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At least 19 recordsLinked to original sources
PubMed1979

Complexing of reduced technetium and tin (II) by chelating phosphate compounds. I. Chemical state of technetium.

Complexing of reduced 99mTc, 99Tc and of 113Sn(II) by pyrophosphate was studied, using the in vivo distribution in the rat as an indicator for complex formation. 99mTc-pyrophosphate was only formed at very low technetium concentrations, otherwise colloid formation occurred. Reduced 99mTc in trace amounts and 113Sn(II) complexed equimolarly with pyrophosphate were concentrated in bone and excreted in urine in comparable amounts. The in vivo distribution of 32P-orthophosphate and -pyrophosphate was characterized by a considerable uptake in the liver and a poor urinary excretion. The distribution patterns of 32P-pyrophosphate, complexed equimolarly with tin(II), remained unchanged. Despite these findings it is concluded that real chelates are formed, since non-complexed reduced 99mTc was not concentrated in bone. Two variants of reduced technetium could be discerned: a 99mTc-kidney agent and a 99mTc protein-bound agent. Some evidence was found that reduced technetium may change its oxidation state, but it seems much more likely that both agents are technetium(IV) compounds. It is suggested that the kidney agent is hydrated technetium dioxide whereas the protein-bound agent is a charged technetium(IV) compound. Only hydrated technetium dioxide is obviously complexed by chelating phosphate compounds.

Animals↗
PubMed1978

Skeletal uptake of pyrophosphate labeled with technetium-95m and technetium-96, as evaluated by autoradiography.

For animal experimentation, the 95m and 96 technetium isotopes offer many advantages over technetium-99m. Their long physical half-lives and the emission of extranuclear electrons of low penetrating power make it possible to obtain autoradiograms of a great precision. The uptake of technetium stannous pyrophosphate by the epiphyseal plate was studied using liquid-emulsion microautoradiography, 3 hr after i.v. injection into 10-week-old rabbits. Microautoradiograms showed a well-defined and rather specific pattern of localization with intense uptake beneath the epiphyseal disk on the extremities of the vascular buds and a lack of accumulation in the cartilage, whether calcified or uncalcified. In the metaphysis, the label was located where new bone was being laid down and also over the cytoplasm of osteoclasts. We deduce from these results that in normal bone the general distribution of this tracer reflects mainly the arrangement of the blood supply, but the specific sites of accumulation are the bone-forming surfaces and the active resorbing osteoclasts.

Animals↗
PubMed1976

Liver and gall-bladder imaging with technetium-99m dihydorthioctic acid and technetium-99m pyridoxylidene glutamate-a study in the young pig.

Seventeen scans on ten young pigs were performed after injection of Technetium-99m labelled dihydrothioctic acid (99Tcm-DHT) and Technetium-99m labelled pyridoxylidene glutamate (99Tcm-PG) using a gamma-camera. Sequential images of the liver, gall-bladder and intestine were observed in all healthy animals. 99Tcm-DHT produced the clearer liver images, whereas 99Tcm-PG produced more rapid and intense gall-bladder images. Analysis of hepatic bile in three animals also suggested a more rapid and higher concentration of 99Tcm-PG than 99Tcm-DHT (36% vs. 4% of the injected dose over two hours). Bowel images were not seen in an animal that had undergone exicision of the extrahepatic biliary tract, but scans performed after hepaticojejunostomy demonstrated intestinal transit of isotope. This study shows that the hepatobiliary system can be easily imaged using Technetium-99m labelled compounds which are excreted into bile. These agents may be useful in the diagnosis of obstructive lesions of the extrahepatic biliary tract of adults and infants.

Animals↗
PubMed1975

Technetium-99m-methylene diphosphonate--a superior agent for skeletal imaging: comparison with other technetium complexes.

Methylene diphosphonate (MDP) was formulated as a complex of 99mTc for skeletal imaging. This agent was compared with three other bone-seeking technetium agents: ethane-1-hydroxy-1, 1-diphosphonate (EHDP), pyrophosphate, and polyphosphate. In tissue radioassay experiments in rodents, the technetium complexes of MDP and EHDP were similar, but skeletal concentration with both of these agents was higher than that with pyrophosphate or polyphosphate. The total-body retention of MDP and EHDP complexed with 95mTc was studied in beagle dogs for 35 days by excretion measurements and total-body counting and compared with polyphosphate and pertechnetate. The long-term retention was greater for MDP. The 5-day cumulative fecal excretion of 95mTc was low when administered as EHDP or polyphosphate complexes and negligible when administered as MDP complex. In six human volunteers the blood clearance of 99mTc-mdp was similar to that of 18F and significantly faster than that of 99mTc-EHDP. Pyrophosphate cleared from the blood much faster than polyphosphate but slower than the diphosphonates. The urinary excretion of the MDP complex was greater than for EHDP within the first 2-3 hr after injection. The 24-hr urinary excretion of pyrophosphate and polyphosphate complexes was not as complete as for the diphosphonates. All four 99mTc complexes proved satisfactory for clinical imaging studies. The MDP complex produced images of superior quality as early as 2 hr after administration, attributable to its more rapid clearance from the blood and soft tissues. On the contrary, a longer interval of 3-4 hr after injection was usually needed for 99mTc-EHDP; pyrophosphate and polyphosphate complexes regularly required a waiting period of 4 hr. Comparitive radiation dose estimates were made based on the available biologic distribution data for these 99mTc skeletal-localizing agents.

Animals↗
PubMed1978

Characterization of tin-technetium colloid in technetium-labeled albumin preparations.

The Tc-99m human serum albumin (HSA) system has been reinvestigated with gel filtration as the assay method. Other than Tc-99m HSA, two radioactive components have been isolated by this technique. Both components are tin-technetium colloids of differing particle sizes, and the relative quantity of each one is pH-dependent. The colloid has been further characterized by protein-induced x-ray emission analysis (PIXE) and by tissue distribution in rats. By this gel-filtration method, commercial Tc-99m HSA kits have been evaluated and have revealed varying amounts of colloids present.

Animals↗
PubMed1978

Clinical comparison of cardiac blood pool visualization with technetium-99m red blood cells labeled in vivo and with technetium-99m human serum albumin.

Technetium-99m red blood cells (Tc-RBC) labeled by an in vivo technique were compared with two preparations of Tc-99m human serum albumin (HSA) for cardiac blood-pool imaging. Relative distribution of the tracers was analyzed on end-diastolic frames of gated blood-pool studies and on whole-body (head to mid-thigh) anterior pinhole images. The Tc-RBC demonstrated greater relative percentage localization in the cardiac blood pool, higher target-to-background ratios in the left ventricle, and less liver concentration. For cardiac blood-pool imaging, Tc-RBC labeled by the in vivo approach appears to be superior to the two Tc-HSA preparations studied.

Cardiac Volume↗
PubMed1975

[Technetium polyphosphate and technetium diphosphonate. A comparative study].

99mTc-labelled phosphates are the bone seeking agents of choice. The comparison of 99mTc-polyphosphate (Poly-P) and 99mTc-ethane-1-hydroxy-1,1-diphosphonate (EHDP) shows a better in vitro stability of the latter during the first two hours after preparation. The blood clearance of EHDP is superior to Poly-P resulting in reduced background activity at scanning time. Renal excretion over a 4-hour period of urine sampling showed no significant differences between both substances. Blood activity is independent of diuresis.

Adult↗
PubMed1975

A precise chromatography system for specific technetium-99m radiopharmaceuticals.

New chromatographic procedures are needed to accurately determine the radiochemical purity of technetium-99m labeled radiopharmaceuticals. A chromatography system has been developed for technetium-99m diethylenetriaminepentacetic acid, technetium-99m diphosphonate, and technetium-99m pyrophosphate. The technique involves spotting the radiopharmaceuticals on instant thin layer chromatography-silica gel and developing with acetone (solvent from migrates approximately 12 cm from the origin), air drying, and redeveloping the strip in normal saline (solvent front migrates approximately 6 cm from the origin). The procedure is simple to perform, rapid, accurate, and clearly separates technetium-99m pertechnetate, the technetium-99m radiopharmaceutical, and hydrolyzed reduced technetium-99m. It can be applied in most nuclear medicine laboratories and has the potential to predict the quality of radionuclide images obtained.

Chromatography, Thin Layer↗
PubMed1978

Uptake by bone of pyrophosphate, diphosphonates and their technetium derivatives.

1. The uptake of inorganic pyrophosphate (PPi) from blood to bone was investigated in the rat in vivo. 2. PPi is taken up by the bone, where it appears both as PPi and as inorganic orthophosphate (Pi). The latter is due at least partly to local hydrolysis. 3. The fraction of injected PPi taken up by bone, measured as total PPi, was in the same range as that of technetium-tin-PPi, diphosphonates, technetium-tin-ethane-1-hydroxy-1,1-diphosphonate and Pi, but lower than that of calcium. 4. The plasma half-life of PPi is in the same order of magnitude as that of technetium-tin-PPi, diphosphonates, technetium-tin-ethane-1-hydroxy-1,1-diphosphonate, Pi and calcium. 5. PPi, diphosphonates and their technetium complexes are only partly ultrafiltrable in plasma. 6. It appears that the technetium complexes behave in a similar fashion to free PPi or diphosphonate.

Animals↗
PubMed1978

Early quantification of experimental myocardial infarction with technetium-99m glucoheptonate: scintigraphic and anatomic studies.

Recent advances in understanding of the pathophysiology of myocardial necrosis indicate the need for a noninvasive method that will allow detection and quantification of infarcts in the first few hours after the onset of infarction. Myocardial infarct scintigraphy using technetium-99m glucoheptonate is capable of detecting infarction in dogs and man within 4 to 6 hours of onset. Studies were performed in 45 dogs with acute myocardial infarction: 28 with with an anterior infarct, 5 with an inferior infarct, 6 with an anterior infarct studied after infusion of mannitol and 6 with ligation of the left anterior descending coronary coronary artery and reperfusion of the ischemic area. The dogs were given 20 m Ci of technetium-99m glucoheptonate 1 hour after coronary occlusion, subjected to imaging 5 to 9 hours later and then killed. The experiments revealed that (1) scintigraphic infarct size correlated with infarct weight for anterior (r = 0.85) and inferior (r = 0.88) infarcts; (2) technetium-99m glucoheptonate also concentrated in a rim of myocardium around the infarct that probably represented the ischemic zone; and (3) technetium-99m glucoheptonate uptake by infarcted myocardium could be greatly increased with mannitol and reperfusion.

Animals↗
PubMed1975

Technetium-99m polyphosphate bone image for early detection of skeletal metastasis. Correlation with other diagnostic parameters.

Technetium 99m-polyphosphate bone images are correlated with bone roentgenography, and serum calcium, phosphorus and alkaline phosphatase in 91 patients with suspected bone metastasis. Technetium polyphosphate bone images are the most sensitive and serum level of calcium and phosphorus are the least sensitive indicator of bone lesions. Bone roentgenography is not as sensitive as technetium polyphosphate images. Abnormal bone images with normal or abnormal bone roentenography associated with increased alkaline phosphatase in the absence of liver metastasis are highly suggestive of metastatic bone disease. Abnormal bone images adjoining the joints, associated with normal serum alkaline phosphatase and abnormal joint roentgenography suggest arthritis. It is recommended that technetium 99m-labelled phosphate bone images are considered to be the diagnostic procedure of choice to detect skeletal lesions. Polyphosphate bone images are highly sensitive, with the combination of elevated alkaline phosphatase they become relatively more specific for a metastatic bone disease.

Alkaline Phosphatase↗
PubMed1977

[Analysis of one thousand liver scans carried out using technetium phytate (author's transl)].

One thousand liver scans were carried out using technetium phytate. This soluble compound is transformed in the circulating blood into a colloid by chelation of serum calcium, thereby forming a macromolecular phytate of calcium and technetium. The presenting symptoms are compared with the isotopic findings. This microcolloid has the advantages common to all technetium tracers and, in addition, is easy to prepare and has the advantage of a distribution between the liver, spleen and bone of the same type as that seen with colloidal gold 198 without the dosimetric problems associated with the latter. Although it has a level of hepatic fixation which is less than that of certain sulphide complexes of technetium, the authors feel that it appears to provide a better relfection of the colloidopexic function of the liver.

Adult↗
PubMed1979

Abnormal technetium-99m pyrophosphate images in unstable angina: ischemia versus infarction?

There is controversy concerning the specificity of myocardial infarct imaging with technetium-99m pyrophosphate due to the high frequency of false positive images, especially in patients with unstable angina. In this study technetium-99m pyrophosphate images were compared with frequent determinations of plasma creatine kinase, MB isoenzyme (MB CK) activity in 116 patients admitted with the diagnosis of unstable angina. It was hypothesized that frequent measurement of MB CK activity, a sensitive and specific marker for myocardial necrosis, using sensitive assay techniques would detect small amounts of myocardial necrosis which might have been unrecognized by conventional clinical methods. The scintigraphic results and isoenzyme determinations agreed in 88 percent of patients; both tests were normal in 69 percent and both were abnormal, indicating acute myocardial infarcation, in 19 percent of patients. In the remaining 14 patients (12 percent), the scans were abnormal, but MB CK activity was normal. In five of these patients (4 percent), abnormal scintigrams presumably reflected persistent scan positivity after previous myocardial infarction. Only the remaining nine patients (8 percent) could be classified as having unexplained false positive scans, a frequency substantially less than that reported by other investigators who based the diagnosis of myocardial infarction on conventional clinical criteria. These results suggest that abnormal technetium-99m pyrophosphate images in patients with unstable angina generally indicate myocardial necrosis.

Adult↗
PubMed1977

New approach to interpretation of technetium-99m pyrophosphate scintigraphy in detection of acute myocardial infarction: clinical assessment of diagnostic accuracy.

A modified classification for interpreting technetium-99m pyrophosphate scintigrams defines the 2+ diffuse pattern of tracer uptake as equlvocal rather than positive for acute myocardial infarction. Results of scintigraphy using this classification were compared with results of standard diagnostic tests for myocardial infarction in 235 patients admitted to a coronary care unit with acute chest pain. Of 81 patients with acute transmural infarction by standard clinical, electrocardiographic and serum enzyme criteria, 76 had a positive, 5 an equivocal and none a negative scintigram. Of 18 with acute nontransmural infarction by standard criteria, 7 had a positive, 9 an equivocal and 2 a negative scintigram. This it was uncommon for a patient with acute myocardial infarction, transmural or nontransmural, to have a definitely negative technetium-99m pyrophosphate study. Ten patients had equivocal evidence of infarction by standard criteria. Of the remaining 126 patients with no evidence of acute myocardial infarction by standard criteria, 87 had a negative, 35 an equivocal and 4 a definitely positive scintigram. Thus the definitely positive scintigraphic pattern was relatively highly specific for acute myocardial infarction. If the 2+ pattern had been considered positive, the specificity of the technique would have been greatly decreased. Computer processing strengthened observer certainty of the visual impression but changed the scintigraphic evaluation in only eight cases. Thus, use of an equivocal pattern renders technetium-99m pyrophosphate imaging both an extremely sensitive and specific method for detecting acute myocardial infarction.

Acute Disease↗
PubMed1975

Technetium stannous pyrophosphate myocardial scintigrams in patients with chest pain of varying etiology.

Technetium-99m stannous pyrophosphate was utilized for myocardial imaging in 202 patients admitted to the hospital with chest pain of uncertain etiology. One hundred and one patients had clinical and evolved electrocardiographic and enzymatic evidence of acute myocardial infarction. Ninety-six of these 101 patients had increased myocardial uptake of the technetium stannous pyrophosphate and positive myocardial scintigrams; there was nearly precise correlation between the ECG and myocardial imaging localization of the area of infarction for acute transmural myocardial infarctions. In the five patients with negative myocardial images the scintigrams were obtained after seven or more days had elapsed following the myocardial infarction. In the remaining 101 patients no clinical, ECG, or enzymatic evidence of infarction developed; 92 of these patients had negative myocardial scintigrams. Seven of the remaining nine patients were admitted with "unstable angina pectoris", and despite the absence of diagnostic ECG and enzyme evolution each of these patients had faintly and diffusely positive myocardial scintigrams. The remaining two patients had positive myocardial scintigrams but no definite ECG or enzymatic evidence of acute myocardial infarction. Thus the technetium pyrophosphate imaging technique appears safe, inexpensive and to correlate well with ECG and enzyme identification of the presence of infarction and with ECG localization of myocardial infarction. In addition the positive myocardial scintigrams in some patients with "unstable angina" suggest that there may be limited myocardial necrosis that is ordinarily undetected by ECG and enzymes in these patients. The incidence of false positive and false negative scintigrams appears to be small.

Angina Pectoris↗