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Biomedical subjects

W J MacIntyre

Publications and source records attributed to W J MacIntyre.

At least 73 records · Page 4Linked to original sources
PubMed1980

Abnormal left ventricular relaxation in hypertensive patients.

1. The maximum rates of left ventricular ejection and filling were derived (Fourier analysis) from the left ventricular volume curve (99m technetium-human serum albumin gated blood pool studies) in 12 normotensive subjects and 15 hypertensive patients of matched age groups. 2. Average values of cardiac output, ejection fraction, heart rate and left ventricular ejection rate were not significantly different in the two groups. 3. Hypertensive patients had a slower rate of left ventricular filling (P < 0.05), suggesting diminished left ventricular compliance in hypertension.

Adult↗
PubMed1980

Acoustic shadow formation by gallstones.

Schlieren photography of gallstones and models of gallstones made from amorphous substances has demonstrated that acoustic shadowing depends primarily on the orientation of the surface of the stone in relation to the sound beam, not the composition of the stone.

Cholelithiasis↗
PubMed1980

Digital subtraction angiography of the human cardiovascular system.

Initial clinical application of a system for digital subtraction angiography (DSA) to the human cardiovascular system in 88 patients is reported. The equipment consisted of a specially designed computer system integrated with a fluoroscopic and radiographic apparatus for digitization, manipulation, and display of data. After intravenous injection of contrast material, adequate visualization of the heart and carotid, thoracic, abdominal, and femoral arteries was obtained with sufficient quality to obviate conventional angiography in many clinical settings. In this mode, nonselective opacification is obtained. However, DSA was also used to extend the capability of selective angiography. The availability of quantitative information permitted the determination of rates of transit of contrast material in various organs which may give insights of their physiologic performance.

Aneurysm↗
PubMed1979

Automated computer program for radionuclide cardiac output determination.

Radionuclides have provided a safe, reliable, and minimally invasive method for repeated determinations of cardiac output. A completely automated computer program for data analysis is described. Cardiac output values obtained by this technique correlated closely with values obtained by manual determination of the region of interest (r = 0.90 for right-ventricular and 0.98 for left-ventricular outputs, p less than 0.001 for both). Further, cardiac output determined by computer selection of either left-ventricular area of interest or of the "whole heart region" correlated significantly with that simultaneously determined by dye-dilution technique (indocyanine green; r = 0.86, p less than 0.001 for both). The automated approach allows greater objectivity in the selection of the regions of interest, faster turnaround of calculated results, and use of a smaller dose of radionuclide.

Adult↗
PubMed1977

Camera-computer systems for rapid dynamic imaging studies.

The extraction of valuable diagnostic information from rapid, dynamic studies performed on a gamma camera requires that the data be recorded for latter analysis. If these data are to be available rapidly and if quantitative analysis is to be performed, it is imperative that a computer be used in conjuction with the gamma camera. This review describes the more important features of a nuclear medicine computer system both from the point of view of hardware and software. The various aspects that cause some limitations to be imposed on the capability of the system in order to carry out fast, dynamic studies are described and some possible solutions are suggested.

Analog-Digital Conversion↗
PubMed1977

White and gray matter of the brain differentiated by computed tomography.

The white and gray matter of the brain can be clearly differentiated by computed tomography (CT). The differentiation is enhanced by the administration of contrast material. Without contrast material, the mean attenuation number of the white matter was 29 units, of the gray matter, 35 units. The effective low contrast resolving power of CT scanners can be clinically evaluated by comparing their ability to differentiate the white and gray matter of the brain.

Brain↗
PubMed1976

Comparative modulation transfer functions of the EMI and Delta scanners.

Spatial resolution of the EMI and Delta computed tomographic scanners has been measured by recording the response to a nylon and water sunburst phantom (Siemens star) and calculating the modulation transfer function at radii corresponding to various spatial frequencies. The resolution appears to be related primarily to the size of the matrix element, and exhibits an upper cut-off frequency somewhat in excess of 3 cycles/cm.

Computers↗
PubMed1976

The effects of biological motion on CT resolution.

A variety of periodic and aperiodic psyiologic motions affect the quality of CT images. This study was initiated to estimate what an optimal scan period should be in the design of CT units. Ultrashort scan periods were experimentally similated in the heart and liver to approximate the parameters of future technology.

Animals↗
PubMed1975

Computed tomography of the thorax and abdomen; a preliminary report.

The utility of computed tomography (CT) in the study of the anatomy, physiology, and pathology of the human body has been the subject of considerable interest since the introduction of CT scanning. The advent of a new prototype scanning device has made it possible to examine a variety of abnormalities in the abdomen and thorax in a manner not previously possible. This development permits a remarkable insight into the study of human disease in vivo.

Aortography↗