Biomedical subjects

Matthijs Oudkerk

Publications and source records attributed to Matthijs Oudkerk.

At least 37 records · Page 2Linked to original sources

PubMed2005

The association between angiotensin-converting enzyme gene polymorphism and coronary calcification. The Rotterdam Coronary Calcification Study.

BACKGROUND: An insertion/deletion (I/D) polymorphism in the gene encoding angiotensin-converting enzyme (ACE) has been associated with serum ACE levels. The association between the ACE I/D polymorphism and coronary heart disease is unclear. Electron-beam-computed tomography (EBT) is a technique to non-invasively quantify the amount of coronary calcification. We investigated the association between the ACE I/D polymorphism and coronary calcification. METHODS AND RESULTS: The Rotterdam Coronary Calcification Study is a population-based study in subjects aged 55 years and over. EBT scanning was performed in 2013 participants. Coronary calcification was quantified according to the Agatston score. The ACE I/D polymorphism was available for 1976 subjects. Geometric mean calcium scores in men with the II, ID and DD genotype were 167, 207 and 219, respectively. However, the difference in calcium score (p=0.19 for ID versus II; p=0.15 for DD versus II) and the trend (ptrend=0.17) were not significant. Calcium scores in women with the II, ID and DD genotype were 44, 42 and 36, respectively. There were no significant differences in calcium score (p=0.78 for ID versus II; p=0.29 for DD versus II), neither was the trend (ptrend=0.27). After we stratified on cardiovascular risk factors, no associations were present. CONCLUSION: The present study failed to show an association between the ACE I/D polymorphism and coronary calcification in the general population. Also, no significant associations were present between the ACE I/D polymorphism and coronary calcification in strata of cardiovascular risk factors.

Aged↗

PubMed2004

1H Magnetic resonance spectroscopy of the internal capsule in human brain: a feasibility study to detect lactate following contralateral motor activity.

Animal experiments suggest that astrocytic glycogen may act as an energy source for axons especially during heightened activity. In this model astrocytic glycogen breaks down to lactate that is shuttled to axons where it is metabolized oxidatively to generate ATP. The aim of this study was to investigate whether (1)H-magnetic resonance spectroscopy could be used to detect a rise in lactate levels in human white matter during enhanced axonal activation. Six healthy volunteers (four women and two men; age range 21-38 years) participated in the study. We were unable to detect any significant MR spectral change, i.e. neither in the peak areas of inositol, choline, creatine, glutamate and N-acetylaspartate nor in the lactate level, in the contralateral posterior limb of the internal capsule during intense motor activation of the hand (four successive episodes of squeezing a soft ball for 7 min followed by 7 min rest). Possible explanations are that the technique is not sensitive enough to detect a small rise in lactate, or lactate turnover is too fast to be detected, or that another monocarboxylate different from lactate may be involved in axonal energy metabolism.

Adenosine Triphosphate↗

PubMed2004

Alcohol consumption and coronary calcification in a general population.

BACKGROUND: A U- or J-shaped association exists between alcohol consumption and coronary heart disease. One of the proposed mechanisms for this association involves atherogenesis, but there are no data on the association between alcohol consumption and coronary atherosclerosis in asymptomatic subjects. Coronary calcification, a measure of coronary atherosclerosis, allows for the study of the association. METHODS: This cross-sectional study was performed using data from the population-based Rotterdam Coronary Calcification Study. Data on alcohol consumption were available for 1795 individuals without coronary heart disease. Mean +/- SD age of the participants was 71 +/- 5.7 years. Coronary calcification was detected on electron beam computed tomographic scans and quantified as a calcium score by the Agatston method. Extensive coronary calcification was defined as a calcium score above 400. RESULTS: In this population, 15.8% of individuals consumed no alcohol; 46.5% consumed 1 alcoholic drink or less per day; 16.9% consumed 1 to 2 drinks per day; and 20.9% consumed more than 2 drinks per day. A U-shaped association was found between alcohol consumption and coronary calcification. Compared with nondrinkers, the odds ratio of extensive coronary calcification was 0.60 (95% confidence interval [CI], 0.44-0.82) for those who consumed 1 drink or less daily; 0.51 (95% CI, 0.35-0.76) for those who consumed 1 to 2 drinks daily; and 0.90 (95% CI, 0.62-1.29) for those who consumed more than 2 drinks. The association remained after multivariate adjustment. CONCLUSIONS: The consumption of 2 alcoholic drinks or fewer per day was inversely associated with extensive coronary calcification. The risk of extensive coronary calcification was 50% lower in individuals who consumed 1 to 2 alcoholic drinks per day than in nondrinkers.

Aged↗

PubMed2004

Visual stimulation, 1H MR spectroscopy and fMRI of the human visual pathways.

The purpose was to assess changes in lactate content and other brain metabolites under visual stimulation in optical chiasm, optic radiations and occipital cortex using multiple voxel MR spectroscopy (MRS). 1H chemical shift imaging (CSI) examinations of transverse planes centered to include the above structures were performed in four subjects at an echo time of 135 ms. Functional MRI (fMRI) was used to confirm the presence of activity in the visual cortex during the visual stimulation. Spectral maps of optical chiasm were of poor quality due to field disturbances caused by nearby large blood vessels and/or eye movements. The optic radiations and the occipital lobe did not show any significant MR spectral change upon visual stimulation, i.e., the peak areas of inositol, choline, creatine, glutamate and N-acetylaspartate were not affected. Reproducible lactate signals were not observed. fMRI confirmed the presence of strong activations in stimulated visual cortex. Prolonged visual stimulation did not cause significant changes in MR spectra. Any signal observed near the 1.33 ppm resonance frequency of the lactate methyl-group was artifactual, originating from lipid signals from outside the volume of interest (VOI). Previous claims about changes in lactate levels in the visual cortex upon visual stimulation may have been based on such erroneous observations.

Adult↗

PubMed2004

The association between blood pressure, hypertension, and cerebral white matter lesions: cardiovascular determinants of dementia study.

Cerebral white matter lesions are frequently observed on magnetic resonance imaging (MRI) scans in elderly people and are associated with stroke and dementia. Elevated blood pressure is presumed one of the main risk factors, although data are almost exclusively derived from cross-sectional studies. We assessed in 10 European cohorts the relation between concurrently and previously measured blood pressure levels, hypertension, its treatment, and severe cerebral white matter lesions. In total, 1805 nondemented subjects aged 65 to 75 years were sampled from ongoing community-based studies that were initiated 5 to 20 years before the MRI. White matter lesions in the periventricular and subcortical region were rated separately using semiquantitative measures. We performed logistic regression analyses adjusted for potential confounders in 1625 people with complete data. Concurrently and formerly assessed diastolic and systolic blood pressure levels were positively associated with severe white matter lesions. Both increases and decreases in diastolic blood pressure were associated with more severe periventricular white matter lesions. Increase in systolic blood pressure levels was associated with more severe periventricular and subcortical white matter lesions. People with poorly controlled hypertension had a higher risk of severe white matter lesions than those without hypertension, or those with controlled or untreated hypertension. Higher blood pressure was associated with an increased risk of severe white matter lesions. Successful treatment of hypertension may reduce this risk; however, a potential negative effect of decreasing diastolic blood pressure level on the occurrence of severe periventricular white matter lesions should be taken into account.

Aged↗

PubMed2004

Detection, visualization and evaluation of anomalous coronary anatomy on 16-slice multidetector-row CT.

Early identification and evaluation of relatively frequent anomalous coronary anatomy is quite relevant because of the occurrence of sudden cardiac death or related symptoms of myocardial ischemia. Selective coronary angiography (CAG) is invasive, expensive and cannot always provide the required information adequately. Recently, non-invasive imaging techniques such as magnetic resonance imaging and multidetector-row computed tomography (MDCT) have been shown to provide a good anatomical view of the coronary artery tree. This study aims to demonstrate the value of 16-MDCT for evaluation of anomalous coronary anatomy. In 13 patients scanned using 16-MDCT, six different coronary anomalies were diagnosed [two absent left main, one single vessel left coronary artery (LCA), three LCA originating from the right (two with interarterial course), six right coronary artery originating from the left, one double left anterior descending (LAD)]. Mean diagnostic quality, recorded by two observers using a 5-point scale (1= non-diagnostic to 5= excellent diagnostic quality), resulted in a mean score of 3.73 (SD 1.19) without any non-diagnostic result. MDCT offers an accurate diagnostic modality to visualize the origin and course of anomalous coronary arteries by a three-dimensional display of anatomy. Shortcomings in CAG can be overcome by the use of contrast-enhanced MDCT.

Adult↗

PubMed2004

Influence of scoring parameter settings on Agatston and volume scores for coronary calcification.

Current multi-detector CT and electron beam tomography (EBT) technology enables the evaluation of coronary calcification. Multiple software packages are available to quantify calcification using several scoring algorithms implementing user-definable scoring parameters. We investigated the effect of scoring parameters on the calcium score outcome. Three parameters (four-connected or eight-connected, lesion size threshold and interpolation) are evaluated. Their theoretical influence on the scoring outcome is shown using simplified examples. To evaluate the effect in real data, we performed calcium scoring on randomly chosen EBT scans from 50 participants in an epidemiological study. Both the Agatston and volume scores were calculated. Changing from eight-connected to four-connected connectivity decreased both Agatston and volume scores (mean variability Agatston 3.15% and volume score -3.52%). Decreasing the threshold from 4 to 2 pixels increased the calcium scores because smaller lesions were also selected as calcified plaques (mean variability Agatston 16.23% and volume score 18.66%). Finally, the use of interpolation had a large negative effect on the volume score (mean variability -29.67%) and almost no effect on the Agatston score. Parameter settings in software for quantification for coronary calcification affect the calcium score outcome. Therefore, parameter settings for calcium scoring should be standardized.

Aged↗

PubMed2004

1H MR chemical shift imaging detection of phenylalanine in patients suffering from phenylketonuria (PKU).

Short echo time single voxel methods were used in previous MR spectroscopy studies of phenylalanine (Phe) levels in phenylketonuria (PKU) patients. In this study, apparent T2 relaxation time of the 7.3-ppm Phe multiplet signal in the brain of PKU patients was assessed in order to establish which echo time would be optimal. 1H chemical shift imaging (CSI) examinations of a transverse plain above the ventricles of the brain were performed in 10 PKU patients and 11 persons not suffering from PKU at 1.5 T, using four echo times (TE 20, 40, 135 and 270 ms). Phe was detectable only when the signals from all CSI voxels were summarized. In patients suffering from PKU the T2 relaxation times of choline, creatine and N-acetyl aspartate (NAA) were similar to those previously reported for healthy volunteers (between 200 and 325 ms). The T2 of Phe in brain tissue was 215 +/- 120 ms (standard deviation). In the PKU patients the brain tissue Phe concentrations were 141 +/- 69 microM as opposed to 58 +/- 23 microM in the persons not suffering from PKU. In the detection of Phe, MR spectroscopy performed at TE 135 or 270 ms is not inferior to that performed at TE 20 or 40 ms (all previous studies). Best results were obtained at TE=135 ms, relating to the fact that at that particular TE, the visibility of a compound with a T2 of 215 ms still is good, while interfering signals from short-TE compounds are negligible.

Adolescent↗

PubMed2004

Dobutamine stress MRI. Part I. Safety and feasibility of dobutamine cardiovascular magnetic resonance in patients suspected of myocardial ischemia.

The aim of the study was to evaluate safety and feasibility of dobutamine cardiovascular magnetic resonance (CMR) in patients with proven or suspected coronary artery disease. Dobutamine CMR was evaluated retrospectively in 400 consecutive patients with suspicion of myocardial ischemia. Dobutamine was infused using an incremental protocol up to 40 microg/kg body weight per minute. All anti-anginal medication was stopped 4 days before the CMR study and infusion time of dobutamine was 6 min per stage. Hemodynamic data, CMR findings and side effects were reported. Patients with contraindications to CMR (metallic implants and claustrophobia) were excluded from analysis. Dobutamine CMR was successfully performed in 355 (89%) patients. Forty-five (11%) patients could not be investigated adequately because of non-cardiac side effects in 29 (7%) and cardiac side effects in 16 (4%) patients. Hypotension (1.5%) and arrhythmias (1%) were the most frequent cardiac side effects. One patient developed a severe complication (ventricular fibrillation) at the end of the study. There were no myocardial infarctions or fatal complications of the stress test. The most frequent non-cardiac side effects were nausea, vomiting and claustrophobia. Age >70 years, prior myocardial infarction and rest wall motion abnormalities showed no significant differences with side effects (P>0.05). Dobutamine CMR is safe and feasible in patients with suspicion of myocardial ischemia.

Aged↗

PubMed2004

Dobutamine stress MRI. Part II. Risk stratification with dobutamine cardiovascular magnetic resonance in patients suspected of myocardial ischemia.

The aim of this study was to determine the prognostic value of dobutamine cardiovascular magnetic resonance (CMR) in patients suspected of myocardial ischemia. Clinical data and dobutamine-CMR results were analyzed in 299 consecutive patients. Follow-up data were analyzed in categories of risk levels defined by the history of coronary artery disease and presence of rest wall motion abnormalities (RWMA). Major adverse cardiac events (MACE) as evaluated end points included cardiac death, nonfatal myocardial infarction and clinically indicated coronary revascularization. Follow-up was completed in 214 (99%) patients with a negative dobutamine-CMR study (no signs of inducible myocardial ischemia) with an average of 24 months. The patients with a negative dobutamine-CMR study and RWMA showed a significantly higher annual MACE rate (18%) than the patients without RWMA (0.56%) ( P<0.001). Patients without RWMA showed an annual MACE rate of 2% when they had a history of coronary artery disease and <0.1% without a previous coronary event ( P<0.001). Dobutamine-CMR showed a positive and negative predictive value of 95 and 93%, respectively. The cardiovascular occurrence-free survival rate was 96.2%. In patients suspected of myocardial ischemia, dobutamine-CMR is able to assess risk levels for coronary events with high accuracy.

Cardiotonic Agents↗

PubMed2004

Cerebral white matter lesions and the risk of dementia.

OBJECTIVE: To study the association between white matter lesions (WML) in specific locations and the risk of dementia. DESIGN: The Rotterdam Scan Study, a prospective population-based cohort study. We scored periventricular and subcortical WML on magnetic resonance imaging and observed participants until January 2002 for incident dementia. SETTING: General population. PARTICIPANTS: We included 1077 people aged 60 to 90 years who did not have dementia at baseline. MAIN OUTCOME MEASURE: Incident dementia by Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM III-R) criteria. RESULTS: During a mean follow-up of 5.2 years, 45 participants developed dementia. Higher severity of periventricular WML increased the risk of dementia, whereas the association between subcortical WML and dementia was less prominent. The adjusted hazard ratio of dementia for each standard deviation increase in periventricular WML severity was 1.67 (95% confidence interval, 1.25-2.24). This increased risk was independent of other risk factors for dementia and partly independent of other structural brain changes on magnetic resonance imaging. CONCLUSION: White matter lesions, especially in the periventricular region, increase the risk of dementia in elderly people.

Age Factors↗

PubMed2004

The association of Rose questionnaire angina pectoris and coronary calcification in a general population: the Rotterdam Coronary Calcification Study.

PURPOSE: The Rose questionnaire is a standardized method of measuring angina pectoris in general populations. Electron-beam computed tomography (CT) is a non-invasive technique to quantify the amount of coronary calcification. In a population-based study, we investigated the association between Rose questionnaire angina pectoris and coronary calcification. METHODS: The Rotterdam Coronary Calcification Study is embedded in the Rotterdam Study, a population-based study in subjects aged > or = 55 years. Participants of the Rotterdam Coronary Calcification Study underwent an electron-beam CT scan between 1997 and 2000. Coronary calcification was quantified in a calcium score according to Agatston's method. Rose questionnaire angina pectoris was assessed during a home interview. The first 2013 participants were included in the present analyses. RESULTS: In men, the presence of Rose questionnaire angina pectoris was associated with a 12.9-fold (95% confidence interval: 3.8-43.7) increased risk of a calcium score >1000 (reference: calcium score 0-100). The corresponding relative risk in women was 4.8 (2.0-11.3). Similar results were found when we computed sex-specific quartiles of the calcium score. CONCLUSIONS: Rose questionnaire angina pectoris is strongly associated with the amount of coronary calcification. Rose questionnaire angina pectoris corresponds better with the amount of coronary calcification in men than in women.

Aged↗

PubMed2004

Risk factors for coronary calcification in older subjects. The Rotterdam Coronary Calcification Study.

AIMS: We examined associations between cardiovascular risk factors and coronary calcification assessed by electron-beam tomography (EBT) in an unselected population of older subjects. METHODS AND RESULTS: The Rotterdam Coronary Calcification Study is a population-based study in subjects > =55 years. Participants underwent EBT scanning. Coronary calcification was quantified according to the Agatston score. Cardiovascular risk factors were assessed 7 years before and concurrently to scanning. We used the first 2013 participants for the present analyses. Risk factors assessed 7 years before scanning were strongly associated with calcium score. Associations with blood pressure and cholesterol attenuated when measured concurrently to scanning. Although the number of risk factors was strongly associated with a high calcium score in asymptomatic subjects, 29% of the men and 15% of the women without risk factors had a high calcium score. CONCLUSIONS: This population-based study in older subjects shows that cardiovascular risk factors are associated with coronary calcification. Associations were stronger for risk factors measured at earlier age. Almost 30% of the men and 15% of the women without risk factors had extensive coronary calcification.

Age Distribution↗

PubMed2003

Coronary calcification at electron-beam CT: effect of section thickness on calcium scoring in vitro and in vivo.

PURPOSE: To compare the accuracy of electron-beam computed tomography (CT) with 3.0- and 1.5-mm section thickness for calcium quantification and the prevalence of coronary calcifications with each. MATERIALS AND METHODS: Electron-beam CT images were acquired with nonoverlapping 1.5- and 3.0-mm section thickness. Scans were obtained in an anthropomorphic thorax phantom with calcium cylinders of different sizes and densities, as well as in 1,302 study participants. A calcified lesion was defined as a minimum of 2 pixels (area, 0.52 mm2) with a minimum attenuation of 130 HU. The calcified lesions were quantified by means of a volumetric method with isotropic interpolation. From the phantom scans, mean volume scores, SDs, and measurement variations were calculated. From the participant scans, median volume scores and interquartile ranges were calculated. Participants were classified in categories based on cutoff levels for volume score quartiles for the 1.5-mm scans. An intraclass correlation coefficient (kappa value) was calculated as a measure of correlation between categories. RESULTS: In the phantom, deviations of calculated volumes from the true cylinder volumes and measurement variations were generally higher for the 3.0-mm protocol than for the 1.5-mm protocol. In the participants, the median volume score was 100 mm3 (interquartile range, 11-409 mm3) for the 3.0-mm protocol and 144 mm3 (interquartile range, 35-513 mm3) for the 1.5-mm protocol. Agreement between classifications of volume scores for the 1.5- and 3.0-mm scans was good (kappa = 0.62, P <.001). Compared with the quartile classification for the 1.5-mm scan, however, classifications for 370 (28%) participants were put in a different category with the 3.0-mm protocol. CONCLUSION: In a phantom, electron-beam CT scans with 3.0-mm section thickness yield less accurate estimates of calcified volume than do 1.5-mm scans. Electron-beam CT protocols with thinner sections considerably affect classification of individuals on the basis of the amount of coronary calcification depicted.

Aged↗

PubMed2003

Coronary artery imaging with multidetector CT: visualization issues.

Noninvasive imaging of the coronary arteries has attracted growing interest in the past few years. One of the possible acquisition techniques is multidetector computed tomography (CT) that produces large three-dimensional (3D) data sets that require visualization techniques for data evaluation. The objective of this article is to increase knowledge of possible 3D visualization techniques together with their advantages and disadvantages for the routine evaluation of cardiac data sets. Common imaging techniques available to the radiologist at standard workstations are multiplanar reformation (MPR), oblique MPR, curved MPR, maximum-intensity projection (MIP), shaded-surface display, and direct volume rendering. Each of these techniques has its advantages and disadvantages for the visualization of the coronary artery tree. Several additions to the basic techniques have been developed to overcome some of their shortcomings. Different clinical examinations, such as stent evaluation, stenosis evaluation, and bypass evaluation, require different visualization techniques. The choice of preferred technique for each clinical study depends on the advantages and disadvantages of the various techniques as described in the literature. Because of the large number of possible settings and projection angles, it is important for users to interactively manipulate the images and review the whole vessel volume rather than just looking at static reformatted images. Errors such as findings of false stenoses can be avoided by means of accurate and appropriate use of software features. This requires training of users both with regard to the capabilities of the software and the background of the different techniques and their possible pitfalls. The authors believe that volume rendering of the whole heart is useful for anatomic evaluation of the coronary arteries. For more detailed observation of specific lesions, slab imaging with volume rendering or MIP is required.

Coronary Angiography↗

PubMed2003

Dobutamine cardiovascular magnetic resonance for the detection of myocardial ischemia with the use of myocardial tagging.

BACKGROUND: The purpose of this study was to assess the value of high-dose dobutamine cardiovascular magnetic resonance (CMR) with myocardial tagging for the detection of wall motion abnormalities as a measure of myocardial ischemia in patients with known or suspected coronary artery disease. METHODS AND RESULTS: Two hundred eleven consecutive patients with chest pain underwent dobutamine-CMR 4 days after antianginal medication was stopped. Dobutamine-CMR was performed at rest and during increasing doses of dobutamine. Cine-images were acquired during breath-hold with and without myocardial tagging at 3 short-axis levels. Regional wall motion was assessed in a 16-segment short-axis model. Patients with new wall motion abnormalities (NWMA) were examined by coronary angiography. Dobutamine-CMR was successfully performed in 194 patients. Dobutamine-CMR without tagging detected NWMA in 58 patients, whereas NWMA were detected in 68 patients with tagging (P=0.002, McNemar). Coronary angiography showed coronary artery disease in 65 (96%) of these 68 patients. All but 3 of the 65 patients needed revascularization. In the 112 patients with a negative dobutamine-CMR study, without baseline wall motion abnormalities, the cardiovascular occurrence-free survival rate was 98.2% during the mean follow-up period of 17.3 months (range, 7 to 31). CONCLUSIONS: Dobutamine-CMR with myocardial tagging detected more NWMA compared with dobutamine-CMR without tagging and reliably separated patients with a normal life expectancy from those at increased risk of major adverse cardiac events.

Coronary Angiography↗

PubMed2003

Brain changes with aging: MR spectroscopy at supraventricular plane shows differences between women and men.

PURPOSE: To assess the effect of aging on the proportions of choline (Cho), creatine, and N-acetylaspartate (NAA) in the brains of elderly women and men. MATERIALS AND METHODS: A transverse plane above the ventricle of the brain was mapped with magnetic resonance spectroscopy. Examinations were performed in 1995-1996 with 271 healthy subjects (age range, 60-90 years; mean age, 73 years) and were repeated 4 years later (1999-2000). Student t tests were used for statistical analysis. RESULTS: Difference analysis of the changes in 4 years (paired data) reproduced the decrease in Cho in women only (2.9% per year, P <.001) that had been indicated with intersubject correlation analyses. Decreases in NAA, though significant in both men and women according to age correlation analyses (P <.01 for both), did not reach significance. The resulting sex difference in the Cho/NAA ratio at a mean age of 77 years, while not yet significant at a mean age of 73 years, was especially manifest in the posterior half of the plane analyzed. CONCLUSION: Increasing sex differences in Cho/NAA ratios in a supraventricular plane indicate that brain metabolite levels differ between women and men at advanced age.

Aged↗

PubMed2003

MRI for the diagnosis of pulmonary embolism.

Pulmonary embolism (PE) is one of the most frequently encountered clinical emergencies. The diagnosis often involves multiple diagnostic tests, which need to be carried out rapidly to assist in the safe management of the patient. Recent strides in computed tomography (CT) have made big improvements in patient management and efficiency of diagnostic imaging. This review article describes the developments in magnetic resonance (MR) techniques for the diagnosis of acute PE. Techniques include MR angiography (MRA) and thrombus imaging for direct clot visualization, perfusion MR, and combined perfusion-ventilation MR. As will be demonstrated, some of these techniques are now entering the clinical arena, and it is anticipated that MR imaging (MRI) will have an increasing role in the initial diagnosis and follow-up of patients with acute PE.

Acute Disease↗