-fMRI) and positron emission tomography (PET) are two functional neuroimaging techniques that have been demonstrated to hold significant value for diagnosis of human function and have elucidated neurobiological processes [1,2,3]
The current study aimed to investigate the relationship between relative glucose uptake assessed by fluorodeoxyglucose positron emission tomography (FDG-PET) and four metrics derived from resting-state BOLD-fMRI, i.e., amplitude of low frequency fluctuations (ALFF), fractional amplitude of low frequency fluctuations, regional homogeneity (ReHo), and degree of centrality (DC), of a few sub-frequency bands
Our findings of the overall significant across-voxel correlation mean that the spatial pattern of regional glucose metabolism was similar to that of RS-fMRI metrics

Summary

Introduction

Blood-oxygenation-level dependent (BOLD) resting-state functional magnetic resonance imaging (RS-fMRI) and positron emission tomography (PET) are two functional neuroimaging techniques that have been demonstrated to hold significant value for diagnosis of human function and have elucidated neurobiological processes [1,2,3]. Several studies have investigated the relationship between glucose metabolism and BOLD signal activity using combined PET/fMRI imaging techniques [8,9,10]. Aiello and colleagues investigated the correlation between regional glucose metabolism and regional RS-fMRI metrics in two ways, i.e., subjectwise across-voxel correlation and voxel-wise across-subject correlation [10]. They found that the subject-wise across-voxel correlation showed significant similar spatial pattern between glucose metabolism and RS-fMRI metrics, only a few brain regions showed significant voxel-wise across-subject correlation [10]

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Conclusion