What does hybrid PET-MRI imaging bring to the study of neurodegenerative pathologies?

The interest of hybrid imaging systems combining positon emission tomography (PET) and magnetic resonance imaging (MRI) is to simultaneously acquire metabolic and molecular images from PET scans, and anatomical and functional images from MRI scans. In order to develop these systems, a number of technological obstacles had to be overcome, primarily related to the detection mode traditionally used in PET machines, which was incompatible with the magnetic field of MRI. The second technological challenge is the MR-based attenuation correction of PET images, when it depends on magnetic properties of tissues, without direct relation to their attenuation coefficient. Integrated PET-MRI has many applications, particularly in brain imaging for the study of neurodegenerative diseases. This technique provides access to simultaneous evaluation of topographical and pathophysiological biomarkers, thus increasing the diagnostic performance of each of the two modalities taken separately. It allows advanced MRI techniques or emerging PET tracers to be cross-validated in the diagnosis of Alzheimer's disease. It also plays a crucial role in a better knowledge of normal and pathological brain function, based on the synergistic effects of both techniques. Hybrid PET-MRI is a novel imaging modality in its own right, opening up new horizons for the study of neurodegenerative pathologies, both in research and in clinical practice. (c) 2021 l'Academie nationale de medecine. Published by Elsevier Masson SAS. All rights reserved.