In the Memory Unit, we perform imaging studies focused on Alzheimer’s disease and other related disorders that allow us to correlate structural, functional or even metabolic brain measures with several cerebrospinal fluid (CSF), clinical or neuropsychologic biomarkers. The neuroimage research line, led by Dr. Fortea, is funded by 3 active grants from the Spanish Government that focus on brain structure (MRI) and metabolism (PET-FDG) and the correlation of these parameters with clinical variables, CSF biomarkers and other imaging biomarkers (PET-Florbetapir). This internationally recognized research line has published multiple scientific papers in high-impact journals (Fortea et al. Ann Neurol 2014, Alcolea et al. Neurobiol Aging 2015, Pegueroles et al. Alzheimer’s Dement. 2017 among others).
These studies are made possible due to our active collaboration with the Nuclear Department at Hospital de Sant Pau, led by Dr Ignasi Carrió and Dr Valle Camacho, and the Radiology Department at Hospital del Mar, led by Dr. Sofía González Ortiz and Dr. Santiago Medrano.
Below is a summary of the main neuroimaging techniques used in our laboratory and NeuroImaging Core.
Structural Magnetic Resonance Imaging (MRI)
Recent studies in Alzheimer’s disease have reported that differences in brain structure can be detected in asymptomatic subjects several years prior to the appearance of any clinical symptom. Consequently, our group is focused on studying how and when these changes occur. Structural MRI, one of the most widely used tools to study the human brain, takes advantage of the different physical properties of the various brain tissues to create an image of brain morphology. With the appropriate software (Freesurfer, https://surfer.nmr.mgh.harvard.edu/) we can observe areas of degeneration (atrophy) or alterations in the different tissues that make up the brain. Moreover, by performing MRI on the same subject biannually, we can study how atrophy progresses over time and assess how the cerebral cortex evolves in relation to other biomarkers.
Alterations in the connectivity between different brain regions can precede the cognitive changes in neurodegenerative diseases such as Alzheimer’s or frontotemporal dementia. The diffusion MRI technique allows the indirect visualization of neuronal projections that connect the brain regions by quantifying the movement of water particles through the brain. Our Neuroimaging Core has an optimized image processing protocol for diffusion MRI that allows quantification of not only white matter microstructure, but also changes in the gray matter of the brain.
It has been demonstrated that changes in brain networks in Alzheimer’s disease could precede the appearance of clinical symptoms by more than a decade. Functional MRI has become an essential tool to understand how our brain works. This technique allows visualization of the activation and de-activation of specific brain regions by detecting blood flow changes in the brain. Regions that form part of the same network will be activated concomitantly. By analyzing these networks using protocols from the field of telecommunications valuable information can be extracted about how our brain works.
Positron Emission Tomography
The first signs of amyloid deposition in the brain can manifest a decade before the appearance of the first clinical symptoms. The Positron Emission Tomography (PET) is a non-invasive technique that allows the study of metabolic and biochemical properties of the brain. When combined with an amyloid tracer such as Pittsburgh Compound B or florbetapir, PET can be used to study the deposition of the amyloid protein in the brain. Additionally, a tau tracer such as Flortaucipir can be used to study the presence of tau inclusions, a core pathological feature of the Alzheimer’s disease brain. Alternatively, PET can be combined with a fludeoxyglucose tracer, which allows the study of brain metabolism and can determine which brain areas are still functional and which ones are damaged.