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At least 19 recordsLinked to original sources
PubMed1997

Evaluation of mitral valve prolapse by four-dimensional echocardiography.

To observe the stereoscopic structure and the motion of the prolapsing mitral valve and its regurgitant jet in comparison with the normal mitral valve, four-dimensional (or dynamic three-dimensional) echocardiography of mitral valve apparatus was obtained in 20 patients with mitral valve prolapse and 10 unaffected subjects by use of transthoracic and transesophageal methods. The normal mitral valve apparatus has a consistent saddle-shaped configuration, with its anterior and posterior high points located near the aortic root and posterior left ventricular wall, respectively, and its low points located medially and laterally. In mitral valve prolapse, the spatial relation of mitral leaflets and anulus can be observed in four dimensions either from the left ventricle toward the left atrium or from the left atrium toward the left ventricle; the position, size, shape, motion, and extent of functional abnormality of the prolapsing mitral valve were clearly displayed. On the long-axis view of the left ventricle and the apical four-chamber view of four-dimensional echocardiography, the part of prolapsing mitral valve that protruded into the left atrium appeared as a spoon-like depression. We also obtained four-dimensional images of regurgitant blood flow to observe the stereoscopic view of blood flow column and its cross-sectional area, spatial position, and dynamic changes. This technique is of great value in evaluating patients with mitral valve prolapse, increasing the diagnostic sensitivity and specificity, and giving assistance to the surgeons in making preoperative therapeutic decisions and assessing the intraoperative and postoperative results.

Adult↗
PubMed1994

Three-dimensional and four-dimensional echocardiography.

Since its introduction in 1974, 3-D reconstruction of the heart has undergone significant technological refinements in image acquisition, processing and display techniques. Image acquisition for transthoracic 3-D reconstruction utilizes the parasternal or apical windows, or combinations of the two. The parasternal approach allows better endocardial border detection, while the apical approach allows a more complete visualization of the left ventricular apex. Computer algorithms are used to process images with various display techniques incorporated into the algorithm. Transesophageal image acquisition overcomes a significant limitation of the transthoracic approach, which is variable and sometimes poor image quality. Both a multiplane approach and a computerized tomographic approach have been successfully used by several investigators. Potential applications of 3-D echocardiography include reconstruction of the mitral annulus, dynamic cardiac anatomy and function and volume calculations. A major limitation is the need for considerable computer time for image processing and display; furthermore, errors may be introduced by the various smoothing and contouring algorithms. Despite these limitations, 3-D echocardiography has considerable potential for clinical utility, particularly in the areas of reconstructive cardiac surgery and congenital heart disease.

Echocardiography↗
PubMed1996

Four-dimensional echocardiography: methods and clinical application.

4DE (i.e., dynamic three-dimensional) echocardiography is a new developing technique in recent years. In our study, a three-dimensional echo scan computer system was used to acquire and store the two-dimensional information, then to reconstruct the stereoscopic image of the heart according to its space-time continuum. It can yield a better approach, which can help identify the various structures of the heart and great arteries and facilitate understanding of spatial relations and motion. In addition, it can display physiologic information such as the direction, course, size, and shape of the blood flow. We have examined 138 patients by both transthoracic and transesophageal approaches. Our preliminary experience shows that 4DE is of great value in diagnosing congenital heart disease and valvular disease.

Adolescent↗
PubMed2000

[Free hand acquisition, reconstruction and visualization of 3D and 4D ultrasound].

3D Ultrasound will find in the next years a wide popularity under the medical imaging applications. The method expands the well-known sonography on the third dimension, therefore it becomes possible to generate spatial 3D views of internal organs. It is further possible to display static (3D) as well as dynamic organs (4D, e.g. pulsating heart). The clarity of the three-dimensional presentation supports very effectively the navigation. In this article we review the upgrading of conventional ultrasound devices on 3D and 4D capabilities, as well as the display of the datasets by corresponding visualisation and filtering approaches.

Computer Graphics↗
PubMed1996

Fetal echocardiography in three and four dimensions.

A three-dimensional (3D) acquisition system using an electromagnetic position sensor attached to a standard transducer on an unmodified ultrasound scanner was developed to capture two-dimensional (2D)-fetal echocardiograms at various positions and orientations. Operating in real-time directed M-mode allowed recording of 2D structural images and cardiac motion curves, from which the fetal cardiac phase could be determined. By digitising over 100 image frames for each scanning sequence, and by selecting frames at particular phases, 3D views of the fetal heart were reconstructed for each phase. Of 20 sequences of six fetuses scanned, 13 sequences successfully demonstrated usable 3D fetal heart structures, including four cardiac chambers, ventricular and atrial septa, foramen ovale and some of the cardiac valves and great vessels. Rearrangement of those phased 3D images into a cyclic sequence could generate dynamic 3D views of a beating fetal heart. We believe that, with further technical development, this new approach will be of use in the diagnosis of prenatal cardiac malformations and malfunctions, in in utero cardiac surgery and in fetal cardiology teaching.

Echocardiography, Four-Dimensional↗
PubMedDate not supplied

Computer system for four-dimensional transesophageal echocardiographic image reconstruction.

This paper presents a system for reconstructing a four-dimensional (4D) heart-beating image from transesophageal echocardiographic (TEE) data acquired with a rotational approach. The system consists of the necessary processing modules for two-dimensional (2D) echocardiogram reformation and 3D/4D-image reconstruction. These include the modules of image decoding, image re-coordinating, and three-dimensional (3D) volume rendering. The system is implemented under PC platform with Windows 95 operating system (with Intel Pentium-166 CPU, 64 MB RAM on board, and 2.0 GB hard disk capacity). It takes 6 min to reconstruct a 4D echocardiographic data set. The resultant 2D/3D/4D echocardiographic image provide the tools for investigating the phenomenon of heart beating, exploring the heart structure, and reformatting the 2D echocardiograms in an arbitrary plane. The functions provided by the system can be applied for further studies, such as 3D cardiac shape analysis, cardiac function measurement, and so forth.

Computer Systems↗
PubMed1993

Three- and four-dimensional cardiovascular ultrasound imaging: a new era for echocardiography.

Three-dimensional and four-dimensional ultrasonography were pioneered in the 1960s yet have been used little clinically. Only recently have advances in cardiovascular ultrasound equipment and in digital image storage, manipulation, and display techniques made three- and four-dimensional imaging clinically feasible. In this report, we review the historical development of these technologies during 3 decades to their culmination in current state-of-the-art technology. Examples of such multidimensional images are presented, with special emphasis on clinical applications. Although several limitations persist, three-dimensional cardiovascular ultrasonography seems likely to enhance imaging of the heart and vessels in a manner similar to the advent of two-dimensional echocardiography in the M-mode era. Clinician-scientists will soon be able to extract an object, such as the heart, from the body electronically for the purpose of anatomic, functional, and histologic analysis without adverse effect on the patient.

Echocardiography↗
PubMed1993

Multidimensional visualization in echocardiography: an introduction.

X-ray films depict three-dimensional objects as shadows in a two-dimensional plane; thus, objects become superimposed. Computed tomography and other types of tomographic imaging, such as ultrasonography, acquire two-dimensional images of a material property within a thin slice. Sequential adjacent two-dimensional tomograms can be used to construct three-dimensional displays of objects. Visualization, a field of computer science, enables scientists to measure image attributes (extraction of features), identify features (classification), separate objects from one another (segmentation), and produce comprehensible, information-dense images from three-dimensional data sets (rendering). A three-dimensional rendering of the heart can be used to represent only one component of the heart, such as the atrial septum or the ventricular chamber, and can be shaded or colored to enhance comprehension. Three-dimensional images rendered sequentially over time result in a dynamic four-dimensional display. This report describes multidimensional visualization of objects and tissues and specifically discusses examples from echocardiography.

Echocardiography↗
PubMed1997

Transesophageal echocardiography and the perioperative management of valvular heart disease.

Transesophageal echocardiography (TEE) is an integral part of decision-making and monitoring in the perioperative period for patients undergoing valvular heart surgery. Multiplanar probes with improved pre- and intraoperative evaluation, eg, improved accuracy of estimation of mitral regurgitation jet size, have led to a more precise surgical approach. In the intensive care unit, TEE is proving invaluable in diagnosing occult causes of clinical instability that are usually surgically correctable. Advances in imaging technology with three- and four-dimensional TEE will facilitate preoperative decision-making, determine intraoperative approaches to valvular surgery, and provide earlier recognition of complications in the intensive care unit.

Aortic Valve↗
PubMed1995

Congenital heart disease: wide-field, three-dimensional, and four-dimensional ultrasound imaging.

The next significant advance for cardiovascular ultrasound will be the introduction of clinical three-dimensional (3-D) imaging. With increasing computer power and software and hardware, 3-D ultrasound imaging will become a reality over the next few years. Of all cardiovascular abnormalities, congenital heart disease is one of the most logical entities to lend itself to wide-field and 3-D presentation. Tomographic two-dimensional (2-D) echocardiography has in great part replaced cardiac catheterization as the means of accurately visualizing congenital cardiac defects. However, two distinct limitations exist with current 2-D presentations: (1) limited field of view (ie, 90 degrees sector) and (2) tomographic slices that must be assimilated by the examiner into a 3-D or four-dimensional diagnosis. True 3-D imaging has the ultimate capability of rendering anatomy in a format comparable to looking at the actual cardiac specimen. If electronic rendering were really feasible and of suitable quality, one could envision electronically extracting the heart from a living human and examining abnormalities much as one might examine a cardiac specimen (ie, "electronic vivisection"). This article reviews the state of the art of wide-field and 3-D cardiovascular ultrasound in the assessment of congenital heart disease.

Adult↗
PubMed1992

Three-dimensional and four-dimensional transesophageal echocardiographic imaging of the heart and aorta in humans using a computed tomographic imaging probe.

We evaluated the clinical applicability of a prototype tomographic transesophageal echocardiographic (TEE) system, which not only provides conventional TEE images but also three-dimensional tissue reconstruction and four-dimensional display capabilities. The probe was used in 16 patients in the echocardiographic laboratory, intensive care unit, and the operating room. The instrument is a 5-MHz, 64-element, phased array unit mounted on a sliding carriage within a casing. After appropriate probe placement within the esophagus, the probe is straightened, a balloon surrounding the probe is inflated, and data acquisition begun with ECG and respiration gating. With computer controlled transducer movement at 1-mm increments, a complete cardiac cycle is recorded at each tomographic level. These are processed using a dedicated four-dimensional software, and displayed as a dynamic three-dimensional tissue image of the heart. We were able to see the dynamic motion of the ventricles and all the valves in the four-dimensional format. In addition to four-dimensional display, we were able to cut and visualize the heart in dynamic mode in any desired plane and also in multiple planes. Patients tolerated the procedure well. We conclude that this tomographic four-dimensional approach, which does not require tedious off-line processing, can easily be performed in patients and has a strong clinical potential.

Aorta↗
PubMed1994

Automated method for characterization of diastolic transmitral Doppler velocity contours: late atrial filling.

We develop an automated method of characterizing the late atrial filling phase of diastole by fitting a kinematic model for diastolic filling to the clinical Doppler A-wave contour. The result is a set of model parameters which completely characterizes the contour. We have previously derived a parameterized diastolic filling (PDF) model, which predicts the time-dependent transmitral blood flow velocity obtained by Doppler echocardiography. An automated method to determine the PDF model parameters for early rapid filling from the clinical Doppler E-wave has also been developed and validated. The method consists of digitizing the acoustic Doppler waveform, recreating the Doppler velocity profile, extracting the maximum velocity envelope, and fitting the PDF model for early filling to the envelope. In the current work, we apply the same general approach for PDF parameter determination for the late atrial filling phase of diastole. To assess the presence and significance of near-degeneracies in the model parameter set, numerical experiments (consisting of fitting the model to a model-generated contour to which Gaussian noise was added) were performed. These revealed a two-dimensional degeneracy in four-dimensional parameter space which could be removed by using two kinematic simplifications: critical damping and resonant forcing. We show that these degeneracy-eliminating approximations do not limit the ability of the model to predict clinical A-wave contours.

Atrial Function↗
PubMedDate not supplied

Segmentation of sequences of echocardiographic images using a simplified 3D active contour model with region-based external forces.

A method of segmenting echocardiography images based on three dimensional (two spatial and one time) surface was developed and tested on transcutaneous images from 38 patients and a four-dimensional (three spatial and one time) transesophageal scan of one patient. Active contour models with finite elements representing the curves in the imaging planes and finite difference description linking curves from time frame to time frame were employed. Region-based external forces were incorporated into the framework of the model and an analytical procedure for estimating the values of most of the model parameters was developed and used.

Algorithms↗
PubMed2000

Four-dimensional B-spline based motion analysis of tagged MR images: introduction and in vivo validation.

In MRI tagging, magnetic tags-spatially encoded magnetic saturation planes-are created within tissues acting as temporary markers. Their deformation pattern provides useful qualitative and quantitative information about the functional properties of underlying tissue and allows non-invasive analysis of mechanical function. The measured displacement at a given tag point contains only unidirectional information; in order to track the full 3D motion, these data have to be combined with information from other orthogonal tag sets over all time frames. Here, we provide a method to describe the motion of the heart using a four-dimensional tensor product of B-splines. In vivo validation of this tracking algorithm is performed using different tagging sets on the same heart. Using the validation results, the appropriate control point density was determined for normal cardiac motion tracking. Since our motion fields are parametric and based on an image plane based Cartesian coordinate system, trajectories or other derived values (velocity, acceleration, strains ...) can be calculated for any desired point within the volume spanned by the control points. This method does not rely on specific chamber geometry, so the motion of any tagged structure can be tracked. Examples of displacement and strain analysis for both ventricles are also presented.

Algorithms↗
PubMed1994

Dynamic three-dimensional echocardiography with a computed tomography imaging probe: initial clinical experience with transthoracic application in infants and children with congenital heart defects.

OBJECTIVE: To assess the clinical applicability of a prototype computed tomographic echocardiographic imaging probe in paediatric patients with congenital heart disease. DESIGN: A phased array echocardiographic transducer (64 elements, 5 MHz) mounted on a sliding carriage was used transthoracically in various positions on the chest. The transducer moves from the outflow tract to the apex of the heart in 0.5 to 1.3 mm increments and records a tomographic slice of the heart at each increment level. Parallel images are recorded at a frame rate of 25-30 images/s. At each level a complete cardiac cycle is recorded. The images are digitised and stored in the image processing computer, which reconstructs the anatomical structures of the heart in a three-dimensional format by means of different grey scales. PATIENTS: 45 paediatric patients (age range 3 days to 17 years) with various congenital heart defects who had been admitted to hospital for diagnostic or therapeutic cardiac catheterisation or surgery. RESULTS: Good quality echocardiographic pictures were obtained in all but two of the 45 patients. Three-dimensional reconstructions of the heart were possible from transthoracic echocardiograms. The recorded cardiac chambers and valves were displayed in three-dimensions in real time (four-dimensionally). The heart was also displayed in real time in any desired plane and in up to five planes simultaneously without having to change the position of the transducer on the chest. Different parts of the heart were displayed in a view similar to that seen by a surgeon during an operation. Image acquisition took 3-5 minutes and three-dimensional reconstruction of various cardiac structures 20-90 minutes. CONCLUSIONS: The computed tomographic imaging probe facilitates acquisition of echocardiographic data as multiple planes can be obtained from one transducer position. Display of three-dimensional structures of the heart may enhance the understanding of cardiac anatomy.

Adolescent↗