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PubMed1985

Radiopharmaceuticals for cardiac imaging.

A number of new radiopharmaceuticals have been developed to increase the diagnostic utility of nuclear medicine in cardiac diseases. The radiochemistry and dosimetry of and clinical experience with these new agents are summarized, and are compared with more widely used methods for assessing myocardial perfusion (thallium-201 scintigraphy) and ventricular function (technetium-99m radioangiography). Emerging techniques for the evaluation of myocardial necrosis and metabolism are also presented, with emphasis on the use of radiolabeled antimyosin antibody and fatty acid analogue imaging in ischemic heart disease.

Glucose↗
PubMedDate not supplied

[In vivo study of the distribution, affinity for cartilage and metabolism of glycosaminoglycan polysulphate (GAGPS, Arteparon)].

37 patients suffering from osteoarthritis and 10 arthritic patients received intramuscular (i.m.), partly also intraarticular (i.ac.) injections of GAGPS; whereupon pharmacokinetics in serum, synovial fluid, urine, and cartilage were investigated. Cartilage was obtained during endoprosthetic hip surgery. The concentrations were determined by radiochemistry, partly after gel chromatography and electrophoresis respectively. Serum levels in patients with osteoarthritis after i.m. administration of 50 mg were 0.55 microgram/ml 3 hrs later, and 0.11 microgram/ml 24 hrs later. Patients with arthritis showed similar serum levels which were slightly higher after i.ac. injection, and which rose proportionally when the dosage was increased to 125 mg. With the arthritic patients, also the concentrations in the synovium were comparable, in the cases with osteoarthritis concentrations were slightly higher, which in both cases suggests that the synovial membrane is promptly penetrated. However, the concentrations in cartilage following a dosage of 50 mg within 24 hours rose as high as 1.45 micrograms/g which corresponds roughly to three times the serum level 3 hours after application. According to biochemical data, injections of 1 to 2 micrograms/ml should yield chondroprotective effects. Hitherto therapy has relied mainly on i.ac. injections; it may now be expanded by the i.m. route of administration. GAGPS was bound to serum proteins, in the synovia, however, it was found unbound. The main portion of the compound excreted via urine within 12 hrs (30 to 40 percent) was mainly unaltered; later, a partial degradation of the chain length and of the degree of sulfation was observed. Animal experiments on rats showed an increased affinity of GAGPS to inflamed tissues (Freund's adjuvant, carageenan edema).

Arthritis↗
PubMed1980

Tomographic assessment of cerebral perfusion using a single-photon emitter (krypton-81m) and a rotating gamma camera.

Continuous carotid infusion of short-lived krypton-81m (t1/2 13 sec) yields an assessment of regional cerebral perfusion. This assessment can be obtained in three dimensions if activity is recorded with a rotating gamma camera and a computer to reconstruct krypton-81m distribution in tomographic sections. These showed several advantages over conventional views: (a) visualization of blood-flow distribution within brain structures (gray and white matter, basal ganglia); (b) more accurate location and evaluation of areas of relatively reduced or increased perfusion; (c) better definition of patterns of collateral circulation; (d) greater sensitivity and specificity in detecting and defining blood-flow changes during physiological activation studies. A limitation of the krypton-81m technique is its invasiveness. However, this study shows that the combination of new advances in radiochemistry with single-photon emission computed tomography may result in accessible methods for assessing, noninvasively and in three dimensions, the behavior of cerebral function in man.

Brain Diseases↗
PubMed1995

Functional brain imaging with SPECT in normal aging and dementia. Methodological, pathophysiological, and diagnostic aspects.

New developments in instrumentation, radiochemistry, and data analysis, particularly the introduction of 99M TC-labeled brain-retained tracers for perfusion studies, have opened up a new era of single photon emission computed tomography (SPECT). In this review critical methodological issues relating to the SPECT instrument, the radioactive tracers, the scanning procedure, the data analysis and interpretation of data, and subject selection are discussed together with the changes in regional cerebral blood flow (rCBF) observed in normal aging. An overview is given of the topography and the pathophysiological and diagnostic significance of focal rCBF deficits in Alzheimer's disease and in other dementia disorders, in which SPECT is capable of early or preclinical disease detection. In Alzheimer's disease, the diagnostic sensitivity and specificity of focal rCBF deficits measured with SPECT and brain-retained tracers are very high, in particular when combined with medial temporal lobe atrophy on CT. Together with neuropsychological testing, SPECT serves to map the topography of brain dysfunction. Thus, in the clinical setting, SPECT provides information that is supplemental to that obtained in other studies. Future applications include neuroreceptor studies and treatment studies, in which SPECT may serve as a diagnostic aid in the selection of patients and as a potential mean for monitoring treatment effects. Although positron emission tomography is the best characterized tool for addressing some of these clinical and research issues in dementia, only the less expensive and technically simpler SPECT technique will have the potential of being available as a screening diagnostic instrument in the clinical setting. It is concluded that, properly approached, functional brain imaging with SPECT represents an important tool in the diagnosis, management, and research of dementia disorders.

Aging↗
PubMed1994

[Positron emission tomography and radiation exposure].

With the ever increasing number of PET-systems in operation the associated problems of radiation protection gain increasing significance. Compared to "conventional" nuclear medicine there is a need for better shielding since the production of positron emitters also yields neutrons and secondary gamma radiation. Due to the short half-lives involved the radiochemistry has to handle high initial activities. Moreover the 511 keV energy of the positron-emitters results in the vicinity of the patient in a higher exposure rate than other nuclear medicine isotopes. For these reasons the typical effective dose to cyclotron personnel is about 2 mSv per year. The whole-body dose to the radiochemists is reported to be 0-20 microSv per charge, and to the medical personnel 10-50 microSv per application. The radiation exposures of the patients are comparable to those common in "conventional" nuclear medicine.

Gamma Rays↗
PubMed1975

Bifunctional chelates for radio-pharmaceutical labeling.

The use of the first of a new class of chelating agents for the binding of metal ions to macromolecules as a novel approach to radiopharmaceutical labeling is described. Advantages are mild reaction conditions, large variety of accessible radionuclides and reactive groups, and separation of synthetic organic chemistry from radiochemistry. Human serum albumin and bovine fibrinogen labeled with 111Indium using this technique were relatively stable in vitro and in vivo, showed little alteration in function, and have potential as tumor localizing agents in humans.

Animals↗
PubMed1997

Positron emission tomography: background, possibilities and perspectives in neuroscience.

Positron Emission Tomography (PET) is a method for determining biochemical and physiological processes in vivo in a quantitative way. This includes the measurement of the pharmacokinetics of labeled drugs and the measurement of the effects of drugs and/or therapy on metabolism. Also deviations of normal metabolism can be measured and insight in biological processes responsible for diseases can be obtained. To accomplish these measurements a multi-disciplinary team is necessary for the expertise in the fields of radionuclide production, radiochemistry, pharmacy, medicine, nuclear imaging and data analysis.

Cyclotrons↗
PubMed1997

Radiochemical studies on contact lens soilation. II. Lens uptake of cholesteryl oleate and dioleoyl phosphatidylcholine.

Employing an artificial tear preparation composed of six proteins and six lipids as a deposit model, uptake of the lipids 3H-cholesteryl oleate and 14C-dioleoyl phosphatidylcholine was measured on contact lenses representative of the four FDA hydrogel groups and on select RGP lenses. Cholesteryl oleate uptake after 24 h at 37 degrees C generally was less than 1 microgram/lens although occasionally reaching 1-2 micrograms. DuraSoft 3 lenses (Group IV) accumulated the deposits in greater amounts (p = 0.04) with other lens groups not differing significantly from each other. Ionic DuraSoft 2 and 3 lenses bound more phosphatidylcholine (also < 1 microgram) than other lens groups, possibly reflecting an interaction between the positively charged choline residue and the negative surface of the lens. Lysozyme deposition, measured simultaneously with cholesteryl oleate, bound to a far greater extent to Group IV lenses (e.g., DuraSoft 3, mean surface deposit 279 micrograms) than to other lens types (p < 0.01). Multiple application of the artificial tear solution did not produce a statistically significant increase in cholesteryl oleate accumulation.

Cholesterol Esters↗
PubMed1988

Relationship of radioactive radon daughters and cigarette smoking in the genesis of lung cancer in uranium miners.

This article documents the study of 383 cases of lung cancer in uranium miners and presents for the first time the relationship of radioactive radon gas and cigarette smoking. There is evidence that alpha radiation from radon gas at exposure levels above 465 working level months (WLM) is a strong contributor to the development of lung cancer. Cigarette smoking plays the most significant role in causing lung tumor; this is also noticed in nonminers who smoke cigarettes. A synergistic or additive effect of these two carcinogens is strongly suggested. The data indicate that small cell tumors develop in younger nonsmoking miners exposed to radon levels above 465 WLM. Lung cancers develop in smoking miners at lower levels of radon exposure than in nonsmoking miners. Based on an average mining experience of 15 years, there is substantial evidence that the present maximum allowable limit of 0.3 working levels (WL), or 4 working level months (WLM) per year, is safe, representing a margin of safety of approximately 10:1. Furthermore, a comparison of these data with the radon levels in some homes, averaging in the neighborhood of 0.025 WL, would indicate that health risks at these levels are negligible. It is suggested that 20 picocuries/liter, which equals 0.10 WL, be the maximum allowable level in homes.

Adult↗