http://repub.eur.nl/res/aut/16285/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/40064/ 2013-08-01T00:00:00Z Anatomical alignment in neuroimaging studies is of such importance that considerable effort is put into improving the registration used to establish spatial correspondence. Tract-based spatial statistics (TBSS) is a popular method for comparing diffusion characteristics across subjects. TBSS establishes spatial correspondence using a combination of nonlinear registration and a "skeleton projection" that may break topological consistency of the transformed brain images. We therefore investigated feasibility of replacing the two-stage registration-projection procedure in TBSS with a single, regularized, high-dimensional registration.To optimize registration parameters and to evaluate registration performance in diffusion MRI, we designed an evaluation framework that uses native space probabilistic tractography for 23 white matter tracts, and quantifies tract similarity across subjects in standard space. We optimized parameters for two registration algorithms on two diffusion datasets of different quality. We investigated reproducibility of the evaluation framework, and of the optimized registration algorithms. Next, we compared registration performance of the regularized registration methods and TBSS. Finally, feasibility and effect of incorporating the improved registration in TBSS were evaluated in an example study.The evaluation framework was highly reproducible for both algorithms (R20.993; 0.931). The optimal registration parameters depended on the quality of the dataset in a graded and predictable manner. At optimal parameters, both algorithms outperformed the registration of TBSS, showing feasibility of adopting such approaches in TBSS. This was further confirmed in the example experiment. http://repub.eur.nl/res/pub/39906/ 2013-03-19T00:00:00Z Background: Uric acid has been associated with focal vascular brain disease. However, it is unknown whether uric acid also relates to global brain changes such as brain atrophy. We therefore studied the relation of uric acid to brain atrophy and whether this is accompanied by worse cognitive function. Methods: In 814 persons of the population-based Rotterdam Study (mean age 62.0 years), we studied the relation of uric acid levels to brain tissue atrophy and cognition using linear regression models adjusted for age, sex and putative confounders. Brain atrophy was assessed using automated processing of magnetic resonance imaging. Cognition was assessed using a validated neuropsychological test battery and we computed compound scores of cognitive domains. Results: Higher uric acid levels were associated with white matter atrophy [difference in Z-score of white matter volume per standard deviation increase in uric acid: -0.07 (95% CI: -0.12; -0.01)], but not with gray matter atrophy. This was particularly marked when comparing hyperuricemic to normouricemic persons [Z-score difference: -0.27 (-0.43; -0.11)]. Worse cognition was primarily found in persons with hyperuricemia [-0.28 (-0.48; -0.08)]. Conclusions: Hyperuricemia is related to white matter atrophy and worse cognition. Copyright http://repub.eur.nl/res/pub/37434/ 2012-12-01T00:00:00Z Hippocampal atrophy on MRI and changes in diffusion tensor imaging (DTI) measures of the hippocampus have been reported in patients with Alzheimer's disease. We examined the association between hippocampal volumes, DTI measures of the hippocampus and memory performance in 892 non-demented persons (age. ≥. 55. years) across different age groups. Hippocampal volume was segmented on 3D volumetric MRI scans. The segmentations were co-registered to mean diffusivity (MD) and fractional anisotropy (FA) maps to yield mean hippocampal MD and FA measurements. Higher MD of the hippocampus was associated with impaired verbal memory performance. In all persons ≥. 55. years, a higher MD of the hippocampus was associated with a worse memory performance. Hippocampal volumes were very weakly positively associated with delayed recall and only in persons >. 65. years. FA of the hippocampus was not associated with memory performance. Follow-up studies will be needed to determine whether higher MD of hippocampus at younger ages could be an earlier marker of incident Alzheimer's disease than hippocampal volume. http://repub.eur.nl/res/pub/37438/ 2012-12-01T00:00:00Z In a population-based study of 3962 community-dwelling nondemented elderly we investigated the relation of age, sex, cardiovascular risk factors, and the presence of infarcts with cerebellar volume, and its interrelationship with cerebral volumes. Cerebellar and cerebral gray and white matter were segmented using Freesurfer version 4.5 (http://surfer.nmr.mgh.harvard.edu/). We used linear regression analyses to model the relationship between age, sex, cardiovascular risk factors, brain infarcts, white matter lesions (WMLs) and cerebellar and cerebral volume. Smaller cerebellar volumes with increasing age were mainly driven by loss of white matter. Diabetes, higher serum glucose and lower cholesterol levels were related to smaller cerebellar volume. No association was found between hypertension, smoking, apolipoprotein E (ApoE) genotype, and cerebellar volume. Supratentorial lacunar infarcts and WMLs were related to smaller cerebellar volume. Infratentorial infarcts were related to smaller cerebellar white matter volume and total cerebral volume. This study suggests that determinants of cerebellar volume do not entirely overlap with those established for cerebral volume. Furthermore, presence of infarcts or WMLs in the cerebrum can affect cerebellar volume. http://repub.eur.nl/res/pub/37761/ 2012-09-01T00:00:00Z BACKGROUND AND PURPOSE: The clinical relevance of improved detection of cerebral microbleeds by using advanced-versus-conventional MR imaging techniques remains uncertain. As part of the population-based Rotterdam Scan Study, we compared whether participants whose microbleeds were only demonstrated on a high-resolution MR imaging sequence differed with respect to risk profile and risk of new microbleeds from participants whose microbleeds were also depicted on a conventional MR imaging sequence. MATERIALS AND METHODS: Two hundred participants (mean age, 79.2 years) underwent both conventional 2D T2*-weighted MR imaging and high-resolution 3D T2*-weighted MR imaging at 1.5T. Vascular risk factors, APOE allele status, and markers of small vessel disease and risk of incident microbleeds were compared for microbleed status by using logistic regression models adjusted for age and sex. RESULTS: There were no significant associations between any of the factors and microbleed presence in participants whose microbleeds were only demonstrated on a high-resolution MR imaging sequence. However, the estimates in these participants were more similar to those in participants whose microbleeds were also depicted on a conventional MR imaging sequence than to those in participants without microbleeds. Moreover, significantly more participants whose microbleeds were only demonstrated on high-resolution MR imaging developed new CMBs during follow-up compared with participants without CMBs (25.0% versus 5.9%; OR, 5.98; 95% CI, 1.35-26.49). CONCLUSIONS: Improved detection of microbleeds may contribute to more accurate identification of persons with underlying small-vessel pathology in the general elderly population. Further studies are needed to replicate these findings and firmly establish the role of improved detection of CMBs in the identification of persons with vasculopathy. http://repub.eur.nl/res/pub/34857/ 2012-01-01T00:00:00Z Aims Components of carotid atherosclerotic plaque such as intraplaque haemorrhage and lipid core are important determinants of plaque progression and destabilization. The association between plaque components and risk factors for cardiovascular disease is not well studied. Methods and Results Participants from the population-based Rotterdam Study with carotid wall thickening on ultrasound (n= 1006) underwent high-resolution magnetic resonance imaging for carotid plaque characterization. Maximum wall thickening, the degree of stenosis, and the presence of intraplaque haemorrhage, lipid core, and calcification were assessed in both carotid arteries and their associations with cardiovascular risk factors were investigated. Intraplaque haemorrhage and lipid core were present in almost 25 of plaques, respectively, and occurred simultaneously in 9 of plaques. In men, intraplaque haemorrhage and lipid core were more prevalent compared with women (28.8 vs. 18.3 and 28.9 vs. 21.7, respectively). Intraplaque haemorrhage occurred more frequently at older age [odds ratio (OR) per 10 years 1.8, 95 confidence interval 1.62.1], in men (OR 2.2, 1.72.9), in persons with hypertension (multivariate adjusted OR 1.4, 1.11.8), and in current smokers (multivariate adjusted OR 1.6, 1.22.3). Men (OR 1.5, 1.21.9) and subjects with hypercholesterolaemia (multivariate adjusted OR 1.4, 1.11.7) more often exhibited a lipid core. Conclusion In subjects from the general population with carotid wall thickening, intraplaque haemorrhage and lipid coreboth considered indicators of unstable plaqueare highly frequent and more prevalent in men compared with women. Furthermore, different risk factors are associated with these plaque components: hypertension and current smoking were risk factors for the presence of intraplaque haemorrhage, and hypercholesterolaemia was the only risk factor for lipid core presence. http://repub.eur.nl/res/pub/33223/ 2011-11-01T00:00:00Z BACKGROUND AND PURPOSE-: Recently, the first genomewide association study on cerebral white matter lesion burden identified chr17q25 to be significantly associated with white matter lesions. We report on the first independent replication study of this genetic association. METHODS-: In a population-based cohort study, we investigated the association between the 6 genomewide significant single nucleotide polymorphisms at that locus and cerebral white matter lesion volume on MRI, measured quantitatively, adjusted for age, sex, and intracranial volume. Adjustments for ApoE4 carriership and cardiovascular risk factors were evaluated separately. Finally, we performed a meta-analysis of all published data for the single most significant single nucleotide polymorphism, rs3744028. RESULTS-: The risk alleles of all the 6 single nucleotide polymorphisms were significantly associated with white matter lesion volume with P=1.1*10 for rs3744028, adjusted for age, sex, and intracranial volume. Additional adjustments only had minor influence on these associations. A meta-analysis with all published data for rs3744028 resulted in a probability value of 5.3*10. CONCLUSIONS-: This study further establishes chr17q25 as a novel genetic locus for WML volume. http://repub.eur.nl/res/pub/33828/ 2011-10-01T00:00:00Z Neuroimaging plays an important role in etiologic research on neurological diseases in the elderly. The Rotterdam Scan Study was initiated as part of the ongoing Rotterdam Study with the aim to unravel causes of neurological disease by performing neuroimaging in a population-based longitudinal setting. In 1995 and 1999 random subsets of the Rotterdam Study underwent neuroimaging, whereas from 2005 onwards MRI has been implemented into the core protocol of the Rotterdam Study. In this paper, we discuss the background and rationale of the Rotterdam Scan Study. We also describe the imaging protocol and post-processing techniques, and highlight the main findings to date. Finally, we make recommendations for future research, which will also be the main focus of investigation in the Rotterdam Scan Study. http://repub.eur.nl/res/pub/34156/ 2011-10-01T00:00:00Z OBJECTIVE-: Calcification in atherosclerotic plaques is a novel marker of atherosclerosis and is related to cardiovascular disease. However, its relationship with cerebrovascular disease has not been investigated extensively. We investigated the relationship between calcification in various vessel beds outside the brain and imaging markers of vascular brain disease. METHODS AND RESULTS-: A total of 885 community-dwelling people (mean age, 66.7 years) underwent computed tomography of the coronary arteries, aortic arch, and extracranial and intracranial carotid arteries to assess arterial calcification. Brain magnetic resonance imaging scans were performed to assess cerebral infarcts, microbleeds, and white matter lesions (WMLs). Calcification in each vessel bed was associated with presence of cerebral infarcts and with larger WML volume. The most prominent associations were found between intracranial carotid calcification and WML volume and between extracranial carotid calcification and infarcts. Adjustment for cardiovascular risk factors or ultrasound carotid plaque scores did not change these results. No associations were found between calcification and cerebral microbleeds. CONCLUSION-: Arterial calcification in major vessel beds is associated with vascular brain disease on magnetic resonance imaging. Most notably, larger intracranial carotid calcification load relates to larger WML volumes, and larger extracranial carotid calcification load relates to the presence of cerebral infarcts, independently of ultrasound carotid plaque score. This suggests that calcification of atherosclerotic plaque yields other information in addition to merely the presence of plaques, providing novel insights into the etiology of vascular brain disease. http://repub.eur.nl/res/pub/25879/ 2011-08-31T00:00:00Z Abstract The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods. http://repub.eur.nl/res/pub/26612/ 2011-07-01T00:00:00Z Objective: White matter hyperintensities (WMHs) detectable by magnetic resonance imaging are part of the spectrum of vascular injury associated with aging of the brain and are thought to reflect ischemic damage to the small deep cerebral vessels. WMHs are associated with an increased risk of cognitive and motor dysfunction, dementia, depression, and stroke. Despite a significant heritability, few genetic loci influencing WMH burden have been identified. Methods: We performed a meta-analysis of genome-wide association studies (GWASs) for WMH burden in 9,361 stroke-free individuals of European descent from 7 community-based cohorts. Significant findings were tested for replication in 3,024 individuals from 2 additional cohorts. Results: We identified 6 novel risk-associated single nucleotide polymorphisms (SNPs) in 1 locus on chromosome 17q25 encompassing 6 known genes including WBP2, TRIM65, TRIM47, MRPL38, FBF1, and ACOX1. The most significant association was for rs3744028 (pdiscovery= 4.0 × 10-9; preplication= 1.3 × 10-7; pcombined= 4.0 × 10-15). Other SNPs in this region also reaching genome-wide significance were rs9894383 (p = 5.3 × 10-9), rs11869977 (p = 5.7 × 10-9), rs936393 (p = 6.8 × 10-9), rs3744017 (p = 7.3 × 10-9), and rs1055129 (p = 4.1 × 10-8). Variant alleles at these loci conferred a small increase in WMH burden (4-8% of the overall mean WMH burden in the sample). Interpretation: This large GWAS of WMH burden in community-based cohorts of individuals of European descent identifies a novel locus on chromosome 17. Further characterization of this locus may provide novel insights into the pathogenesis of cerebral WMH. Copyright http://repub.eur.nl/res/pub/25802/ 2011-05-01T00:00:00Z Objective: To investigate the distribution of lobar microbleeds over the different lobes, taking into account lobar volume and clustering effects of multiple microbleeds. Design: Population-based, cross-sectional analysis. Setting: The Rotterdam Scan Study. Participants: A total of 198 persons (age range, 61-95 years) with lobar microbleeds. Main Outcome Measures: Distribution of microbleeds over different lobes. Results:Wefoundthat lobar cerebralmicrobleedsoccurred significantlymoreoften inthetemporallobe, aregionknown to be more affected in cerebral amyloid angiopathy. Conclusion: This study corroborates the presumed association of lobar microbleeds with cerebral amyloid angiopathy. http://repub.eur.nl/res/pub/34231/ 2011-03-15T00:00:00Z Diffusion MRI can be used to study the structural connectivity within the brain. Brain connectivity is often represented by a binary network whose topology can be studied using graph theory. We present a framework for the construction of weighted structural brain networks, containing information about connectivity, which can be effectively analyzed using statistical methods. Network nodes are defined by segmentation of subcortical structures and by cortical parcellation. Connectivity is established using a minimum cost path (mcp) method with an anisotropic local cost function based directly on diffusion weighted images. We refer to this framework as Statistical Analysis of Minimum cost path based Structural Connectivity (SAMSCo) and the weighted structural connectivity networks as mcp-networks. In a proof of principle study we investigated the information contained in mcp-networks by predicting subject age based on the mcp-networks of a group of 974 middle-aged and elderly subjects. Using SAMSCo, age was predicted with an average error of 3.7. years. This was significantly better than predictions based on fractional anisotropy or mean diffusivity averaged over the whole white matter or over the corpus callosum, which showed average prediction errors of at least 4.8. years. Additionally, we classified subjects, based on the mcp-networks, into groups with low and high white matter lesion load, while correcting for age, sex and white matter atrophy. The SAMSCo classification outperformed the classification based on the diffusion measures with a classification accuracy of 76.0% versus 63.2%. We also performed a classification in groups with mild and severe atrophy, correcting for age, sex and white matter lesion load. In this case, mcp-networks and diffusion measures yielded similar classification accuracies of 68.3% and 67.8% respectively. The SAMSCo prediction and classification experiments indicate that the mcp-networks contain information regarding age, white matter lesion load and white matter atrophy, and that in case of age and white matter lesion load the mcp-network based models outperformed the predictions based on diffusion measures. http://repub.eur.nl/res/pub/23813/ 2011-03-01T00:00:00Z BACKGROUND AND PURPOSE - Cerebral microbleeds are frequently seen in the general elderly population, but it is unknown at what rate they occur with aging and whether once present can disappear over time. METHODS - As part of the Rotterdam Scan Study, 831 persons (mean age, 68.5 years) underwent repeated brain MRI with a mean interval of 3.4 years. We assessed determinants of incident microbleeds in relation to their location with multiple logistic regressions. RESULTS - Overall prevalence of microbleeds increased from 24.4% at baseline to 28.0% at follow-up. Eighty-five persons (10.2%) developed new microbleeds. Microbleeds at baseline predicted development of new microbleeds (OR, 5.38; 95% CI, 3.34 to 8.67). In only 6 persons with microbleeds at baseline, fewer microbleeds were present at the follow-up examination. Cardiovascular risk factors, presence of lacunar infarcts, and larger white matter lesion volume at baseline were all associated with incident deep or infratentorial microbleeds, whereas people with the apolipoprotein E ε4/ε4 genotype or larger white matter lesion volume had a higher risk of incident strictly lobar microbleeds. CONCLUSIONS - Incidence of microbleeds in the general population over a 3-year interval was substantial and microbleeds rarely disappeared. Risk factors for incident microbleeds were similar to those for prevalent microbleeds and differed according to microbleed location. These results support the assessment of microbleeds on T2*-weighted MRI as a possible marker of both cerebral amyloid angiopathy and hypertensive vasculopathy progression. http://repub.eur.nl/res/pub/33554/ 2011-01-01T00:00:00Z Background: Asymptomatic cerebral lesions on MRI such as white matter lesions (WML), lacunes and microbleeds are commonly seen in older people. We examined the role of a series of candidate genes involved in blood pressure regulation and amyloid metabolism. Materials and Methods: The study was embedded in a family-based cohort sampled from a Dutch genetically isolated population. We selected individuals between 55 and 75 years of age with hypertension (N=129). Volumes of WML and presence of lacunes and microbleeds were assessed with MRI. We studied three genes involved in blood pressure regulation (angiotensin, angiotensin II type 1 receptor, α-adducin) and two genes involved in the amyloid pathway (apolipoprotein E (APOE) and sortilin-related receptor gene (SORL1)). Results: All participants had WML (median volume, 3.1 ml; interquartile range, 1.5e6.5 ml); lacunar infarcts were present in 15.5% and microbleeds in 23.3%. Homozygosity for the APOE ε4 allele was associated with lacunes (OR, 4.8; 95% CI, 1.2 to 19.3). Individuals carrying two copies of the variant allele of four single nucleotide polymorphism (SNPs) located at the 3'-end of SORL1 (rs1699102, rs3824968, rs2282649, rs1010159) had significantly more often microbleeds (highest OR, 6.87; 95% CI, 1.78 to 26.44). Conclusion: The association of SORL1 with microbleeds suggests that the amyloid cascade is involved in the aetiology of microbleeds in populations with hypertension. http://repub.eur.nl/res/pub/27998/ 2010-11-22T00:00:00Z We present a framework for statistical analysis in large cohorts of structural brain connectivity, derived from diffusion weighted MRI. A brain network is defined between subcortical gray matter structures and a cortical parcellation obtained with FreeSurfer. Connectivity is established through minimum cost paths with an anisotropic local cost function and is quantified per connection. The connectivity network potentially encodes important information about brain structure, and can be analyzed using multivariate regression methods. The proposed framework can be used to study the relation between connectivity and e.g. brain function or neurodegenerative disease. As a proof of principle, we perform principal component regression in order to predict age and gender, based on the connectivity networks of 979 middle-aged and elderly subjects, in a 10-fold cross-validation. The results are compared to predictions based on fractional anisotropy and mean diffusivity averaged over the white matter and over the corpus callosum. Additionally, the predictions are performed based on the best predicting connection in the network. Principal component regression outperformed all other prediction models, demonstrating the age and gender information encoded in the connectivity network. http://repub.eur.nl/res/pub/24033/ 2010-10-06T00:00:00Z Introduction: After minor head injury (MHI), post-concussive symptoms commonly occur. The purpose of this study was to correlate the severity of post-concussive symptoms in MHI patients with MRI measures of microstructural brain injury, namely mean diffusivity (MD) and fractional anisotropy (FA), as well as the presence of microhaemorrhages. Methods: Twenty MHI patients and 12 healthy controls were scanned at 3 T using diffusion tensor imaging (DTI) and high-resolution gradient recalled echo (HRGRE) T2*-weighted sequences. One patient was excluded from the analysis because of bilateral subdural haematomas. DTI data were preprocessed using Tract Based Spatial Statistics. The resulting MD and FA images were correlated with the severity of post-concussive symptoms evaluated with the Rivermead Postconcussion Symptoms Questionnaire. The number and location of microhaemorrhages were assessed on the HRGRE T2*-weighted images. Results: Comparing patients with controls, there were no differences in MD. FA was decreased in the right temporal subcortical white matter. MD was increased in association with the severity of post-concussive symptoms in the inferior fronto-occipital fasciculus (IFO), the inferior longitudinal fasciculus and the superior longitudinal fasciculus. FA was reduced in association with the severity of post-concussive symptoms in the uncinate fasciculus, the IFO, the internal capsule and the corpus callosum, as well as in the parietal and frontal subcortical white matter. Microhaemorrhages were observed in one patient only. Conclusions: The severity of post-concussive symptoms after MHI was significantly correlated with a reduction of white matter integrity, providing evidence of microstructural brain injury as a neuropathological substrate of the post-concussion syndrome. http://repub.eur.nl/res/pub/27280/ 2010-10-01T00:00:00Z BACKGROUND AND PURPOSE-: We previously reported on the high prevalence of cerebral microbleeds (CMBs) in community-dwelling people aged 60 years and older. Moreover, we found that their spatial distribution likely reflects differences in underlying etiology. We have since almost quadrupled the number of participants in our study and expanded it to include persons of 45 years and older. We examined the prevalence and determinants of microbleeds in this larger and younger cohort from the general population. METHODS-: In 3979 persons (mean age, 60.3 years), we performed brain MRI at 1.5T, including a sequence optimized for visualization of CMBs. Associations between APOE genotype, cardiovascular risk factors, and markers of cerebrovascular disease with the presence and location of CMBs were assessed by multiple logistic regression adjusted for age, sex, and relevant confounders. RESULTS-: Microbleed prevalence gradually increased with age, from 6.5% in persons aged 45 to 50 years to 35.7% in participants of 80 years and older. Overall, 15.3% of all subjects had at least 1 CMB. Cardiovascular risk factors and presence of lacunar infarcts and white matter lesions were associated with microbleeds in a deep or infratentorial region, whereas APOE ϵ4 and diastolic blood pressure were related to microbleeds in a strictly lobar location. CONCLUSIONS-: Findings in this larger population are in line with our previous results and, more importantly, extend these to a younger age group. CMBs are already present at middle age, and prevalence rises strongly with increasing age. We confirmed that determinants of the presence of cerebral microbleeds differ according to their location in the brain. http://repub.eur.nl/res/pub/28271/ 2010-07-01T00:00:00Z The ability to study changes in brain morphometry in longitudinal studies majorly depends on the accuracy and reproducibility of the brain tissue quantification. We evaluate the accuracy and reproducibility of four previously proposed automatic brain tissue segmentation methods: FAST, SPM5, an automatically trained k-nearest neighbor (kNN) classifier, and a conventional kNN classifier based on a prior training set. The intensity nonuniformity correction and skull-stripping mask were the same for all methods. Evaluations were performed on MRI scans of elderly subjects derived from the general population. Accuracy was evaluated by comparison to two manual segmentations of MRI scans of six subjects (mean age 65.9 ± 4.4. years). Reproducibility was assessed by comparing the automatic segmentations of 30 subjects (mean age 57.0 ± 3.7. years) who were scanned twice within a short time interval. All methods showed good accuracy and reproducibility, with only small differences between methods. The conventional kNN classifier was the most accurate method with similarity indices of 0.82/0.90/0.94 for cerebrospinal fluid/gray matter/white matter, but it showed the lowest reproducibility. FAST yielded the most reproducible segmentation volumes with volume difference standard deviations of 0.55/0.49/0.38 (percentage of intracranial volume) respectively. The results of the reproducibility experiment can be used to calculate the required number of subjects in the design of a longitudinal study with sufficient power to detect changes over time in brain (tissue) volume. Example sample size calculations demonstrate a rather large effect of the choice of segmentation method on the required number of subjects. http://repub.eur.nl/res/pub/27776/ 2010-03-01T00:00:00Z We investigated in a population-based cohort study the association of global and lobar brain tissue volumes with specific cognitive domains and risk of dementia. Participants (n = 490; 60-90 years) were non-demented at baseline (1995-1996). From baseline brain MRI-scans we obtained global and lobar volumes of CSF, GM, normal WM, white matter lesions and hippocampus. We performed neuropsychological testing at baseline to assess information processing speed, executive function, memory function and global cognitive function. Participants were followed for incident dementia until January 1, 2005. Larger volumes of CSF and WML were associated with worse performance on all neuropsychological tests, and an increased risk of dementia. Smaller WM volume was related to poorer information processing speed and executive function. In contrast, smaller GM volume was associated with worse memory function and increased risk of dementia. When investigating lobar GM volumes, we found that hippocampal volume and temporal GM volume were most strongly associated with risk of dementia, even in persons without objective and subjective cognitive deficits at baseline, followed by frontal and parietal GM volumes. http://repub.eur.nl/res/pub/28245/ 2010-01-01T00:00:00Z Background: Cross-sectional studies have shown an association between vascular brain disease and depression. Longitudinal data are scarce. In a population-based study we investigated this relationship both cross-sectionally and longitudinally. Methods: Brain MRIs were administered to 479 persons aged 60-90 years at baseline (1995-1996). Brain atrophy, white matter lesions and brain infarcts are all markers of vascular brain disease. At baseline and at follow-up examinations, we also identified persons with depressive symptoms and syndromes using the Center for Epidemiological Studies Depression Scale and psychiatric interviews. Medical records were continuously monitored to identify incident depression. Follow-up was complete until October 2005. Results: At baseline, 36 persons had depressive symptoms. Brain atrophy, white matter lesions, and infarcts were associated with presence of depressive symptoms. During follow-up, 92 persons developed depressive symptoms, 35 of whom were categorized as having depressive syndrome. There was no association of any MRI marker with incident depressive symptoms or syndromes. Conclusions: Markers of vascular brain disease were associated with depression cross-sectionally. However, when these markers and risk of depression were assessed longitudinally, no relationship was found. http://repub.eur.nl/res/pub/17987/ 2009-07-24T00:00:00Z http://repub.eur.nl/res/pub/25166/ 2009-06-01T00:00:00Z Background: Cerebral microbleeds are hemosiderin deposits in the brain that are indicative of microangiopathy. Microbleeds in strictly lobar brain locations have been related to cerebral amyloid angiopathy, a bleeding-prone disease state. Objective: To investigate the relation between antithrombotic drug use and the presence of cerebral microbleeds, especially those in strictly lobar locations. Design: A population-based, cross-sectional analysis that used magnetic resonance imaging (MRI) to assess the presence and location of microbleeds. Complete information on outpatient use of platelet aggregation inhibitors and anticoagulant drugs before MRI was obtained from automated pharmacy records. Setting: The Rotterdam Scan Study, a population-based imaging study in a general elderly community in the Netherlands. Participants: A population-based sample of 1062 persons from a longitudinal cohort, 60 years and older, free of dementia, who underwent MRI examinations between August 15, 2005, and November 22, 2006. Main Outcome Measures: Presence of cerebral microbleeds on MRI. Results: Compared with nonusers of antithrombotic drugs, cerebral microbleeds were more prevalent among users of platelet aggregation inhibitors (adjusted odds ratio [OR], 1.71; 95% confidence interval [CI], 1.21-2.41). We did not find a significant association for anticoagulant drugs and microbleed presence (OR, 1.49; 95% CI, 0.82-2.71). Strictly lobar microbleeds were more prevalent among aspirin users (adjusted OR compared with nonusers, 2.70; 95% CI, 1.45-5.04) than among persons using carbasalate calcium (adjusted OR, 1.16; 95% CI, 0.66-2.02). This difference was even more pronounced when comparing persons who had used similar dosages of both drugs. Conclusions: This cross-sectional study shows that use of platelet aggregation inhibitors is related to the presence of cerebral microbleeds. Furthermore, aspirin and carbasalate calcium use may differently relate to the presence of strictly lobar microbleeds. http://repub.eur.nl/res/pub/16391/ 2009-05-01T00:00:00Z Context: The role of macrostructural white matter changes, such as atrophy and white matter lesions, in cognitive decline is increasingly being recognized. However, in the elderly population, these macrostructural changes do not account for all variability in cognition. Measures reflecting white matter microstructural integrity may provide additional information to investigate the relation between white matter changes and cognition. Objective: To study the relation between white matter integrity and cognition in the general elderly population, using diffusion tensor imaging and taking into account macrostructural white matter changes. Design: Cross-sectional population-based study. Setting: A general community in the Netherlands. Participants: A population-based sample of 860 persons, older than 60 years, free of dementia. We performed multisequence magnetic resonance imaging, which included diffusion tensor imaging, and extensive neuropsychological testing. Fractional anisotropy, mean diffusivity, and directional diffusivities were measured globally in white matter lesions and normal-appearing white matter. Main Outcome Measures: Performance on neuro- psychological tests in the following cognitive domains: memory, executive function, information processing speed, global cognition, and motor speed. Results: Regardless of macrostructural white matter changes, a higher mean diffusivity or higher axial and radial diffusivities within white matter lesions or normal- appearing white matter were related to worse performance on tasks assessing information processing speed and global cognition. In addition, diffusivity within white matter lesions related to memory, while in normal-appearing white matter, it furthermore related to executive function. Lower mean fractional anisotropy in white matter lesions or normal-appearing white matter related to worse information processing speed and motor speed. Conclusions: Microstructural integrity of both white matter lesions and normal-appearing white matter is associated with cognitive function, regardless of white matter atrophy and white matter lesion volume. This suggests that measuring white matter integrity has added value beyond macrostructural assessment of white matter changes to study the relation between white matter and cognition. http://repub.eur.nl/res/pub/24482/ 2009-05-01T00:00:00Z A fully automated brain tissue segmentation method is optimized and extended with white matter lesion segmentation. Cerebrospinal fluid (CSF), gray matter (GM) and white matter (WM) are segmented by an atlas-based k-nearest neighbor classifier on multi-modal magnetic resonance imaging data. This classifier is trained by registering brain atlases to the subject. The resulting GM segmentation is used to automatically find a white matter lesion (WML) threshold in a fluid-attenuated inversion recovery scan. False positive lesions are removed by ensuring that the lesions are within the white matter. The method was visually validated on a set of 209 subjects. No segmentation errors were found in 98% of the brain tissue segmentations and 97% of the WML segmentations. A quantitative evaluation using manual segmentations was performed on a subset of 6 subjects for CSF, GM and WM segmentation and an additional 14 for the WML segmentations. The results indicated that the automatic segmentation accuracy is close to the interobserver variability of manual segmentations. http://repub.eur.nl/res/pub/15054/ 2009-03-11T00:00:00Z The objective of the studies described in this thesis was to investigate with magnetic resonance imaging (MRI) brain changes that may function as preclinical imaging markers for neurodegenerative and cerebrovascular disease. For this goal, advanced MRI techniques were applied in the Rotterdam Scan Study, a large population-based brain imaging study among middle-aged and elderly persons. We studied the prevalence and distribution of age-related brain changes on MRI, investigated associated risk factors and related these brain changes to cognitive functioning. We found that cerebral microbleeds were present in 1 in 5 persons over age of 60. This prevalence is much higher than reported previously, which in part may be explained by the use of a more sensitive MRI sequence. Furthermore, we showed that risk factors for microbleeds varied according to the location of microbleeds in the brain. By measuring cerebral blood flow, we assessed that persons with low total brain perfusion had significantly more white matter lesions compared to those with high total brain perfusion. This suggests that tissue hypoperfusion may contribute to white matter lesion pathogenesis. Microstructural integrity within white matter lesions or normal-appearing white matter was associated with cognitive function, even when taking into account volume of white matter lesions and white matter atrophy. This indicates that the deleterious effect of white matter changes on cognition not only depends on lesion burden or amount of atrophy, but also on characteristics that are not easily evaluated by conventional MRI. The studies described in this thesis have identified several age-related brain changes that have potential to serve as imaging markers for neurodegenerative or cerebrovascular disease. http://repub.eur.nl/res/pub/14935/ 2009-03-01T00:00:00Z Brain atrophy and small vessel disease increase the risk of dementia and stroke. In a population-based cohort study (n = 490; 60-90 years) we investigated how volumetric measures of atrophy and small vessel disease were related to mortality and whether this was independent of incident dementia or stroke. Brain volume and hippocampal volume were considered as measures of atrophy, whereas white matter lesions (WML) and lacunar infarcts reflected small vessel disease. We first investigated all-cause mortality in the whole cohort. In subsequent analyses we censored persons at incident dementia or incident stroke. Finally, we separately investigated cardiovascular mortality. The average follow-up was 8.4 years, during which 191 persons died. Brain atrophy and hippocampal atrophy, as well as WML increased the risk of death. The risks associated with hippocampal atrophy attenuated when censoring persons at incident dementia, but not at incident stroke. Censoring at either incident dementia or stroke did not change the risk associated with brain atrophy and WML. Moreover, WML were particularly associated with cardiovascular mortality. http://repub.eur.nl/res/pub/14956/ 2009-02-01T00:00:00Z Cerebral microbleeds (CMBs) are increasingly recognised neuroimaging findings in individuals with cerebrovascular disease and dementia, and in normal ageing. There has been substantial progress in the understanding of CMBs in recent years, particularly in the development of newer MRI methods for the detection of CMBs and the application of these techniques to population-based samples of elderly people. In this Review, we focus on these recent developments and their effects on two main questions: how CMBs are detected, and how CMBs should be interpreted. The number of CMBs detected depends on MRI characteristics, such as pulse sequence, sequence parameters, spatial resolution, magnetic field strength, and image post-processing, emphasising the importance of taking into account MRI technique in the interpretation of study results. Recent investigations with sensitive MRI techniques have indicated a high prevalence of CMBs in community-dwelling elderly people. We propose a procedural guide for identification of CMBs and suggest possible future approaches for elucidating the role of these common lesions as markers for, and contributors to, small-vessel brain disease. http://repub.eur.nl/res/pub/14517/ 2008-11-15T00:00:00Z The importance of macrostructural white matter changes, including white matter lesions and atrophy, in intact brain functioning is increasingly being recognized. Diffusion tensor imaging (DTI) enables measurement of the microstructural integrity of white matter. Loss of white matter integrity in aging has been reported, but whether this is inherent to the aging process itself or results from specific white matter pathology is unknown. In 832 persons aged 60 years and older from the population-based Rotterdam Study, we measured fractional anisotropy (FA) and directional diffusivities in normal-appearing white matter using DTI. All subjects' DTI measures were projected onto a common white matter skeleton to enable robust voxelwise comparison. With increasing age, multiple regions showed significant decreases in FA or increases in axial or radial diffusivity in normal-appearing white matter. However, nearly all of these regional changes were explained by either white matter atrophy or by white matter lesions; each of which related to changes in distinct brain regions. These results indicate that loss of white matter integrity in aging is primarily explained by atrophy and lesion formation and not by the aging process itself. Furthermore, white matter atrophy and white matter lesion formation relate to loss of integrity in distinct brain regions, indicating the two processes are pathophysiologically different. http://repub.eur.nl/res/pub/14216/ 2008-11-01T00:00:00Z http://repub.eur.nl/res/pub/32275/ 2008-11-01T00:00:00Z http://repub.eur.nl/res/pub/14792/ 2008-10-01T00:00:00Z Cerebral hypoperfusion has been associated with worse cognitive function. We investigated the association between cerebral blood flow and cognition and whether this association is independent of brain volume. In 892 participants, aged 60 to 91 years, of the population-based Rotterdam Scan study, we measured total cerebral blood flow (tCBF) and brain volume using magnetic resonance imaging. Lower tCBF was associated with worse information-processing speed, executive function, and global cognition. However, after correcting tCBF for brain volume, these associations disappeared. The association between tCBF and cognition may be mediated or confounded by brain atrophy. Future studies on tCBF should take into account brain atrophy. http://repub.eur.nl/res/pub/28901/ 2008-07-01T00:00:00Z http://repub.eur.nl/res/pub/29074/ 2008-07-01T00:00:00Z The purpose of this study was to prospectively compare high-spatial- resolution accelerated three-dimensional (3D) T2*-weighted gradient-recalled-echo (GRE) magnetic resonance (MR) images with conventional two-dimensional (2D) T2*-weighted GRE MR images for the depiction of cerebral microbleeds. After obtaining institutional review board approval and informed consent, 200 elderly participants (age range, 69.7-96.7 years; 108 [54%] women) were imaged at 1.5 T by using both sequences. Presence, number, and location of microbleeds were recorded for both sequences, and differences were tested by using McNemar and signed rank tests. Cerebral microbleeds were detected in significantly more participants on 3D T2*-weighted GRE images (35.5%) than on 2D T2*-weighted GRE images (21.0%; P < .001). Furthermore, in persons with microbleeds visualized on both image sets, significantly more microbleeds (P < .001) were seen on 3D images than on 2D images. For both sequences, the proportion of participants with a microbleed in a lobar (cortical gray and subcortical white matter), deep, or infratentorial location was similar. In conclusion, accelerated 3D T2*-weighted GRE images depict more microbleeds than do conventional 2D T2*-weighted GRE images. http://repub.eur.nl/res/pub/29272/ 2008-06-01T00:00:00Z We investigated how volumes of cerebrospinal fluid (CSF), grey matter (GM) and white matter (WM) varied with age, sex, small vessel disease and cardiovascular risk factors in the Rotterdam Scan Study. Participants (n = 490; 60-90 years) were non-demented and 51.0% had hypertension, 4.9% had diabetes mellitus, 17.8% were current smoker and 54.0% were former smoker. We segmented brain MR-images into GM, normal WM, white matter lesion (WML) and CSF. Brain infarcts were rated visually. Volumes were expressed as percentage of intra-cranial volume. With increasing age, volumes of total brain, normal WM and total WM decreased; that of GM remained unchanged; and that of WML increased, in both men and women. Excluding persons with infarcts did not alter these results. Persons with larger load of small vessel disease had smaller brain volume, especially normal WM volume. Diastolic blood pressure, diabetes mellitus and current smoking were also related to smaller brain volume. In the elderly, higher age, small vessel disease and cardiovascular risk factors are associated with smaller brain volume, especially WM volume. http://repub.eur.nl/res/pub/29317/ 2008-05-01T00:00:00Z Objective: Retinal vessel diameters, in particular larger venular diameters, have been associated with cerebrovascular disease. Larger retinal venular diameters may reflect cerebral ischemia. The authors investigated whether arteriolar oxygen saturation (SaO2) and total cerebral blood flow (CBF), indicators of cerebral oxygen supply, are associated with retinal arteriolar or venular diameters. Design: Cross-sectional study performed within the population-based Rotterdam Study. Participants: Randomly selected participants aged 55 years or older (n = 696), who underwent both an eye examination and brain magnetic resonance imaging (MRI). Methods: Arteriolar oxygen saturation was determined by pulse oximetry on the right index finger. Cerebral blood flow was assessed using a phase-contrast MRI sequence that measured the flow in the basilar and both internal carotid arteries. Brain volume was measured to express CBF per 100 ml brain volume. Retinal arteriolar and venular diameters were measured on digitized fundus color transparencies on 1 eye of each participant. Regression models were used to investigate the association of SaO2and CBF with retinal vessel diameters. Main Outcome Measures: Mean retinal arteriolar and venular diameters (in micrometers). Results: Lower SaO2was associated with larger venular diameters. Persons with SaO2less than 96% (n = 113) had on average 5 μm larger venular diameters compared with those with SaO2of 96% or more (n = 583; age- and gender-adjusted mean difference, 5.6 μm; 95% confidence interval, 1.2-10.0). Cerebral blood flow was not related to venular diameters when analyzed separately. Additional analyses showed that the association between SaO2and venular widening was confined to participants within the lowest tertile of CBF. No associations were found between SaO2or CBF and arteriolar diameters. Additional adjustment for established cardiovascular risk factors did not change the results. Conclusions: An association of lower SaO2with larger retinal venular diameters was observed, in particular in the presence of lower CBF. These findings suggest that venular widening may reflect a lower oxygen supply, especially to the brain. http://repub.eur.nl/res/pub/29097/ 2008-04-01T00:00:00Z BACKGROUND: Cerebral microbleeds are focal deposits of hemosiderin that can be visualized with MRI. Little is known on their prevalence in the general population and on their etiology. It has been suggested that, in analogy to spontaneous intracranial hemorrhage, the etiology of microbleeds differs according to their location in the brain, with lobar microbleeds being caused by cerebral amyloid angiopathy and deep or infratentorial microbleeds resulting from hypertension and atherosclerosis. We investigated the prevalence of and risk factors for microbleeds in the general population aged 60 years and older. METHODS: This study is based on 1,062 persons (mean age 69.6 years) from the population-based Rotterdam Scan Study. MRI was performed at 1.5 T and included a sequence optimized to increase the conspicuity of microbleeds. We assessed the relation of APOE genotype, cardiovascular risk factors, and markers of small vessel disease to the presence and location of microbleeds with multiple logistic regression. RESULTS: Overall prevalence of cerebral microbleeds was high and increased with age from 17.8% in persons aged 60-69 years to 38.3% in those over 80 years. APOE ε4 carriers had significantly more often strictly lobar microbleeds than noncarriers. In contrast, cardiovascular risk factors and presence of lacunar infarcts and white matter lesions were associated with microbleeds in a deep or infratentorial location but not in a lobar location. CONCLUSION: The prevalence of cerebral microbleeds is high. Our data support the hypothesis that strictly lobar microbleeds are related to cerebral amyloid angiopathy, whereas microbleeds in a deep or infratentorial location result from hypertensive or atherosclerotic microangiopathy. http://repub.eur.nl/res/pub/29489/ 2008-02-01T00:00:00Z Reduced cerebral perfusion may contribute to the development of cerebrovascular and neurodegenerative diseases. Little is known on cerebral perfusion in the general population, as most measurement techniques are too invasive for application in large groups of healthy individuals. Total cerebral blood flow (tCBF) can be noninvasively measured by magnetic resonance imaging (MRI) but is highly correlated with brain volume. We calculated total brain perfusion by dividing tCBF by brain volume, and we investigated determinants of total brain perfusion in comparison with tCBF. Secondly, we studied whether persons with a low tCBF or low total brain perfusion have a larger volume of white matter lesions (WML). This study is based on 892 persons aged 60 to 91 years from the Rotterdam Study, a population-based cohort study. We performed two-dimensional (2D) phase-contrast MRI for tCBF measurement. Brain volume and WML volume were quantitatively assessed. Cardiovascular determinants were assessed by interview and physical examination. We assessed associations between cardiovascular determinants and flow measures with linear regression models, adjusted for age and sex. Associations between tCBF or total brain perfusion and WML volume were assessed using general linear models. We found that determinants of tCBF and total brain perfusion differed largely due to the large influence of brain volume on tCBF values. Persons with low total brain perfusion had a significantly larger WML volume compared with those with high total brain perfusion. Prospective studies are required to unravel whether hypoperfusion contributes to WML formation or that tissue damage, manifested by WML, leads to brain hypoperfusion. http://repub.eur.nl/res/pub/28785/ 2008-01-01T00:00:00Z BACKGROUND AND PURPOSE - Poor kidney function, as measured by glomerular filtration rate (GFR), is closely associated with presence of glomerular small vessel disease. Given the hemodynamic similarities between the vascular beds of the kidney and the brain, we hypothesized an association between kidney function and markers of cerebral small vessel disease on MRI. We investigated this association in a population-based study of elderly persons. METHODS - We measured GFR using the Cockcroft-Gault equation in 484 participants (60 to 90 years of age) from the Rotterdam Scan Study. Using automated MRI-analysis we measured global as well as lobar and deep volumes of gray matter and white matter, and volume of WML. Lacunar infarcts were rated visually. Volumes of deep white matter and WML and presence of lacunar infarcts reflected cerebral small vessel disease. We used linear and logistic regression models to investigate the association between GFR and brain imaging parameters. Analyses were adjusted for age, sex, and additionally for cardiovascular risk factors. RESULTS - Persons with lower GFR had less deep white matter volume (difference in standardized volume per SD decrease in GFR: -0.15 [95% CI -0.26 to -0.04]), more WML (difference per SD decrease in GFR: 0.14 [95% CI 0.03 to 0.25]), and more often lacunar infarcts, although the latter was not significant. GFR was not associated with gray matter volume or lobar white matter volume. Additional adjustment for cardiovascular risk factors yielded similar results. CONCLUSIONS - Impaired kidney function is associated with markers of cerebral small vessel disease as assessed on MRI. http://repub.eur.nl/res/pub/35140/ 2007-11-01T00:00:00Z Background: Magnetic resonance imaging (MRI) of the brain is increasingly used both in research and in clinical medicine, and scanner hardware and MRI sequences are continually being improved. These advances are likely to result in the detection of unexpected, asymptomatic brain abnormalities, such as brain tumors, aneurysms, and subclinical vascular pathologic changes. We conducted a study to determine the prevalence of such incidental brain findings in the general population. Methods: The subjects were 2000 persons (mean age, 63.3 years; range, 45.7 to 96.7) from the population-based Rotterdam Study in whom high-resolution, structural brain MRI (1.5 T) was performed according to a standardized protocol. Two trained reviewers recorded all brain abnormalities, including asymptomatic brain infarcts. The volume of white-matter lesions was quantified in milliliters with the use of automated post-processing techniques. Two experienced neuroradiologists reviewed all incidental findings. All diagnoses were based on MRI findings, and additional histologic confirmation was not obtained. Results: Asymptomatic brain infarcts were present in 145 persons (7.2%). Among findings other than infarcts, cerebral aneurysms (1.8%) and benign primary tumors (1.6%), mainly meningiomas, were the most frequent. The prevalence of asymptomatic brain infarcts and meningiomas increased with age, as did the volume of white-matter lesions, whereas aneurysms showed no age-related increase in prevalence. Conclusions: Incidental brain findings on MRI, including subclinical vascular pathologic changes, are common in the general population. The most frequent are brain infarcts, followed by cerebral aneurysms and benign primary tumors. Information on the natural course of these lesions is needed to inform clinical management. Copyright http://repub.eur.nl/res/pub/20946/ 2007-08-01T00:00:00Z BACKGROUND AND PURPOSE: Our goal was to improve the preoperative assessment of the cortico- spinal tract (CST) in patients with brain tumors. We investigated whether the integration of functional MR imaging (fMRI) data and diffusion tensor (DT) tractography can be used to evaluate the spatial relationship between the hand and foot fibers of the CST and tumor borders. MATERIALS AND METHODS: We imaged 10 subjects: 1 healthy volunteer and 9 patients. Imaging consisted of a 3D T1-weighted sequence, a gradient-echo echo-planar imaging (EPI) sequence for fMRI, and a diffusion-weighted EPI sequence for DT tractography. DT tractography was initiated from a seed region of interest in the white matter area subjacent to the maximal fMRI activity in the precentral cortex. The target region of interest was placed in the cerebral peduncle. RESULTS: In the healthy volunteer, we successfully tracked hand, foot, and lip fibers bilaterally by using fMRI-based DT tractography. In all patients, we could track the hand fibers of the CST bilaterally. In 4 patients who also performed foot tapping, we could clearly distinguish hand and foot fibers. We were able to depict the displacement of hand and foot fibers by tumor and the course of fibers through areas of altered signal intensity. CONCLUSION: Incorporating fMRI into DT tractography in the preoperative assessment of patients with brain tumors may provide additional information on the course of important white matter tracts and their relationship to the tumor. Only this approach allows a distinction between the CST compo- nents, while visualization of the CST is improved when fiber tracking is hampered by tumor (infiltration) or perifocal edema. http://repub.eur.nl/res/pub/36607/ 2007-08-01T00:00:00Z Conventional k-Nearest-Neighbor (kNN) classification, which has been successfully applied to classify brain tissue in MR data, requires training on manually labeled subjects. This manual labeling is a laborious and time-consuming procedure. In this work, a new fully automated brain tissue classification procedure is presented, in which kNN training is automated. This is achieved by non-rigidly registering the MR data with a tissue probability atlas to automatically select training samples, followed by a post-processing step to keep the most reliable samples. The accuracy of the new method was compared to rigid registration-based training and to conventional kNN-based segmentation using training on manually labeled subjects for segmenting gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) in 12 data sets. Furthermore, for all classification methods, the performance was assessed when varying the free parameters. Finally, the robustness of the fully automated procedure was evaluated on 59 subjects. The automated training method using non-rigid registration with a tissue probability atlas was significantly more accurate than rigid registration. For both automated training using non-rigid registration and for the manually trained kNN classifier, the difference with the manual labeling by observers was not significantly larger than inter-observer variability for all tissue types. From the robustness study, it was clear that, given an appropriate brain atlas and optimal parameters, our new fully automated, non-rigid registration-based method gives accurate and robust segmentation results. A similarity index was used for comparison with manually trained kNN. The similarity indices were 0.93, 0.92 and 0.92, for CSF, GM and WM, respectively. It can be concluded that our fully automated method using non-rigid registration may replace manual segmentation, and thus that automated brain tissue segmentation without laborious manual training is feasible. http://repub.eur.nl/res/pub/36667/ 2007-04-15T00:00:00Z Previously reported leftward asymmetry in language-related gray and white matter areas of the brain has been proposed as a structural correlate of left-sided functional hemispheric language lateralization. However, structural asymmetry in non-left-sided functional language lateralization has as yet not been studied. Furthermore, the neuroanatomical basis of the reported volumetric white matter asymmetry is not fully understood. In 20 healthy volunteers, including 13 left-handers, we performed functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). We studied the relative fiber density (RFD) of the arcuate fasciculus (AF), using DT-tractography, in relation to functional hemispheric language lateralization. Hemispheric language lateralization was right-sided in five left-handed individuals. We demonstrated an overall significant leftward asymmetry in RFD of the AF, irrespective of handedness or functional language lateralization. Furthermore, in right-handers, the degree of structural asymmetry was found to be correlated with the degree of functional lateralization. We conclude that structural asymmetry in the AF does not seem to reflect functional hemispheric language lateralization, as has been proposed previously. Our findings suggest that the previously reported white matter asymmetry may be explained by a structural asymmetry in the arcuate fasciculus. These findings have important implications for the understanding of the functional and structural lateralization of brain regions as well as for the clinical evaluation of language function.