18F-florbetapir PET/MRI for quantitatively monitoring myelin loss and recovery in patients with multiple sclerosis: A longitudinal study

Background: Amyloid positron emission tomography (PET) can measure in-vivo demyelination in patients with multiple sclerosis (MS). However, the value of F-18-labeled amyloid PET tracer,F-18-florbetapir in the longitudinal study for monitoring myelin loss and recovery has not been confirmed. Methods: From March 2019 to September 2020, twenty-three patients with MS and nine healthy controls (HCs) underwent a hybrid PET/MRI at baseline and expanded disability status scale (EDSS) assessment, and eight of 23 patients further underwent follow-up PET/MRI. The distribution volume ratio (DVR) and standard uptake value ratio (SUVR) of F-18-florbetapir in damaged white matter (DWM) and normal-appearance white matter (NAWM) were obtained from dynamic and static PET acquisition. Diffusion tensor imaging-derived parameters were also calculated. Data were expressed as mean +/- standard deviation with 99% confidence interval (99%CI). Finding: The mean DVR (1.08 +/- 0.12, 99%CI [1.02 1.14]) but not the mean SUVR of DWM lesions was lower than that of NAWM in patients with MS (1.25 +/- 0.10, 99%CI [1.20 1.31]) and HCs (1.29 +/- 0.08, 99%CI [1.23 1.36]). A trend toward lower mean fractional anisotropy (374.95 +/- 45.30 vs. 419.07 +/- 4.83) and higher mean radial diffusivity (0.45 +/- 0.05 vs. 0.40 +/- 0.01) of NAWM in patients with MS than those in HCs was found. DVR decreased in DWM lesions with higher MD (rho =-0.261, 99%CI [-0.362 -0.144]),higher AD (rho = 0.200, 99%CI [-0.318 -0.070])and higher RD (rho =-0.198, 99%CI [-0.313 -0.075]). Patients' EDSS scores were reduced (B = 0.04, 99%CI [-0.005 0.084]) with decreased index of global demyelination in the longitudinal study. Interpretation: Our exploratory study suggests that dynamic F-18-florbetapir PET/MRI may be a very promising tool for quantitatively monitoring myelin loss and recovery in patients with MS. (C) 2021 The Authors. Published by Elsevier Ltd.

Automated summary

The study found that the DVR of DWM lesions were lower in MS patients compared to HCs, while NAWM in MS patients had lower FA and higher RD. The decrease in DVR was associated with higher MD, AD, and RD in DWM lesions. Patients' EDSS scores decreased with a reduction in the index of global demyelination.