Tc-99m human serum albumin: a suitable agent for plasma volume measurements in man.

In 16 patients we have carried out simultaneous plasma-volume measurements with human serum albumins tagged with Tc-99m (Tc-99m HSA) and I-131 (I-131 HSA). The correlation coefficient was 0.987. Tc-99m HSA, prepared from kits that predictably yield high labeling efficiency (and thereby negligible amounts of TCO4-), is clearly a superior agent for repeat plasma volume determinations, because of its shorter half-life and the reduced radiation dose to the subject.

A study of age-dependent changes in thyroid function tests in adults.

Total serum thyroxine (T4), triiodothyronine (T3), T3 resin uptake (T3U), thyrotrophin (TSH), and reverse T3 (rT3) were measured in 209 healthy adults 20--89 yr old. Mean T4 values for men were stable throughout life, but in females under age 60, T4 values were significantly higher than in older women. Values for T3U in males were significantly higher than in females throughout all decades, although females had a significant increase in T3U after age 60. TSH values increased significantly in females over age 60. Throughout all decades, males had stable TSH levels that were slightly higher than the female results before age 60 and lower thereafter. Mean serum T3 declined similarly for both sexes with increasing age, although not to the extent previously reported. Men had significantly higher mean rT3 values over all decades than females, although female rT3 levels decreased after age 50 whereas males maintained stable values. The physiologic reasons for these findings may be due to sex-related changes in binding proteins and alterations in metabolic clearance rates, production, and degradation of these hormones with increasing age.

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.

A simple method to measure mesenteric arteriovenous shunt flow during arteriography.

A quantitative method for external detection of mesenteric arteriovenous shunts was developed. 99mTc-Human Serum Albumin Microspheres (15--30 microns) were injected into the superior mesenteric artery of dogs through an angiographic catheter, followed by external scintillation counting of the liver activity, which represented the shunted spheres. Thereafter, 99mTc-sulfur colloid was injected identically and the liver activity counted again. The liver net count after sulfur colloid represented a 100% shunt, when a correction factor for the actual liver uptake was applied. The a shunt rate was calculated. Eleven animal studies were performed and shunt rates similar to previous in vitro determinations were obtained. This method is suitable for clinical investigation and can conveniently be applied to mesenteric arteriography.

Bowel visualization during indium-111-labelled diethylene triamine penta-acetic acid cisternography due to massive cerebrospinal fluid leak. Case report and review of the literature.

We report a case of massive cerebrospinal fluid (CSF) leakage where the tracer injected intra-thecally for radionuclide cisternography was later visualized in the bowel as well as the nasopharynx. We discuss the potential implications of this finding in patients with CSF leaks. A brief review of the diagnosis of CSF leaks is included.

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.