Author Of 1 Presentation
P0553 - Bundle-specific microstructural alterations in normal appearing white matter of cognitively preserved MS patients using advanced diffusion MRI (ID 1718)
Abstract
Background
Although diffusion tensor imaging (DTI) has been widely used to investigate the microstructure of white matter (WM) in patients with multiple sclerosis (MS), it has several limitations; thus different approaches to model diffusion magnetic resonance imaging (dMRI) data are needed.
Objectives
To investigate alterations in the normal appearing WM (NAWM) of cognitively preserved relapsing remitting MS (RRMS) patients using different modelling of dMRI data.
Methods
We included 39 patients (23 females; mean age: 34±6.7 years; median EDSS: 2, range 0-4; mean disease duration: 7±4.6 years) and 39 age- and gender-matched healthy controls (HC). All subjects underwent cognitive (corsi block, n-back, PASAT) and clinical assessment (EDSS) as well as MRI using a 3 Tesla scanner (Siemens Prisma). We assessed 14 diffusion measures applying DTI, freewater volume fraction (FW) corrected tissue DTI (tDTI) and High Angular Resolution Diffusion Imaging (HARDI). Streamline-based particle filtering tractography was used to extract 33 major WM bundles with a multi-atlas/multi-parameter version of RecoBundle. For every bundle, the average of each diffusion measure was computed for the NAWM section. Groups were compared using t-tests and corrected for multiplicity (FDR, q=0.05).
Results
Patients and controls did not differ in cognitive performance. For each measure, the number of bundles showing a group difference and the effect size are reported: DTI (AD: 3 bundles, effect size r:0.3-0.47; RD: 16, r:0.29-0.44; MD: 16, r:0.29-0.48; FA: 11, r:-0.28- -0.5, MODE: 1,r:-0.29), tDTI (FW: 16, r:0.28-0.56; ADt: 2, r:0.34-0.44; RDt: 15, r:0.28-0.43; MDt: 14, r:0.29-0.41; FAt: 11, r:-0.29- -0.5) and HARDI (apparent fiber density (AFD): 9, r:-0.31- -0.41; generalized fractional anisotropy (GFA): 10, r:-0.29- -0.5; anisotropic power (AP): 10, r:-0.28- -0.51; number of fiber orientations (NuFO): 2, r:0.28-0.29). Differences were most prominent in the right arcuate fasciculus, right inferior fronto-occipital fasciculus, bilateral inferior longitudinal fasciculus, right optic radiation and right superior longitudinal fasciculus.
Conclusions
All approaches used to model dMRI data showed structural alterations of several major WM bundles associated with cognitive functions despite patients’ normal cognitive performance. Hence, diffusion MRI could be used to assess disease progression in early stages of the disease when compensatory mechanisms can still support normal cognitive performance.