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Biomedical subjects

D Koller

Publications and source records attributed to D Koller.

5 recordsLinked to original sources
PubMed1990

Decrease in xenon clearance during response to cold, dry air: problems of interpretation.

In order to increase our understanding of the nasal response to cold, dry air (CDA), we studied changes in xenon clearance as an indicator of nasal blood flow. Eight individuals previously shown to respond to CDA had measurements of xenon clearance made in the left inferior turbinate before, during, and after a 15-minute exposure to either CDA (-7 degrees C to 0 degrees C, less than 10% relative humidity) or room air. The half-life in seconds for xenon clearance on the day when CDA was inhaled was 56 +/- 6, 41 +/- 5, and 110 +/- 31, before, during, and 10 minutes after challenge, respectively. On the control day, with subjects breathing room air, the equivalent measurements of half-life in seconds were 54 +/- 8, 41 +/- 6, and 42 +/- 4, respectively. Xenon clearance was prolonged significantly (p less than .01) after exposure to CDA during the clinical response. The interpretation of the change in xenon clearance as an indicator of nasal blood flow is discussed.

Air↗
PubMed1988

Short-axis circumferential profiles of the heart in healthy subjects: comparison of T1-201 SPECT and two-dimensional echocardiography.

To correlate the findings at thallium-201 single photon emission computed tomography (SPECT) with left ventricular anatomy, circumferential wall thickness was measured in 12 healthy subjects with two-dimensional echocardiography. At the midpapillary level, eight anatomic structures were identified with echocardiography, as were four maxima (papillary muscles and junctions of the left ventricular myocardium with the right ventricle, both anteriorly and posteriorly) and the intervening minima (including the septum). Tl-201 SPECT was performed in the same subjects. The normalized circumferential count profiles of the short-axis sections that included the papillary muscles showed the same basic pattern as that on echocardiograms. In most cases, the posterior papillary muscle and the posterior junction with the right ventricle were not distinguishable from each other, which produced three circumferential profile maxima instead of four. When values from all subjects were averaged, left ventricular anatomy was less evident in the circumferential profile. Left ventricular anatomic structures were reflected to a similar degree with either 180 degrees or 360 degrees data sampling.

Adult↗
PubMed1985

Right ventricular ejection fraction measured by first-pass intravenous krypton-81m: reproducibility and comparison with technetium-99m.

Study of the effects of various diseases and therapeutic manipulation of pulmonary vascular resistance on the right ventricle has been restricted by methodologic limitations. The radioactive gas in solution, krypton-81m was used to study the right ventricle and the technique was compared with a technetium-99m method. In 22 subjects, first-pass krypton-81m right ventricular ejection fraction, acquired both in list mode and electrocardiogram-gated frame mode, correlated well (r = 0.81 and 0.86, respectively, p less than 0.01) with that determined by technetium-99m first-pass studies over a broad range of ventricular function. The reproducibility of the technique was excellent (r = 0.84 and 0.95 for each acquisition mode, respectively). Krypton-81m first-pass studies provide accurate and reproducible estimates of right ventricular function. Use of krypton allows multiple measurements, with or without perturbations, over a short period of time.

Heart Ventricles↗
PubMed1982

Performance of a fully automated program for measurement of left ventricular ejection fraction.

A fully automated program developed by us for measurement of left ventricular ejection fraction from equilibrium gated blood pool studies was evaluated in 130 additional patients. Both 6-min (130 studies) and 2-min (142 studies in 31 patients) gated blood pool studies were acquired and processed. The program successfully generated ejection fractions in 86% of the studies. These automatically generated ejection fractions were compared with ejection fractions derived from manually drawn regions of interest. When studies were acquired for 6-min with the patient at rest, the correlation between automated and manual ejection fractions was 0.92. When studies were acquired for 2-min, both at rest and during bicycle exercise, the correlation was 0.81. In 25 studies from patients who also underwent contrast ventriculography, the program successfully generated regions of interest in 22 (88%). The correlation between the ejection fraction determined by contrast ventriculography and the automatically generated radionuclide ejection fraction was 0.79.

Cardiac Output↗