Novel Quantitative Approach in Functional and Structural Imaging of Brain in Normal Aging and Neurodegenerative Disorders: Part I. Basic Considerations in PET and MRI

The advent of new neuroimaging modalites in recent decades, along with the increasing prevalence of neurological disorders and a rise in life expectancy over the past century, have collectvely led to the numerous studies trying to explain the anatomical and functonal changes in the human brain following the disease. Other investgators have atempted to fnd the differences in brain structures and functons following normal aging, since understanding age-related changes in the brain might be the frst step to shed light on the pathophysiology of various neurological disorders. In this review, we describe the existng and novel quanttatve approaches of functonal positron emission tomography (PET) imaging. Moreover, we describe novel volumetric studies assessing global and regional volume changes based on advanced computerised techniques of magnetc resonance (MR) analysis such as voxel-based morphometry (VBM) and non-conventonal MR techniques such as diffusion tensor imaging (DTI) and magnetzaton transfer imaging (MTI) followed by a brief review of arterial spin labeling (ASL) imaging.