Author Of 1 Presentation
P0656 - Unraveling deep grey matter atrophy, iron and myelin changes in Multiple Sclerosis (ID 1287)
Modifications of magnetic susceptibility, seemingly reflecting iron accumulation/depletion, have been consistently demonstrated in subcortical gray matter (GM) of MS patients, but some questions remain unanswered regarding the underlying neurobiological processes and their clinical relevance.
to disentangle the contribution of atrophy, iron and myelin changes to deep GM (DGM) damage in MS, simultaneously exploring their relationship with clinical disability through the application of quantitative susceptibility mapping (QSM) and longitudinal relaxation rate (R1) relaxometry.
In this cross-sectional study, 91 patients and 55 healthy controls were imaged with 3T MRI to compute QSMs and R1 maps, from which iron and myelin concentration maps were estimated by applying an external model. Modifications of DGM iron and myelin (mean concentration-dependent from atrophy and total content-independent from atrophy) were investigated at both global and regional levels. Significantly altered MRI features were tested as disability predictors in hierarchical linear regression models.
Compared to controls, MS patients showed reduced thalamic(p<0.001) and increased pallidal(p<0.001) iron concentrations. No differences emerged regarding total myelin or iron content in the basal ganglia, while actual iron depletion was found in the thalamus(p<0.001). At the voxel-based analysis, patients showed increased iron concentration in the basal ganglia(p≤0.001) and reduced iron and myelin local content in thalamic posteromedial regions(p≤0.004), corresponding to reduced iron and myelin content in the pulvinar(p≤0.001) at the subnuclei analysis. Thalamic volume(B=-0.341,p=0.02), iron concentration(B=-0.379,p=0.005) and content(B=-0.406,p=0.009) significantly predicted disability, as well as pulvinar iron(B=-0.415,p=0.003) and myelin(B=-0.406,p=0.02) content, independently of atrophy.
Quantitative MRI suggests an atrophy-related iron increase within the basal ganglia of MS patients, along with an absolute reduction of thalamic iron and myelin, which correlates with disability. Atrophy-independent depletions of thalamic iron and myelin may represent clinically relevant, sensitive markers of subcortical GM damage.