Myelin imaging measures as predictors of cognitive impairment in MS patients: A hybrid PET-MRI study

Abstract

Background: Cognitive impairment is one of the concerns of Multiple Sclerosis (MS) and has been related to myelin loss. Different neuroimaging methods have been used to quantify myelin and relate it to cognitive dysfunctions, among them Magnetization Transfer Ratio (MTR), Diffusion Tensor Imaging (DTI), and, more recently, Positron Emission Tomography (PET) with C-11-PIB. Objective: To investigate different myelin imaging modalities as predictors of cognitive dysfunction. Methods: Fifty-one MS patients and 24 healthy controls underwent clinical and neuropsychological assessment and MTR, DTI (Axial Diffusion-AD and Fractional Anisotropy-FA maps), and C-11-PIB PET images in a PET/MR hybrid system. Results: MTR and DTI(FA) differed in patients with or without cognitive impairment. There was an association of DTI(FA) and DTI(AD) with cognition and psychomotor speed for progressive MS, and of C-11-PIB uptake and MTR for relapsing-remitting MS. MTR in the Thalamus (beta=-0.51, p=0.021) and Corpus Callosum (beta=-0.24, p=0.033) were predictive of cognitive impairment. DTI-FA in the Caudate (beta=-26.93, p=0.006) presented abnormal predictive result. Conclusion: Lower myelin content by C-11-PIB uptake was associated with worse cognitive status. MTR was predictive of cognitive impairment in MS.