Gray matter microglial activation in relapsing vs progressive MS: A [F-18]PBR06-PET study

Area of Science:

• Neuroimaging
• Radiochemistry
• Neurology

Background:

• Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system.
• Microglial activation is a key pathological feature in MS, contributing to neurodegeneration.
• Assessing microglial activation non-invasively is crucial for understanding MS progression and evaluating therapeutic strategies.

Purpose of the Study:

• To evaluate the utility of [F-18]PBR06-PET for quantifying microglial activation in the cerebral gray matter of MS patients.
• To correlate PET findings with clinical disability and brain atrophy measures.

Main Methods:

• 12 MS patients (7 relapsing-remitting, 5 secondary progressive) and 5 healthy controls underwent [F-18]PBR06-PET and 3T MRI.
• PET data were analyzed for standardized uptake value ratios (SUVRs) in segmented gray matter regions.
• Statistical parametric mapping (SPM) was used for voxel-by-voxel analysis, and brain parenchymal volumes (BPVs) were calculated from MRI.

Main Results:

• Cortical SUVRs were altered in MS patients compared to controls in specific regions.
• Subcortical gray matter SUVR was significantly higher in secondary progressive MS (SPMS) compared to relapsing-remitting MS (RRMS) and healthy controls (HCs).
• Subcortical gray matter SUVR, thalamic SUVR, and putaminal SUVRs positively correlated with Expanded Disability Status Scale (EDSS) scores and timed 25-foot walk (T25FW), and negatively with brain parenchymal volume (BPV).

Conclusions:

• [F-18]PBR06-PET effectively detects widespread microglial activation in the cerebral gray matter of MS patients.
• Increased translocator protein binding in subcortical gray matter is associated with brain atrophy and may be linked to disease progression in MS.
• This imaging modality holds promise for monitoring disease activity and therapeutic response in MS.