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Biomedical subjects

R D Neirinckx

Publications and source records attributed to R D Neirinckx.

30 records · Page 2Linked to original sources
PubMed1980

Potential column chromatography for ionic Ga-68. II: Organic ion exchangers as chromatographic supports.

A potential Ge-68 leads to Ga-68 generator system, based on the adsorption of Ge-68 from a dilute hydrofluoric acid eluent onto a commercially available organic anionexchange resin, is described. The distribution coefficients between the resin and dilute hydrofluoric acid were measured for germanium and gallium, and the breakthrough of germanium from a generator column determined. Using 0.01 N HF, the Kd values are 27 and greater than 4,000 for gallium and germanium, respectively. Gallium-68 can be quantitatively collected with 4 ml of 0.01 N HF. After neutralization, this provides a biologically safe concentration of NaF for injection. The breakthrough levels of germanium-68 remain lower than 10(-4) for up to 600 collections.

Chromatography, Ion Exchange↗
PubMed1979

Cardiac imaging with tantalum-178.

Tantalum-178 is a potential tracer for the first transit studies of the heart. It has a short physical half-life (9.3 minutes) and is obtained as a generator product from its long-lived (21.3 days) parent, tungsten-178. First transit studies were performed in the monkey and dog following the intravenous injection of 20 mCi (740 MBq) of tantalum-178. Imaging was performed with a large field of view single crystal camera and a multicrystal camera. Pulmonary dilution curves were derived for the analysis of left-to-right intracardiac shunting and high temporal resolution studies were obtained to assess left ventricular function and to measure left ventricular ejection fraction. The short physical half-life of tantalum-178 permits fraction. The short physical half-life of tantalum-178 permits multiple sequential studies with reduced patient radiation dose compared to the current radionuclide of choice, technetium-99m.

Angiocardiography↗
PubMed1979

Potential column chromatography generators for ionic Ga-68. I. Inorganic substrates.

Chemical separations for Ga-68 from Ge-68 using adsorption chromatography on inorganic materials are described. The adsorbents used were TiO2, ZrO2, and SiO2. Distribution coefficients for Ge and Ga on these absorbents were determined as a function of reagent concentration and duration of equilibration. The distribution coefficient (w/w) for Ge on SiO2 reached 250 in 6 N HNO3, whereas Ga was no significantly adsorbed. Therefore, Ga-68 can be collected with a mall volume of 6 N HNO3 eluent. By contrast, large volumes of 1 N HNO3 were necessary to collect Ga-68 from ZrO2, since the KD of Ga under these circumstances was about 50. The Ga-68 eluted from TiO2 was chemically contaminated with titanates and would require additional chemical manipulation in order to make it injectable. All the adsorbents could lead to chromatographic systems that would allow acceptable chemical separations. However, the specific requirements for a radionuclide generator, usable in a hospital environment, make the SiO2-based system the most attractive.

Chromatography↗
PubMed1979

Tantalum-178-labeled agents for lung and liver imaging.

Despite its 9.3-min half-life, Ta-178 can be used to produce radiopharmaceuticals for lung and liver imaging. A variety of human serum albumin microspheres and other particulate radiopharmaceuticals were labeled with Ta-178. A period of approximately 10 min was required for their preparation and administration to rats. Extrapolation to the clinical situation suggests that imaging could take place after one half-life of the nuclide has elapsed. We found that satisfactory imaging is possible using Ta-178 radiopharmaceuticals with the Anger camera and a pinhole collimator. Since short imaging times, high spatial resolution, and low patient doses are reasonable objectives in pediatric scintigraphy, these new radiotracers may prove useful for lung and liver imaging in children.

Animals↗
PubMed1979

Scintigraphic imaging with tantalum-178 and the Anger scintillation camera: concise communication.

Tantalum-178 is a short-liver radionuclide (T 1/2 = 9.3 min.) and emits primarily 56- to 64-keV characteristic x-rays. We have determined the imaging characteristics with this radionuclide and a large-field-of-view Anger camera. With a pinhole collimator, good spatial resolution is possible with Ta-178, although the image quality is superior with Tc-99m under comparable conditions. Spatial resolution with parallel-hole or converging collimators was much less satisfactory with Ta-178 because of septal penetration by high-energy photons. Pulmonary perfusion and liver-spleen images of excellent quality were obtained in the rabbit using the pinhole collimator and Ta-178-labeled agents.

Animals↗
PubMed1978

Tantalum-178--a short-lived nuclide for nuclear medicine: production of the parent W-178.

The physical decay characteristics of the short-lived radionuclide Ta-178 (half-life 9.3 min) appear to be suitable for use in conjunction with low-energy detection systems such as the multiwire proportional camera. This camera is inefficient for emissions with energies greater than 100 keV. The gamma-ray spectrum of Ta-178 is dominated by the characteristic hafnium x-rays (55--65 keV), emitted as a result of electron-capture decay. The parent nuclide, W-178 (half-life 21.7 d), was produced in the Michigan State University cyclotron by proton bombardment of stacked natural tantalum-foil targets. Optimum production was found to occur with an incident proton energy of 34 MeV at an effective activity of 1.1 mCi/muA-hr per MeV of target thickness. Tungsten-178 was chemically separated from the Ta foils with a yield of 98%.

Particle Accelerators↗
PubMed1978

Tantalum-178--a short-lived nuclide for nuclear medicine: development of a potential generator system.

We describe a chemical separation that may form the basis of a generator system for the short-lived radionuclide Ta-178 (T 1/2 = 9 min). The parent nuclide W-178 (T 1/2 = 21.7 days) is loaded on an anion-exchange column and the daughter eluted with a mixture of dilute hydrochloric acid and hydrogen peroxide. The yields of tantalum and the breakthrough of the tungsten parent as a function of the eluting conditions are discussed, and preliminary animal distribution data are presented for various treatments of the eluant solution.

Animals↗
PubMedDate not supplied

In vivo 19F NMR imaging of liver, tumor, and abscess in rats. Preliminary results.

In vivo magnetic resonance imaging (MRI) has employed almost exclusively the proton because of its high gyromagnetic ratio and natural abundance relative to other nuclei. Recent research has focused on imaging using nuclei other than 1H, but has been limited by the decreased sensitivity and/or low biologic concentrations of the nuclei. Fluorine (19F), with a gyromagnetic ratio second only to that of hydrogen, is a theoretically attractive nucleus for MRI, but fluorine is present in only minute amounts in most tissues. Perfluorochemical emulsions (PFC), developed as blood replacement agents, appear to be safe vehicles for fluorine administration. We report our initial results of in vivo 19F magnetic resonance imaging of liver, tumor, and abscess in rats given exogenous fluorine.

Abscess↗