Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RUBIDIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1995

Serial myocardial perfusion imaging with dipyridamole and rubidium-82 to assess restenosis after angioplasty.

UNLABELLED: The purpose of this study was to determine whether patients at high risk for clinical restenosis, following coronary angioplasty, could be identified by myocardial perfusion imaging performed with dipyridamole- 82Rb PET. METHODS: Forty-five patients (34 men, 11 women; mean age 58.5 yr) who had successful single-vessel angioplasty and were asymptomatic had dipyridamole-82Rb PET at 1 and 3 mo after the procedure. Abnormal flow reserve in the distribution of the angioplasty artery on PET was considered to be a decrease of > or = 1 perfusion grade in response to dipyridamole (assessed qualitatively from tomographic images and polar coordinate maps). Follow-up was performed for 6 mo postangioplasty. Clinical restenosis was defined as recurrent angina similar to that occurring before angioplasty and/or > or = 50% stenosis at the angioplasty site documented angiographically. We analyzed abnormal flow reserve in the distribution of the angioplasty vessel to identify which patients were at high risk for clinical restenosis. RESULTS: Fourteen patients developed clinical restenosis between 1 and 6 mo postangioplasty. Abnormal relative flow reserve in the distribution of the angioplasty vessel was present prior to the development of symptoms in 13 of 14 patients with clinical restenosis and in 8 of 31 patients without clinical restenosis (sensitivity 93%, specificity 74%, p < 0.0001). PET imaging successfully separated postangioplasty patients into groups with high (62%) and low (4%) risk of clinical restenosis. CONCLUSION: Abnormal relative flow reserve in the distribution of the angioplasty vessel on dipyridamole PET identifies asymptomatic postangioplasty patients at risk for clinical restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1976

[Preliminary observations on changes in pancreatic blood flow studied with the use of rubidium (Rb86) in acute experimental pancreatitis].

Initial results of research into pancreatic blood flow by the use of a gammaemitting radioisotope, Rubidium86 (Rb86) are reported. The experiments were carried out on normal dogs and on dogs with acute pancreatitis that had been brought on by various techniques. Some of the physiopathological aspects of the role of microcirculatory changes within the pancreas in the genesis of acute necrotico-haemorrhagic pancreatitis are discussed.

Acute Disease↗
PubMed1995

Variability and reproducibility of rubidium-82 kinetic parameters in the myocardium of the anesthetized canine.

UNLABELLED: Kinetic analysis of 82Rb dynamic PET data produces quantitative measures which could be used to evaluate ischemic heart disease. These measures have the potential to generate objective comparisons of different patients or the same patient at different times. To achieve this potential, it is essential to determine the variability and reproducibility of the kinetic parameters. METHODS: A total of 48 82Rb dynamic PET datasets were acquired from two pure bred beagles. Each animal underwent eight 82Rb PET studies with essentially the same protocol for three successive weeks. Data were acquired with the Donner 600-Crystal Positron Tomograph (PET600). In each week, single-slice dynamic 82Rb PET datasets were collected with the animal at rest at three different gantry positions separated by 5 mm. Additional dataset were collected after dipyridamole infusion and after administration of aminophylline to induce a return to rest. A two-compartment kinetic model with correction for myocardial vasculature and spillover from the left ventricular blood pool was used to analyze the dynamic datasets. Model parameters for uptake (k1), washout (k2) and vascular fraction (fv) were estimated in 11-14 myocardial regions of interest (ROIs) using a weighted least-squares criterion. Statistical fluctuation due to the PET acquisition process was minimized by using a relatively high 82Rb dose (about 30 mCi) to take advantage of the high count rate capacity of the PET600. RESULTS: The variation in mean k1, where the mean is taken over the myocardial ROIs was 10%-20% (Dog 1) and 15%-50% (Dog 2) among the rest studies conducted on the same date. Similar variation was evident in comparing studies in the same animal for different weeks. CONCLUSION: Spatial and temporal variation in estimates of the uptake rate (k1) of 82Rb in the resting myocardium of the anesthetized canine are small in relation to the functional increase in k1 following dipyridamole infusion.

Aminophylline↗
PubMed1994

A retrospective study of the diagnostic accuracy of a community hospital-based PET center for the detection of coronary artery disease using rubidium-82.

UNLABELLED: A retrospective analysis has been carried out to determine the diagnostic accuracy of PET of the heart with 82Rb at a community hospital based center. METHODS: Utilization statistics were derived from a total of 1460 patients scanned for the first 36 mo of the center's operation. Diagnostic accuracy for detection of coronary artery disease (CAD) was assessed using three readers blinded to the clinical information. A total of 287 rest and dipyridamole-stress scans of patients who had coronary angiograms within 6 mo of the PET scan were selected by the computer for this study. Each rest/stress scan was read by at least two of the three readers. RESULTS: The average sensitivity for all three readers was 87% for greater than 67% diameter stenosis and the average specificity was 88% for myocardial regions perfused by normal coronary arteries. The average accuracy was 88% for patients with greater than 67% diameter stenosis. Sensitivity and accuracy improved to 92% and 91% respectively for stenosis greater than 90% in diameter. CONCLUSION: These results compare well with published results from major hospital-based centers and the recently published results from a private PET center in Georgia.

Coronary Angiography↗
PubMed1977

Rubidium-82 generators for imaging studies.

Strontium-82, produced by spallation reaction with medium-energy proton beams, was used to evaluate Bio-Rex 70 and Chelex-100 ion-exchange resins for use in a compact Rb-82 generator. Adsorption of Sr-82 to the resin column, Rb-82 elution yields, Sr breakthrough, and 82Rb-Sr separation factors were determined for newly prepared columns and for longterm elution conditions. Separation factors of 10(7) to 10(8) were obtained with 2% NaCl elutions from Bio-Rex 70 resin columns while the separation factors was about 5 X 10(4) with the Chelex-100 resin column.

Evaluation Studies as Topic↗
PubMed1993

Nicotinic receptor function determined by stimulation of rubidium efflux from mouse brain synaptosomes.

The ability of nicotinic agonists to activate ion channels resulting in Na+ and K+ fluxes has been used to develop a functional assay by using mouse brain synaptosomes. Synaptosomes prepared using Percoll gradients were enriched in binding sites for [3H]nicotine and were capable of accumulating the K+ analog, 86Rb+. The efflux of 86Rb+ from the synaptosomes was subsequently monitored using continuous superfusion at 21 degrees C. Ion flux was stimulated in a concentration-dependent manner by several nicotinic agonists, including L-nicotine, acetylcholine, N-methylcarbamylcholine and dimethylphenylpiperazinium. The process was stereoselective: L-nicotine was 30-fold more potent than D-nicotine. Cytisine stimulated ion flux at low concentrations, but this drug was less efficacious than most other agonists tested. Anabasine was also less efficacious than the other agonists. The EC50 values for agonist-stimulated efflux correlated closely to the IC50 values for inhibition of [3H]nicotine binding, but concentrations required to inhibit binding were lower than those required to stimulate ion flux. Nicotine-induced 86Rb+ efflux was blocked by several nicotinic antagonists including mecamylamine, D-tubocurarine, hexamethonium and decamethonium. Mecamylamine was approximately 50 times as potent as hexamethonium. Neither alpha-bungarotoxin nor atropine were effective antagonists and neuronal-bungarotoxin was a relatively ineffective inhibitor. The amount of nicotine-induced efflux varied among brain regions with midbrain (thalamus and mesencephalon) having the largest response and cerebellum the smallest. The magnitude of the ion flux correlated closely with the amount of [3H] nicotine binding in each brain region. The results indicate that a nicotinic-receptor-mediated ion flux can be measured in brain tissue and that the ion flux may serve as a useful functional assay for nicotinic receptors in the central nervous system. Furthermore, it is postulated that the nicotinic-agonist stimulated ion flux may be mediated by receptors measured by high affinity [3H]nicotine binding.

Acetylcholine↗
PubMed1993

Clinical outcome of cardiac patients with negative thallium-201 SPECT and positive rubidium-82 PET myocardial perfusion imaging.

In a previous comparison of 202 consecutive patients who underwent myocardial perfusion imaging with both 201Tl SPECT and 82Rb PET, 27 patients were identified as having true-positive 82Rb images, but false-negative 201Tl images. The purpose of this report is to determine the effect of correct image interpretation of coronary artery disease on the final management of those patients and compare it to the previous management scheme wherein a negative image was usually accepted as the end point unless clinical symptoms dictated otherwise. A follow-up study of the clinical course and outcome of these studies showed that 63% (17/27) of the patients with a true-positive 82Rb PET image were recommended for revascularization procedures. It is doubtful that this majority of patients would have received either surgical or interventional management based on the false-negative 201Tl SPECT procedure alone.

Angioplasty, Balloon, Coronary↗
PubMed1996

Coronary flow and flow reserve by PET simplified for clinical applications using rubidium-82 or nitrogen-13-ammonia.

UNLABELLED: To validate routine, noninvasive determination of absolute myocardial perfusion and coronary flow reserve (CFR), cardiac PET was performed in animals using a simplified imaging protocol, high-dose dipyridamole and a simplified quantitative algorithm specific for 82Rb and 13N-ammonia. METHODS: One hundred thirty-five PET scans were obtained in eight dogs after intravenous 13N-ammonia or 82Rb using serial dynamic PET or a simple two-image dataset. A simple flow model using the two-image dataset was developed for each radionuclide to account for varying arterial input function, flow-dependent myocardial extraction and increased permeability surface area (PS) product due to capillary recruitment at high flows not incorporated into previous models. Myocardial perfusion by the simple model was compared to standard, complete, two-compartment kinetic models validated by comparison to electromagnetic flow meter. RESULTS: For 13N-ammonia, myocardial perfusion by the simple PET model correlated with that by complete compartmental analysis of multiple serial PET images with r = 0.94, slope = 0.96; CFR by compartmental analysis correlated with CFR by electromagnetic flow meter with r = 0.94, slope = 0.97. For 82Rb, myocardial perfusion determined by the simple model correlated with that determined by complete compartmental analysis of multiple serial PET images with r = 0.98, slope = 1.06; CFR determined by compartmental analysis correlated with CFR by electromagnetic flow meter with r = 0.88, slope = 1.13. CONCLUSION: A simplified PET protocol using 13N-ammonia or 82Rb and simple flow models provide noninvasive measurement of CFR up to six times baseline flow throughout the heart and diagnostic image quality for routine clinical application.

Ammonia↗
PubMed1976

Potentiation by lithium and protection by rubidium of digitalis intoxication.

Investigating the effects of Li and Rb on the toxicity of digoxin and ouabain revealed Li to be a potentiator while Rb to be a protector. The effects of Rb in this respect are, more or less, qualitatively comparable to those of K; the intensity of Rb effects is more than that of K. In case of digoxin the effect produced from the combined use of both Rb and K is more than each individual effect. With ouabain, however, whereas Rb offered protection K failed to do so. Electrolyte changes in cardiac tissue showed that Li increased the tissue content of Ca while Rb produced the opposite effect. In comparing Rb with K, both increased the K level in the cardiac muscle. However, in the case of ouabain the infusion of K failed to decrease the Ca level and this might explain its failure to protect against ouabain toxicity. This points to the importance of Ca, rather than K, in controlling the excitability of the cardiac muscle and in effecting the toxicity of cardiac glycosides. Evidences presented indicate the superiority of Rb over K and propose its trial in clinical practice.

Animals↗