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A de Roos

Publications and source records attributed to A de Roos.

At least 73 records · Page 4Linked to original sources
PubMed1999

Biventricular diastolic cardiac function assessed by MR flow imaging using a single angulation.

PURPOSE: To evaluate whether one single angulation is reliable for biventricular diastolic MR flow measurements across both the mitral and tricuspid valves. MATERIAL AND METHODS: MR flow imaging was performed in 14 healthy volunteers and 14 patients with pulmonary fibrosis. Flow curve parameters were calculated from the mitral valve in mitral valve angulation, the tricuspid valve in tricuspid valve angulation, and also from the mitral valve in tricuspid valve angulation and the tricuspid valve in mitral valve angulation. RESULTS: For flow through the mitral valve, there were no significant differences between angulation set parallel to the mitral valve and angulation set parallel to the tricuspid valve for the diastolic inflow volume, the E-peak and the E:A ratio as measured in healthy volunteers and patients. The tricuspid valve flow was imaged well when the angulation was set parallel to the tricuspid valve, but not when angulation was set parallel to the mitral valve. The results indicate that the inflow volumes, the E-peak, and the E:A peak ratios across the mitral valve and tricuspid valve can be obtained using one single angulation which is set parallel to the tricuspid valve. CONCLUSION: Biventricular diastolic flow measurements can be obtained using one single angulation set parallel to the tricuspid valve.

Blood Flow Velocity↗
PubMed1998

Changes in aortic distensibility and pulse wave velocity assessed with magnetic resonance imaging following beta-blocker therapy in the Marfan syndrome.

It has been shown that beta-adrenergic blocking agents may reduce the rate of aortic root dilation and the development of aortic complications in patients with the Marfan syndrome. This may be due to beta-blocker-induced changes in aortic stiffness, of which distensibility and pulse wave velocity are in vivo measurable derivatives. We studied changes in distensibility at 4 levels of the aorta and pulse wave velocity along the entire aorta after 2 weeks of beta-blocker therapy in 6 Marfan syndrome patients and in 6 healthy volunteers, using magnetic resonance imaging (MRI) combined with brachial artery blood pressure measurements. In both groups, mean blood pressure decreased significantly (Marfan: 86 +/- 6 vs 78 +/- 5 mm Hg, p <0.05; control: 80 +/- 8 vs 73 +/- 3 mm Hg, p <0.05) (all data expressed as mean +/- 1 SD). At baseline, the Marfan syndrome patients exhibited decreased distensibility at the level of the ascending aorta (2 +/- 1 vs 6 +/- 2 10(-3)mm Hg(-1), p <0.01) and increased pulse wave velocity (6.2 +/- 0.4 vs 3.9 +/- 0.4 ms(-1), p <0.01) compared with control subjects. Only the Marfan syndrome patients had a significant increase in aortic distensibility at multiple levels and a significant decrease in pulse wave velocity after beta-blocker therapy (ascending aorta distensibility: 2 +/- 1 vs 4 +/- 1 10(-3)mm Hg(-1), p <0.05; abdominal aorta distensibility: 5 +/- 2 vs 8 +/- 3 10(-3)mm Hg(-1), p <0.05; pulse wave velocity: 6.2 +/- 0.4 vs 5.0 +/- 1.0 ms(-1), p <0.05). Thus, aortic stiffness in Marfan syndrome, together with mean blood pressure, is reduced by beta-blocker therapy, and MRI is well suited to detect these changes by measuring distensibility and pulse wave velocity.

Adolescent↗
PubMed1998

Functional and metabolic evaluation of the athlete's heart by magnetic resonance imaging and dobutamine stress magnetic resonance spectroscopy.

BACKGROUND: The question of whether training-induced left ventricular hypertrophy in athletes is a physiological rather than a pathophysiological phenomenon remains unresolved. The purpose of the present study was to detect any abnormalities in cardiac function in hypertrophic hearts of elite cyclists and to examine the response of myocardial high-energy phosphate metabolism to high workloads induced by atropine-dobutamine stress. METHODS AND RESULTS: We studied 21 elite cyclists and 12 healthy control subjects. Left ventricular mass, volume, and function were determined by cine MRI. Myocardial high-energy phosphates were examined by 31P magnetic resonance spectroscopy. There were no significant differences between cyclists and control subjects for left ventricular ejection fraction (59+/-5% versus 61+/-4%), left ventricular cardiac index (3.4+/-0.4 versus 3.4+/-0.4 L x min(-1) x m[-2]), peak early filling rate (562+/-93 versus 535+/-81 mL/s), peak atrial filling rate (315+/-93 versus 333+/-65 mL/s), ratio of early and atrial filling volumes (3.0+/-1.0 versus 2.6+/-0.6), mean acceleration gradient of early filling (5.2+/-1.4 versus 5.8+/-1.9 L/s2), mean deceleration gradient of early filling(-3.1 +/- 0.9 versus -3.2 +/- 0.7 L/s2), mean acceleration gradient of atrial filling (3.6+/-1.8 versus 4.5+/-1.7 L/s2), and atrial filling fraction (0.23+/-0.06 versus 0.26+/-0.04, respectively). Cyclists and control subjects showed similar decreases in the ratio of myocardial phosphocreatine to ATP measured with 31P magnetic resonance spectroscopy during atropine-dobutamine stress (1.41+/-0.20 versus 1.41+/-0.18 at rest to 1.21+/-0.20 versus 1.16+/-0.13 during stress, both P=NS). CONCLUSIONS: Left ventricular hypertrophy in cyclists is not associated with significant abnormalities of cardiac function or metabolism as assessed by MRI and spectroscopy. These observations suggest that training-induced left ventricular hypertrophy in cyclists is predominantly a physiological phenomenon.

Adaptation, Physiological↗
PubMed1998

Activity of Crohn's disease assessed by measurement of superior mesenteric artery flow with Doppler ultrasound.

PURPOSE: To investigate the value of superior mesenteric artery (SMA) Doppler flow measurements as a marker for disease activity in patients with Crohn's disease. MATERIALS AND METHODS: Duplex Doppler sonographic measurements of SMA bloodflow volume were obtained in 90 patients with suspected or known Crohn's disease in three separate studies. The first study was a pilot study to ascertain the value of Doppler measurements in patients with proven active or inactive disease and to check our performance. In two following studies prospectively a correlation was sought between the independent assessment of Doppler flow measurements and our standard of reference based on clinical history, physical examination, laboratory values, endoscopy, surgery and/or follow-up and prospectively a correlation was sought between Doppler studies and the results of enteroclysis. RESULTS: In all but two patients (study II) adequate measurements of SMA flow were obtained. In the active patient groups the Doppler SMA flow was significantly increased (P < 0.05) compared to the inactive patient groups and the control groups. CONCLUSION: These studies show that SMA Doppler flow measurements can be used as a parameter to assess disease activity in patients with Crohn's disease.

Adolescent↗
PubMed1998

A new diagnostic approach to vascular rings and pulmonary slings: the role of MRI.

UNLABELLED: The conventional diagnostic work-up of a patient suspected of having a vascular cause for stridor, or dysphagia, includes esophagography and bronchoscopy to delineate the abnormal structure without imaging the structure itself. Cine-angiography is regarded as the golden standard, but is not routinely performed. Magnetic resonance imaging (MRI) is non-invasive and has the important advantage over cine-angiography of depicting all structures in the field of view. Color Doppler echocardiography depicts the great vessels, but not the esophagus and trachea. In 14 patients with obstructive symptoms and in four patients without obstructive symptoms MRI successfully imaged the abnormal structure, as was the case in two symptomatic patients using computer tomography. In this series, the findings were confirmed at surgery or by cine-angiography. CONCLUSION: we suggest that in patients suspected of having a vascular cause for stridor or dysphagia, MRI should be performed. If there is need for a screening procedure, color Doppler echocardiography should be used and if that is equivocal or non-conclusive, esophagography and bronchoscopy should be used. If MRI is difficult to interpret, it should be augmented by magnetic resonance angiography before considering cine-angiography.

Adult↗
PubMed1998

Objective stenosis quantification from post-stenotic signal loss in phase-contrast magnetic resonance angiographic datasets of flow phantoms and renal arteries.

In this study a semi-automated and observer-independent algorithm for quantifying post-stenotic signal loss (PSL) in three-dimensional phase-contrast (PC) magnetic resonance angiography (MRA) of patients with renal artery stenosis is presented. This algorithm was developed on MRA datasets of stenotic phantoms, included in a flow circuit with stationary flows. The length and the severity of the PSL (incorporating both the length and the degree of PSL) in the MRA datasets were proposed for quantifying the stenoses. The algorithm was tested in renal arteries; ten patients with renal artery stenosis and seven healthy volunteers were investigated. Digital subtraction angiography was performed in the patients and served as the gold standard. Stenosis severity showed better correlation with the severity of the PSL than with the length, both for in vitro and in vivo measurements. Spearman correlation coefficients (rs) showed statistically significant correlations between the severity of the PSL and parameters determined by digital subtraction angiography, i.e., percent diameter stenosis (rs = 0.90). The length of the PSL showed no correlation with the diameter stenosis (rs = 0.37). In conclusion, this study presents a semi-automated and observer-independent way of quantifying signal loss, and the severity of the PSL is proposed for quantifying stenoses, rather than the length of PSL.

Aged↗
PubMed1998

Ultrasmall superparamagnetic particles of iron oxide (USPIO) MR imaging of infarcted myocardium in pigs.

The purpose of this study is to assess the potential value of ultrasmall superparamagnetic iron oxide (USPIO) for the detection of acute myocardial infarction by magnetic resonance (MR) imaging. Spin-echo magnetic resonance imaging of the heart was performed before, immediately after, and approximately 35 and 90 min after 30 micromol Fe/kg of USPIO administration in seven pigs with surgically induced myocardial infarction. Gradient-echo sequences were used to identify contraction abnormalities at the site of infarction. Myocardial signal intensities were measured using region-of-interest analysis in normal and infarcted myocardium. In addition, liver and lung signal intensities were measured. Pathologic correlation was performed after sacrificing the animals. The infarct area was located with wall-motion analysis. The site of infarction was confirmed at pathologic examination. The signal-intensity ratio between infarcted and normal myocardium was not significantly changed after USPIO administration at equilibrium stages (immediately after injection p = 0.64, at 35 min p = 0.32, at 90 min p = 0.73). The signal intensity of the liver decreased significantly after contrast administration (p < 0.05). For the lung, the change in signal intensity after USPIO administration was not significant. This pig model is well suited to study wall motion abnormalities after induction of acute myocardial infarction. USPIO-enhanced magnetic resonance imaging does not improve the visualization of acute myocardial infarction at equilibrium stage.

Animals↗
PubMed1998

MR of the heart under pharmacologic stress.

Magnetic resonance imaging is one method for assessing cardiac function and perfusion at rest and under stress conditions. In this article, the potential of stress magnetic resonance imaging for evaluating ischemic heart disease is reviewed, and technical aspects of some developments that may contribute to comprehensive magnetic resonance imaging assessment of heart disease under rest and stress are discussed.

Cardiotonic Agents↗
PubMed1998

Diagnosis of cardiac abnormalities in patients with nonischemic tachyarrhythmias: additional value of MR imaging.

PURPOSE: To assess the contribution of cardiac magnetic resonance (MR) imaging in the evaluation of patients with nonischemic tachyarrhythmias and equivocal diagnosis following echocardiography and cardiac angiography. METHODS AND RESULTS: Twenty-five patients with nonischemic tachyarrhythmias and equivocal diagnosis were studied using MR imaging. Before the MR examination all patients underwent two-dimensional echocardiography and cardiac catheterization. The type of additional information, obtained with MR imaging, ranged from confirming a suspected diagnosis in 5 patients (20%) to the identification of new important anatomic or functional information, allowing a correct diagnosis in 18 patients (72%). In two patients (8%) the MR diagnosis was incomplete. CONCLUSION: MR imaging may be an important additional diagnostic tool in the evaluation of cardiac abnormalities in patients with nonischemic tachyarrhythmias.

Adult↗
PubMed1998

Diagnosis of Crohn's ileitis and monitoring of disease activity: value of Doppler ultrasound of superior mesenteric artery flow.

OBJECTIVE: To assess the value of measurements of superior mesenteric artery flow using Doppler ultrasound for detecting disease activity in patients with proven or suspected Crohn's disease. METHODS: Superior mesenteric artery flow was measured prospectively in 31 patients with known or suspected small-bowel disease. Sixteen patients were known to suffer from Crohn's disease and were suspected of having active disease. Fifteen patients had abdominal complaints without a specific diagnosis. Enteroclysis was used as the standard of reference to detect Crohn's disease, to define the location of small-bowel Crohn's disease, and to assess disease activity by demonstrating cobblestoning. Disease activity was further substantiated by clinical signs, laboratory values, and clinical follow-up. RESULTS: Ten patients with active disease on enteroclysis made up group 1. Group 2 comprised nine patients known to have Crohn's disease but without active disease (inactive small-bowel disease). The remaining 12 patients made up group 3. In group 1, the flow volume values were significantly higher than those in group 2 and group 3: 738 +/- 411 (mean +/- SD) versus 364 +/- 101 and 300 +/- 91, respectively (p < 0.05). CONCLUSIONS: Whereas the initial diagnosis of small-bowel involvement in Crohn's disease may rely on enteroclysis, Doppler measurements of superior mesenteric artery flow are useful to monitor the activity of Crohn's disease.

Adult↗
PubMed1997

Metabolic response of normal human myocardium to high-dose atropine-dobutamine stress studied by 31P-MRS.

BACKGROUND: 31P-MRS during cardiac stress may provide (patho)physiological insights into the high-energy phosphate metabolism of the myocardium. Accordingly, the purpose of the present study was to determine the metabolic response of normal human myocardium to severe atropine-dobutamine (A-D) stress. To corroborate the results from the present in vivo study, a 31P-MRS experiment was performed with a moving phantom to simulate respiratory motion. METHODS AND RESULTS: The phantom experiment showed no relation (P=.371) between the intensity ratio of two separate phosphate peaks and amplitude of phantom excursions. The phosphocreatine (PCr) and ATP signal strength and the PCr/ATP ratio were determined from the left ventricular wall in 20 healthy subjects (posttest likelihood for coronary artery disease was <2.5%) with 31P-MRS at rest and during high-dose A-D stress (rate-pressure product increased threefold). Stress-induced changes were -21% for PCr (P<.001) and -9% for ATP (P<.05). The average PCr/ATP value at rest was 1.42+/-0.18 and decreased by 14% to 1.22+/-0.20 during stress (P<.001). CONCLUSIONS: The phantom experiment shows that the in vivo decrease of myocardial PCr/ATP due to high-dose A-D stress we observed is not a motion artifact. Consequently, this indicates that myocardial high-energy phosphate metabolism of the normal human heart is altered at high workloads.

Adenosine Triphosphate↗
PubMed1997

Value of fast gradient echo magnetic resonance angiography as an adjunct to coronary arteriography in detecting and confirming the course of clinically significant coronary artery anomalies.

We investigated the additional value of magnetic resonance (MR) angiography in 12 patients with clinically significant coronary anomalies. In 5 patients, the referring cardiologist requested additional evaluation because coronary arteriography was inconclusive about the course of the anomaly. For comparison, 7 patients with known anomalous coronary arteries were collected from our database. In these patients, there had been no doubt about the course of the anomalous coronary arteries. MR angiography provided the diagnosis in all 5 patients in whom the diagnosis was inconclusive beforehand. From the 7 patients in whom diagnosis had been established previously by contrast arteriography, the anomaly was confirmed in 5 by MR angiography. In 1 patient, the initial diagnosis at contrast arteriography had to be changed as a result of MR angiography. In 1 patient, the MR image was of insufficient quality to be conclusive. In conclusion, in patients with angiographically suspected coronary anomalies, fast gradient echo MR angiography is a helpful adjunct to coronary arteriography in identifying and confirming the origin and course of clinically significant coronary anomalies. The additional value of fast gradient echo MR coronary angiography is the visualization of both the artery and its surrounding structures.

Adult↗
PubMed1997

Detection and quantification of dysfunctional myocardium by magnetic resonance imaging. A new three-dimensional method for quantitative wall-thickening analysis.

BACKGROUND: Regional left ventricular dysfunction is a major consequence of myocardial ischemia, and its extent determines long-term prognosis. Accurate and reproducible analysis of left ventricular dysfunction is therefore useful for risk stratification and patient management. METHODS AND RESULTS: Short-axis cardiac cine magnetic resonance (MR) imaging was performed in 25 patients after anterior myocardial infarction at 21 +/- 2.1 days after the acute onset. The MR images were analyzed with the use of a dedicated analytical software package (MASS version 1.0), which includes a modified centerline method and a new three-dimensional analysis approach. A database of 48 healthy volunteers was constructed to objectively depict myocardial dysfunction in the patients; this database was compared with enzymatically determined infarct size. The mean (+/-SEM) quantity of dysfunctional myocardium and enzymatically calculated infarct size equaled 24.0 +/- 3.0 and 22.3 +/- 2.9 g, respectively (P = .69). Enzymatically determined infarct size correlated strongly with left ventricular dysfunction determined by cine MR imaging (y = 0.90x + .92. P < .0001). Segments related to the distribution of the left anterior descending coronary artery showed a significantly lower percentage wall thickening in patients than did corresponding segments of 48 normal subjects (46.0 +/- 8.22% versus 87.1 +/- mean SEM, respectively; P < .001). The mean (+/-SEM) end diastolic wall thickness of the infarcted segment did not differ from that of corresponding normal segments (7.4 +/- 0.33 versus 7.5 +/- 0.15 mm; P = .75). CONCLUSIONS: We conclude that the use of three-dimensional quantitative analysis of cine MR images accurately quantities the extent of regional left ventricular dysfunction in the infarcted heart. This method of analysis may be useful in assessing the effect of interventional therapies.

Adolescent↗