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PubMed1996

Regional myocardial perfusion assessed with generator-produced copper-62-PTSM and PET.

UNLABELLED: We have previously demonstrated that myocardial perfusion can be estimated accurately in experimental animals with the generator-produced positron-emitting tracer, 62Cu-pyruvaldehyde bis (N4-methylthio- semicarbazone)(62Cu-PTSM) and PET. This study evaluated the feasibility of quantifying regional myocardial blood flow using 62Cu-PTSM and PET in human subjects. METHODS: Regional perfusion was estimated using a previously described and validated two-compartment model from dynamic PET scans obtained after an intravenous bolus of 62Cu-PTSM in 10 healthy volunteers and in 6 patients with coronary artery disease at rest: and in 9 of the volunteers and 4 of the patients after administration of dipyridamole intravenously. Flow estimates were compared with those obtained using H2(15)O. RESULTS: Contrast was high between myocardium and blood or lung with 62Cu-PTSM, resulting in high-quality myocardial images. Liver uptake was also high. At flows of up to 1.5 ml/g/min, flow estimated with 62Cu-PTSM correlated closely with estimates obtained with H2(15)O (y = 0.71x .21, n = 169 regional comparisons, r = 0.66, p < 0.55), but this relationship was not maintained at higher flows. CONCLUSION: The results demonstrate that quantification of myocardial perfusion with 62Cu-PTSM is feasible in human subjects but cannot be used to estimate hyperemic flows due most likely to the strong binding of the tracer to human serum albumin. Copper-62-PTSM congeners with less avidity for human albumin may prove more suitable for evaluation of hyperemic flows.

Adult↗
PubMed1996

Generator-produced copper-62-PTSM as a myocardial PET perfusion tracer compared with nitrogen-13-ammonia.

UNLABELLED: The purpose of this study was to determine the suitability of 62Cu-pyruvaldehyde bis(N4-methylthiosemicarbazone) (62Cu-PTSM) for estimating myocardial blood flow (MBF) over a wide range of flow by comparison with 13N-ammonia (13NH3). METHODS: PET studies using 62Cu-PTSM and 13NH3 were performed at rest and after pharmacological vasodilatation in 9 normal subjects and 13 patients with coronary artery disease (CAD). According to the microsphere method, values for the product of the extraction fraction and MBF (ExMBF) were calculated using both tracers. In static images, the percent uptake (normalized to the peak count) of each tracer was measured in patients with CAD. RESULTS: The myocardial tracer distribution in the normal subjects was significantly higher in the inferior wall in the 62Cu-PTSM studies and lower in the lateral wall in the 13NH3 studies. The ExMBF values showed linear correlation for both tracers in a low flow range. In a high flow range, however, the ExMBF values for 62Cu-PTSM were nonlinearly proportional to the increase of those for 13NH3 (y = 1.1 x -0.21x2, r = 0.81). The percent uptake for both tracers at baseline well correlated linearly (y = 10.4 + 0.88x, R = 0.91). After pharmacological vasodilatation underestimation of blood flow with 62Cu-PTSM was noted compared to that with 13NH3 at high flows (y = 31.8 + 0.63x, r = 0.76). CONCLUSION: These results suggest that the MBF estimates using 62Cu-PTSM in a low flow range may be as accurate as those with 13NH3. In a high flow range, however, the extraction fraction of 62Cu-PTSM is considered to be lower than that of 13NH3, and this may limit the estimation of MBF with 62Cu-PTSM after pharmacological vasodilatation.

Ammonia↗
PubMed1994

Production of no-carrier-added 64Cu from zinc metal irradiated under boron shielding.

BACKGROUND: Positron emission tomography offers advantages for radioimmunodiagnosis of cancer but requires radionuclides of appropriate half-life that have high specific activity and high radio-purity. This work was designed to develop a viable method to produce and purify 64Cu, which has high specific activity, for positron emission tomography. METHODS: 64Cu was produced at the University of Missouri Research Reactor by the nuclear reaction, 64Zn(n,p)64Cu. Highly pure zinc metal (99.9999%) was irradiated in a specially designed boron nitrite lined container, which minimized thermal neutron reactions during irradiation. A new two-step procedure was developed to chemically separate the no-carrier-added 64Cu from the zinc metal target. RESULTS: 64Cu recovery for 24 runs averaged 0.393 (+/- 0.007) mCi per milligram of zinc irradiated. The boron-lined irradiation container reduced unwanted zinc radionuclides 14.3-fold. Zinc radionuclides and non-radioactive zinc were separated successfully from the 64Cu. The new separation technique was fast (2 hours total time) and highly efficient for removing the zinc. The zinc separation factor for this technique averaged 8.5 x 10(-8), indicating less than 0.0000085% of the zinc remained after separation. Thus far, the highest 64Cu specific activity at end of irradiation was 683 Ci/mg Cu, with an average of 512 Ci/mg Cu for the last six analyzed runs. CONCLUSION: The boron-lined irradiation container has sufficient capacity for 75-fold larger-sized zinc targets (up to 45 g). The new separation technique was excellent for separating 64Cu, which appears to be a radionuclide with great potential for positron emission tomography.

Boron↗
PubMed1981

The phenomenon of 'tired moly-99Mo'.

The phenomenon of 'tired moly-99Mo' results in poor yields of 99mTcO4- obtained from 99MoO4 2-. The solvated electron has been conceived to explain this phenomenon, especially when it occurs in highly alkaline media as obtained in the solvent extraction type of separation system.

Radionuclide Generators↗
PubMed1985

Bromine-82 contamination in fission product 99mTc-generator eluate.

Following receipt of fission product 99mTc-generators, results of radionuclide purity analysis, performed within 30 min after the first elution, demonstrated detectable levels of a contaminate radionuclide not previously reported. Gamma spectroscopy and half-life determinations confirmed the presence of 82Br. Bromine-82 activity, in eluates from the first elution of 30 generators, received weekly during a 7-month period, ranged from 0.22 microCi (8.235 kBq) to 0.67 microCi (24.68 kBq) per eluate. The ratio of 99Mo to 99mTc ranged from 0.13 nCi to 0.39 nCi per mCi 99mTc. The presence of 82Br in 99mTc-generator eluate resulted in falsely elevated 99Mo assay determinations using whole vial 99Mo assay procedures. For every 0.1 microCi 82Br present in 99mTc eluate the 99Mo assay results were elevated by 1 microCi. Gamma spectroscopy of eluates from additional elutions of these generators failed to detect the presence of 82Br demonstrating the displacement of monovalent bromine anions from the alumina column during the first elution.

Bromine↗
PubMed1981

Production of Curie quantities of high purity I-123 with 15 MeV protons.

Using the technology described for electrodeposition of elemental tellurium, it is possible to bombard a target with 2 kW of proton beam power without significant loss of radio iodine. If Te-123 enriched to 96% is used as target material, the I-123 yield would be about 1 Curie with a 0.23% I-124 impurity for a 2-h bomardment with 130 muA of 15 MeV protons. The same I-124 impurity level can be maintained with a lower enrichment of Te-123 by reducing the proton energy to 11.5 meV, but with a consequent reduction in I-123 yield.

Iodine Radioisotopes↗
PubMed1990

Production of carrier-free 66Ga and labeling of antimyosin antibody for positron imaging of acute myocardial infarction.

A method for labeling monoclonal antimyosin antibodies with 66Ga is described. The radionuclide is a positron emitter (t1/2: 9.4h) produced by means of the 63Cu (4He, n) 66Ga reaction. Purification of the 66Ga from the copper target is described in detail. Monoclonal antimyosin antibodies are labeled with 66Ga at a high yield (99%) by transcomplexation from an acetate buffer with the diethylenetriamine pentaacetic acid (DTPA)-labeled antibody and preliminary evaluated in two dogs for imaging of myocardial necrosis by positron emission tomography.

Animals↗
PubMed1995

Failure to label red blood cells adequately in daily practice using an in vivo method: methodological and clinical considerations.

This study was conducted to evaluate the frequency and possible causes of poor red blood cell (RBC) labelling when performing equilibrium gated blood pool (GBP) radionuclide angiography at rest with an in vivo method. The influence of the mode of administration on tagging efficiency was studied by investigating the image quality in 160 patients referred for evaluation of left ventricular (LV) function prior to or after coronary angiography, while using a roughly standardized administration protocol. The patients were subclassified into four groups according to the way both molecules involved in the tagging procedure were administered. When poor image quality was found (in 9.4% of the patients), the labelling efficiency was quantified and the frequency of failed tagging in each group was calculated. A significant association was found between poor labelling and the use of a Teflon catheter or butterfly needle for the injection of the stannous agent. In another 737 patients, in order to avoid the problems observed in the first group, a strict administration protocol was applied to analyse the frequency of poor tagging and its possible causes. Suboptimal image quality was present in 88 patients (11.9%). Quantitatively confirmed poor tagging was present in 36 of the 88 (40.9%, or 4.9% of the whole group); the remaining 52 patients showed borderline normal labelling (> 80% bound fraction). Drug interference was studied by comparing the medications used by the 36 patients showing poor binding with those used by 44 control patients. A significant relationship was found between the use of heparin or chemotherapy and the tagging. The influence of several clinical factors on the labelling was also investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1982

Excitation functions for 3He-Particle induced nuclear reactions on 76Se, 77Se and natSe: possibilities of production of 77Kr.

Thin selenium films were prepared by cathodic deposition on aluminium foils. The Al-Se-Al sandwich stacks were used for measurement of the excitation functions of the 76Se(3He,2n)77Kr, 77Se(3He,3n)77Kr and natSe(3He,xn)77Kr reactions up to 3He-particle energy of 36 MeV. Excitation functions were also measured for the competing reactions 76Se(3H,3n)76Kr, 76Se(3He,pn)77Br, 76Se(3He,p2n)76Br, 76Se(3He,p3n)75Br, 76Se(3He, alpha)75Se, 77Se(3He,n)79Kr, 77Se(3He,4n)76Kr, 77Se(3He,pn)78Br, 77Se(3He,p2n)77Br, 77Se(3He,p3n)76Br, 77Se(3He, alpha n)75Se, natSe(3He,xn)79Kr and natSe(3He,xn)76Kr. Thick target yields were calculated for the formation of krypton and bromine isotopes in 3He-induced reactions on 76Se and 77Se and for krypton isotopes in reactions on natural selenium. The possibilities of production of 77Kr using 3He-particle induced reactions on 76Se, 77Se and natSe were investigated. From the viewpoint of yield and purity, for the production of 77Kr the reactions 76Se(3He,2n)77Kr and 77Se(3He,3n)77Kr were found to be very suitable, the former at low energies and the latter at relatively higher energies. In the case of 76Se(3He,2n)77Kr reaction, a target thickness corresponding to E3Hc = 25 leads to 15 MeV leads to a theoretical thick target yield of 7.5 mCi 77Kr/micro Ah; the 76Kr impurity at EOB amounts to 0.45%. In the case of 77Se(3He,3n)77Kr reaction, on the other hand, for a target thickness corresponding to E3Hc = 36 leads to 15 MeV the calculated thick target yield of 77Kr is 11.5 mCi/micro Ah and the levels of impurities 79Kr and 76Kr at EOB amount to 0.35 and 0.36% respectively.

Helium↗