The Dynamic Spatial Reconstructor is a unique high speed volume imaging X-ray scanner based on computed tomographic principles. It has several potential advantages over conventional angiographic methods, including reduced invasion, reduced rate of false negative results and increased accuracy of measurements of structure and function. To evaluate the utility of the Dynamic Spatial Reconstructor in the investigation of congenital heart disease, scanning was performed in several pediatric patients with pulmonary valve atresia.
View Article and Find Full Text PDFAm J Physiol
November 1984
The dynamic spatial reconstructor (DSR), an x-ray-computed, tomography-based imaging machine, scans a cylindrical volume up to 39 cm in transaxial diameter and 21.5 cm in axial height with scan repetition rate up to 60 per second. We applied this technique to three dogs in order to investigate the accuracy with which stomach shape, dimensions, and motility can be measured.
View Article and Find Full Text PDFThe dynamic spatial reconstructor (DSR), a high temporal resolution, three-dimensional roentgenographic, computed tomography scanner, was used to scan the coronary arteries of five dogs. After one injection of contrast medium into the left main coronary artery or into the aortic root of each dog, all major epicardial coronary arteries and the septal artery could be imaged. After selective removal of all nonangiographically enhanced anatomical structures within the three-dimensional images, pseudo three-dimensional displays were generated to show the arteries from all possible views--even the strictly cranial view--so that superposition of arteries could be avoided.
View Article and Find Full Text PDFJ Comput Assist Tomogr
June 1984
The accuracy in determining the three-dimensional anatomy of a vessel network by computed tomography (CT) is evaluated using a glass model of a pulmonary artery. The dynamic spatial reconstructor (DSR), a high temporal resolution, volumetric, roentgenographic, CT scanner, was used to scan the model. The glass of the model had a roentgen attenuation coefficient mu = 0.
View Article and Find Full Text PDFThree-dimensional (3-D) dynamic computed tomography of the heart with the dynamic spatial reconstructor (DSR) is being used for studies of cardiovascular function. Formerly, continuous infusion of bilateral bolus injections of contrast medium were required to visualize both sides of the heart simultaneously. The DSR was used to circumvent many of the drawbacks of these methods.
View Article and Find Full Text PDFUsing the Dynamic Spatial Reconstructor (DSR), a unique multiple X-ray source, high-repetition-rate CAT scanner, we estimated left ventricular (LV) myocardial volume and chamber volume of eight dogs ranging from 2.5 to 32.5 kg.
View Article and Find Full Text PDFCardiovasc Intervent Radiol
October 1984
The Dynamic Spatial Reconstructor (DSR) is a high-temporal resolution, three-dimensional (3-D) X-ray scanning device based on computed tomography (CT) principles. It was designed for investigation of some problems inherent in current diagnostic imaging techniques, and to allow quantitative studies of cardiovascular structure and function. One of the research protocols in which DSR is currently used involves studying selected pediatric patients with complex congenital heart disease.
View Article and Find Full Text PDFThe facilities that make up the Mayo Biodynamics Research Unit include the dynamic spatial reconstructor (DSR), which when fully operational will generate raw data at 200 million samples per second. Processing of these data will require a computer capable of several billion arithmetic operations per second.
View Article and Find Full Text PDFJ Appl Physiol Respir Environ Exerc Physiol
May 1983
The Dynamic Spatial Reconstructor (DSR) can be used to determine detailed structure-to-function relationships or organ systems in vivo. A basic index of lung structure (shape and dimensions) is total lung volume. We checked the accuracy with which in vivo lung volumes can be measured by comparing lung volume (air plus tissue) determined by DSR scanning with that determined by excision and water displacement.
View Article and Find Full Text PDFVerapamil has a negative inotropic action in isolated cardiac muscle. Its effects on left ventricular function were tested in 25 patients with suspected coronary artery disease. A double-blind, randomized, placebo-controlled study design was used.
View Article and Find Full Text PDFThe Dynamic Spatial Reconstructor system has been developed to dynamically (up to 60/sec) image the entire 3-D volume (up to 240 adjacent 1-mm-thick transverse sections) encompassing moving organs of the body, particularly the heart and lungs, or the circulation in any organ. This capability permits accurate regional and global measurements to be made of the important relationships between structure and function within and among these organs, which in turn facilitates achievement of new insights into the basic physiological processes of these organs, and promises increased sensitivity and specificity in the diagnosis of pathology that affects normal organ function. This article explains the biomedical and technological rationale for development of the DSR, describes the design concepts and practical operation of the system, and presents preliminary results obtained with the system, including initial data from one of the first patient studies.
View Article and Find Full Text PDFJ Comput Assist Tomogr
December 1982
Spatial, density, and temporal resolution of the dynamic spatial reconstructor (DSR), a multiple X-ray source, high speed, computed tomography scanning system, are evaluated. Hole-pair resolution was evaluated in a stationary phantom surrounded with air, 15 cm of water, or 20 cm of water. Temporal resolution was evaluated by rotation of one of the resolution phantoms during the scan, and with a balloon inflated to a known volume and at a known rate to approximate a typical left ventricular chamber volume and filling rate.
View Article and Find Full Text PDFThe effects of step-wise reduction in left circumflex coronary blood flow on: 1) posteroinferior wall dynamics; 2) normally-perfused anterior wall dynamics; and 3) cavity function were assessed simultaneously by roentgen videometric analysis of left ventricular angiograms in open-chest dogs during normal and increased afterload. At control coronary flow with normal afterload, peak rates of systolic thickening and diastolic thinning of the posteroinferior and anterior walls were similar. Step-wise reduction in circumflex coronary flow resulted in a progressive fall in systolic and diastolic posteroinferior wall dynamics.
View Article and Find Full Text PDFLeft ventricular performance was studied before and late (mean 12-17 months) after aortocoronary artery bypass surgery by quantitative, computer-based videoangiography. We measured total function (left ventricular ejection fraction, volumes and end-diastolic pressure) at rest (in 60 patients) and before and after exercise (abnormal exercise hemodynamics preoperatively in 32 patients) and regional function (peak rate of systolic wall thickening) at rest (in 60 patients) and before and after administration of nitroglycerin (in 19 patients). Total left ventricular function at rest is usually unchanged postoperatively.
View Article and Find Full Text PDFA prototype synchronous volumetric computed tomographic X-ray scanner was used to demonstrate, in individual experiments, the possibility of estimating percent coronary arterial stenosis, regional myocardial blood supply and regional myocardial wall dynamics. Scans were obtained during angiography in intact anesthetized dogs or in an isolated metabolically supported working left ventricular preparation. Percent arterial stenosis was quantitated using the percent change in brightness area product of successive cross-sectional images of contrast agent-filled Tygon tubing sutured to the epicardium.
View Article and Find Full Text PDFRadiol Clin North Am
December 1980
A particularly important potential value of the Dynamic Spatial Reconstructor approach is that all the above data will be obtainable from a single injection of contrast agent into the right ventricle or pulmonary artery. On the basis of preliminary experimental data, a concentration of at least 80 mg of iodine per ml of contrast agent should be present in the aortic root for adequate opacification of the coronary arteries and myocardium; a bolus of at least 0.5 ml of contrast medium per kg, injected into the venous circulation, is required.
View Article and Find Full Text PDFA new imaging device, the dynamic spatial reconstructor (DSR), is described. It differs from commercially available computed tomography scanners in several ways. It images a volume rather than a slice; it images the volume in stop-action to minimize blurring due to motion; and it repeats the scan 60 times per second so that the functional movements of heart muscle and lung tissue and the distribution of roentgen contrast medium in blood can be quantitated in any portion of the body, especially in the heart, great vessels, and lungs.
View Article and Find Full Text PDFTohoku J Exp Med
September 1980
Incompressibility of left ventricular myocardium was tested utilizing isolated canine working left ventricular preparations. This ventricle functioned at levels comparable to the intact heart. The ventricular muscle volume was calculated with the videometric border recognition technique, which is probably the most satisfactory among the presently available techniques to measure left ventricular volume.
View Article and Find Full Text PDFThe constitutive equation with stress-dependent coefficients for laminated composite is derived and employed for iterative determination of myocardial fiber's stiffness equation E(f) = Ksigma(f) + C from myocardial strip's stiffness equation E(s) = K(s)sigma(s) + C(s). The strip's stiffness constants K(s) and C(s) are estimated by the least-square curve fitting of the stress-strain data experimentally obtained from uniaxially stretching of strips of left ventricular heart wall excised from seven canine hearts. The values of K and C computed at selected fiber orientations across the thickness of the strip and using three, five, and ten-layer approximations are reported.
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