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Biomedical subjects

M V Green

Publications and source records attributed to M V Green.

85 records · Page 5Linked to original sources
PubMed1978

Radionuclide cineangiography during stress.

A "real-time" ECG-gated scintigraphic image system was developed at NIH, Bethesda. This system presents in real-time manner 1) an image sequence, that spans a complete heart cycle, 2) a regional time activity curve, in which later distolic phenomena are correctly portrayed, and 3) a beat length distribution function. This system is suitable especially for stress investigations. Normal subjects showed an increase of ejection fraction, whereas patients with CAD revealed a decrease of EF.

Cineangiography↗
PubMed1977

Real-time radionuclide cineangiography in the noninvasive evaluation of global and regional left ventricular function at rest and during exercise in patients with coronary-artery disease.

Although coronary angiography defines regions of potential ischemia in patients with coronary-artery disease, accurate assessment of the presence and functional importance of ischemia requires appraisal of regional and global left ventricular function during stress. To perform such assessment, we developed a noninvasive real-time radionuclide cineangiographic procedure permitting continuous monitoring and analysis of left ventricular function during exercise. In 11 patients with coronary disease who had normal regional and global ventricular function at rest, new regions of dysfunction developed during exercise (P less than 0.001), and in 10, global ejection fraction dropped 7 to 47 per cent. Fourteen age-matched normal subjects were studied; during exercise none had regional dysfunction, and each increased global ejection fraction (average increase, 23 +/- 3 per cent [+/-S.E.], P less than 0.001 as compared with patients with coronary disease). Radionuclide cineangiography during exercise permits accurate assessment of the presence and functional severity of ischemic heart disease.

Adult↗
PubMed1977

A real-time system for multi-image gated cardiac studies.

A minicomputer-based system is described that allows real-time construction and simultaneous display, in flicker-free movie format, of a cardiac-cycle-spanning sequence of ECG-gated scintigraphic images. In as little as 2 min, the endless-loop flicker-free movier clearly displays cardiac anatomy, time-dependent volume variations of cardiac chambers, and abnormalities of cardiac wall motion that would be difficult or impossible to detect from static gated images. Simultaneously, a time-activity curve with high temporal resolution can be generated from a previously defined region of interest, thereby quantifying additional parameters of cardiac function. Because the movie and time-activity curve are displayed in real time and require only a short data-collection interval to achieve statistical reliability, the physician can use the system interactively, modifying the form, intensity, or duration of diagnostic and therapeutic interventions based on the observed response. This system is well suited for intervention studies, for continuous cardiac monitoring, and for the rapid screening of patients with suspected cardiac disease.

Computers↗
PubMed1977

ECG-gated scintillation probe measurement of left ventricular function.

A nonimaging, ECG-gated scintillation-probe system is described that permits real-time quantification, at high temporal resolution, of the time variation of left ventricular (LV) volume over a complete, average cardiac cycle. Linearity between counting rate and volume, probe positioning, and background correction were investigated for both cylindrically collimated (CC) and parallel-hole-collimated (PC) detectors. In 53 patient studies, results obtained with these probes were compared with results obtained from an ECG-gated gamma camera system (CS) with high temporal resolution. Time-activity curves obtained by all three devices were essentially identical in shape (for CC against CS, r=0.93; for PC against CS, r=0.98) and in intracycle timing. Left-ventricular ejection fractions obtained with the probes showed workable agreement with the camera; for CC against CS, r=0.85 (N=31; for PC against CS, r=0.90 (N=21). When LV background is removed as a source of error, the correlation between (PC) probe and camera is improved (r=0.95, N=21). This suggests that the portable probe system be used in circumstances where exact knowledge of LV background is minimally important--e.g., continuous bedside monitoring of changes in LV function.

Adult↗
PubMedDate not supplied

High resolution PET, SPECT and projection imaging in small animals.

Positron emission tomography, single photon emission computed tomography and planar projection imaging of radioactive tracers have long been in use for detecting and diagnosing disease in human subjects. More recently, advanced versions of these same technologies have begun to be used across the breadth of modern biomedical research to study non-invasively small laboratory animals in a myriad of experimental settings. In this report, we describe some of the new instruments and techniques that make these measurements possible and illustrate, with a few examples, the potential power of these methods in modern biomedical research.

Animals↗
PubMedDate not supplied

Stochastic analysis of 133xe clearance for determining regional cerebral blood flow in a primate model.

A technique for stochastic analysis of 133Xe washout using a computer-assisted Anger camera is described. The technique produces functional maps of both regional cerebral blood flow (rCBF) and error in rCBF. The calculational limitations of the technique are discussed and an experimental estimate made of the physical limitations associated with the low energy photon emitted by 133Xe. The method is demonstrated in a rhesus monkey model before and after surgical occlusion of the middle cerebral artery.

Animals↗