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At least 19 recordsLinked to original sources

Survival of red blood cells in rabbits after acute administration of unlabeled stannous pyrophosphate: Concise communication.

We investigated the possibility that acute administration of unlabeled stannous pyrophosphate may adversely affect red blood cells in the rabbit. Our method was similar to the in vivo labeling of RBCs with technetium-99m for blood-pool scanning. The investigation showed that dosages recommended in the literature produce no demonstrable difference between pre- and postdose RBC survival, which strongly suggests that the stannous content of the pharmaceutical is not harmful to red blood cells.

Animals↗

Value and limitations of technetium-99m stannous pyrophosphate in the detection of acute myocardial infarction.

Technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial imaging was performed in 436 consecutive patients for the evaluation of chest pain and suspected acute myocardial infarction (AMI). Scintigrams were assessed independently by three observers with a 90% interobserver agreement. In 134 patients with documented AMI (97 TRANSMURAL, 37 NONTRANSMURAL), THE SENSITIVITY OF 99MTc-PYP imaging was significantly lower in patients with nontransmural AMI (41%) than in patients with transmural AMI (78%), 99mTc-PYP imaging correctly localized the site of transmural infarction in 53 patients (70%). A diffuse 99mTc-PYP uptake was found in nine (10%) of 91 patients with positive scintigrams: six of these had a transmural AMI and three nontransmural AMI. In 226 patients without AMI, the specificity of infarct imaging was 95%. A false-positive scintigram was found in 0%, 8%, 9%, and 2% of patients with unstable angina, progressive angina, stable angina, and noncardiac chest pain, respectively. A diffuse uptake was found in six (54%) of 11 patients with false-positive scintigrams. No patient with the clinical diagnosis of noncardiac chest pain showed discrete uptake. In 76 patients with uncertain diagnosis for AMI, 99Tc-PYP imaging was considered of value in 11 patients with ventricular conduction defects (two patients with WPW syndrome, nine patients with LBBB). These data suggest that: 1. 99mTc-PYP imaging is moderately sensitive in detecting and localizing transmural AMI and is insensitive in detecting nontransmural AMI; 2. A discrete 99mTc-PYP uptake is highly specific for AMI; 3. a diffuse uptake is neither sensitive to, nor specific for AMI. Myocardial imaging with 99m-Tc-PYP is of clinical value when the standard electrocardiographic and enzymatic techniques are inadequate for an accurate diagnosis of AMI.

Acute Disease↗

Stabilization of stannous pyrophosphate kits with gentisic acid.

We evaluated the ability of gentisic acid, an antioxidant, to stabilize stannous pyrophosphate (Sn:PPi) kits and extend the shelf-life of the kit after reconstitution. In vitro studies showed that gentisic acid (0.5 mg/mL) stabilized the stannous ion against oxidation by various levels of exogenous hydrogen peroxide. In patients who received stabilized Sn:PPi for in vivo red blood cell labelling, the left ventricle-to-background activity ratio was significantly higher than that in patients who received a standard formation of Sn:PPi. Gentisic acid is now used routinely in the Sn:PPi kit formulation in this institution.

Drug Stability↗

The use of Technetium-99m stannous pyrophosphate scintigraphy to identify muscle damage in acute electric burns.

High-voltage electric burns are often associated with deep muscle damage in addition to a limited cutaneous burn. Technetium-99m stannous pyrophosphate (99mTc-PYP) scintigrams were evaluated as a diagnostic tool to detect and localize both large and focal areas of skeletal muscle necrosis. Scintigrams were performed in 14 patients between the first and fifth postinjury days and imaging was done over areas of suspected and clinically apparent muscle injury. Muscle damage was identified by an increased cellular uptake of the tagged material. All 14 patients had gross and histologic evidence of muscle necrosis. Muscle necrosis was identified as early as 24 hours and as late as 6 days postinjury. The location and extent of muscle injury was correctly ascertained preoperatively in all patients.

Burns, Electric↗

Technetium-99m stannous pyrophosphate myocardial scintiphotos in patients admitted to rule out acute myocardial infarction.

Technetium-99m stannous pyrophosphate (Tc-PYP) cardiac scintiphotos were performed on 101 of 221 patients admitted to the Coronary Care Unit to rule out acute myocardial infarction (AMI). Criteria were defined for the diagnosis of AMI, variant angina and unstable angina. 42 patients were diagnosed as having had an AMI. 22 patients had transmural and 20 patients had nontransmural AMI. 40 of the 42 patients with AMI (95%) had positive scintophotos; 2 (5%) had negative scintiphotos. 59 patients did not have an AMI; (97%) had negative scintiphotos. Four of these 59 patients had variant angina; all had negative scintiphotos. Seven of these 59 patients had unstable angina; 2 had positive scintiphotos. Tc-PYP scintiphotos have high sensitivity and specificity and are accurate in correctly classifying patients as having or not having AMI.

Acute Disease↗

Myocardial uptake of technetium-99m stannous pyrophosphate in experimental viral myopericarditis.

Distribution of technetium-99m stannous pyrophosphate was studied in mice with experimentally induced viral myopericarditis. Myocardial and bone uptakes of Tc-PPi were compared in 55 mice inoculated with coxsackievirus B3 (Nancy strain). The myocardium-to-bone uptake ratio in 33 mice with myopericarditis was increased to a greater extent than that seen in 22 mice without myopericarditis (p less than 0.001). In the severely involved heart, the uptake per gram exceeded that in the bone. Myocardial uptake in myopericarditis can be visualized on a whole-body image using a pinhole collimator and a left lateral view. Our experimental studies suggest the potential clinical usefulness of myocardial scintigraphy in viral myopericarditis.

Animals↗

Effect of methylprednisolone upon technetium-99m pyrophosphate assessment myocardial necrosis in the canine countershock model.

Repeat DC countershock reproducibly results in myocardial necrosis in dogs. In this model, myocardial technetium-99m pyrophosphate (PYP) uptake correlates linearly with tissue creatine kinase depletion (r = -0.83). The effect of pretreatment with methylprednisolone (MP) was studied with PYP in 25 dogs. In myocardium damaged by countershock, 12 MP dogs had higher tissue radioactivity sample:normal (S:N) ratios than control (P less than 0.05), suggesting increased tissue injury. However, by several other measures of tissue damage, the two groups did not differ. MP-elevated PYP S:N ratios were explained by reduced PYP activity in normal myocardium of MP dogs. Further experiments in 21 dogs revealed that renal PYP clearance, which correlated with glomerular filtration rate (GFR) as measured by creatinine clearance, was increased in Mp dogs, resulting in accelerated urinary excretion of PYP (46.9+/-3.6 vs 35.8+/-2.4 percent injected dose in one hour, P less than 0.01), and reduced blood PYP. Thus MP does not modify countershock-induced myocardial injury. However, by increasing GFR, MP increased PYP excretion, resulting in lowered blood and normal zone myocardial PYP, thereby spuriously affecting myocardial PYP tissue uptake data.

Animals↗

Detection and localization of gastrointestinal bleeding using Tc-99m-pyrophosphate in vivo labeled red blood cells.

Eighteen patients with either clinically or laboratory-detectable gastrointestinal bleeding were studied using Tc-99m-PYP in vivo labeled red blood cells. In those patients with massive gastrointestinal bleeding, the site of bleeding was usually detected within the first half-hour of scanning. Slower bleeding required longer scanning time. In several patients, bleeding sites were detected which could not be located by other means. It was experimentally determined that as little as 5 ml of ingested whole blood labeled in vivo with Tc-99m-PYP could be detected in the upper gastrointestinal tract.

Erythrocytes↗

Technetium-99m labeling of polymorphonuclear leukocytes: preparation with two different stannous agents.

A technique for in vitro labeling of human polymorphonuclear leukocytes with Tc-99m is described. Titration of stannous fluoride and stannous pyrophosphate concentrations for pretinning was performed, and optimal amounts of the stannous agents were added to polymorphonuclear leukocytes efficiently isolated from 100 ml of blood. Labeling with 10-15 mCi Tc-99m resulted, after three washings of cell suspensions, in yields of 1.6-4.8 mCi, corresponding to 20.5-33.5% of added tracer. Cell-bound activity in the final cell suspensions was 92.3% +/- 1.9 of the added dose. Cell function was not impaired by the labeling technique. Sterility and exclusion of bacterial endotoxins in the final cell suspensions were demonstrated. The method may prove of diagnostic value in the isolation, labeling, and reinjection of autologous leukocytes for scintigraphic imaging of acute inflammatory lesions.

Cell Separation↗