OBJECTIVES: Although white matter hyperintensities (WMHs) are quite commonly found incidentally, their aetiology, structural characteristics, and functional consequences are not entirely known. The purpose of this study was to quantify WMHs in a sample of young, neurologically asymptomatic adults and evaluate the structural and functional correlations of lesion load with changes in brain volume, diffusivity, and functional connectivity. METHODS: MRI brain scan using multimodal protocol was performed in 60 neurologically asymptomatic volunteers (21 men, 39 women, mean age 34.5 years). WMHs were manually segmented in 3D FLAIR images and counted automatically. The number and volume of WMHs were correlated with brain volume, resting-state functional MRI (rs-fMRI), and diffusion tensor imaging (DTI) data. Diffusion parameters measured within WMHs and normally appearing white matter (NAWM) were compared. RESULTS: At least 1 lesion was found in 40 (67%) subjects, median incidence was 1 lesion (interquartile range [IQR] = 4.5), and median volume was 86.82 (IQR = 227.23) mm3. Neither number nor volume of WMHs correlated significantly with total brain volume or volumes of white and grey matter. Mean diffusivity values within WMHs were significantly higher compared with those for NAWM, but none of the diffusion parameters of NAWM were significantly correlated with WMH load. Both the number and volume of WMHs were correlated with the changes of functional connectivity between several regions of the brain, mostly decreased connectivity of the cerebellum. CONCLUSIONS: WMHs are commonly found even in young, neurologically asymptomatic adults. Their presence is not associated with brain atrophy or global changes of diffusivity, but the increasing number and volume of these lesions correlate with changes of brain connectivity, and especially that of the cerebellum. KEY POINTS: • White matter hyperintensities (WMHs) are commonly found in young, neurologically asymptomatic adults. • The presence of WMHs is not associated with brain atrophy or global changes of white matter diffusivity. • The increasing number and volume of WMHs correlate with changes of brain connectivity, and especially with that of the cerebellum.

• Klíčová slova
• Diffusion tensor imaging, Functional magnetic resonance imaging, Healthy volunteers, White matter,
• MeSH
• asymptomatické nemoci MeSH
• bílá hmota patologie   MeSH
• difuzní magnetická rezonance metody   MeSH
• dospělí MeSH
• leukoaraióza diagnóza   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• šedá hmota patologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: To compare clinical and MRI parameters between patients with clinically isolated syndrome and those converting to clinically definite multiple sclerosis within 2 years, to identify volumetric MRI predictors of this conversion and to assess effect of early relapses. METHODS: The SET study comprised 220 patients with clinically isolated syndrome treated with interferon beta (mean age, 29 years; Expanded Disability Status Scale, 1.5). Three patients with missing data were excluded from the analysis. Physical disability, time to clinically definite multiple sclerosis and volumetric MRI data were recorded for 2 years. RESULTS: Patients reaching clinically definite multiple sclerosis showed impaired recovery of neurological function, faster decrease in corpus callosum cross-sectional area, higher T2 lesion volume and more contrast-enhancing lesions. Six-month decrease in corpus callosum cross-sectional area (≥ 1%) and baseline T2 lesion volume (≥ 5 cm(3)) predicted clinically definite multiple sclerosis within 2 years (hazard ratios 2.5 and 1.8, respectively). Of 22 patients fulfilling both predictive criteria, 83% reached clinically definite multiple sclerosis (hazard ratio 6.5). More relapses were associated with poorer recovery of neurological function and accelerated brain atrophy. CONCLUSIONS: Neurological impairment is more permanent, brain atrophy is accelerated and focal inflammatory activity is greater in patients converting to clinically definite multiple sclerosis. Six-month corpus callosum atrophy and baseline T2 lesion volume jointly help predict individual risk of clinically definite multiple sclerosis. Early relapses contribute to permanent damage of the central nervous system.

• MeSH
• corpus callosum patologie   MeSH
• demyelinizační nemoci diagnóza   farmakoterapie   MeSH
• dospělí MeSH
• interferon beta terapeutické užití   MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• longitudinální studie MeSH
• magnetická rezonanční tomografie metody   MeSH
• prediktivní hodnota testů MeSH
• progrese nemoci MeSH
• proporcionální rizikové modely MeSH
• recidiva MeSH
• roztroušená skleróza diagnóza   patologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• interferon beta MeSH