Research Applications of Positron Emission Tomography/Magnetic Resonance (PET/MR) Imaging in Alzheimer’s Disease (AD)

Abstract

Alzheimer’s disease (AD) is the most common type of neurodegenerative disease and is primarily characterized by progressive cognitive dysfunction and behavioral impairment. It accounts for approximately 50–75% of senile dementia cases. Mild cognitive impairment (MCI) is an intermediate state of cognition, somewhere between normal aging and dementia, and has a high risk of conversion to AD or other types of dementia, with approximately 10–15% of MCI cases converting to AD each year. With the steady increase in life expectancy, the incidence of AD has grown each year, and the number of patients with AD worldwide is projected to reach 130 million by 2050, which will place an immense burden on social development and home care. However, the pathogenesis of AD remains poorly understood, and currently, there is no effective pharmaceutical treatment. Therefore, AD continues to be a key focus of and challenge to research in the field of global medicine. The characteristic pathological changes observed in AD involve senile plaques that are formed by the extracellular deposition of β-amyloid (Aβ), intracellular neurofibrillary tangles (NFTs) that are formed of hyperphosphorylated tau protein, and extensive neuronal loss. The primary imaging techniques currently utilized in AD research include MRI and PET. Structural MRI can show the atrophy of the medial temporal lobe (MTL), which is now considered to be a diagnostic marker of AD, while functional MRI (fMRI) is a valuable tool for exploring the functional changes of the brain and the neurobiological mechanisms of AD. PET, however, is an important imaging technique for the detection of AD-specific brain metabolism and the in vivo assessment of pathological proteins. In this chapter, we will summarize the advances in research regarding the application of fMRI, PET, and PET/MR in the study of AD.