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PubMed1977

Positive 99mTc-stannous pyrophosphate myocardial image in a patient with carcinoma of the lung.

A "false-positive" 99mTc-stannous pyrophosphate (99mTc-PYP) myocardial image was seen in a patient with epidermoid carcinoma of the lung. The location of the increased activity corresponded to an area of direct invasion of the heart by carcinoma with associated multiple microscopic foci of myocardial necrosis. Metastatic carcinoma with myocardial necrosis should therefore be considered as a possible cause of a positive 99mTc-PYP myocardial image.

Aged↗
PubMed1980

A computer-based scintigraphic method for sizing acute inferior myocardial infarcts.

A modeling procedure, employing multiple 99mTc-PYP myocardial scintigrams, was applied to acute inferoposterior myocardial infarcts in 12 dogs. Four modeling schemes were developed, and the model volume predictions were correlated with morphometrically determined infarct masses. Correlation values ranged from r = 0.66 (p less than 0.02) to r = 0.80 (p less than 0.005), suggesting that the method may enable noninvasive quantitative sizing of acute inferoposterior myocardial infarcts.

Animals↗
PubMed1984

Technetium 99m autoradiography of labelled white cells.

The cellular uptake of technetium 99m was determined on white blood cells (WBC) by autoradiography, after 'cold' tin pyrophosphate prelabelling followed by pertechnetate labelling. The autoradiographic method gave visible tracks of 99mTc internal conversion and Auger electrons. 75 +/- 5% of the treated WBC were labelled but none of the control WBC. The number and length of tracks per cell varied greatly. This was perhaps due to imaging conditions as well as to variations in cell uptake.

Autoradiography↗
PubMed1976

Myocsrdial uptake of technetium-99m stannous pyrophosphate following direct current transthoracic countershock.

The effect of direct current (DC) countershock upon myocardial technetium-99m stannous pyrophosphate (PYP) uptake was studied in 22 dogs. All eight dogs imaged had positive abnormal PYP scintigrams that were usually indistinguishable from experimental infarction. In three animals, additional areas of radionuclide uptake were seen in overlying noncardiac tissue. Left and right ventricular myocardial PYP uptake averaged (+/- SEM) 23 +/- 5 times control and 24 +/- 6 times control, respectively. These activity ratios occurred without reduction in regional myocardial blood flow (RMBF), and were associated with histologic evidence of necrosis. The necrosis was usually epicardial, corresponding to the transmural site of greatest PYP uptake. The magnitude of PYP accumulation and the weight of damaged tissue increased with increasing applied energy. Thus, PYP uptake following DC countershock could result in false-positive interpretation of acute ischemic myocardial infarction. Since RMBF is normal in regions of PYP uptake, the major determinant of radionuclide accumulation is the extent of cellular damage.

Animals↗
PubMed1979

Clinicopathologic findings in 52 patients studied by technetium-99m stannous pyrophosphate myocardial scintigraphy.

Scintigraphic, clinical and pathological findings were correlated in 52 patients studied by technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigraphy before death or surgical resection of myocardium. Fifty-nine clinical events were studied with scintigraphy in the 52 patients; 41 of the 59 were associated with one or more abnormal 99mTc-PYP studies and 18 with normal 99mTc-PYP scintigrams. Myocardial scintigrams were positive in 29 of 31 cases with clinicopathological evidence of a corresponding discrete, grossly obvious acute myocardial infarct, including 16 of 16 transmural myocardial infarcts and 13 of 15 subendocardial infarcts. In 16 of 18 cases, negative myocardial scintigrams correlated with the absence of acute myocardial infarction determined by clinicopathological evidence. In two cases small subendocardial infarcts (less than 3 g) were not detected by 99mTc-PYP myocardial scintigraphy. Of the 12 additional instances of positive 99mTc-PYP myocardial scintigrams, five were associated with clinical unstable angina pectoris and seven were in the category of persistently positive scintigrams, since the scans were obtained 2.5 months or longer after proven or suspected acute myocardial infarcts. In all 12 instances, the positive 99mTc-PYP scintigrams were associated with evidence of multifocal irreversible myocardial damage consisting of myocytolysis, coagulation necrosis and/or fibrosis, and the histological age of the lesions was compatible with acute injury corresponding to the time of scintigraphy. The findings indicate that a positive 99mTc-PYP myocardial scintigram is a sensitive indicator of significant myocardial injury which may occur as confluent coagulation necrosis corresponding to clinical acute myocardial infarction, or as multifocal coagulation necrosis or myocytolysis associated with unstable angina pectoris or recurrent ischemic heart disease, especially after previous infarctions.

Acute Disease↗
PubMed1979

Technetium-99m stannous pyrophosphate myocardial scintigraphy after cardiopulmonary resuscitation with cardioversion.

Thirty consecutive patients underwent technetium-99m stannous pyrophosphate myocardial scintigraphy 48--72 hours after successful cardiopulmonary resuscitation and direct current cardioversion. Five patients with transmural myocardial infarctions by ECG and enzyme determinations were correctly identified by scintigraphy. Myocardial scans were positive in five of nine patients with nontransmural infarction. Of 16 patients without evidence of myocardial infarction, only two (13%) had false-positive myocardial scans. The overall accuracy of imaging in this series was 80%. We conclude that false-positive scans after cardiopulmonary resuscitation with electrical cardioversion are infrequent, and do not significantly detract from the value of myocardial scintigraphy in the diagnosis of myocardial infarction.

Aged↗
PubMed1980

Ordering patterns and clinical impact of cardiovascular nuclear medicine procedures.

We analyzed the ordering and impact of the first 171 fee-for-service cardiovascular nuclear medicine procedures at one hospital. The ordering physicians said 72% of the study results were useful and 28% contributed to changes in patient management. Experienced cardiology reviewers, however, felt that only 65% of studies were appropriately ordered, that 97% of appropriately ordered studies provided potentially useful information, and that 12% of all studies made important contributions to appropriate changes in patient management. The revieweres were most likely to rate exercise thallium procedures and procedures ordered by physicians from distant hospitals as being appropriately ordered and having important clinical impact. We conclude that (1) ordering physicians and revieweres may disagree substantially in their estimates of the impact of a diagnostic test; and (2) although a test may yield important information in appropriate patients, its total clinical impact will depend on how often it is suitably ordered and used.

Cardiovascular Diseases↗
PubMed1987

Mechanisms of changes in nitrogen washout and lung volumes after saline infusion in humans.

This study was performed to determine the roles of increased intrathoracic blood volume and increased vagal tone in the changes in lung volume and nitrogen washout produced by saline infusion. In the first study, measurements of TLC, VC, FRC, ERV, and slope of phase III nitrogen washout (delta N2) were made on 8 subjects before, during, and after inflation of the leg compartments of medical anti-shock trousers (MAST). In the second study, 13 volunteers were infused intravenously with warm saline (30 ml/kg) for 30 min. Repeat measurements were made approximately 20 and 40 min after infusion. Each subject then received intravenously 0.03 mg/kg atropine, and measurements were repeated. In 7 of these subjects, a third study was performed in which the atropine was injected before saline infusion. Inflation of the MAST (see figures 5 and 6) caused a 1.9% decrease in VC, 5.3% decrease in FRC, and no change in delta N2. Saline infusion caused decreases in TLC, VC, and FRC (4.0, 3.1, and 10.1%, respectively) and a 15.0% increase in delta N2. Atropine reversed the change in delta N2 after saline infusion and prevented these changes when given prior to saline. Atropine had no effect on lung volumes whether given before or after saline infusion. We speculate from our data that saline infusion has 2 effects on the lung. One is a simple displacement of air by increased intravascular volume producing the reduction in lung volumes. The second is an increase in small airways resistance that is mediated by vagal reflex and blocked with atropine.

Adult↗
PubMed1977

Imaging of experimental myocardial contusion: observations and pathologic correlations.

Myocardial contusions of variable severity were experimentally produced by an air-driven piston or serrated clamp in 29 dogs. Two 99mTc-labeled bone-seeking agents (99mTc pyrophosphate and 99mTc tetracycline) were used with cardiac scintigraphy to determine the sensitivity of these agents in detecting different degrees of myocardial damage. Results showed that 99mTc tetracycline was not a suitable scanning agent. 99mTc pyrophosphate produced positive scans in cases of complete (or nearly complete) transmural myocardial necrosis. Positive cardiac scans in clinical myocardial contusion may indicate the severity of the lesions and have prognostic significance.

Animals↗
PubMed1978

Plaque-inhibiting effect of dentifrices containing stannous fluoride.

The present study showed that the plaque inhibiting effect of aqueous solutions of stannous fluoride can be maintained in toothpastes. A commercial toothpaste containing 0.4 per cent of water soluble tin was effective whereas one containing 0.03 per cent showed no effect. The plaque inhibiting effect was shown in one study where the toothpastes were applied in cap splints and the plaque was scored after four days by the Plaque Index of Löe, and in another where the effect of locally applied pastes was monitored 24 hours later by the Gingival margin Plaque Index of Harrap. The present investigation supports the view that the stannous ion is essential in the plaque inhibition caused by stannous fluoride preparation. The exact mechanism is unknown but it is speculated that a change in the surface potential of oral bacteria through interaction with the stannous ion may be important.

Chlorhexidine↗
PubMed1981

Creatine kinase MB isoenzyme in dermatomyositis: a noncardiac source.

Three patients with polymyositis had elevated serum levels of creatine kinase MB isoenzyme. The presence of this isoenzyme is used extensively to diagnose myocardial infarction, but the isoenzyme is also found in sera of patients with primary muscular and neuromuscular disorders. We studied cardiac function in two of our patients with electrocardiograms, technetium stannous pyrophosphate scanning, and technetium 99m-labeled erythrocyte gated blood pool imaging and in the third patient by postmortem examination. There was no evidence of myocardial involvement to account for the high serum levels of isoenzyme. Creatine kinase MB in the sera of patients with polymyositis does not necessarily indicate myocardial necrosis.

Adult↗
PubMed1976

Efficiency of in vivo labeling of red blood cells with 99mTc.

The effectiveness of three commercial bone scintigraphic agents and freshly made stannous chloride in labeling erythrocytes with 99mTc was compared. Our results indicate that tin pyrophosphate is the agent of choice and that it is most effective when injected at least 15 minutes before the 99mTc-pertechnetate is administered. This technique of labeling red blood cells in vivo could be applied in performing blood pool studies.

Animals↗
PubMed1976

[Diagnosis of cerebrovascular disorders using stannous technetium pyrophosphate].

A total of 122 cases of various neurological diagnoses (among which 72 cerebral infarcts, 7 intracerebral hematomas and 38 intracranial tumors) had two separate brain scans, performed within 48 hours of each other after the administration of pertechnetate and technetium stannous pyrophosphate. The comparison of the resulting seans indicates that, in addition of an osseous accumulation, the pyrophosphate localizes greatly in ischemic cerebral lesions, especially those observed during the second week of evolution. It seems that the uptake of pyrophosphate reflects the area of anaerobic changes whereas the accumulation of pertechnetate depends on the disruption of the blood brain barrier. The scintigraphic diagnostic of cerebral infarctions is greatly improved.

Brain Neoplasms↗
PubMedDate not supplied

[Radiochemical purity and stability of Tc-99m-pyrophosphate].

INTRODUCTION: In vitro stability of 99mTc-radiopharmaceuticals is an important parameter of quality. In the paper the shelf-life of the bone-seeking radiopharmaceutical 99mTc(Sn)-pyrophosphate was examined under different experimental conditions. MATERIAL AND METHODS: The solution of pyrophosphate was prepared and dispensed into 2-ml fractions which were kept at-20 degrees C. In different time intervals the samples were thawed and labeled. The in vitro stability of labeled preparation was examined on the unprotected and the samples protected by nitrogen purge or by addition of solutions of ascorbic or genetisic acid of known concentrations. The content of 99mTc-pertechnetate was determined by paper chromatography. RESULTS AND DISCUSSION: In comparison with unprotected, samples protected by nitrogen purge exhibit better, but not satisfactory stability. Best results are obtained by using chemical stabilizers. The presence of 50-60 micrograms/ml of ascorbic acid keeps the content of 99mTc-pertechnetate below 5% during six hours even in solutions of high initial radioactive concentrations (up to about 814 MBq/ml). With this concentration of ascorbic acid, good results are obtained also by labeling inactive solutions kept at low temperatures during seven days. Genetisic acid is also efficient but its concentration should be about ten times higher. CONCLUSION: The in vitro stability of 99mTc(Sn)-pyrophosphate depends on the initial radioactive concentration of 99mTc and time after labeling. Best results were obtained when the preparation contained ascorbic acid as a chemical stabilizer. Its concentration in the range of 50-60 micrograms/ml is sufficient to keep the content of 99mTc-pertechnetate below 5% during six hours, both in freshly prepared samples and those kept at low temperatures for seven days.

Drug Stability↗