Signal quality as Achilles’ heel of graph theory in functional magnetic resonance imaging in multiple sclerosis

Background
Graph-theoretical analysis is a novel tool to understand the organisation of the brain.
Objective
Assessing whether altered graph theoretical parameters, as observed in multiple sclerosis (MS), reflect pathology-induced restructuring of the brain's functioning or result from a reduced signal quality in functional MRI (fMRI).
Methods
In a cohort of 49 people with MS and a matched group of 25 healthy subjects (HS), we performed a cognitive evaluation and acquired fMRI. From the fMRI measurement, Pearson correlation-based networks were calculated and graph theoretical parameters reflecting global and local brain organisation were obtained. Additionally, we assessed metrics of scanning quality (signal to noise ratio (SNR)) and fMRI signal quality (temporal SNR and contrast to noise ratio (CNR)).
Results
In accordance with the literature, the network parameters were altered in MS compared to HS. Furthermore, no significant link was found with cognition. Scanning quality (SNR) did not differ between both cohorts. Yet measures of fMRI signal qualitywere significantly different and fully explained the differences observed in GTA parameters.
Conclusion
Our results suggest that differences in network parameters between MS and HS in fMRI do not reflect a functional reorganisation of the brain, but rather occur due to reduced fMRI signal quality.

Publication year:2021

Keywords:magnetic resonance imaging

BOF-keylabel:yes

IOF-keylabel:yes

BOF-publication weight:2

Authors:International

Authors from:Government, Higher Education, Hospital

Accessibility:Open