[¹⁸F]Florbetapir PET/MR imaging to assess demyelination in multiple sclerosis

Area of Science:

• Neuroimaging
• Radiochemistry
• Neurology

Background:

• Multiple Sclerosis (MS) is a central nervous system disease characterized by demyelination.
• Accurate in-vivo assessment of myelin damage is crucial for MS management.
• Conventional MRI detects lesions but may not fully capture diffuse white matter changes.

Purpose of the Study:

• To evaluate myelin changes in the central nervous system of MS patients using hybrid [18F]florbetapir Positron Emission Tomography-Magnetic Resonance Imaging (PET-MR).
• To assess the efficacy of [18F]florbetapir PET imaging in quantifying myelin integrity in MS.
• To compare [18F]florbetapir quantification methods and correlate findings with diffusion tensor imaging and arterial spin labeling.

Main Methods:

• Hybrid [18F]florbetapir PET-MR imaging was performed on 18 relapsing-remitting MS patients and 12 healthy controls.
• [18F]florbetapir binding was quantified using distribution volume ratio (DVR) and standard uptake value (SUV).
• Diffusion tensor imaging and arterial spin labeling were used to assess white matter integrity and cerebral blood flow.

Main Results:

• [18F]florbetapir DVRs were significantly reduced in normal-appearing white matter and T2 lesions compared to controls.
• Myelin damage measures correlated with diffusion metrics (fractional anisotropy, diffusivity) within T2 lesions.
• Cerebral blood flow was reduced in MS white matter areas, and both SUV and DVR effectively discriminated between intact and damaged myelin.

Conclusions:

• [18F]florbetapir PET imaging provides a reliable in-vivo measure of myelin damage in MS patients.
• Demyelination in MS extends beyond conventional MRI-detected lesions to involve normal-appearing white matter.
• [18F]florbetapir PET imaging shows potential for clinical application in managing MS patients, pending longitudinal studies.