Diminished systolic function or inappropriate hypertrophy are considered risk factors for outcome following the Fontan procedure. These parameters are difficult to assess in univentricular hearts that do not conform to the uniform shapes prescribed by conventional 2-dimensional imaging volume algorithms. Three-dimensional echocardiography requires no geometric assumptions and has been validated in both normal and distorted left ventricles. To assess the feasibility and accuracy of this technique in patients with univentricular hearts, we compared 2- and 3-dimensional echocardiographic estimates of ventricular volume, ejection fraction, and mass in patients with functionally single left ventricles with results obtained by magnetic resonance imaging (MRI). Twelve patients with functionally single left ventricles (6 months to 22 years) underwent examination by all 3 modalities. Correlation and agreement with MRI were calculated for volumes, ejection fraction, and mass. Three-dimensional echocardiographic comparison with MRI yielded a bias of 3.4 +/- 5.5 ml and 14.2 +/- 8.3 ml for systolic and diastolic volumes, respectively. Agreement analysis for mass showed a bias of 5.8 +/- 8.4 grams. Two-dimensional echocardiography showed less agreement for both volumes and mass (bias of -2.9 +/- 8.1, 2.9 +/- 10.4 ml and -8.3 +/- 12.0 g for volume and mass, respectively, p >0.05). Ejection fraction by 3-dimensional echocardiography showed significantly closer agreement with MRI (bias of 4.4 +/- 5.3%) than 2-dimensional echocardiography (bias of 8.5 +/- 10.3%, p = 0.04). Thus, 3-dimensional echocardiography provides estimates of ventricular volumes, ejection fraction, and mass that are comparable to MRI in this select group of patients with single ventricles of left ventricular morphology.

Adolescent↗

PubMed1997

Radiological case of the month. Homozygous familial hypercholesterolemia.

Explore the source record for details and available documents.

Adolescent↗

PubMed1997

Aneurysms of the digital arteries: a case report and literature review.

Aneurysms of the digital vessels are rare. An aneurysm of the radial digital artery of the index finger in a child is reported to illustrate the clinical presentation and value of magnetic resonance arteriography in diagnosis. Literature review reveals that only 18 cases have been reported. These cases are analyzed in terms of digit involvement, vessel affected, mechanism of injury, and treatment.

Aneurysm, False↗

PubMed1997

Freehand three-dimensional echocardiography for determination of left ventricular volume and mass in patients with abnormal ventricles: comparison with magnetic resonance imaging.

OBJECTIVE: The objective of this study was to validate the freehand three-dimensional echocardiographic method in patients with abnormal ventricular geometry compared with two-dimensional echocardiography using magnetic resonance imaging as a standard. BACKGROUND: Two-dimensional echocardiographic methods for estimating left ventricular volume and mass in clinical use today are limited by inaccuracies and variations caused by use of geometric assumptions and errors in image plane positioning. Freehand three-dimensional echocardiography with operator guidance by a "line of intersection" display eliminates these assumptions and errors. This method of volume and mass computation has been validated as highly accurate and reproducible in healthy subjects. METHODS: Left ventricular end-systolic and end-diastolic volumes and myocardial mass were determined by freehand three-dimensional echocardiography, by conventional two-dimensional echocardiography using the apical biplane summation of discs method (volume) and the truncated ellipsoid method (mass), by M-mode echocardiography using the Penn method (mass), and by magnetic resonance imaging in 30 patients selected only for the presence of an abnormal ventricle. Results were compared by means of linear regression and the Bland-Altman method of analysis. RESULTS: There was excellent correlation, low bias, and low variability between three-dimensional echocardiography and magnetic resonance imaging for end-diastolic volume (r = 0.90, standard error of the estimate = 31.8 ml, bias = -28.4 ml), end-systolic volume (r = 0.93, standard error of the estimate = 24.1 ml, bias = -13.1 ml), and mass (r = 0.90, standard error of the estimate = 27.3 gm, bias = -22.6 ml). Two-dimensional echocardiography was less accurate and more variable as follows: end-diastolic volume (r = 0.70, standard error of the estimate = 39.8 ml, bias = -33.5 ml), end-systolic volume (r = 0.78, standard error of the estimate = 31.2 ml, bias = -26.7 ml), and mass (r = 0.80, standard error of the estimate = 37.3 gm, bias = 28.9 ml). M-mode echocardiography mass determination (Penn method) was least accurate and most variable (r = 0.075, standard error of the estimate = 78.3 gm, bias = 78.3 gm). CONCLUSIONS: Freehand three-dimensional echocardiography is a method of high accuracy and low variability for computing left ventricular volume and mass in clinical patients with abnormal ventricles. It is superior to conventional one- and two-dimensional echocardiography. The improvement achieved is attributed to elimination of geometric assumptions and image plane positioning errors and additional sampling of the ventricle.

Adolescent↗

PubMed1996

Quantitative three dimensional echocardiography in patients with pulmonary hypertension and compressed left ventricles: comparison with cross sectional echocardiography and magnetic resonance imaging.

OBJECTIVE: To evaluate the accuracy of quantitative three dimensional echocardiography in patients with deformed left ventricles. DESIGN: Three dimensional and cross sectional echocardiographic estimates of left ventricular volume and ejection fraction were prospectively compared to those obtained from magnetic resonance imaging. SETTING: Echocardiography laboratory of a university hospital. PATIENTS: 26 patients (9 months to 42 years, median age 11 years) with pulmonary hypertension and fixed reversal of normal interventricular septal curvature. MAIN OUTCOME MEASURES: Left ventricular end diastolic and end systolic volumes and ejection fraction. RESULTS: Three dimensional echocardiographic comparison to magnetic resonance imaging (MRI) yielded r values of 0.94 and 0.87 with a bias of -6.9 (SD 6.9) ml and -16 (11.2) ml for systolic and diastolic volumes respectively. Inter-observer variability was minimal (8.3% and 7.6% respectively). Cross sectional echocardiography gave correlation coefficients of 0.62 and 0.80 and bias of 3.1 (14.1) ml and 16.3 (18.3) ml for systolic and diastolic volumes respectively. Ejection fraction by three dimensional echocardiography also had closer agreement with MRI (bias = 1.1 (7.7)%) than cross sectional echocardiography (bias = 4.4 (13.9)%). CONCLUSIONS: Three dimensional echocardiography provides reliable estimates of left ventricular volumes and ejection fraction, comparable to magnetic resonance imaging in pulmonary hypertension patients with compressed ventricular geometry. Because it eliminates the need for geometric assumptions it shows closer agreement with magnetic resonance imaging in that setting than cross sectional echocardiography.

Adolescent↗

PubMed1996

How to perform cardiac MR imaging.

The complex motion of the beating heart provides a challenge to the clinical MR imager. Use of ECG gating, however, "stops" the heart, allowing for acquisition of diagnostic quality images of the cardiac chambers, valves, pericardium, and great arteries and veins and their branches. Attention to placement of chest wall ECG electrodes and the course of ECG-leads from the patient maximizes the quality of the gating signal and results in better quality imagery; however, ECG gating increases image acquisition time of the cardiac examination. Therefore, care must be taken to perform the most efficient possible examination. Prior to commencing the examination, the imager must have a clear understanding of the clinical question of the referring physician so that a clinical protocol can be applied to acquire relevant morphologic and physiologic data. The intracardiac anatomy may not always be best demonstrated using standard axial, coronal, and sagittal image sections. Therefore, with an understanding of basic intracardiac anatomy, standard imaging planes parallel or orthogonal to the intrinsic cardiac axes may be constructed and observation of abnormalities better appreciated. If care is taken in the planning and execution of the cardiac MR examination, the radiologist will be able to exploit this exciting new technology to its full potential as a noninvasive cardiac imaging modality.

Electrocardiography↗

PubMed1996

MR imaging of acquired heart disease.

Spin echo and gradient reversal MR imaging techniques provide a noninvasive means of analyzing the state of ventricular myocardium in patients with atherosclerotic and valvular heart disease. Local ischemic changes are manifested on spin echo MR examination as loci of increased signal intensity, most likely representing accumulation of local myocardial edema. Administration of intravenous paramagnetic contrast material further enhances local changes, increasing the sensitivity of MR methods for detecting such change. Application of spin echo and gradient reversal techniques also provides direct demonstration of morphologic changes in chamber volume and myocardial wall thickness and thickening, the sequelae of ischemic and acquired valvular heart disease, as well as direct demonstration of abnormal blood flow across diseased valves. Newer methods of analysis of these flow abnormalities provide information concerning pressure gradients across stenotic valves and regurgitant fractions across insufficient valves. Thus, application of MR imaging techniques provides clinically relevant information needed by referring clinicians for the management of patients with acquired heart disease.

Coronary Disease↗

PubMed1996

MR imaging of pulmonary hypertension and right ventricular dysfunction.

Right ventricular cardiac function is altered by abnormalities affecting primarily the left-sided cardiac structures, the lungs, or the right-sided cardiac structures themselves. The most common cardiac causes for right ventricular dysfunction are chronic left ventricular ischemia and rheumatic mitral valvular disease. Pulmonary diseases that result in right ventricular dysfunction include pulmonary air-space disease, including emphysema, and pulmonary interstitial and parenchymal diseases, including idiopathic pulmonary fibrosis and cystic fibrosis. Chronic pulmonary vascular disease, including chronic thromboembolism and PPH have a significant effect on right ventricular performance. Common to all of these diseases is elevation of pulmonary vascular resistance with a commensurate increase in right ventricular pressure, resulting in right ventricular hypertrophy. The limited ability of right ventricular myocardium to function in the face of increased pulmonary resistance results in right ventricular dilatation, tricuspid regurgitation, and ultimately right ventricular failure. MR imaging provides direct, noninvasive visualization of the right ventricular chamber as well as the myocardium itself, allowing reliable demonstration of morphologic changes in the size and shape of the ventricle, thickness of the myocardium, and presence of abnormal infiltration by fat or edema. Furthermore, because MR imaging techniques do not depend upon geometric assumptions about the complex shape of the right ventricle, they may be used for accurate and reproducible quantitation of right ventricular volume and myocardial mass.

Heart↗

PubMed1996

MR imaging of congenital heart disease.

Patients with congenital heart disease often require mild sedation for the performance of their examination. If adequate monitoring of systemic oxygen saturation and heart rate is performed, then these patients may be adequately studied by MR imaging. Cardiac examination using spin echo pulse sequences provides morphologic information that allows evaluation of situs, ventricular morphology, and atrioventricular and ventriculoarterial connection. Gradient reversal acquisitions display changes in the size and shape of the atria and ventricles as well as demonstration of intracardiac and extracardiac shunts and abnormal flow across the cardiac valves. This information allows evaluation of the underlying congenital abnormality as well as the pathologic sequelae of the cardiac dysmorphology. Cardiac MR examination is a useful means of minimally invasive diagnosis of congenital heart disease and evaluation of its surgical palliation.

Heart Defects, Congenital↗

PubMed1995

Breakthrough of single-quantum coherence and its elimination in double-quantum filtering.

Breakthrough of single-quantum coherence is shown to occur after application of a double-quantum filter with the conventional four-step phase-cycling scheme. This single-quantum breakthrough is due to the intersequence stimulated echo which has been generated by the radiofrequency pulses in the preceding pulse sequence and appears at the same time as the double-quantum coherence signal in the current pulse sequence. Moreover, the phase of the intersequence stimulated echo is the same as the phase of the double-quantum coherence signal; i.e., the phase of the intersequence stimulated echo is twice the phase change of the radiofrequency pulses in the creation period when their phase is rotated in accordance with the conventional four-step phase-cycling scheme. Consequently, the intersequence stimulated echo passes through the double-quantum filtration in the conventional four-step phase-cycling scheme and gradient pulses. A new phase-cycling scheme which can filter out the single-quantum breakthrough signal is proposed here and its effectiveness is verified experimentally and by computer simulations.

Computer Simulation↗