PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Tin Polyphosphates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 199 records · Page 11Linked to original sources
PubMed1982

Attenuation compensation in single-photon emission tomography: a comparative evaluation.

Attenuation of photons in single-photon emission tomography (SPECT) makes three-dimensional reconstruction of unknown radioactivity distributions a mathematically intractable problem. Approaches to approximate SPECT reconstruction range from ignoring the effect of photon attenuation to incorporating assumed attenuation coefficients into an iterative reconstruction procedure. We have developed a computer-based simulation method to assess the relative effectiveness of attenuation compensation procedures. The method was used to study four procedures for myocardial SPECT using an infarct-avid radiopharmaceutical, Tc-99m stannous pyrophosphate. Reconstructions were evaluated by two criteria: overall (sum-of-squares) accuracy, and accuracy of lesion sizing. For moderate- to high-contrast studies there were no significant differences among the reconstructions by either evaluation criterion; for low contrast ratios the iterative method produced lower sum-of-squares criterion; for low contrast ratios the iterative method produced lower sum-of-squares error. We conclude that the additional expense of the iterative method is not justified under the conditions of this study. The approach used here is a convenient tool for evaluating specific SPECT reconstruction alternatives.

Humans↗
PubMed1981

Quantitation of skeletal-muscle necrosis in a model compartment syndrome.

UNLABELLED: Skeletal-muscle necrosis was evaluated in previously pressurized canine compartments using technetium-99m stannous pyrophosphate and classic histological criteria. Intracompartmental necrosis was quantitated in the anterolateral muscle compartment of each dog by uptake of 99mTc stannous pyrophosphate using the contralateral anterolateral compartment as an internal control. Representative specimens of muscle were sampled in experimental and control legs of each dog and were analyzed by qualitative histological techniques. Muscle necrosis was assessed in compartments forty-eight hours after pressurization to levels of ten to 120 millimeters of mercury for eight hours in thirty-seven dogs. In another dog, neither anterolateral compartment was pressurized so that both compartments acted as control muscle. The results in these experiments identify a threshold pressure level (thirty millimeters of mercury) and duration (eight hours) at which significant muscle necrosis occurs at normal blood pressure. Our findings imply that a quantitative relationship exists between incorporation of 99mTc stannous pyrophosphate and the level of intracompartmental pressure. This uptake technique, however, is not suitable for diagnosing compartment syndrome in patients with a threatened compartment syndrome. We suggest that intracompartmental pressure measurements by the wick-catheter technique, in conjunction with clinical findings, offer the best means for diagnosing compartment syndrome. CLINICAL RELEVANCE: Significant muscle necrosis associated with an impending compartment syndrome occurs at a threshold intracompartmental pressure of thirty millimeters of mercury after eight hours. Since time variables are often unknown in suspected compartment syndromes, fasciotomy is recommended when intracompartmental pressure exceeds thirty millimeters of mercury in a patient with normal blood pressure. The use of this threshold pressure level as an indication for fasciotomy requires a device for measuring intracompartmental pressure such as the wick catheter.

Animals↗
PubMed1978

Sequential myocardial scintigraphy with technetium-99m stannous pyrophosphate following myocardial infarction.

Studies have shown that technetium-99m stannous pyrophosphate (Tc-PPi) is effective for the detection and imaging of acute myocardial infarction. Positive Tc-PPi myocardial scintigrams, however, have been reported in patients with other forms of heart disease and no evidence of recent myocardial infarction. To help define the usefulness of this test, we undertook a prospective study to ascertain when Tc-PPi myocardial scintigrams return to normal after myocardial infarction. Twenty patients with acute myocardial infarction were followed with Tc-PPi scintigrams at 1 and 2 wk, and 1, after infarction. The serial scintigrams revealed that a) 15 of 18 scintigrams were positive within the first week after infarction, b) the number of markedly positive scintigrams decreased promptly after the first week, and c) some scintigrams (11 of 18 at 1 mo, and 3 of 18 at 9 mo) remained positive throughout the study. The possible explanations for persistently positive scintigrams are discussed. Persistently positive scintigrams may hinder the usefulness of Tc-PPi myocardial scintigraphy for the diagnosis of acute myocardial infarction in patients who have had a myocardial infarction within the previous 9 mo.

Acute Disease↗
PubMedDate not supplied

[Value of scintigraphy for the early diagnosis of spondylitis ankylosans].

Quantitative sacroiliac scintigraphy was performed in 33 patients with ankylosing spondylitis (AS), 34 patients with nonspecific low back pain, and 30 control subjects. Significantly increased uptakes over the sacroiliac joints (SIJ) were found in patients with AS and in patients with degenerative changes of the SIJ. No significant differences were found between patients with mechanical low back pain by lumbar strain or by degenerative changes of the lumbar spine and the control subjects. But there were 2 of 13 patients with low back pain by lumbar strain with pathologic uptakes over the ISG. Since the scintigraphic technique is not specific, it is necessary to compare the scintigraphic results with clinical and radiological findings in each patient. On this condition sacroiliac scintigraphy is useful in early diagnosis of AS.

Adult↗
PubMed1980

Non-invasive quantification of experimental canine myocardial infarct size using two-dimensional echocardiography.

In order to study whether wall motion abnormalities detected by two-dimensional (2D) echocardiography can be quantified and correlated with infarct size, we compared wall motion abnormalities viewed by 2D echocardiography in experimental canine infarction with post-mortem infarct size. Nineteen mongrel dogs underwent left anterior descending coronary artery snare occlusion. They were sacrificed 6 h later. Infarct sizing was done by technetium 99-m stannous pyrophosphate scintigraphy of the excised, sliced left ventricles. Fourteen dogs had both 2D echo wall motion abnormalities and infarctions. Four dogs failed to develop infarction and had no or minimal wall motion abnormalities. Inter-observer variation in 2D echocardiographic measurements was small. Wall motion abnormalities correlated with infarct size both in the 14-dog subgroup with infarction (r = 0.75, P less than 0.003) and all the 18 dogs that completed the protocol (r = 0.87, P less than 0.001). Thus, wall motion abnormalities in experimental canine myocardial infraction can be roughly quantified by 2D echocardiography and correlated with post-mortem infarct size measured by scintigraphy.

Animals↗
PubMed1977

In vivo labeling of red blood cells with 99mTc: a new approach to blood pool visualization.

A simple and rapid procedure for in vivo labeling of red blood cells (RBC) is presented. The labeling is done with two consecutive intravenous injections, first of "cold" stannous pyrophosphate (Sn-PYP) and then of 99mTc-pertechnetate. Experimentally, a lag time of 30 min between the two injections was found to result in a mean RBC labeling of greater than 95% during the first hour after pertechnetate injection. A total of 75 patients have been explored by scintillation camera imaging of brain, heart, great vessels, aortic bifurcation, testicles, and lower extremities using the technique outlined. High-quality images were obtained.

Erythrocytes↗
PubMed1977

In vitro technetium-99m red blood cell labeling using commercial stannous pyrophosphate.

A simple and rapid technique of preparing technetium-99m-labeled erythrocytes using commercial stannous pyrophosphate as the reducing agent was developed. The technique involves incubating red cells with stannous pyrophosphate, centrifugation, and addition of Tc-99m pertechnetate to the red cell fraction. A mean red cell labeling efficiency of 94% was achieved in 10 patient samples and less than 5% in vitro dissolution of Tc-99m red blood cells occurred up to two hours after preparation.

Drug Stability↗
PubMed1977

A comparative evaluation of techniques for rapid and efficient in vivo labeling of red cells with [99mTc] pertechnetate.

Red blood cells (RBCs) labeled in vivo with 99mTcO4- have recently been recommended for blood-pool imaging, but the optimum conditions for in vivo labeling of RBCs have not been clearly defined. We therefore evaluated several stannous-ion preparations and stannous-ion concentrations to determine which provided the best labeling. The effect of the time interval between the Sn(II) and 99mTcO4- injections and the effect of carrier technetium on labeling efficiency were also studied. Maximal in vivo labeling efficiency was obtained using an intravenous dose of 10 microgram Sn(II)/kg followed 5-30 min later by an injection of 99mTcO4-. Neither the chelated form of stannous ion used in these studies nor the amount of carrier present had a significant effect on labeling efficiency. The biologic half-time of Tc-99m RBCs labeled in vivo was similar to that of Tc-99m RBCs labeled in vitro. In vivo labeling is a rapid and efficient method for the preparation of Tc-99m RBCs.

Animals↗
PubMed1997

Ultratag RBC kit for combined cardiac first-pass and multigated acquisition studies.

UNLABELLED: The authors developed a procedure to use the in vitro Ultratag (Mallinckrodt, St. Louis, MO) red blood cell (RBC) labeling kit for both first-pass (FP) and multigated acquisition (MUGA) studies with a high specific activity in a reduced volume (50 mCi/0.5 ml) and a high labeling efficiency that can be used with a single-crystal camera to yield a quality study. METHODS: A packed red blood cell (PRBC) bolus was created by two methods: (a) reducing the volume of the components of the Ultratag kit and (b) centrifuging the final dose volume. The labeling efficiency of each bolus was evaluated, each PRBC bolus was visually inspected for clots and percent hemolysis was assessed using a hemocytometer at 30 min, 1 hr and 2 hr postcentrifugation. RESULTS: Use of the first method, the 50% kit, provided the best results. However, the resulting volume from this kit only approached 1 ml, which is not clinically adequate for a first-pass study. In the second method, the total volume was centrifuged to form a PRBC bolus, which appeared to be stable in the syringe for at least 2 hr. A combined FP/MUGA study from a centrifuged 50% reduced kit was performed in one normal subject as a preliminary assessment of the clinical utility of this procedure. The image quality of the scan is diagnostically adequate. CONCLUSION: By using the in vitro Ultratag kit, a compact PRBC bolus was created that was stable in the syringe and could be reinjected safely into the patient for combined cardiac FP/MUGA studies.

Blood Coagulation↗
PubMed1976

Perioperative myocardial infarction diagnosed by technetium 99m stannous pyrophosphate myocardial scintigrams.

Two groups of patients have been studied using 99mTc stannous pyrophosphate myocardial imaging prior to and 3-5 days after myocardial revascularization. The first group consisted of 48 patients undergoing revascularization, including 26 with unstable angina and seven with concomitant valve replacement. There were 3 deaths (6%), and the incidence of perioperative infarction by electrocardiogram (ECG) and enzyme analysis was 6/48 (12%), while 15 of 48 (31%) had positive myocardial scintigrams. The second group of 29 patients included one nonischemic death (3%) that was excluded. The operative technique was changed (optical magnification used, silastic tapes avoided, venting avoided, while aortic cross clamping was used frequently). In this latter group two of 29 (7%) had ECG evidence of infarction while four of 28 (14%) had positive scintigrams, compared to the pervious incidence of 31%. The imaging technique is simple, reliable, and probably more sensitive in the postoperative setting than ECG and enzyme analysis. It appears useful in evaluating the influence of changes in operative technique on myocardial preservation.

Female↗