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Biomedical subjects

M A van Buchem

Publications and source records attributed to M A van Buchem.

At least 19 recordsLinked to original sources
PubMed2006

Sources of variation in multi-centre brain MTR histogram studies: body-coil transmission eliminates inter-centre differences.

OBJECT: 1. Identify sources of variation affecting Magnetisation Transfer Ratio (MTR) histogram reproducibility between-centres. 2. Demonstrate complete elimination of inter-centre difference. MATERIALS AND METHODS: Six principle sources of variation were summarised and analysed. These are: the imager coil used for radiofrequency (RF) transmission, imager stability, the shape and other parameters describing the Magnetisation Transfer (MT) pulse, the MT sequence used (including its parameters), the image segmentation methodology, and the histogram generation technique. Transmit field nonuniformity and B1 errors are often the largest factors. PLUMB (Peak Location Uniformity in MTR histograms of the Brain) plots are a convenient way of visualising differences. Five multi-centres studies were undertaken to investigate and minimise differences. RESULTS: Transmission using a body coil, with a close-fitting array of surface coils for reception, gave the best uniformity. Differences between two centres, having MR imagers from different manufacturers, were completely eliminated by using body coil excitation, making a small adjustment to the MT pulse flip angle, and carrying out segmentation at a single centre. Histograms and their peak location and height values were indistinguishable. CONCLUSIONS: Body coil excitation is preferred for multi-centre studies. Analysis (segmentation and histogram generation) should ideally be carried out at a single site.

Artifacts↗
PubMed2006

EEG and MRI correlates of mild cognitive impairment and Alzheimer's disease.

OBJECTIVE: To investigate whether cognitive function in the spectrum of normal aging to Alzheimer's disease is better reflected in MRI or EEG measures, or a combination of both. METHODS: Cognitive functions were tested in 33 elderly subjects: 10 with probable Alzheimer's disease, 11 with mild cognitive impairment and 12 controls. Structural brain parameters were derived from conventional MRI and a quantitative MR technique called magnetization transfer imaging. The EEG provided measures of brain function. We performed multiple linear regression analyses to relate EEG and MRI parameters to global cognition, memory, language and psychomotor speed. RESULTS: The model showed EEG alpha reactivity during eyes open to be the primary factor associated with global cognition, memory and language skills. Brain atrophy was the primary factor associated with psychomotor speed. Furthermore, EEG alpha reactivity during eyes open explained significant additional variability in psychomotor speed. CONCLUSION: EEG and MRI are each associated with different aspects of cognitive function and complement each other in their relations to psychomotor speed.

Aged↗
PubMed2006

Syncope in migraine: the population-based CAMERA study.

OBJECTIVE: To examine the association between migraine and syncope-related autonomic nervous system (ANS) symptoms. METHODS: A population-based study among migraineurs with and without aura (n = 323) and control subjects (n = 153) was conducted. A systematic questionnaire and cardiovascular measurements during rest, while standing, and after venipuncture addressed the prevalence of syncope, orthostatic intolerance, orthostatic hypotension (OH), and the postural tachycardia syndrome (POTS) in migraineurs and control subjects. RESULTS: The lifetime prevalence of syncope in all participants was 41%, more often in women (45 vs 32%; p = 0.02). Compared with control subjects, migraineurs had a higher lifetime prevalence of syncope (46 vs 31%; p = 0.001), frequent syncope (five or more attacks) (13 vs 5%; p = 0.02), and orthostatic intolerance (32 vs 12%; p < 0.001). There was no association between ANS symptoms and the severity of migraine or migraine subtype. Cardiovascular measurements and the prevalence of POTS and OH did not differ significantly between migraineurs and control subjects. CONCLUSION: This population-based study demonstrated an elevated prevalence of syncope and orthostatic intolerance in migraineurs without clear interictal signs of autonomic nervous system dysfunction.

Blood Pressure↗
PubMed2006

Memory activation enhances EEG abnormality in mild cognitive impairment.

This exploratory study investigated EEG power changes during memory activation in patients with amnestic mild cognitive impairment (MCI). Twelve MCI patients and 16 age-matched controls underwent EEG registration during two conventional EEG conditions ('eyes closed' and 'eyes open') and three memory conditions ('word memory', 'picture memory' and 'animal fluency'). For all conditions, EEG power in the theta (4-8 Hz), lower alpha (8-10.5 Hz) and upper alpha (10.5-13 Hz) bands were expressed as percentile changes compared to 'eyes closed'. MCI patients showed significantly less decrease in the lower alpha band than controls (p=0.04) during picture memory activation. The word memory task showed a trend towards a similar effect (p=0.09). This study suggests that memory activation reveals EEG differences between MCI patients and controls while conventional EEG conditions do not.

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PubMed2006

Progression of cerebral white matter lesions is not associated with development of depressive symptoms in elderly subjects at risk of cardiovascular disease: The PROSPER Study.

BACKGROUND: Cerebral white matter hyperintensities on magnetic resonance imaging (MRI) scans have been associated with vascular disease and late-life depression, both in the general population and in psychiatric patients. Therefore, a cerebrovascular etiology for late-onset depression has been hypothesized. However, longitudinal studies on the causal role of white matter hyperintensities in the development of depressive symptoms in elderly adults are lacking. OBJECTIVE: To investigate the relation between white matter hyperintensities and depressive symptoms in elderly subjects at risk of cardiovascular disease. METHODS: In the Dutch sample of the PROSPER (PROspective Study of Pravastatine in the Elderly at Risk of cardiovascular disease) cohort, 527 non-demented elderly, all aged 70 years or older, received a cranial MRI scan and the 15-item Geriatric Depression Scale, at baseline and 33 months (SD 1.6) later. RESULTS: Presence of white matter hyperintensities at baseline was not related to baseline depressive symptoms nor to the development of depressive symptoms during follow-up. Moreover, no association was found between progression of white matter lesion volume and progression of depressive symptoms. CONCLUSION: This longitudinal study does not confirm the involvement of cerebrovascular disease expressed as MRI white matter hyperintensities in the development of depressive symptoms in elderly subjects.

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PubMed2006

Increase in periventricular white matter hyperintensities parallels decline in mental processing speed in a non-demented elderly population.

OBJECTIVE: To investigate the influence of deep white matter hyperintensities (DWMH) and periventricular white matter hyperintensities (PVWMH) on progression of cognitive decline in non-demented elderly people. METHODS: All data come from the nested MRI sub-study of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). We performed a 3 year follow up study on 554 subjects of the PROSPER study using both repeated magnetic resonance imaging and cognitive testing. Cognitive decline and its dependency on WMH severity was assessed using linear regression models adjusted for sex, age, education, treatment group, and test version when applicable. RESULTS: We found that the volume of PVWMH at baseline was longitudinally associated with reduced mental processing speed (p = 0.0075). In addition, we found that the progression in PVWMH volume paralleled the decline in mental processing speed (p = 0.024). In contrast, neither presence nor progression of DWMH was associated with change in performance on any of the cognitive tests. CONCLUSION: PVWMH should not be considered benign but probably underlie impairment in cognitive processing speed.

Aged↗
PubMed2006

Intracranial compartment volumes in normal pressure hydrocephalus: volumetric assessment versus outcome.

BACKGROUND AND PURPOSE: Although enlargement of the cerebral ventricles plays a central role in the diagnosis of normal pressure hydrocephalus (NPH), there are no reports on the use of volumetric assessment to distinguish between patients who respond to ventriculoperitoneal shunt surgery and those who do not. The purpose of this study is to explore the association between preoperative intracranial compartment volumes and postoperative improvement. METHODS: Twenty-six patients (17 men; mean age, 75 years [range, 54-87 years]) with a clinical or radiologic suspicion of NPH were included in the study. Gait, cognition, and bladder function were evaluated by clinical rating. MR imaging of the brain was acquired at 0.5 T and 1.5 T. Total intracranial volume, ventricular volume, brain volume, and pericerebral CSF volume were determined by volumetric assessment. Four imaging variables were determined: ventricular volume ratio, brain volume ratio, pericerebral CSF volume ratio, and the ratio of ventricular volume to pericerebral CSF volume. All patients underwent ventriculoperitoneal shunt surgery. RESULTS: Clinical follow-up was assessed 1 year after shunt surgery. No difference in the mean ventricular volume ratio, the mean brain volume ratio, the mean pericerebral CSF volume ratio, and the mean ratio between ventricular and pericerebral CSF volume was found between subjects who improved on gait or cognition or bladder function and those who did not. CONCLUSION: Volumetric assessment has no predictive value in differentiating between NPH patients who respond to ventriculoperitoneal shunt surgery and those who do not.

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PubMed2006

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: structural MR imaging changes and apolipoprotein E genotype.

BACKGROUND AND PURPOSE: Apolipoprotein E (apoE) genotype plays an important role in the development, maintenance, and response to injury of the central nervous system. It has been suggested that apoE epsilon4 genotype is a risk factor for several neurologic disorders. We investigated the correlation between the apoE genotype and radiologic data in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). METHODS: T1-weighted, dual fast spin-echo, T2*-weighted gradient echo, and fluid-attenuated inversion recovery MR imaging scans were obtained from 36 CADASIL patients (21-59 years of age). The number of lacunar infarcts and microbleeds and the presence of subcortical lacunar lesions were determined. The amount of white matter hyperintensities was assessed by using semiautomated segmentation software. The relation between the radiologic endophenotype of CADASIL and the apoE genotype was assessed by using a Student t test for unpaired data and Fisher exact test. RESULTS: White matter hyperintensities, lacunar infarcts, microbleeds, and subcortical lacunar lesions were not found to be associated with the presence of an epsilon4 allele. CONCLUSION: The variability of structural MR imaging lesions in CADASIL is independent of apoE genotype and other processes must underlie the variable natural history of the disease.

Adult↗
PubMed2006

Measuring longitudinal white matter changes: comparison of a visual rating scale with a volumetric measurement.

BACKGROUND AND PURPOSE: Detection of longitudinal changes in white matter hyperintensities (WMH) by using visual rating scales is problematic. We compared a widely used visual rating scale with a volumetric method to study longitudinal white matter changes. METHODS: WMH were assessed with the visual Scheltens scale and a volumetric method in 100 elderly subjects aged 70-81 years for whom repetitive MR images were available with an interval of 33 (SD, 1.4) months. Reliability was determined by intraclass correlation coefficients. To examine the sensitivity of both the visual and volumetric method, we calculated Spearman rank correlations of WMH ratings and volume measurements with age. RESULTS: Reliability of the visual rating scale was good, whereas reliability of the volumetric measurement was excellent. For baseline measurements of WMH, we found weaker associations between WMH and age when assessed with the visual scale (r = 0.20, P = .045) than with the volumetric method (r = 0.31, P = .002). Longitudinal evaluation of WMH assessments showed regression in 26% of the subjects when analyzed with the visual rating scale against 12% of the subjects when using volumetric measurements. Compared with the visual rating, the correlation between progression in WMH and age was twice as high when using the volumetric measurement (r = 0.19, P = .062 and r = 0.39, P < .001, respectively). CONCLUSION: Volumetric measurements of WMH offer a more reliable, sensitive, and objective alternative to visual rating scales in studying longitudinal white matter changes.

Aged↗
PubMed2006

Not all age-related white matter hyperintensities are the same: a magnetization transfer imaging study.

PURPOSE: Our aim was to assess whether presumed histologic heterogeneity of age-related white matter hyperintensities (WMH) is reflected in quantitative magnetization transfer imaging measures. MATERIALS AND METHODS: From a group of patients participating in a double-blind placebo-controlled multicenter study on the effect of pravastatin (PROSPER), we selected 56 subjects with WMH. WMH were classified as periventricular WMH (PVWMH) and deep WMH (DWMH). PVWMH were subclassified as irregular or smooth, depending on the aspect of their border. Signal intensity of WMH on T1-weighted images was scored as iso- or hypointense. The mean magnetization transfer ratio (MTR) value of different types of WMH was assessed and compared. As a control group, we selected 19 subjects with no or limited WMH. RESULTS: Mean (SE) MTR of PVWMH (frontal, 31.2% [0.2%]; occipital, 32.2% [0.2%]) was lower than that of DWMH (33.7% [0.5%]). The mean MTR of frontal PVWMH (31.2% [0.2%]) was lower than that of occipital PVWMH (32.2% [0.2%]). Compared with occipital PVWMH, frontal PVWMH more often had a smooth lining (72% frontal versus 8% occipital) and an area with low signal intensity on T1-weighted images (76% frontal versus 35% occipital). MTR did not differ between smooth (31.1% [0.3%]) and irregular (31.6% [0.5%]) PVWMH. CONCLUSION: Age-related WMH are heterogeneous, despite their similar appearance on T2-weighted images. By taking into account heterogeneity of age-related WMH, both in terms of etiology and in terms of severity of tissue destruction, one may obtain better understanding on the causes and consequences of these lesions.

Age Factors↗
PubMed2005

Magnetization transfer imaging of gray and white matter in mild cognitive impairment and Alzheimer's disease.

OBJECTIVE: To assess whether structural brain damage as detected by magnetization transfer imaging (MTI) in Alzheimer's disease (AD) and mild cognitive impairment (MCI) is located in the gray matter (GM) and/or the white matter (WM). METHODS: Fifty-five AD patients, 19 MCI patients and 43 subjects with normal cognitive function participated in this study. GM and WM segmentations were generated from dual fast spin-echo MR images. These masks were co-registrated to MT images for volumetric MTI-analysis of the GM and WM. RESULTS: AD patients had a lower GM volume than controls. Both MCI and AD patients had more structural brain damage in both GM and WM than subjects with normal cognition. Cerebral lesion load in both GM and WM was associated with the degree of cognitive impairment. CONCLUSION: Using MTI, structural brain changes that are related to cognitive impairment could be demonstrated in both GM and WM of patients with AD and MCI. These results suggest that cerebral changes are present in GM and WM even before patients are clinically demented.

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PubMed2005

A randomized crossover study of bee sting therapy for multiple sclerosis.

BACKGROUND: Bee sting therapy is increasingly used to treat patients with multiple sclerosis (MS) in the belief that it can stabilize or ameliorate the disease. However, there are no clinical studies to justify its use. METHODS: In a randomized, crossover study, we assigned 26 patients with relapsing-remitting or relapsing secondary progressive MS to 24 weeks of medically supervised bee sting therapy or 24 weeks of no treatment. Live bees (up to a maximum of 20) were used to administer bee venom three times per week. The primary outcome was the cumulative number of new gadolinium-enhancing lesions on T1-weighted MRI of the brain. Secondary outcomes were lesion load on T2*-weighted MRI, relapse rate, disability (Expanded Disability Status Scale, Multiple Sclerosis Functional Composite, Guy's Neurologic Disability Scale), fatigue (Abbreviated Fatigue Questionnaire, Fatigue Impact Scale), and health-related quality of life (Medical Outcomes Study 36-Item Short Form General Health Survey). RESULTS: During bee sting therapy, there was no significant reduction in the cumulative number of new gadolinium-enhancing lesions. The T2*-weighted lesion load further progressed, and there was no significant reduction in relapse rate. There was no improvement of disability, fatigue, and quality of life. Bee sting therapy was well tolerated, and there were no serious adverse events. CONCLUSIONS: In this trial, treatment with bee venom in patients with relapsing multiple sclerosis did not reduce disease activity, disability, or fatigue and did not improve quality of life.

Adult↗
PubMed2005

Fully automatic segmentation of white matter hyperintensities in MR images of the elderly.

The role of quantitative image analysis in large clinical trials is continuously increasing. Several methods are available for performing white matter hyperintensity (WMH) volume quantification. They vary in the amount of the human interaction involved. In this paper, we describe a fully automatic segmentation that was used to quantify WMHs in a large clinical trial on elderly subjects. Our segmentation method combines information from 3 different MR images: proton density (PD), T2-weighted and fluid-attenuated inversion recovery (FLAIR) images; our method uses an established artificial intelligent technique (fuzzy inference system) and does not require extensive computations. The reproducibility of the segmentation was evaluated in 9 patients who underwent scan-rescan with repositioning; an inter-class correlation coefficient (ICC) of 0.91 was obtained. The effect of differences in image resolution was tested in 44 patients, scanned with 6- and 3-mm slice thickness FLAIR images; we obtained an ICC value of 0.99. The accuracy of the segmentation was evaluated on 100 patients for whom manual delineation of WMHs was available; the obtained ICC was 0.98 and the similarity index was 0.75. Besides the fact that the approach demonstrated very high volumetric and spatial agreement with expert delineation, the software did not require more than 2 min per patient (from loading the images to saving the results) on a Pentium-4 processor (512 MB RAM).

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PubMed2005

Effect of pravastatin on cerebral infarcts and white matter lesions.

The authors examined the effect of pravastatin 40 mg daily on the progression of ischemic brain lesions using repeated brain MRI. After a mean treatment period of 33 months, there was an increase in total ischemic lesion load of 1.1 cm3 (p < 0.001) in the 270 placebo-treated subjects and 1.1 cm3 (p < 0.001) in the 265 pravastatin-treated subjects. There was no difference between the two treatment groups (p = 0.73).

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PubMed2005

Microbleeds in hereditary cerebral hemorrhage with amyloidosis-Dutch type.

In a hereditary variant of cerebral amyloid angiopathy (CAA), cerebral hemorrhage with amyloidosis-Dutch type, supratentorial microbleeds were found to occur independently of the presence of hypertension, whereas hypertension probably contributed to the development of cerebellar microbleeds. This predictable hereditary variant of CAA may be a useful model to study microbleeds in relation to CAA.

Adult↗
PubMed2005

MRI findings in migraine.

INTRODUCTION: For long time, migraine has been considered to be an episodic, multifactorial, neurovascular disorder, without long-term consequences to the brain, although an association between migraine and clinical stroke and white matter hyperintense lesions has been suggested in numerous studies. Due to various methodological problems no definite conclusion could be drawn from these studies. STATE OF THE ART: Recently, data from a population-based cross-sectional MRI study were published, establishing migraine to be a true and independent risk factor for white matter lesions (in female migraine patients) and subclinical posterior circulation territory infarcts. PERSPECTIVES: The methodology and results of previous investigations of a relationship between migraine and clinical ischemic stroke, silent infarction and white matter lesions are reviewed, and integrated in the results from the new population-based MRI study. CONCLUSION: Brain infarction occurs far more frequently than expected in migraine patients, most pronounced in migraine with aura (8 percent have subclinical cerebellar infarcts), although most infarcts remain clinically silent. Female migraine patients are at increased risk of deep white matter lesions, independent of the effects of cardiovascular risk factors. The influence of migraine severity (attack frequency) on the risk of both types of lesions suggests a causal relationship between migraine severity and lesion load. Future studies are needed to assess whether these (probably) ischemic lesions have relevant (long-term) functional correlates.

Brain↗
PubMed2004

Different progression rates for deep white matter hyperintensities in elderly men and women.

The authors investigated the progression of white matter hyperintensities (WMHs) in a large population of elderly men and women. After 3 years of follow-up, women had accumulated approximately twice as much deep WMH (DWMH) as men. The progression of periventricular WMH was the same for men and women. Gender differences may affect the pathogenesis of DWMH, which in turn may result in different clinical consequences in women.

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