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PubMed1981

Effect of coronary blood flow and site of injection on Tc-99m PPi detection of early canine myocardial infarcts.

The effect of blood flow and site of injection on Tc-99m PPi uptake in acute myocardial infarction was studied in a group of 24 dogs. Temporary (3 hr) and permanent LAO occlusion models were used. Animals with the temporary occlusions showed scintigraphic visualization of the infarcts and reversal of the normal epito-endocardial Tc-99m PPi ratio in contrast to those with permanent coronary occlusions. The data demonstrate that early (within 3 hr) experimental canine myocardial infarcts can be detected with Tc-99m PPi if reflow to the area of infarction is provided. Delayed development of abnormal Tc-99m PPi scintigrams with acute infarction is related primarily to the initial lack of adequate blood flow to the damaged tissue, with subsequent development of adequate collateral flow allowing delivery and uptake of sufficient amount of the radiopharmaceutical for in vivo scintigraphic detection of the damaged area(s).

Animals↗
PubMed1982

Autoradiographic comparison of 96Tc-pyrophosphate and 45Ca bone uptake.

To compare the skeletal distribution of calcium and pyrophosphate complexes, autoradiograms of the growing zone of 10-week-old rabbit femurs were performed. Due to its stability to chemical and enzymatic hydrolysis and to the relatively long half-life of the isotope, 96Tc-labelled pyrophosphate was used. Calcium uptake was studied with carrier free 45Ca. For both tracers, the blood supply plays a significant role by delivering the radiopharmaceuticals. In a second step their partition was governed by mixing in different bone structures: calcium was incorporated inside the bone trabeculae and the mineral mass whereas labelled pyrophosphate remained in linear patterns surrounding bone spicules.

Animals↗
PubMed1980

Modifying effect of commercially available stannous pyrophosphate (PYRO-Sn) on the tissue affinity of 99mTc pertechnetate.

Investigations were performed to examine the conditions required for in vivo labelling of red blood cells (RBCs) with 99mTc after injection of stannous pyrophosphate. It was found that good in vivo labelling of RBCs is possible and that the efficacy of this procedure is high. The highest concentration of 99mTc in the blood occurred in the first 2 h after pertechnetate injection, and the optimum time between stannous pyrophosphate and pertechnetate injection ranged from 10 to 30 min.

Animals↗
PubMed1983

Failure in labelling of red blood cells with 99mTc: interaction between intravenous cannulae and stannous pyrophosphate.

The effect of different methods of stannous pyrophosphate (SnPYP) administration on a modified in vivo technique for labelling red blood cells (RBCs) with 99mTc has been studied. Retention of 99mTc in the bloodstream was measured and parallel in vitro RBC labelling experiments were performed. After administration of SnPYP or a mixture of SnPYP and heparin via the metal needles of intravenous cannulae, the mean 30-min retentions of 99mTc were 96.8% (SD 8.6) and 95.3% (SD 12.4) respectively and the mean in vitro labelling efficiencies were 86.9% (SD 5.0) and 81.9% (SD 18.2) respectively. When the SnPYP was administered via teflon cannulae, the mean 30-min retention of 99mTc was 40.0% (SD 16.7) and the in vitro labelling efficiency was 18.7% (SD 27.0). Reduced RBC labelling and rapid clearance of 99mTc from the bloodstream were not explained by adsorption of stannous ion or pyrophosphate onto the teflon cannulae or retention of SnPYP in the cannulae. When labelling RBCs with 99mTc it is important that SnPYP is not injected via a teflon cannula.

Erythrocytes↗
PubMed1988

Usefulness of early positive technetium-99m stannous pyrophosphate scan in predicting reperfusion after thrombolytic therapy for acute myocardial infarction.

To test the hypothesis that scans with technetium-99m pyrophosphate (Tc-99m-PPi) are positive when performed early after successful thrombolytic therapy for acute myocardial infarction (AMI), 16 consecutive patients with AMI who received thrombolytic therapy within 5 hours after the onset of chest pain were studied. Patients were included if chest pain lasted for greater than 30 minutes, was unresponsive to sublingual nitroglycerin and was associated with at least 0.2 mV ST-segment elevation in at least 2 contiguous electrocardiographic leads. All patients received 1.5 million IU of streptokinase intravenously, a mean of 195 +/- 99 minutes after onset of chest pain. Tc-99m-PPi scans and coronary cineangiograms were recorded 491 +/- 156 minutes and 518 +/- 202 minutes, respectively, after the onset of symptoms. Effective reperfusion was present in 10 patients, 6 of whom had positive Tc-99m-PPi scans (sensitivity of 60% to detect reperfusion). Of the 6 patients without effective reperfusion, 3 had positive Tc-99m-PPi scans (specificity of 50%, p greater than 0.05). Analysis of the data using various definitions of effective reperfusion or artery patency yielded similar results. Thus, our findings indicate that early AMI scanning with Tc-99m-PPi does not accurately detect the presence or absence of reperfusion in patients with AMI after treatment with intravenous streptokinase. At this time, coronary cineangiography is the only reliable method to detect reperfusion promptly after thrombolytic therapy.

Aged↗
PubMed1981

Pancreatic uptake of 99Tc stannous pyrophosphate in experimental viral pancreatitis in mice.

The pancreatic uptake of 99mTc stannous pyrophosphate (99mTc-PYP) in acute pancreatitis in mice induced by coxsackievirus B3 was studied. 99mTc-PYP uptake ratio, measured by the ratio of counts/min/g for the pancreas to counts/min/g for the skull, began to increase 2 days after virus inoculation and markedly increased on day 3 when necrosis of pancreatic acinar cells was evident. On day 5, 99mTc-PYP ratio reached a maximum (2.95 +/- 1.85, mean +/- SD) and histologically fine granules of calcification were seen in the necrotic acinar cells. Thereafter, cellular infiltrations increased and were most severe on day 7, but 99mTc-PYP ratio had began to decrease. On day 28, the necrotic areas of the pancreas were replaced with fatty cells and calcification was still present, though 99mTc-PYP ratio had decreased. The present findings may provide a basis for 99mTc-PYP imaging in cases of clinical viral pancreatitis.

Animals↗
PubMed1987

Relationship between Tl-201, Tc-99m (Sn) pyrophosphate and F-18 2-deoxyglucose uptake in ischemically injured dog myocardium.

We have previously demonstrated that enhanced glucose utilization in reperfused myocardium as assessed by F-18 2-deoxyglucose (FDG) and positron tomography predicts functional recovery. In this study, we compared segmental uptake of F-18 FDG with that of Tl-201 and Tc-99m (Sn) pyrophosphate (Tc-99m PPi) as conventional markers of tissue viability in seven dogs after a 3-hour intracoronary balloon occlusion and 20 hours of reperfusion. Myocardial blood flow was determined with microspheres. Regional retention fractions were calculated from tracer tissue concentrations, the arterial input function, and blood flow. Ischemic injury was assessed by triphenyltetrazolium chloride (TTC) staining and histologic analysis. At 24 hours, blood flow was 22% lower in reperfused than in control myocardium (p less than 0.05). Uptake of Tl-201 was related linearly to blood flow (r = 0.92), while glucose utilization and Tc-99m PPi were 2.9 (p less than 0.01) and 4.7 (p less than 0.05) times higher in reperfused than in control myocardium. Retention fractions of Tc-99m PPi increased with the degree of ischemic injury, while F-18 FDG uptake was highest in segments with mild cell injury. Thus, in ischemically injured myocardium, Tl-201 primarily reflects blood flow. F-18 FDG as a marker of glucose utilization identifies ischemically injured but viable tissue. The admixture of necrotic cells can be determined with Tc-99m PPi. Our results indicate that a dual tracer approach might best characterize the presence and extent of reversibly and of irreversibly injured tissue in a given myocardial region.

Animals↗
PubMed1980

Pathophysiologic considerations and clinicopathological correlates of technetium-99m stannous pyrophosphate myocardial scintigraphy.

99mTc-PYP myocardial scintigrams represent a means to detect and localize acute myocardial necrosis. These scintigrams are expected to be abnormal with acute myocardial infarcts of at least 3 grams in weight if serial imaging is utilized and proper attention to technique is provided. Any etiology of myocardial necrosis may produce abnormal 99mTc-PYP scintigrams if the damage is relatively localized and includes at least 3 grams of tissue. It is possible to accurately size acute anterior and anterolateral transmural myocardial infarcts using area or 2 dimensional measurements. Further development in imaging cameras and computer techniques allowing three dimensional reconstruction of myocardial infarcts with this and similar imaging techniques may allow relatively precise quantitation of other types of myocardial infarcts. The "doughnut" and "persistently abnormal" 99mTc-PYP scintigrams appear to have anatomic and prognostic significance at least in subsets of patients studied, but larger numbers of individuals need to be evaluated before final conclusions regarding their ultimate prognostic significance can be reached.

Animals↗
PubMed1982

Clinical experience with the radioisotope varicocele scan as a screening method for the detection of subclinical varicoceles.

The association of varicoceles and subfertility has been well documented. Although varicoceles remain the most common surgically correctable cause of male infertility the diagnosis of small varicoceles remains a challenge. We evaluated 40 men with an isotope blood pooling scan. Seven volunteers served as either positive or negative controls. Complete correlation between physical findings and the isotope scan was found. The 6 patients with obvious clinical varicoceles and a stress pattern on semen analysis all had positive scans. The 18 patients with a stress pattern and who were clinically suspected of having a varicocele all had positive scans. Of 9 patients evaluated for infertility with a stress pattern but no clinical evidence of varicocele 6 had positive scans. We believe that the isotope scan will prove to be a useful procedure in the detection of nonpalpable varicoceles in selected subfertile men.

Adult↗
PubMed1987

Quantification of myocardial injury produced by temporary coronary artery occlusion and reflow with technetium-99m-pyrophosphate.

Previously, technetium-99m-stannous pyrophosphate (99mTc-PPi) has been used to localize and estimate the size of myocardial infarcts in animals after permanent coronary artery occlusion. This study tested the hypothesis that 99mTc-PPi accurately sizes myocardial infarctions produced by temporary coronary artery occlusion and reflow in dogs. Three groups of dogs were studied: group A underwent 3 hr of occlusion followed by 2 hr of reperfusion, with 99mTc-PPi injected 10 min after reflow (n = 10); group B underwent 3 hr of occlusion followed by 2 hr of reperfusion, with 99mTc-PPi injected 90 min after reflow (n = 11); and group C underwent 3 hr of occlusion followed by reflow with 99mTc-PPi injected at 10 min and again at 48 hr after reflow (n = 5). Myocardial slices from group A and B dogs were imaged in vitro. Group C dogs were imaged with single photon-emission computed tomography (SPECT) in vivo, and myocardial slices were imaged in vitro at the conclusion of the study. The extent of myocardial infarction was defined with triphenyltetrazolium chloride (TTC) staining, and coronary blood flow was estimated with radioactive microspheres. In addition, transmural myocardial tissue samples were taken from the center of the myocardial infarction, the lateral portion of the myocardial infarction, the normal myocardium adjacent to the lateral aspect of the infarcts, and from the normal myocardium and counted for 99mTc-PPi activity. A significant correlation was found between infarct size determined by areas of increased 99mTc-PPi uptake and that estimated from TTC staining for both group A (r = .89) and group B animals (r = .98).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Regional scintimetry in scaphoid fractures.

A quantitative scintigraphic method was introduced to examine the proximal, middle and distal third of the carpal scaphoid bone. 99mTc-Sn-pyrophosphate scintimetry was obtained by the use of a gamma camera equipped with a pinhole collimator. Of six patients in whom a unilateral fresh fracture of the scaphoid was clinically suspected, radiology showed a fracture of the scaphoid in four and no fractures in two. The method may be suitable in early diagnosis and further localization of clinically suspected fractures with initially non-diagnostic radiographs.

Adolescent↗
PubMed1990

[Myocardial 99mTc-pyrophosphate scintigraphy in acute heart infarct].

50 consecutive patients hospitalized because of suspected myocardial infarction were examined by 99mTc-pyrophosphate scintigraphy. The scans were interpreted blind by one of the authors. There were positive results in 17 of 21 patients with myocardial infarction (sensitivity 0.81). However, scintigraphy was also positive in 13 patients with no evidence of myocardial infarction as assessed by ECG and enzyme criteria (specificity 0.55). We conclude that, in our hospital, 99mTc-pyrophosphate myocardial scintigraphy did not contribute valuable information to the routine diagnosis of myocardial infarction.

Humans↗
PubMed1986

[Diagnostic significance of electrocardiography and myocardial scintigraphy with 99m Tc-Sn-pyrophosphate and 99m Tc-Sn-phosphone in patients with stenocardia].

Altogether 123 angina patients were examined using electrocardiography and scintigraphy of the myocardium with two 99m Tc radiopharmaceutical complexes: pyrophosphate and phosphone. A comparative analysis of the results obtained with different methods of investigation before and after an attack of angina pectoris was made. The authors have shown some peculiarities of radionuclide distribution in the myocardium and the diagnostic value of each method of investigation in patients with different clinical forms of angina pectoris.

Angina Pectoris↗