Biomedical subjects

W Moshage

Publications and source records attributed to W Moshage.

At least 37 records · Page 2Linked to original sources

PubMed2000

Noninvasive detection of coronary artery stenosis using contrast-enhanced three-dimensional breath-hold magnetic resonance coronary angiography.

OBJECTIVES: The purpose of this study was to evaluate a contrast-enhanced three-dimensional (3D) breath-hold magnetic resonance (MR) technique for detection of coronary artery stenoses. BACKGROUND: The accuracy of previously published MR coronary angiography protocols varies widely. Recently, coronary artery imaging using T1-shortening contrast agent has become possible, but so far there are no data concerning its clinical application. METHODS: Magnetic resonance coronary angiography was performed in 50 patients with suspected coronary artery disease. Magnetic resonance data acquisition using an ultrafast 3D gradient-echo sequence lasted over 32 heartbeats within one single breath-hold. Twenty milliliters of gadopentetate dimeglumine was injected at a flow rate of 1 ml/s for two successive studies covering the main coronary arteries in single-oblique planes. Stenosis assessment by MR was compared with significant (diameter stenosis > 50%) stenoses on X-ray angiography. Evaluation was limited to the proximal and mid-coronary artery segments. RESULTS: Two hundred sixty-eight of 350 artery segments (76.6%) could be evaluated. Left circumflex coronary artery was only evaluable in 50% of cases by MR. In the evaluable segments, 48 of 56 stenoses and 193 of 212 nonstenotic segments were correctly classified by MR. On a patient basis, MR correctly identified 34 of 36 patients with and 8 of 14 patients without significant coronary stenoses as demonstrated by X-ray angiography (sensitivity 94.4%, specificity 57.1%). CONCLUSIONS: Oblique projection contrast-enhanced MR coronary angiograms obtained within one single breath-hold permit identification of patients with coronary stenoses in the proximal and mid segments of the major coronary arteries with satisfactory accuracy.

Adult↗

PubMed2000

Prenatal diagnosis of QT prolongation by magnetocardiography.

Magnetocardiography constitutes a new tool for monitoring fetal cardiac activity. The fetal magnetocardiogram (FMCG) recorded noninvasively over the maternal abdomen is detectable with high temporal resolution and permits analysis of all parts of the PQRST waveform. In this way measurements of cardiac time intervals, including the QT interval, become possible. The following article constitutes the first report of antenatal detection of QT prolongation in two fetuses by FMCG.

Adult↗

PubMed2000

Contrast enhanced electron beam computed tomography to analyse the coronary arteries in patients after acute myocardial infarction.

OBJECTIVE: To evaluate the accuracy of contrast enhanced electron beam computed tomography (EBCT) after acute myocardial infarction in determining patency of the infarct related artery and detecting high grade stenoses and occlusions in the coronary vessels. DESIGN: Case study using blinded comparison with invasive coronary angiography. PATIENTS: 36 patients (mean age 53 years) 4-70 days after acute myocardial infarction. INTERVENTIONS: The patients were studied by EBCT and invasive coronary angiography. For EBCT, 50 axial images of the heart (3 mm slice thickness) were acquired. They were triggered by the ECG during breath holding, after intravenous injection of contrast agent. The original images, surface reconstructions, and maximum intensity projections were evaluated for the presence of high grade stenoses and occlusions of the coronary arteries. MAIN OUTCOME MEASURES: EBCT results were compared with invasive coronary angiography. RESULTS: Of a total of 144 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery in 36 patients), 29 (20%) were unevaluable by EBCT. In the remaining arteries, 33 of 36 high grade lesions were correctly detected (92% sensitivity). Specificity was also 92% (73/79). Patency of the infarct related artery was correctly detected in 15 of 16 cases (94%). Five of the 14 occluded infarct related arteries (35%) were mistaken as stenotic but patent, and six could not be assessed. CONCLUSIONS: EBCT is very accurate in detecting significant coronary artery lesions in patients after acute myocardial infarction, but differentiation between occluded and patent infarct related arteries is currently unreliable.

Adult↗

PubMed2000

In-plane coronary arterial motion velocity: measurement with electron-beam CT.

PURPOSE: To determine the speed of and changes in the speed of coronary arterial movement during the cardiac cycle with electron-beam computed tomography (CT). MATERIALS AND METHODS: With electron-beam CT, 20 consecutive cross-sectional images were acquired at the mid right coronary artery (with 50-msec acquisition time, 8-msec intersection delay, 7-mm section thickness, and intravenous administration of 40 mL of contrast agent) in 25 patients. On the basis of the displacement of the left anterior descending, left circumflex, and right coronary arterial cross sections from image to image, movement velocity in the transverse imaging plane was calculated and was correlated with the simultaneously recorded electrocardiogram. RESULTS: The velocity of in-plane coronary arterial motion varied considerably during the cardiac cycle. Peaks were caused by ventricular systole and diastole and by atrial contraction. The mean velocity was 46.6 mm/sec +/- 12. 5 (SD). The mean velocity of right coronary arterial movement (69.5 mm/sec +/- 22.5) was significantly faster than that of the left anterior descending (22.4 mm/sec +/- 4.1) or the left circumflex coronary artery (48.4 mm/sec +/- 15.0). The lowest mean velocity (27. 9 mm/sec) was at 48% of the cardiac cycle. CONCLUSION: The lowest velocity of coronary arterial movement, which displays considerable temporal variation, was at 48% of the cardiac cycle.

Aged↗

PubMed1999

Coronary arteries: MR angiography with fast contrast-enhanced three-dimensional breath-hold imaging--initial experience.

Gadolinium-enhanced, three-dimensional, breath-hold magnetic resonance (MR) coronary angiography was performed in two healthy volunteers and 11 patients suspected or known to have coronary artery disease. MR angiograms were compared with those obtained with retrospective respiratory gating. Of 52 main coronary arteries, 47 could be visualized with the breath-hold technique and 49 with the gating technique. Signal-to-noise and contrast-to-noise ratios were significantly higher with the breath-hold technique. Overall image quality was slightly lower with breath-hold imaging. With either technique, three of five, significant coronary stenoses were correctly identified.

Contrast Media↗

PubMed1998

Value of electron-beam computed tomography for the noninvasive detection of high-grade coronary-artery stenoses and occlusions.

BACKGROUND: Reliable noninvasive assessment of coronary-artery stenoses and occlusions would constitute an advantage in the care of patients with known or suspected coronary artery disease. We investigated the accuracy of contrast-enhanced electron-beam computed tomography (CT) for the detection of high-grade coronary-artery stenoses and occlusions. METHODS: Electron-beam CT was performed in 125 patients. After intravenous injection of a contrast agent, 40 cross-sectional images of the heart were acquired during inspiration, triggered by the electrocardiogram in diastole. Three-dimensional reconstructions of the heart and coronary arteries were rendered to facilitate evaluation of the images. The proximal and middle segments of the major coronary arteries were evaluated for the presence or absence of high-grade stenoses and occlusions. The results were compared with those of invasive coronary angiography in a blinded fashion. RESULTS: Because of technical problems that impaired the quality of the images, 124 (25 percent) of the 500 coronary arteries studied (left main, left anterior descending, left circumflex, and right coronary) in a total of 125 patients were excluded from evaluation. No vessels could be evaluated in 19 patients (15 percent), and another 28 patients (22 percent) had one, two, or three vessels that could not be evaluated. In the remaining coronary arteries with adequate image quality, electron-beam CT permitted visualization of 69 of 75 high-grade stenoses and occlusions (sensitivity, 92 percent), whereas in 282 of 301 arteries, the absence of high-grade stenoses and occlusions was correctly detected (specificity, 94 percent). CONCLUSIONS: When image quality is adequate, electron-beam CT may be useful to detect or rule out high-grade coronary-artery stenoses and occlusions.

Adult↗

PubMed1998

Noninvasive coronary angiography by contrast-enhanced electron beam computed tomography.

Electron beam computed tomography (EBCT) is a cross-sectional imaging method with high temporal and spatial resolution. So far, it has mainly been applied for the detection of coronary artery calcifications which permit the very sensitive detection of coronary atherosclerosis even in the very early stages. However, after intravenous injection of a contrast agent, EBCT also permits the direct visualization of the coronary artery lumen. For these investigations, a volume data set is acquired that consists of 40 axial cross-sections of the heart (3 mm slice thickness). To evaluate the coronary arteries as to the presence of stenoses and occlusions, various forms of post-processing, including shaded surface display, maximum intensity projection, and multiplanar reconstruction, are applied. The sensitivities and specificities for the detection of coronary artery stenoses and occlusions are about 90%. Best results are obtained for coronary artery bypass grafts, the left main coronary artery, and the left anterior descending coronary artery, while reduced image quality impairs the results for the right coronary artery and the left circumflex coronary artery.

Contrast Media↗

PubMed1998

[Prenatal recording of fetal heart action with magnetocardiography].

Fetal magnetocardiography (fMCG) registers the magnetic field generated by the fetal heart. In contrast to the fetal electrocardiogram, fECG permits non-invasive registration of fetal heart activity and documentation of all parts of the PQRST-wave-forms from the second trimenon onwards. This facilitates the determination of cardiac time intervals and establishment of reference values for different stages of pregnancy. We examined 53 women in 104 recordings from the 10th week of gestation onwards (1 to 10 recordings per individual). The fMCG (37 magnetic channels, sampling rate 1024 Hz, bandwidth 1-200 Hz) was recorded non-invasively over the mother's abdomen in a magnetically shielded room. Registration of fetal heart beats was generally successful from the 20/21th week of gestation onwards. In a few cases, fetal heart beats could be registered as early as in the 16th week. Cardiac time intervals and amplitudes of fMCG increased concordantly with fetal growth. Mean P wave duration increased from 31 to 49 ms (p < 0.05), PQ interval from 95 to 107 ms (n.s.) and QRS duration from 36 to 52 ms (p < 0.01). The mean amplitudes of the P and R waves also increased. FMCG, furthermore permits a prenatal diagnosis of fetal cardiac arrhythmias. We recorded fetal arrhythmias in 20 cases (26-38th week), including episodes of ventricular and supraventricular arrhythmias or atrioventricular blockings. Due to its high resolution, fMCG offers new information on the development of fetal cardiac activity which cannot be achieved by conventional methods like cardiotocography or dopplerultrasound. Therefore, fMCG could become a new diagnostic instrument for monitoring fetal wellbeing during pregnancy.

Adult↗

PubMed1998

[Evaluation of coronary artery stenosis with respiratory gated NMR angiography].

Respiratory gated MR coronary angiography is a new MR imaging technique which permits reconstruction of the coronary arteries from a three-dimensional data set obtained from contiguous parallel sections. In this study, respiratory gated MR angiography was applied to assess significant coronary artery stenoses (> or = 50%). MR imaging was performed in 68 patients (50 men, 18 women) who had been referred to cardiac catheterization because of suspected or known coronary artery disease. The evaluation of coronary artery stenoses was performed in a blinded manner in the proximal, middle, and distal vessel segments after multiplanar coronary reconstruction of the MR images. Of the 680 coronary segments, 275 (40%) were located outside the imaging volume and were, therefore, excluded from further analysis. The highest sensitivity for stenosis detection was found in the proximal left anterior descending (LAD) and right coronary artery (RCA) with 75% and 71%, respectively. The overall sensitivity, however, was low with 48%. The overall specificity was 92%. The positive and negative predictive values were 67% and 85%, respectively. This study shows that significant coronary artery stenoses, especially in the proximal LAD and RCA, can be correctly identified using respiratory gated MR angiography. However, further technical improvements are necessary before this method may become a reliable diagnostic tool in clinical practice.

Adult↗

PubMed1998

[Possibilities and limits of electron beam tomography].

Electron beam CT, which does not require mechanical movement of an X-ray tube, has a temporal resolution which exceeds that of conventional computed tomography by a factor of about ten. Axial images of the heart can be acquired within 50 to 100 ms with a spatial resolution below 0.5 mm2 and permit precise visualization of all cardiac structures. ECG-triggered acquisition of 30 to 40 axial images (3 mm slice thickness) in a short inspiratory breathhold allows one to sample a 3-dimensional volume data set which covers the complete heart. Overall acquisition times are approximately 30 to 50 seconds. While electron beam CT in general permits a complete cardiac investigation, including morphology, function, and perfusion, the method's most important application is non-invasive imaging of the coronary arteries. Without contrast enhancement, coronary calcifications by EBCT currently constitutes the most sensitive non-invasive marker for the presence even of very early forms of coronary atherosclerosis. Intravenous injection of contrast agent during image acquisition additionally permits the selective visualization of the coronary artery lumen and detection of significant stenoses. This method is especially well suited in the follow-up of coronary interventions and coronary bypass grafting. Breathhold and movement artifacts, superposition of coronary arteries and veins, as well as severe coronary calcifications currently constitute the method's main problems. In spite of these limitations, electron beam CT has been shown to permit clinically valuable non-invasive investigations of the coronary arteries, which may be further refined as technology progresses.

Adult↗

PubMed1998

Evaluation of the Association Between Coronary Calcification Detected by Electron Beam Computed Tomography and Atherosclerosis of Extracranial Carotid Arteries In Vivo.

The aim of this study was to evaluate the association between carotid and coronary atherosclerosis and their diagnostic value for predicting angiographically significant coronary artery disease (CAD). We investigated 80 subjects (mean age 55 +/- 8 years) by electron beam computed tomography (EBT), the most sensitive technology for noninvasive detection of coronary calcification (a marker of coronary atherosclerosis); by carotid sonography; and by coronary angiography. Carotid ultrasound was performed with a 7.5 MHz Duplex probe, EBT was done with an EVOLUTION(R) scanner. In 47 subjects, coronary calcification as well as carotid atherosclerosis was present. Thirteen subjects showed isolated coronary calcification, 10 had isolated carotid atherosclerosis, and 10 showed neither coronary calcification nor carotid atheroscleroosis. The association between carotid atherosclerosis and CAD as well as the relationship between coronary calcification and CAD were statistically significant (p < 0.05), but the correlation between coronary calcification and CAD was higher than between carotid atherosclerosis and CAD (Pearson contingency coefficient: 0.34 vs 0.86). In subjects without carotid atherosclerosis, the mean area of coronary calcificiation was significantly (p < 0.01) lower (41 mm2) than in subjects with carotid atherosclerosis (113 mm2). For noninvasive detection of CAD, electron beam CT was superior to carotid sonography on sensitivity (95% vs 78%) and specificity (81% vs 48%). Former studies suggested that sonography of extracoronary vessels could aid in screening for CAD. In our study, the sonographic status of carotid arteries was associated with cardiovascular atherosclerosis but it did not allow us to make a judgment about the presence of CAD with sufficient reliability and it was inferior to electron beam CT as a noninvasive marker of CAD.

Journal Article↗

PubMed1998

Comparison of vessel diameters in electron beam tomography and quantitative coronary angiography.

Electron beam tomography (EBT) has been shown to permit non-invasive imaging of the coronary arteries after intravenous injection of contrast agent and 3-dimensional reconstruction. We compared the vessel diameters in EBT reconstructions to quantitative coronary angiography (QCA). 10 patients were investigated by EBT and QCA. 3-dimensional EBT reconstructions (shaded surface display) were performed after acquisition of 40 axial cross-sections of the heart with 3 mm slice thickness (1 mm overlap) which were obtained triggered to the ECG in breathhold following intravenous injection of 120-160 ml of contrast agent. A fixed lower reconstruction threshold of 80 HU was used to selectively visualize the contrast-enhanced coronary artery lumen. At 60 sites in the coronary artery system, the vessel diameters measured in the EBT reconstructions were compared to the diameters found in quantitative analysis of the patients' coronary angiograms. The correlation coefficient of the vessel diameters in EBT and QCA was 0.83. Mean vessel diameters were not significantly different in EBT and QCA (3.06 +/- 0.93 vs. 2.97 +/- 0.94 mm). However, very small vessel diameters tended to be underestimated in the EBT reconstructions, which was due to the partial volume effect. It only vessel diameters measured in the left main or left anterior descending coronary artery were compared to QCA, the correlation increased to 0.87, since these vessel segments are less prone to artifacts in the EBT investigation. Vessel diameters in EBT and QCA correlated reasonably well. Due to partial volume effects, the diameter of very small vessels and stenotic segments tends to be underestimated by EBT.

Adult↗

PubMed1998

Assessment of coronary blood flow in humans using phase difference MR imaging. Comparison with intracoronary Doppler flow measurement.

Coronary blood flow quantification provides essential information on the hemodynamic significance of coronary artery stenoses. Recently, magnetic resonance (MR) flow mapping has emerged as a new promising method to noninvasively determine flow velocity and flow volume within the coronary arteries. The aim of this study was to compare phase difference (PD) MR flow quantification with intracoronary Doppler flow measurements in 15 patients with suspected or known coronary artery disease. Flow quantification was attempted before and after systemic application of 5mg Isosorbiddinitrate (ISDN) in order to determine possible alterations in coronary flow volume. PD MR flow mapping was performed successfully in 13 of the 15 patients. For flow velocities and flow volume values, a close correlation between PD MR and Doppler flow measurements was found (r = 0.79 and r = 0.90, respectively). However, average flow measured by PD MR was significantly lower than the invasively obtained values (9.0 +/- 4.4 cm/sec vs. 11.7 +/- 4.9 cm/sec; p < 0.001 and 46.3 +/- 28.7 ml/min vs. 53.4 +/- 32.8 ml/min; p < 0.05). Although the mean flow volume remained constant in the entire patient group after ISDN application, individual changes (increase in 6, decrease in 4 cases) could be documented with PD MR imaging and showed a good correlation to the Doppler method (r = 0.82). In conclusion, PD MR flow mapping is a promising method for the noninvasive quantification of coronary blood flow and therefore offers the potential of assessing coronary artery stenoses. However, technical improvements are mandatory in order to increase accuracy of the method.

Blood Flow Velocity↗

PubMed1998

Non-invasive diagnosis of a congenital coronary artery fistula.

This report describes a large congenital coronary artery fistula of the left circumflex artery draining into the coronary sinus in a 46 year old woman. The fistula was initially diagnosed by cross-sectional and transesopha-geal echocardiography using multiplane probe. Additionally, the entire course of the fistula was visualised in electron beam tomography. Angiography confirmed echocardiographic and tomographic findings.

Arteriovenous Fistula↗

PubMed1998