Multimodal Noninvasive Imaging Strategies for Clinically Monitoring Degenerative Disorders of the Brain

Abstract

Magnetic resonance imaging (MRI) is a valuable tool in a clinical environment for noninvasive monitoring and assessment of neurodegenerative disorders, an umbrella term for diseases causing neural degeneration. Different MRI modalities provide information about underlying neuropathology from different perspectives. Structural MRI (sMRI) is sensitive towards anatomical alterations and assesses neural degeneration-induced tissue atrophy. In addition to volumetric and cortical thickness variations, several quantitative assessments and grading systems are available to calculate disease severity using MRI scans. Furthermore, functional MRI (fMRI) indirectly measures neurotransmission in the functional brain networks and shows differential regional activation in the neurodegenerative brain. In contrast, diffusion tensor imaging (DTI) furnishes the mapping of white matter tracts and anatomical connectivity in the brain networks by measuring aqueous diffusion along the tract scaffold. On the other hand, arterial spin labeling (ASL) is a vascular perfusion MRI technique and safe substitute for invasive FDG-PET that needs vein catheter resection with radioactive tracer administration. Like fMRI, the signals from DTI and ASL show differential anatomical and perfusion patterns in neurodegenerative diseases. Large-scale clinical trials are now enabling precise quantification, making sMRI, fMRI, DTI, and ASL much more reliable in clinical settings.