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At least 73 records · Page 4Linked to original sources
PubMed1983

[Prognostic importance of a positive test of myocardial 99mTc-Sn-pyrophosphate accumulation in patients with stable stenocardia].

The paper reports the results of a retrospective study of the frequency of complications of chronic coronary disease in 51 patients with stable angina subjected to myocardial 99mTc-Sn-pyrophosphate scintigraphy at rest at first screening. In the group with positive scintigraphic results, myocardial infarction and death from cardiac causes was five times as frequent within the next five years as it was in the group where myocardial incorporation of the drug was not observed. The frequency of complications was higher in cases where positive scintigraphic results were combined with cardiomegaly and electrocardiographic signs of transitory ischemia. Positive scintigraphic test with 99mTc-Sn-pyrophosphate can indicate future aggravation of the disease in patients with stable angina pectoris.

Adult↗
PubMed1985

Comparison of technetium-99m pyrophosphate and technetium-99m methylene diphosphonate with variable amounts of stannous chloride in the detection of acute myocardial infarction.

The authors prospectively compared the ability of Tc-99m pyrophosphate (PYP) and Tc-99m methylene diphosphonate (MDP) to detect acute myocardial infarctions. The agents used were PYP (12 mg) with 3.4 mg of stannous chloride, MDP (10 mg) with 1.0 mg of stannous chloride, and MDP (10 mg) with 3.4 mg of stannous chloride. Imaging was performed on three consecutive days on 34 patients with proven myocardial infarctions, using the same agent on the first and third days of the study and an alternate agent on the second day. Agents were assigned randomly to each of six groups of patients. First images were obtained an average of 3.7 days (range, one to six days) following myocardial infarction. Seventeen of 23 patients (75%) had images positive for acute myocardial infarction with Tc-99m PYP, whereas only two of 21 patients (9.5%) had positive studies with Tc-99m MDP with 3.4 mg of stannous chloride and one of 24 patients (4.2%) had positive studies with Tc-99m MDP and 1.0 mg of stannous chloride. All three myocardial infarctions detected by Tc-99m MDP were extensive and transmural. When MDP and PYP were both positive in the same patient, the apparent size of the myocardial infarction was much smaller with the MDP. It is concluded that MDP can detect only large myocardial infarctions, has poor localization in the infarcted tissue, and varying the stannous chloride content of the preparation does not improve the ability of MDP to detect acute myocardial infarctions.

Adult↗
PubMed1981

Use of equilibrium (gated) radionuclide ventriculography to quantitate left ventricular output in patients with and without left-sided valvular regurgitation.

We examined the accuracy with which left ventricular output can be estimated by equilibrium radionuclide ventriculography. After red blood cells were labeled in vivo, we measured left ventricular end-diastolic and end-systolic count rates and the count rate in 5 ml of the patient's blood. After estimating the average ratio of counting efficiency for the left ventricle to counting efficiency for the blood sample (Elv/Es) in six patients, we calculated left ventricular output in 26 other patients as (left ventricular activity ejected per minute divided by activity per liter of blood) divided by the previously estimated Elv/Es. Radionuclide left ventricular output closely approximated Fick cardiac output (r = 0.94) in patients without mitral or aortic regurgitation and exceeded Fick cardiac output in all patients with valvular regurgitation. Regurgitant fraction, calculated as the difference between the radionuclide and Fick outputs divided by the radionuclide output, correlated with the severity of of regurgitation as assessed angiographically. The equilibrium radionuclide ventriculogram is an excellent means for noninvasive estimation of left ventricular output.

Adult↗
PubMed1981

The high-risk angina patient. Identification by clinical features, hospital course, electrocardiography and technetium-99m stannous pyrophosphate scintigraphy.

We evaluated 193 consecutive unstable angina patients by clinical features, hospital course and electrocardiography. All patients were managed medically. Of the 193 patients, 150 (78%) had a technetium-99m pyrophosphate (Tc-PYP) myocardial scintigram after hospitalization. Of these, 49 (33%) had positive scintigrams. At a follow-up of 24.9 +/- 10.8 months after hospitalization, 16 of 49 patients (33%) with positive scintigrams died from cardiac causes, compared with six of 101 patients (6%) with negative scintigrams (p less than 0.001). Of 49 patients with positive scintigrams, 11 (22%) had had nonfatal myocardial infarction at follow-up, compared with seven of 101 patients (7%) with negative scintigrams (p less than 0.01). Age, duration of clinical coronary artery disease, continuing angina during hospitalization, ischemic ECG, cardiomegaly and a history of heart failure also correlated with cardiac death at follow-up. Ischemic ECG and a history of angina with a crescendo pattern also correlated with nonfatal infarction at follow-up. Patients with continuing angina, an ischemic ECG and a positive scintigram constituted a high-risk unstable angina subgroup with a survival rate of 58% at 6 months, 47% at 12 months and 42% at 24 and 36 months. We conclude that the assessment of clinical features, hospital course, ECG and Tc-PYP scintigraphy may be useful in identifying high-risk unstable angina patients.

Acute Disease↗
PubMed1985

[Effect of body loading on the specific blood radioactivity following 99mTc in-vivo erythrocyte labelling. The effects on determining end-diastolic volume in equilibrium radionuclide ventriculography].

In 40 patients who underwent stress-equilibrium-radionuclide-ventriculography, we examined the stress-induced change of blood radioactivity concentration. A significant (p less than 0.025) increase of blood radioactivity concentration after peak exercise (mean +7.2%) was found. This increase was the result of a significant (p less than 0.025) increase of the hematocrit (mean +4.7%) due to a decrease of the plasma volume. The changes of radioactivity concentration and hematocrit neither show any correlation with peak exercise value, integral exercise or duration of exercise, nor with the increase of heart rate or blood pressure. The increase of end-diastolic volume appears to result largely from a stress-induced increase of blood radioactivity concentration. Thus, radioactivity concentration should be measured before and after exercise when evaluating volume changes caused by stress-equilibrium-radionuclide-ventriculography.

Cardiac Output↗
PubMed1984

[Comparative evaluation of methods of myocardial scintigraphy using 99mTc-Sn-glucohepatonate and 99mTc-Sn-pyrophosphate in the diagnosis of acute myocardial infarction and unstable stenocardia].

Scintigraphy with 99mTc -Sn-glucoheptonate permits the determination of the focus of transmural myocardial infarction at the earliest stages of the disease (from three hours to the fifth day of the disease) whereas scintigraphy with 99mTc -Sn-pyrophosphate makes it possible to follow-up the zone of transmural infarction from Day 2 through Day 7-10. Both methods fail to provide enough information to diagnose non-transmural myocardial infarction. A comparative evaluation of the nature of glucohepatonate and pyrophosphate incorporation in the myocardium of patients with unstable angina is suggestive of the severity of ischemic changes in the myocardium.

Adult↗
PubMedDate not supplied

[Bayesian analysis of myocardial scintigraphy using 99mTc-Sn(II)-methylenediphosphonate and using 99mTc-Sn(II)-pyrophosphate].

Myocardial scintigraphy with 99mTc-Sn (II)-Methylenediphosphonate (MDP) and with 99mTc-Sn (II) pyrophosphate (PPi) was performed in 185 patients with proven acute myocardial infarction (90 with MDP; 95 with PPi), and in 65 subjects with acute chest pain of a different etiology (37 with MDP; 28 with PPi), during the first five days after the onset of illness. Sensitivity, specificity and accuracy of the procedure were higher with PPi (0.895, 0.893, 0.894) than with MDP (0.822, 0.865, 0.835) in the diagnosis of AMI. Based on the usual clinical electrocardiographic and biochemical criteria, the likelihood of AMI on the population studied with MDP was of 70.9% and with PPi of 77.2%. Application of Bayes' theorem showed an increase in the likelihood of AMI, when myocardial scintigraphy was positive, from 70.9% to 93.7% when MDP was used, and from 77.2% to 96.6 when PPi was the tracer, with incremental ruling in gaings of 22.8% and 19.4%) respectively. A normal scintigraphy, on the other hand, reduced the likelihood of AMI from 70.9% to 33.4% when MDP was used, and from 77.2% to 29.2% when PPi was the tracer, with respective incremental ruling-out gains of 37.5% and 48.0%. Although homogeinity between the populations studied with each tracer was not proven, existing practical, clinical and biochemical evidence allows the conclusion that PPi is a better agent than MDP in the study of patients with acute chest pain.

Adolescent↗
PubMed1983

Comparative quality control of 99mTc-Pyrophosphate and 99mTc-diphosphonate radiopharmaceuticals.

The results of analysis of 99mTc-Pyrophosphate (99mPyP), taken as a representative of the group of compounds having an organic P-O-P bond, and of the three diphosphonate compounds: methylene diphosphonate (MDP), 2,3-dicarboxy propane diphosphonate (DPD) and ethane-1-hydroxy-1, 1-diphosphonate (EHDP), which differ in their chemical structure, are shown. Also, some physicochemical parameters such as chloroform-water apparent partition coefficient, the osmotic pressure and pH values in final preparations were studied. The radiochemical purity of these radiopharmaceuticals was determined by the two methods: Sephadex chromatography for separation of 99mTc-hydrolysate and TLC on silica gel with 85% methanol for the determination of free 99mTcO-4. The yield of labelling for both methods was over 90%. Also, pharmacokinetic parameters such as binding to the plasma proteins and to erythrocytes were determined. 99mTc-PyP binding to plasma proteins was higher than the binding of diphosphonate compounds. The quantitative distribution of preparations was determined in experimental animals.

Animals↗
PubMed1984

In vivo labelling of RBC with 99mTc for blood pool imaging using different stannous radiopharmaceuticals.

The in vivo 99mTc-RBC labelling efficiency and stability of labelling was assessed after pretinning with a high-stannous content DTPA kit (Sn DTPA) in comparison with Sn-pyrophosphate (Sn PPi) and a low-stannous DTPA kit (DTPA). The distribution in Sprague Dawley rats showed that similar fractions of administered 99mTc remained within the blood pool after pretinning with Sn DTPA and Sn PPi when equal quantities of stannous ions (15 micrograms/kg) and equal time intervals (30 min) between successive IV injections of pretinning agent and 99mTc-pertechnetate were used. Significantly lower fractions were found when DTPA (1.9 micrograms Sn2+/kg) was used for pretinning. The rate of 99mTc elution emphasises the importance of the Sn2+ concentration used, not only for labelling efficiency but also for stability of the labelling. Satisfactory intravascular activity, exceeding 80% during the first hour post-injection, was demonstrated in three volunteers after 99mTc injection, when Sn DTPA was used for pretinning. Left ventricular ejection fractions (LVEF) measured by equilibrium radionuclide angiography after pretinning with Sn DTPA in 24 patients correlated well (r = 0.98) with those obtained by contrast angiographies over a broad spectrum of values (0.14-0.72). Four repeated LVEF measurements at 45-min intervals in six additional patients at rest showed excellent reproducibility in each patient: maximum variation was less than 6%.

Animals↗
PubMed1988

Localization and stability of technetium-99m-Sn-pyrophosphate in rat neutrophils.

Technetium-99m has been suggested as an alternative radiolabel for white cells, and while its physical characteristics are nearly ideal, its stability and site of localization in this procedure are unclear. We examined these parameters by radiolabeling 10(8) neutrophils from rat peritoneum with 74 to 370 MBq technetium-99m-Sn-pyrophosphate. We found that the percentage of initial activity bound to neutrophils was quite variable, possibly because the radiolabel associated with several subfractions: 19.8 +/- 11.5% (mean +/- s.d.) with nuclei and plasma membranes, 25.6 +/- 3.9% with mitochondria, 26.6 +/- 9.8% with microsomes, and 29.2 +/- 6.9% with cytosol. Approximately 80-90% of the radioactivity associated with neutrophils was not bound to protein and only about one-half of the activity localized to cell membranes was removable over 4 hr by pepsin digestion. We concluded that the variable labeling efficiency was due to the radiolabel's rather loose association with several cellular subfractions rather than specific binding to a unique substrate.

Animals↗
PubMed1983

Biological effects and irradiation dose induced in human lymphocytes in vitro by an intracellular radionuclide:99mTc.

Since lymphocyte radiolabeling is widely used for in vitro and in vivo studies and may interfere with the properties of the cells, the purpose of this work was to investigate the effects of 99mTc labeling on lymphocyte morphology and functions. Two ranges of 99mTc activity were used, 37 and 370 MBq, and their effects were compared to those produced by a graduated external irradiation. Electron microscopy was performed and T cells were studied using biological markers (E-Rosette formation, cell proliferation under lectin reactivity, and specific cell-mediated cytolysis). After 370-MBq labeling, an intense cytotoxic effect was observed on cell morphology, drastically impeding T-lymphocyte functions. Thirty-seven-megabecquerel labeling and sham procedure did not significantly affect cell functions. The external irradiation dose-response curve indicated a clear radiation-induced inhibitory effect, especially over 10 Gy. This effect was less intense than that obtained with 370-MBq 99mTc labeling. The labeling cytotoxic effect can then be attributed to a radiolesion due to a radiation dose which is probably higher than 10 Gy. In fact, the dose received by lymphocytes during the 370-MBq labeling procedure was estimated as 70 Gy by calculations, taking into account all emissions of 99mTc.

Humans↗
PubMed1981

Bone healing in rabbits after compression osteosynthesis, studied by Tc-99m(Sn)polyphosphate scintimetry and autoradiography.

The purpose of the present study was to determine the scintimetric time course (STC) for Tc-99m(Sn) polyphosphate in rabbit tibias after various osteosynthetic procedures, and to correlate the findings with those from serial radiographs and with autoradiographic and histologic evaluation of the bone. The STC was similar for all treatment groups, with a peak value within the second week after surgery. Significantly different levels of the STC were found after subperiosteal exploration, plate insertion, osteotomy and compression plating, or osteotomy and medullary nailing. The radiological, autoradiographic, and histological findings revealed that Tc-99m scintimetry monitors callus formation. The STC thus appears to be a valuable tool for the quantitative study of bone healing.

Animals↗
PubMed1980

[Quantitative whole-body bone scintigraphy. II. Pharmacokinetics of osteotropic radiopharmaceuticals (author's transl)].

85Sr, 99mTc-Sn-pyrophosphate and 99mTc-Sn-methylene-diphosphonate, the most important agents for skeletal imaging, are compared with each other by calculation of the plasma clearance and the urinary excretion and by a series of quantitative whole-body scans. 85Sr the distribution volume in equilibrium is the largest, shifting of activity is demonstrable for several days after injection. 99mTc-Sn-MDP is excreted most quickly, equilibrium is reached early. There is no significant difference in skeletal uptake between the phosphate complexes. The distribution however is different: 85Sr is localized to a greater extent in the extremities, the phosphate complexes more in the trunk, 99mTc-Sn-MDP and 85Sr nearer the joints than 99mTc-Sn-pyrophosphate.

Bone and Bones↗
PubMed1981

Pulmonary capillary wedge pressure, as inferred from lung areas in gated blood-pool scintigrams: concise communication.

To determine whether the apex-to-base distribution of pulmonary blood volume, as obtained from gated cardiac blood-pool scans, could be used as a noninvasive method to estimate mean pulmonary capillary wedge pressure (PCWP), gated blood-pool scans were analyzed in 77 patients who also had PCWP measurements at cardiac catheterization. Ten of these patients had gated cardiac blood-pool scans and PCWP measurements both at rest and during exercise. The apex-to-base distribution of pulmonary blood volume was determined from the end-systolic frame of the left anterior oblique view by placing equal-sized regions of interest over the apex and base of the right lung. The ratio of apex counts over base counts (A/B ratio) was considered abnormal if greater than unity. The mean A/B ratio was 1.15 +/- 0.27 (1 s.d.) for the 32 studies associated with an abnormal mean PCWP (greater than 12 mm Hg). The mean A/B ratio was 0.85 +/- 0.23 for the 55 studies associated with a normal mean PCWP (p less than 0.01 comparing normal group with abnormal). The sensitivity of the A/B ratio for a mean PCWP greater than 12 mm Hg was 81%R (26/32). The specificity of the A/B ratio for a mean PCWP greater than or equal to 12 mm Hg was 89% (49/55). Thus, noninvasive determination of the pulmonary apex-to-base ratio from gated cardiac blood-pool scans appears to differentiate subjects with normal and abnormal mean pulmonary capillary wedge pressures.

Adult↗