Centrum semiovale

Abstract: PURPOSE: To establish quantitative standards for the directionally averaged water apparent diffusion coefficient (D) and quantitative diffusion anisotropy (A sigma) of normal brains in newborns by using diffusion tensor magnetic resonance (MR) imaging. MATERIALS AND METHODS: Diffusion tensor MR imaging was performed during the first 36 hours of life in 22 newborns (gestational age range, 31-41 weeks). Values of D and A sigma were measured in regions of interest chosen in the cortical gray matter, centrum semiovale, caudate nuclei, lentiform nuclei, thalami, internal capsules, and cerebellar hemispheres. RESULTS: The D values in the gray and white matter in newborns are considerably higher than those in adults. There is a striking correlation between gestational age and D, with D decreasing as gestational age increases. The A sigma values in the white matter in newborns are lower than those in adults. Values of A sigma show statistically significant correlations with gestational age only in the white matte...

Abstract: Diffusion tensor imaging (DTI) has been proposed as a sensitive biomarker of traumatic white matter injury, which could potentially serve as a tool for prognostic assessment and for studying microstructural changes during recovery from traumatic brain injury (TBI). However, there is a lack of longitudinal studies on TBI that follow DTI changes over time and correlate findings with long-term clinical outcome. We performed a prospective longitudinal study of 30 adult patients admitted for subacute rehabilitation following severe traumatic brain injury. DTI and conventional MRI were acquired at mean 8 weeks (5–11 weeks), and repeated in 23 of the patients at mean 12 months (9–15 months) post-trauma. Using a region-of-interest-based approach, DTI parameters were compared to those of healthy matched controls, scanned during the same time period and rescanned with a similar interval as that of patients. At the initial scan, fractional anisotropy was reduced in all the investigated white matter regions in patients compared to controls ( P ≤ 0.01) due to decreased diffusivity parallel ( λ ∥) and increased diffusivity perpendicular ( λ ⊥) to axonal fibre direction. Fractional anisotropy in the cerebral peduncle correlated with ∼ 1 year Glasgow outcome scale score ( r = 0.60, P < 0.001) and in this sample predicted dichotomized outcome with 76% accuracy when taken alone, and with 100% accuracy in combination with clinical evaluation by functional independence measure at the time of the first scan. At follow-up DTI, fractional anisotropy in patients had increased in the internal capsule and in centrum semiovale ( P ≤ 0.01) due to an interval increase of λ ∥ with unchanged λ ⊥. In these regions, fractional anisotropy and λ ∥ reached normal or supranormal levels, primarily in patients with favourable outcome. In the cerebral peduncle and in corpus callosum, λ ∥ and λ ⊥ both increased during the scan interval and, particularly in patients with unfavourable outcome, fractional anisotropy remained depressed. No significant DTI parameter changes over time were found in controls, or in CSF of patients. These findings support that DTI is a clinically relevant biomarker in TBI, which may have prognostic value and also might serve as a tool for revealing changes in the neural tissue during recovery.

Abstract: Background and Purpose We undertook this study to evaluate the frequency and risk factors of white matter hyperintensities seen on T2-weighted MR imaging. We examined cohorts of neurologically nondiseased elderly subjects participating in a general-community study, the Helsinki (Finland) Aging Brain Study. Cohorts of consecutive subjects aged 55, 60, 65, 70, 75, 80, and 85 years (n=20, 18, 20, 18, 19, 18, and 15, respectively; total, n=128) were divided into a young-old (age <75 years, n=76) group and an old-old (age ≥75 years, n=52) group. Methods Frequency of hyperintensities seen on T2-weighted axial and coronal MR images (0.02 T) was rated using a four-point scale in periventricular and centrum semiovale areas. Results The majority of the subjects showed only mild white matter hyperintensities, which were more frequent in the periventricular areas. Age was the most important factor to explain the presence of hyperintensities. A logistic regression analysis related periventricular hyperintensities in t...

Abstract: Objectives: Increased white matter (WM) lesions on magnetic resonance imaging (MRI) are associated with worse cognitive function in older people. Enlarged perivascular spaces (EPVS) commonly coexist with and share some risk factors for WM lesions but are not quantified in published scales. It is not known whether the extent of EPVS is also associated with cognitive function. We tested the hypothesis that more EPVS would be associated with worse cognitive function. Methods: Ninety seven healthy men (65–70 years), not on medications, underwent MRI scanning and comprehensive cognitive testing. EPVS were quantified in both the basal ganglia/centrum semiovale and the hippocampus, and WM lesions were measured. Results: Scores on published WM lesion rating scales intercorrelated highly significantly and positively (ρ = 0.61 to 0.91, p<0.0001). A summary (WML) factor derived from principal components analysis of the WM scales correlated with EPVS in the basal ganglia/centrum semiovale (ρ = 0.48, p<0.0001) but not in the hippocampus. EPVS scores in the basal ganglia/centrum semiovale correlated significantly and negatively with non-verbal reasoning (ρ = –0.21, p = 0.038) and general visuospatial ability (ρ = –0.22, p = 0.032), adjusted for prior intelligence. The WML factor correlated significantly and negatively with visuospatial ability, as previously reported, and showed an unexpected positive correlation with one test of verbal memory (list-learning). Conclusions: These findings suggest that increased EPVS are correlated with worse cognitive function. Future studies examining changes in WM with ageing should consider incorporating measures of EPVS and examine the sequence of EPVS and WM lesion development over time. More work is needed to develop valid and reliable measures of EPVS.