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PubMed1995

Transfer of technetium from soil to paddy and upland rice.

Soil-plant transfer factors (concentration ratio between the plant and soil) of technetium in paddy and upland rice plants were obtained from laboratory experiments. The transfer factor is one of the most important parameters for environmental radiation dose assessment. Technetim tracer (95mTcO4-) was added to the soil prior to rice cultivation. The transfer factor of technetium for the hulled grains (brown rice) of paddy rice (< or = 0.0002) was much lower than for that of upland (0.021). The transfer factors for both types of hulled grains were much lower than in the leaves. The technetium decontamination rate from hulled grains by polishing was 34%, the percentage of the weight decrease being 12%. The concentration of technetium in the soil solution collected from the paddy rice soil (flooded conditions) decreased rapidly with time due to its adsorption on the soil. In the upland rice soil (non-flooded) solution, the decrease in the technetium concentration was fairly slow. The low transfer factors for the paddy rice plants could be explained by the immobilization of technetium in the flooded soil. The oxidation-reduction potentials (Eh) in the flooded soil decreased rapidly with time. We conclude that technetium tracer added as TcO4- to flooded soil is readily transformed to an insoluble form (e.g. TcO2) under the reducing conditions provided by flooding.

Oryza↗
PubMed1975

A precise chromatography system for specific technetium-99m radiopharmaceuticals.

New chromatographic procedures are needed to accurately determine the radiochemical purity of technetium-99m labeled radiopharmaceuticals. A chromatography system has been developed for technetium-99m diethylenetriaminepentacetic acid, technetium-99m diphosphonate, and technetium-99m pyrophosphate. The technique involves spotting the radiopharmaceuticals on instant thin layer chromatography-silica gel and developing with acetone (solvent from migrates approximately 12 cm from the origin), air drying, and redeveloping the strip in normal saline (solvent front migrates approximately 6 cm from the origin). The procedure is simple to perform, rapid, accurate, and clearly separates technetium-99m pertechnetate, the technetium-99m radiopharmaceutical, and hydrolyzed reduced technetium-99m. It can be applied in most nuclear medicine laboratories and has the potential to predict the quality of radionuclide images obtained.

Chromatography, Thin Layer↗
PubMed1995

Technetium-99m-sestamibi single agent localization versus high resolution ultrasonography for the preoperative localization of parathyroid glands in patients with primary hyperparathyroidism.

Technetium 99m sestamibi, a newer radionuclide agent, has shown promise in parathyroid scintigraphy. Recent studies using technetium 99m sestamibi in conjunction with subtraction iodine I123 imaging have demonstrated accuracy for localizing parathyroid glands in patients with hyperparathyroidism. The effectiveness of technetium 99m sestamibi scanning as a single agent was compared prospectively with conventional high resolution ultrasonography for the preoperative localization of abnormal parathyroid glands in patients with primary hyperparathyroidism. Seventeen patients with primary hyperparathyroidism had preoperative evaluation with high resolution ultrasonography and technetium 99m sestamibi radionuclide scanning. All patients underwent bilateral neck exploration. Ultrasound results were made available to the surgeon preoperatively; however, technetium 99m sestamibi results were withheld unless specifically asked for by the surgeon intraoperatively. Comparison of the imaging studies were correlated with the operative and histological findings. Of 17 patients, 12 had solitary adenomas and four had diffuse hyperplasia. In one patient no abnormal glands were discovered. In patients with technetium 99m sestamibi localization, a solitary adenoma was identified correctly in 10 of 12 patients (83%). Three of four patients with diffuse hyperplasia had parathyroid sestamibi scans showing nonfocal or diffuse uptake in multiple glands. High resolution ultrasonography correctly identified only six of 12 patients with solitary parathyroid adenomas (50%). Of the patients with diffuse hyperplasia, two ultrasound studies showed a single enlarged gland, one study was negative, and one localized two questionable, enlarged glands. Technetium 99m sestamibi is effective as a single agent for preoperative parathyroid scintigraphy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1998

[Evaluation of myocardial viability using perfusion cardiac SPECT. 201-thallium rest/redistribution, 201-thallium rest/reinjection and technetium 99m tetrofosmin rest/postnitrates].

INTRODUCTION AND OBJECTIVES: It has been demonstrated that nitrate administration enhances the detection of myocardial viability in thallium-201 and technetium-99m sestamibi myocardial perfusion studies. The aim of this study was to assess the influence of nitrate administration on technetium-99m tetrofosmin myocardial uptake in patients with coronary artery disease and left ventricular dysfunction. PATIENTS AND METHODS: Twenty eight patients with coronary artery disease, previous myocardial infarction and left ventricular ejection fraction < 40% underwent, within 48 hours, rest/postnitroglycerin (0.4 mg sublingually) technetium-99m tetrofosmin single photon emission tomography (SPET), comparing these results with that of thallium-201 rest/redistribution SPET in 13 patients (first group) and with that of thallium-201 rest/reinjection SPET in the other 15 patients (second group). Tomograms based on the 3 spatial planes were divided into 15 segments and regional tracer uptake was quantitatively analysed. Viability was defined as presence of tracer uptake > or = 50% of peak activity. RESULTS: The percentage of peak activity at rest or after nitrate administration of technetium-99m tetrofosmin correlated, with that of thallium-201, at rest and after redistribution or reinjection (r = 0.8; p < 0.001). On resting technetium-99m tetrofosmin studies 167 of the 420 segments that were analysed had < 50% of peak activity. 14.5% of these segments showed reversibility after nitrate administration, with an increase in 99mTc-tetrofosmin uptake from 45 +/- 5% to 55 +/- 4% of peak activity (p = 0.001), in the first group, and from 40 +/- 9% to 57 +/- 9% of peak activity (p = 0.003), in the second group. Overall agreement between rest/postnitroglycerin technetium-99m tetrofosmin SPET studies and rest/redistribution or rest/reinjection thallium-201 SPET studies, regarding the presence of myocardial viability, was 87% and 90%, respectively. All except one reversible segments on tetrofosmin studies after nitrates had viability criteria on thallium studies. CONCLUSIONS: Nitrate administration at rest enhances the detection of myocardial viability using technetium-99m tetrofosmin SPET, correlating with viability criteria observed on thallium studies. It represents a simple and useful technique in the assessment of myocardial viability.

Aged↗
PubMed1982

Radioactive excretion in human milk following administration of technetium Tc 99m macroaggregated albumin.

Albumin-tagged sodium pertechnetate (technetium) is routinely used in nuclear medicine for scanning procedures of the lung. The rate of excretion of this radionuclide into breast milk and the resultant potential radiation hazard to the nursing infant have received little attention. Therefore the milk from a nursing mother who required a lung scan because of suspected pulmonary emboli using an intravenous injection of 4 mCi of technetium Tc 99 macroaggregated human serum albumin was monitored. Albumin tagging severely limited the entrance of technetium into her milk and the radioactivity of the milk returned to base line by 24 hours. A total of 2.02 muCi of technetium was measured in the 24-hour milk collection after technetium injection and 94% of this amount was excreted by 15.5 hours. This amount of technetium administered orally to a newborn would deliver a total body radiation dose of .3 mrad. Therefore, an infant would receive trivial doses of radiation if breast-feeding were resumed 15.5 hours after administration of the radionuclide to the mother and nursing can clearly be resumed safely 24 hours after injection.

Adult↗
PubMed1981

Technical problems associated with the production of technetium Tc 99m tin(II) pyrophosphate kits.

The amount of tin(II) required for adequate reduction, complexation, and stability of technetium Tc 99m pertechnetate in radiopharmaceutical kits, and methods of preventing the loss of tin(II) during formulation of these lyophilized kits are investigated. Tin(II) loss from stannous chloride solutions was studied under several conditions, including room air versus nitrogen atmospheres, during vial filling in a laminar-flow hood with samples frozen on dry ice versus samples at room temperature, during lyophilization, and during storage under refrigerated, ambient, and elevated temperatures. Various amounts of stannous chloride, ranging from 5 to 1000 microgram/ml, were used in formulating sodium pertechnetate Tc 99m kits containing 100 mCi technetium Tc 99m and 0.4 microgram total technetium. Samples were removed at various times; hydrolyzed technetium, pertechnetate, and technetium Tc 99m pyrophosphate were isolated on instant thin-layer chromatography-silica gel and quantified with a scintillation counter. The time necessary to deoxygenate distilled water by nitrogen purging was measured. Several sources of stannous chloride were assayed for tin(II) content. Tin(II) loss occurs rapidly in solution (15% in one hour) unless continuously protected with nitrogen, and during vial filling in a laminar-flow hood unless frozen with dry ice. No substantial loss of tin(II) was detected during lyophilization or during storage of lyophilized product at any of the three temperatures. A minimum of 400 microgram tin(II) was required to provide 90% technetium Tc 99m pyrophosphate at six hours after preparation. Adequate deoxygenation of small quantities (450 ml) of water was accomplished in less than one hour. Some stannous chloride salts were highly oxidized in the dry state, and only high-purity elemental tin wire gave acceptable yields of tin(II).

Chemistry, Pharmaceutical↗
PubMed1994

Technetium-99m sestamibi myocardial perfusion imaging in the emergency room evaluation of chest pain.

OBJECTIVES: The purpose of this investigation was to evaluate the practicality and short-term predictive value of acute myocardial perfusion imaging with technetium-99m sestamibi in emergency room patients with typical angina and a normal or nondiagnostic electrocardiogram (ECG). BACKGROUND: Accuracy of emergency room chest pain assessment may be improved when clinical and ECG variables are used in conjunction with acute thallium-201 myocardial perfusion imaging. Technetium-99m sestamibi is a new radioisotope that is taken up by the myocardium in proportion to blood flow, but unlike thallium-201, it redistributes minimally after injection. Technetium-99m sestamibi can thus be injected during chest pain, and images acquired 1 to 2 h later (when patients have been clinically stabilized) will confirm whether abnormalities of perfusion were present at the time of injection. METHODS: One hundred two emergency room patients with typical angina (on the basis of a standardized angina questionnaire) and a normal or nondiagnostic ECG had a technetium-99m sestamibi injection during symptoms and were followed up for occurrence of adverse cardiac events (cardiac death, nonfatal myocardial infarction, coronary angioplasty, coronary surgery or coronary thrombolysis). RESULTS: Univariate predictors of cardiac events included the presence of three or more coronary risk factors (p = 0.009, risk ratio 3.3) and an abnormal or equivocal acute technetium-99m sestamibi scan (p = 0.0001, risk ratio 13.9). Multivariate regression analysis identified an abnormal perfusion image as the only independent predictor of adverse cardiac events (p = 0.009). Of 70 patients with a normal perfusion scan, only 1 had a cardiac event compared with 15 patients with equivocal scans or 17 patients with abnormal scans, with a cardiac event rate of 13% and 71%, respectively (p = 0.0004). CONCLUSIONS: Initial myocardial perfusion imaging with technetium-99m sestamibi when applied in emergency room patients with typical angina and a normal or nondiagnostic ECG appears to be highly accurate in distinguishing between low and high risk subjects.

Adult↗
PubMedDate not supplied

Bifunctional chelator for facile preparation of neutral technetium complexes.

The diaminedithiol (DADT) ligand system has proven to be useful as a carrier of technetium-99m in the preparation of a wide variety of site-specific radiopharmaceuticals. To expand the utility of the ligand system, we have designed and synthesized a bifunctional chelating agent based on the ligand system whose adducts generate a neutral technetium complex core and therefore can penetrate intact membranes. We have evaluated both the coupling of the thiolactone reactive moiety of the bifunctional chelate to benzylamine as a model as well as subsequent labeling with technetium-99m. Reaction with benzylamine was complete at room temperature within 2 h, producing the adduct in 74% isolated yield. On coordination of the benzylamine adduct to technetium-99m, one major product was obtained in high yield (> 90%). The product was stable in serum and physiologic saline at 37 degrees C over a 20-h study period. The partition coefficient of the technetium complex was 101 +/- 6.2, indicating that the complex was lipophilic. Biodistribution studies in mice showed that the brain concentration at 5 min postinjection was 0.91 +/- 0.09% injected dose/g indicating that the complex penetrates the intact blood-brain barrier. This is further evidence that the complex is neutral and lipophilic. This bifunctional chelate should facilitate the incorporation of technetium-99m into molecules of biological interest such as drugs, small peptides, and metabolic substrates.

Animals↗
PubMedDate not supplied

Preparation, characterization, and biological evaluation of technetium(V) and rhenium(V) complexes of novel heterocyclic tetradentate N3S ligands.

Various tetradentate N3S ligands which contain pyridyl, morpholino, or imidazolyl moieties were prepared and labeled with technetium and rhenium. Metal complexation of the ligands occurred efficiently over the pH range from 2 to 11. Ligands possessing the S-THP (tetrahydropyranyl)-protected mercapto group labeled efficiently even under alkaline conditions, and among the three types of heterocyclic metal complexes, a marked difference in stability was observed; rhenium complexes decomposed to ReO4 whereas technetium complexes decomposed to TcO2/TcO4. In general, imidazolyl complexes of both technetium and rhenium were very stable in saline; less than 10% decomposition after 24 h. The technetium histidyl complex and technetium pyridyl complex were quite stable even under cysteine challenge; less than 10% decomposition after 24 h. The rhenium and technetium morpholino complexes were very unstable; greater than 10% decomposition after only 1 h in saline and greater than 25% decomposition in 1 h under cysteine challenge. Profound pharmacokinetic differences among these metal complexes were also observed in rat biodistribution studies. The neutral pyridyl complexes exhibited high blood and liver uptake and slow clearance from these tissues. The replacement of a hydroxyl group by a carboxyl group, which resulted in an anionic complex at physiological pH, resulted in a dramatic decrease in blood and liver uptake. The neutral imidazolyl complex exhibited marked reduction in blood uptake and much faster clearance from blood and liver compared to the neutral pyridyl complex. Finally, the anionic histidyl complex, which contains both the imidazolyl and carboxyl groups, had the most favorable pharmacokinetic properties in that it exhibited very low blood, liver, and kidney uptakes and a rapid clearance from the body via the renal system. The combination of the high stability and favorable pharmacokinetic properties of the imidazolyl complexes should render them useful for targeted delivery of the medically important isotopes.

Animals↗
PubMed1978

Uptake by bone of pyrophosphate, diphosphonates and their technetium derivatives.

1. The uptake of inorganic pyrophosphate (PPi) from blood to bone was investigated in the rat in vivo. 2. PPi is taken up by the bone, where it appears both as PPi and as inorganic orthophosphate (Pi). The latter is due at least partly to local hydrolysis. 3. The fraction of injected PPi taken up by bone, measured as total PPi, was in the same range as that of technetium-tin-PPi, diphosphonates, technetium-tin-ethane-1-hydroxy-1,1-diphosphonate and Pi, but lower than that of calcium. 4. The plasma half-life of PPi is in the same order of magnitude as that of technetium-tin-PPi, diphosphonates, technetium-tin-ethane-1-hydroxy-1,1-diphosphonate, Pi and calcium. 5. PPi, diphosphonates and their technetium complexes are only partly ultrafiltrable in plasma. 6. It appears that the technetium complexes behave in a similar fashion to free PPi or diphosphonate.

Animals↗
PubMed2000

Technetium 99m-MIBI-SPECT: A highly sensitive diagnostic tool for localization of parathyroid adenomas.

BACKGROUND: The aim of this study was to assess the value of technetium 99m-MIBI scintigraphy using the single photon emission computed tomography (SPECT) technique for preoperative localization of smaller (</= 1 g) parathyroid adenomas. METHODS: A total of 92 patients (34 men, 58 women; mean age, 60 +/- 13 years) with an established diagnosis of primary hyperparathyroidism and nondiagnostic ultrasonography (inclusion criteria) were scanned preoperatively. After a thyroid examination to check for other possible radionuclide-accumulating thyroid diseases, a planar technetium 99m-pertechnetate/technetium 99m-MIBI subtraction scintigraphy (15 minutes post injection) and tomographic images (120 minutes post injection) were acquired after intravenous injection of 740 MBq of technetium 99m-MIBI and using a 3-head gamma camera (Picker Prism 3000). Sensitivity was defined by the ability to predict the correct site of a parathyroid adenoma. RESULTS: All patients had parathyroid adenomas </= 1 g (53 patients, 0.5 -1.0 g; 39 patients, < 0.5 g). Correct localization of parathyroid adenomas to one side or the other was achieved in 87% of the patients using planar technetium 99m-pertechnetate/technetium 99m-MIBI subtraction scintigraphy. Sensitivity was increased to 95% by supplementary use of the SPECT technique and a 3-D display (volume-rendered reprojection for visualization). There was technetium 99m-MIBI accumulation in 11 benign thyroid nodes, but none of the healthy parathyroid glands were shown on the scan. CONCLUSIONS: This study indicates that technetium 99m-MIBI parathyroid scintigraphy is a sensitive and specific tool for topographic localization even of small parathyroid adenomas, especially with the use of SPECT. This method could help to improve the efficiency of parathyroidectomy (eg, by making unilateral exploration sufficient).

Adenoma↗
PubMed1990

ECG-gated and static technetium-99m-SESTAMIBI planar myocardial perfusion imaging: a comparison with thallium-201 and study of observer variabilities.

To assess the diagnostic accuracy of planar diastolic and static Technetium-99m-SESTAMIBI, myocardial perfusion imaging at rest and during exercise, was performed in 60 consecutive patients. The results were compared with coronary angiographic findings, obtained within 3 months of the exercise test and Thallium-201 images, obtained on the same day and to the same exercise level as Technetium-99m-SESTAMIBI exercise. Exact segmental concordance between static Technetium-99m-SESTAMIBI and Thallium-201 was 77% and between the diastolic images and Thallium-201 76%. Concordance between static and diastolic images was 92%. Nineteen percent of all 900 segments demonstrated ischemia with both static and diastolic Technetium-99m-SESTAMIBI and 20% with Thallium-201. Overall sensitivity to detect hemodynamically significant coronary artery disease with static Technetium-99m-SESTAMIBI was 86%, specificity 78%, with diastolic images 89% and 70% and with Thallium-201 89% and 78% (differences not significant). Vessel-specific comparative detection rates revealed no statistical significant differences between both radiopharmaceuticals as well. Intra-observer variability for the static images was 12%, for the diastolic images 21% and Thallium-201 14%. Inter-observer variability for the static images was 14%, diastolic images 24%, and Thallium-201 17%. Although the physical characteristics of Tc-SESTAMIBI enable to perform high-count density imaging and electrocardiographic gating, no significant differences are found when planar diastolic and static Technetium-99m-SESTAMIBI images are compared with Thallium-201 and are well within observer variabilities.

Coronary Disease↗
PubMed1986

Sequential technetium-99m HMDP-gallium-67 citrate imaging for the evaluation of infection in the painful prosthesis.

In order to evaluate the clinical utility of sequential technetium-99m HMDP-gallium-67 scanning in patients with painful orthopedic prosthesis, a retrospective review was made of 154 sequential scans performed in 130 patients. Criteria for a positive study included spatially incongruent gallium-technetium uptake or gallium uptake that was congruent but more intense than technetium. Images were interpreted as negative if gallium was congruent and less intense than technetium. Sixty-six patients underwent surgery (31 infected, 35 aseptic), and 64 were evaluated clinically (3 infected, 61 aseptic). The combined results of the surgical and nonsurgical patients yielded a sensitivity of 66%, a specificity of 81%, and an accuracy of 77%. In this series, the technetium-gallium scan combination has proven to be helpful but more recent techniques such as indium-111-labeled leukocytes may prove to be superior to sequential technetium-gallium imaging.

Adult↗
PubMed1993

Effect of source and age of sodium pertechnetate Tc 99m on radiochemical purity of technetium Tc 99m exametazime.

The radiochemical purities of technetium Tc 99m exametazime prepared with one-hour-old or six-hour-old sodium pertechnetate Tc 99m from two manufacturers' generators were compared. Eluates from each manufacturer's generators were diluted immediately to provide two solutions of sodium pertechnetate Tc 99m. For the one-hour-old solution, eluate was diluted with 0.9% sodium chloride injection to a concentration of radioactivity of 38 mCi in 5.5 mL and used one hour later. For the six-hour-old solution, eluate was diluted to 65 mCi in 5.5 mL and used six hours later. Technetium Tc 99m exametazime was prepared by injecting 5.0 mL of one of the solutions into an exametazime kit to provide 30 mCi of technetium Tc 99m in 5.0 mL. At 2, 30, and 60 minutes after reconstitution of each kit, the radiochemical purity was measured by high-performance liquid chromatography with radiation detection. At two minutes, all the preparations retained high radiochemical purities. However, at 30 and 60 minutes, the radiochemical purities of technetium Tc 99m exametazime prepared with six-hour-old sodium pertechnetate Tc 99m were significantly lower than those of technetium Tc 99m exametazime prepared with one-hour-old sodium pertechnetate Tc 99m. Similar results were found for each manufacturer's generators. The radiochemical purity of technetium Tc 99m exametazime was affected by the age of the sodium pertechnetate Tc 99m from which it was prepared but not by the generator from which the sodium pertechnetate Tc 99m was obtained.

Humans↗
PubMed1996

Technetium-99m-white blood cell-specific imaging agent developed from platelet factor 4 to detect infection.

UNLABELLED: We have developed a leukocyte-avid, 99mTc-labeled peptide (P483H) as a potential imaging agent for infection. P483H contains the heparin-binding region of platelet factor-4 (PF-4) and a lysine-rich sequence for rapid renal clearance. Technetium-99m-P483H was evaluated for its ability to selectively label white blood cells (WBCs) in vitro and to detect focal E. coli infections in rabbits. METHODS: Technetium-99m-P483H was incubated with citrated whole human blood, layered onto WBC isolation media and subjected to density gradient centrifugation to measure WBC-associated radioactivity. Indium-111-WBCs and 99mTc-gluceptate were used as controls. In the in vivo model, E. coli infected rabbits were imaged and necropsied 4 hr after administration of 99mTc-P483H. Infected and contralateral control muscles were evaluated for %ID, %ID/g, Imax (muscle sample showing the highest uptake, i.e., %ID/g) and Imax-to-blood and Imax-to-control muscle ratios. Indium-111-WBCs, 111In-DTPA, 131I-albumin (HSA), 99mTc-nanocolloid, 67Ga and 99mTc-gluceptate were evaluated as in vivo controls. RESULTS: Technetium-99m-P483H associated predominantly with WBCs in vitro, and 99m-Tc-P483H provided high contrast images of infection in vivo. In vitro, 73% of 99mTc-P483H radioactivity was associated with WBCs. Technetium-99m-P483H outperformed 111In-WBCs, 111In-DTPA, 131I-albumin, 99mTc-nanocolloid, 67Ga-citrate and 99mTc-gluceptate with an infection Imax average of 0.062 %ID/g (+/- 0.029; n = 48). Technetium-99m-P483H also outperformed all controls, including 111In-WBCs, 111In-DTPA, 131I-albumin, 99mTc-nanocolloid, 67Ga-citrate and 99mTc-gluceptate. The Imax-to-blood and Imax-to-control muscle ratios for 99mTc-P483H averaged 3.1 (+/- 2.4) and 26.8 (+/- 16.8), respectively, and again outperformed all controls. CONCLUSION: Technetium-99m-P483H associates predominantly with WBCs in vitro and identified focal infections in vivo within 4 hr versus conventional imaging agents. Additionally, the agent showed rapid blood clearance and exclusive renal excretion, which provides a clear abdominal field for imaging abdominal infections.

Animals↗
PubMed1985

Hypertension in children. Increased efficacy of technetium Tc 99m succimer in screening for renal disease.

Renal scintigraphy with technetium Tc 99m succimer (DMSA) and technetium Tc 99m pentetate (DTPA) was used to study 80 hypertensive pediatric and adolescent patients. Renal abnormalities such as asymmetry of function, size, or shape were identified in 13 patients. Both excretory urography and technetium Tc 99m pentetate studies were successful in detecting 54% of the abnormalities in patients studied; technetium Tc 99m succimer identified 92%. The accuracy of the latter was 96%, with a specificity of 97%. The ability of technetium Tc 99m succimer renal scintigraphy to identify accurately the presence or absence of renal abnormalities warrants its inclusion in the initial examination of pediatric and adolescent patients with hypertension.

Adolescent↗
PubMed1999

Reliability of technetium-99m Q12 and thallium-201 myocardial activity measurements after triphenyl tetrazolium chloride myocardial staining by perfusion.

RATIONALE AND OBJECTIVES: Investigations in animal models of severe myocardial ischemia or infarction use triphenyl tetrazolium chloride (TTC) staining to document infarction size histologically and to correlate these data with uptake measurements of radiolabeled tracers. Previously published data suggest that TTC staining itself has an important impact on myocardial tracer activity measurements. The authors hypothesized that TTC staining by perfusion has no significant effect on relative regional myocardial activity measurements of technetium-99m Q12 and thallium-201 in an open-chest canine model. METHODS: Eight dogs underwent left anterior descending artery occlusion for 2 hours with 30 minutes of reperfusion, followed immediately by injection of technetium-99m Q12 (n = 4) or thallium-201. Total myocardial activity was recorded in a dose calibrator, and regional myocardial samples were obtained by Cope needle biopsies from the ischemic and normal zones, both before and after TTC staining. RESULTS: The mean percent activity retention for the whole heart after perfusion staining with TTC was significantly reduced when compared to the preperfusion value for both technetium-99m Q12 and thallium-201. Regional measurements revealed no significant difference between the mean percent retention of technetium-99m Q12 in the ischemic and normal zones. After TTC perfusion, regional mean percent retention of thallium-201 was similar in the ischemic and normal zones. CONCLUSIONS: In a canine model of myocardial ischemia and infarction with reperfusion, TTC staining can be performed by coronary artery perfusion without significantly affecting comparative regional measurements of either technetium-99m Q12 or thallium-201. Whole heart tracer retention is significantly reduced by TTC perfusion staining, but thallium-201 is more affected than technetium-99m Q12.

Animals↗
PubMed1982

Measurement of infarct size using single photon emission computed tomography and technetium-99m pyrophosphate: a description of the method and comparison with patient prognosis.

The application of dual tracer transaxial emission computed tomography of the heart was studied with use of technetium-99m pyrophosphate and technetium-99m-labeled red blood cells for measuring infarct size in 20 patients with acute myocardial infarction and 10 without infarction. Imaging was performed with a standard gamma camera and with a multidetector transaxial emission computed tomographic body scanner 3 hours after injection of technetium-99m pyrophosphate. Immediately after the scanning procedure, technetium-99m pertechnetate was injected to label red blood cells, and the scanning protocol was repeated. Technetium-99m pyrophosphate was detected in the anterior wall with involvement of the interventricular septum or lateral wall in patients with electrocardiographic criteria for anterior infarction, whereas uptake was detected in the diaphragmatic left ventricular wall with involvement of the posterior, posteroseptal or posterolateral left ventricle or of the right ventricle in patients with electrocardiographic criteria for inferior or posterior infarction. Infarct size measured from transaxial images ranged from 14.0 to 117.0 g in weight. There was a direct relation between infarct size and patient prognosis in that, of the 13 patients with infarct greater than 40 g, 11 (85 percent) had complications, whereas only 2 (29 percent) of 7 patients with an infarct less than 40 g had complications during a follow-up period averaging 17.8 months (p less than 0.05).

Aged↗