Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TECHNETIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 217 records · Page 12Linked to original sources
PubMed1998

Risk assessment using single-photon emission computed tomographic technetium-99m sestamibi imaging.

OBJECTIVES: This review summarizes the results of single-photon emission computed tomographic (SPECT) technetium-99m (Tc-99m) tracer imaging in patients with stable symptoms, patients with acute coronary syndromes, patients undergoing major non-cardiac surgery and patients with chest pain in the emergency department. BACKGROUND: Previous studies have examined the prognostic value of stress thallium imaging in several subsets of patients with ischemic heart disease. At present, >50% of myocardial perfusion studies are performed with technetium-labeled tracers in the United States. Furthermore, there is a shift from diagnostic to the prognostic utility of stress testing. There are important differences between technetium-labeled tracers and thallium-201. It is therefore important to review the prognostic value of technetium-labeled tracers. METHODS: We analyzed published reports in English on risk assessment using Tc-99m perfusion tracers. Results. The largest experience is in patients with stable symptoms, comprising >12,000 patients in 14 studies. In these patients, normal stress SPECT sestamibi images were associated with an average annual hard event rate of 0.6% (death or nonfatal myocardial infarction [MI]). In contrast, patients with abnormal images had a 12-fold higher event rate (7.4% annually). Both fixed and reversible defects are prognostically important, and quantitative analysis shows increased risk in relation to the severity of the abnormality. These results are similar to those obtained with thallium-201. CONCLUSIONS: Patients with stable chest pain syndromes and normal stress SPECT sestamibi images have a very low risk of death or nonfatal MI. It is highly unlikely that coronary revascularization can improve survival in such patients. Patients with abnormal images have an intermediate to high risk for future cardiac events, depending on the degree of the abnormality. Further prospective studies comparing aggressive medical therapy with coronary revascularization in these patients are warranted.

Cause of Death↗
PubMedDate not supplied

An N2S2 bifunctional chelator for technetium-99m and rhenium: complexation, conjugation, and epimerization to a single isomer.

A bifunctional chelator 6 was prepared bearing an N2S2 core for binding rhenium or technetium and a carboxylic acid group for conjugation to amino groups of biomolecules. Complexation of 6 with rhenium(V) resulted in two kinetic isomers, anti-7 and syn-7, being formed in approximately equal amounts. Epimerization with 0.5 M NaOH yields a single isomer anti-7, as determined by NMR spectroscopy and single-crystal X-ray analysis. The 99mTc complex was prepared at the tracer level by reaction of the ligand with 99mTcO4-, tin(II) chloride and sodium gluconate giving a mixture of two isomers, but showing a preference for the anti isomer. Chelation in the presence of 1 M NaOH results in anti-8 being formed as the sole product. The bifunctional ability of the ligand was explored by amide formation with (S)-alpha-phenethylamine, either by direct DCC coupling or through the N-hydroxy succinimidyl ester 9 intermediate. The deprotected bioconjugate 11 was complexed with rhenium, yielding similar amounts of two isomeric rhenium complexes, anti-12 and syn-12, which were isolated and characterized by NMR spectroscopy. Treatment of the kinetic mixture of anti-12 and syn-12 with 1 M NaOH resulted in quantitative conversion to a single rhenium complex anti-12. With technetium-99m in 0.1 M sodium acetate, bioconjugate 11 yielded both technetium-99m complexes anti-13 and syn-13, in a 2:1 ratio, respectively. In contrast, complexation in the presence of 1 M NaOH gave only one technetium-99m complex, assigned the structure anti-13.

Chelating Agents↗
PubMed2005

Evolution of technetium speciation in reducing grout.

Cementitious waste forms (CWFs) are an important component of the strategy to stabilize nuclear waste resulting from plutonium production by the U. S. Department of Energy. Technetium (99Tc) is an abundant fission product of particular concern in CWFs because of the high solubility and mobility of Tc(VII), pertechnetate (TcO4-), the stable form of technetium in aerobic environments. CWFs can more effectively stabilize 99Tc if they contain additives that chemically reduce mobile TcO4- to immobile Tc(IV) species. The 99Tc leach rate of reducing CWFs that contain Tc(IV) is much lower than that for CWFs that contain TcO4-. Previous X-ray absorption fine structure studies showed that Tc(IV) species were oxidized to TcO4- in reducing grout samples prepared on a laboratory scale. Whether the oxidizer was atmospheric O2 or NO3- in the waste simulant was not determined. In actual CWFs, rapid oxidation of Tc(IV) by NO3- would be of concern, whereas oxidation by atmospheric O2 would be of less concern due to the slow diffusion and reaction of O2 with the reducing CWF. To address this uncertainty, two series of reducing grouts were prepared using TcO4- containing waste simulants with and without NO3-. In the first series of samples, referred to as "permeable samples", the TcO4- was completely reduced using Na2S, and the samples were sealed in cuvettes made of polystyrene, which has a relatively large O2 diffusion coefficient. In these samples, all of the technetium was initially present as a Tc(IV) sulfide compound, TcSx, which was characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS data is consistent with a structure consisting of triangular clusters of Tc(IV) centers linked together through a combination of disulfide and sulfide bridges as in MoS3. From the EXAFS model, the stoichiometry of TcSx is TC3S10, which is presumably the compound generally referred to as "Tc2S7". The TcSX initially present in the permeable samples was steadily oxidized over 4 years. In the second series of samples, called "impermeable samples", the TcO4- was not initially completely reduced, and the groutsamples were sealed in cuvettes made of poly-(methyl methacrylate), which has a small O2 diffusion coefficient. In the impermeable samples, the remaining TcO4- continued to be reduced, presumably by blast furnace slag in the grout, as the samples aged. When the impermeable samples were opened and exposed to atmosphere, the lower-valent technetium species were rapidly oxidized to TcO4-.

Nitrates↗
PubMed2001

Pre-operative sestamibi-technetium subtraction scintigraphy in primary hyperparathyroidism: experience with 156 consecutive patients.

AIM: The aim of this study was to assess the usefulness of pre-operative sestamibi-technetium subtraction scintigraphy in a large cohort of patients with primary hyperparathyroidism (HPT). MATERIALS AND METHODS: A group of 156 consecutive patients with biochemically proven HPT underwent sestamibi-technetium subtraction scintigraphy before cervical exploration. Images were interpreted and reported prospectively and influenced the extent of surgical exploration. The intraoperative findings were compared retrospectively with the pre-operative scintigram reports in 154 individuals with technically satisfactory scintigrams. RESULTS: Of the 154 patients with satisfactory scintigrams, 122 (78.2%) demonstrated a single focus of activity following subtraction, 31 (19.9%) had negative findings and the remaining scintigram showed four foci of activity. At operation 138 (89.6%) solitary adenomas were removed, 13 patients (8.4%) had multi-gland disease and in three individuals (2.0%) no abnormal parathyroid tissue was found. The pre-operative scintigram accurately localized 91 of 98 (92.9%) solitary tumours weighing > 500 mg but only 18 of 35 (51.4%) adenomas weighing < 500 mg, (P < 0.0001). Overall sensitivity of sestamibi-technetium scintigraphy for localizing single parathyroid adenomas was 83.7%. CONCLUSION: Sestamibi-technetium subtraction scintigraphy will accurately localize a high proportion of solitary parathyroid adenomas but its usefulness is diminished by its inability to consistently identify smaller tumours.

Adenoma↗
PubMed1981

Localisation of experimental staphylococcal abscesses by 99MTC-technetium-labelled liposomes.

The accumulation of 99mTc-technetium-labelled liposomes in abscesses was studied. Abscesses were produced in the thighs of albino rats by intramuscular injection of Staphylococcus aureus. After 4 days these abscesses were used to determine the localisation of 99mTc-technetium-labelled anionic, cationic and neutral liposomes in the abscess area. This was achieved by radionuclide images produced by a gamma camera and an associated data-processing system. There was a pronounced uptake of 99mTc-technetium-labelled anionic liposomes in the abscess area compared with the corresponding unaffected thigh. Similar uptake was not shown by the 99mTc-technetium-labelled cationic and neutral liposomes. Abscess uptake of anionic liposomes was maximal at or before 30 min after injection and was not enhanced by prior opsonisation with aggregated rat immunoglobulin.

Abscess↗
PubMed1993

Increased technetium uptake is not equivalent to muscle necrosis: scintigraphic, morphological and intramuscular pressure analyses of sore muscles after exercise.

A scintigraphic technique employing technetium pyrophosphate uptake was used to identify the area of skeletal muscle damage in the lower leg of four runners 24 h after an ultramarathon footrace (160 km). Most of the race had been run downhill which incorporated an extensive amount of eccentric work. Soreness was diffuse throughout the posterior region of the lower leg. In order to interpret what increased technetium uptake reflects and to express extreme endurance related damages, a biopsy was taken from the 3-D position of abnormal uptake. In addition, intramuscular pressures were determined in the deep posterior compartment. Scintigraphs revealed increased technetium pyrophosphate uptake in the medial portion of the gastrocnemius muscle. For 3698 fibres analysed, 33 fibres (1%) were necrotic, while a few other fibres were either atrophic or irregular shaped. A cluster of necrotic fibres occurred at the fascicular periphery for one subject and fibre type grouping occurred for another. Ultrastructural analysis revealed Z-line streaming near many capillaries and variously altered subsarcolemmal mitochondria including some with paracrystalline inclusions. The majority of the capillaries included thickened and irregular shaped endothelial cells. Intramuscular pressures of the deep posterior compartment were slightly elevated (12-15 mmHg) for three of the four subjects. Increased technetium uptake following extreme endurance running does not just reflect muscle necrosis but also subtle fibre abnormalities. Collectively, these pathological findings are attributed to relative ischaemia occurring during the race and during pre-race training, whereas, intramuscular pressure elevations associated with muscle soreness are attributed to mechanical stress caused by extensive eccentric work during the race.

Adult↗
PubMed1976

Objective measurement of rheumatoid arthritis using technetium index.

The technetium index was measured in 22 patients with rheumatoid arthritis, before and after 6 months' treatment either with penicillamine or with anti-inflammatory drugs. The index was calculated by dividing the sum of the count rates over both knees and both wrists by the dose of technetium given. In the penicillamine group there was a significant reduction in the technetium index and the changes correlated well with some clinical measurements of improvement. It is suggested that the technetium index is a useful objective measure of the effects of drugs with a specific activity in rheumatoid arthritis.

Anti-Inflammatory Agents↗
PubMed1994

Exercise technetium-99m sestamibi tomography for cardiac risk stratification of patients with stable chest pain.

BACKGROUND: This study was designed to evaluate the prognostic value of symptom-limited maximal exercise treadmill testing with tomographic technetium-99m sestamibi (MIBI) myocardial imaging in patients referred for evaluation of stable angina. Exercise stress thallium-201 myocardial imaging provides prognostic information in coronary artery disease subsets including patients with stable chest pain. The prognostic value of exercise technetium-99m MIBI myocardial tomography has not been established. METHODS AND RESULTS: Of 548 consecutive patients with stable angina pectoris who underwent maximal exercise treadmill stress testing in combination with a same-day "rest-stress" tomographic technetium-99m MIBI myocardial imaging protocol, 521 patients were followed for 13 +/- 5 months to determine the univariate and multivariate variables associated with cardiac events and to define their cardiac event-free survival. Ten patients were lost to follow-up (98% complete), and 17 who had coronary revascularization within 6 months of testing were excluded. Major cardiac events occurred in 24 patients (9%)--nonfatal myocardial infarction in 11 and cardiac death in 13. Univariate Cox survival analysis demonstrated significant relative risk (RR) and 95% confidence intervals (CI) for exercise ST segment depression (RR = 2.3; 95% CI, 1.0 to 5.3), an abnormal MIBI scan (RR = 13.8; 95% CI, 1.9 to 102.3), and a reversible MIBI perfusion defect (RR = 3.2; 95% CI, 1.4 to 7.5). Multivariate models demonstrated that both exercise MIBI perfusion abnormalities (RR = 11.9; 95% CI, 1.6 to 89.4) and reversible MIBI perfusion defects (RR = 2.9; 95% CI, 1.2 to 7.0) had independent predictive value. During 1 year of follow-up, cardiac events occurred in only 0.5% of patients with normal MIBI scans compared with 7% of those with abnormal MIBI scans (P < .001). One-year, cardiac event-free survival was 92% in patients with reversible MIBI perfusion defects (P < .01 versus normal), 96% in patients with fixed defects (P < .01), and 93% in patients with combined reversible and fixed MIBI myocardial perfusion abnormalities (P < .02). CONCLUSIONS: As with exercise thallium-201 myocardial imaging, exercise stress technetium-99m MIBI myocardial tomography provides significant independent information concerning the subsequent risk of serious cardiac events (death, myocardial infarction) in patients with stable angina pectoris. The identification of MIBI perfusion abnormalities, in particular, the presence of reversible MIBI defects, was associated with reduced 1-year, event-free survival. The recognized imaging and radiotracer biokinetic differences between thallium-201 and MIBI do not appear to modulate the prognostic value associated with scintigraphic evidence of ischemic myocardial jeopardy in the stable angina population.

Chest Pain↗
PubMed1981

Evaluation and testing of in vitro labeled technetium Tc-99m red blood cells in two animal models for neonatal RBC volume determinations.

The present study was designed to evaluate the red blood cell (RBC) radiolabeling technique utilizing the short half-lived radionuclide technetium-99m and to compare the results with the well-recognized standard chromium-51 method. The procedure was evaluated in a canine and a newborn lamb model utilizing dual radionuclide labeling and counting techniques. With the express purpose of providing a significant radiation dose reduction, the procedure presented was adapted for utilization in a neonatal patient population. Statistical analysis of the data revealed that there was no significant difference in the radiolabeling efficiency for the two methods (Cr-51, 86.6%; Tc-99m, 92.4%). Assessment of the in vitro stability for technetium-99m RBCs showed that less than a 4% loss of radiolabel from the RBC was seen in a 4-hr time span in the canine model (15 min, 90.5%; 2 hr, 88.9%; 4 hr, 86.6%) when compared to the 15 min equilibrium sample. Evaluation of newborn lamb RBC volumes showed that the technetium-99m RBC volume did not significantly differ from the chromium-51 labeling technique (Cr-51, 24.0 ml/kg; Tc-99m, 23.2 ml/kg). Summarization of the whole-body radiation dose showed that greater than a 30-fold reduction in absorbed dose was achieved in the newborn (Cr-51, 30.0 mrad; Tc-99m, 0.9 mrad). The modified procedure presented for the radiolabeling of the RBC with the short half-lived radionuclide technetium-99m provides a technique comparable to the utilized standard chromium-51 RBC method, yet with a large reduction in absorbed radiation dose. This procedure is presented as a superior technique for the determination of pediatric RBC volumes.

Animals↗
PubMed1984

Bronchoalveolar lavage and technetium-99m glucoheptonate imaging in chronic eosinophilic pneumonia.

A patient with chronic eosinophilic pneumonia was evaluated using bronchoalveolar lavage, technetium-99m glucoheptonate, and transbronchial lung biopsy. Bronchoalveolar lavage revealed 43 percent eosinophils and correlated well with results of transbronchial lung biopsy. Technetium-99m glucoheptonate lung imaging demonstrated intense parenchymal uptake. After eight weeks of corticosteroid therapy, the bronchoalveolar lavage eosinophil population and the technetium-99m glucoheptonate uptake had returned to normal. We suggest that bronchoalveolar lavage, with transbronchial lung biopsy, is a less invasive way than open lung biopsy to diagnose chronic eosinophilic pneumonia. The mechanism of uptake of technetium-99m glucoheptonate in this disorder remains to be defined.

Aged↗
PubMed2004

Artifactual reduction in bone density as a result of technetium-99m MDP for bone scanning: report of two cases.

We present two patients in whom marked changes in dual-energy X-ray absorptiometry (DXA)-measured bone mineral density were found to be the result of prior administration of technetium-99m methylene diphosphonate (MDP) for bone scanning. In patient 1, an artifactual 50% decrease in lumbar spine and 19% decrease in left total hip bone density over a 14-mo period was the result of technetium-99m injection 3 h before the second bone density measurement. In patient 2, a dramatic increase in bone density at 6 mo was the result of artifactual reduction in bone density on the baseline study as a result of technetium-99m injection 2 h earlier. Clinicians and technologists should be aware that technetium-99m used for bone scanning could cause artifactual reduction in DXA-measured bone mineral density.

Absorptiometry, Photon↗
PubMed1975

Technetium-99m polyphosphate bone image for early detection of skeletal metastasis. Correlation with other diagnostic parameters.

Technetium 99m-polyphosphate bone images are correlated with bone roentgenography, and serum calcium, phosphorus and alkaline phosphatase in 91 patients with suspected bone metastasis. Technetium polyphosphate bone images are the most sensitive and serum level of calcium and phosphorus are the least sensitive indicator of bone lesions. Bone roentgenography is not as sensitive as technetium polyphosphate images. Abnormal bone images with normal or abnormal bone roentenography associated with increased alkaline phosphatase in the absence of liver metastasis are highly suggestive of metastatic bone disease. Abnormal bone images adjoining the joints, associated with normal serum alkaline phosphatase and abnormal joint roentgenography suggest arthritis. It is recommended that technetium 99m-labelled phosphate bone images are considered to be the diagnostic procedure of choice to detect skeletal lesions. Polyphosphate bone images are highly sensitive, with the combination of elevated alkaline phosphatase they become relatively more specific for a metastatic bone disease.

Alkaline Phosphatase↗
PubMed1989

[Preoperative localization of parathyroid adenoma with technetium and thallium double-labeling scintigraphy. Difficulties related to associated thyroid lesions].

Technetium and thallium double-labeling scintigraphy with image subtraction was carried out on 63 patients suspected of having primary hyperparathyroidism, with or without thyroid involvement. Forty-four patients had a normal thyroid image with technetium. The positive foci located by double-labeling in patients who were to undergo surgery always coincided with parathyroid adenoma. In the 16 cases where the initial diagnosis of hyperparathyroidism was not substantiated, the double-labeling test was normal. Thus for these 44 patients, scintigraphy sensitivity was 75% and specificity was 100%. Nineteen patients had an abnormal thyroid image with technetium. In 7 cases, image subtraction following double-labeling yielded uninterpretable data. In 12 other patients, the positive foci located outside the thyroid by double-labeling coincided with a parathyroid adenoma, whereas this was true for only one patient whose positive foci were located inside the thyroid; a parathyroid adenoma was not detected preoperatively in 4 patients. This double-labeling test is thus useful in locating parathyroid adenomas when technetium scintigraphy of the thyroid is normal; when it is abnormal, double-labeling is advantageous only in cases of extra-thyroid foci.

Adenoma↗
PubMed1989

Diagnosis of diaphragmatic injury using intraperitoneal technetium.

The diagnosis of diaphragmatic injury following blunt or penetrating trauma is often made after appreciable delay. The purpose of the present study was to evaluate the use of intraperitoneal technetium in diagnosing diaphragmatic tears in dogs. Six dogs were divided into two groups. In Group 1, thoracotomy was performed bilaterally and 1 cm diaphragmatic tears were made. Peritoneal lavage with technetium-99 sulphur colloid was then performed after closure of the thoracotomy sites. In Group 2 animals, only lavage instillation of technetium was done. Scans were then performed and counts recorded over the chest and abdomen. A ratio of two body areas was then computed and compared between the two groups of animals. There was a statistically significant difference in the ratio between the two groups (P less than 0.05). We conclude that intraperitoneal technetium is a sensitive test for diagnosing diaphragmatic injuries.

Animals↗
PubMed1977

[Analysis of one thousand liver scans carried out using technetium phytate (author's transl)].

One thousand liver scans were carried out using technetium phytate. This soluble compound is transformed in the circulating blood into a colloid by chelation of serum calcium, thereby forming a macromolecular phytate of calcium and technetium. The presenting symptoms are compared with the isotopic findings. This microcolloid has the advantages common to all technetium tracers and, in addition, is easy to prepare and has the advantage of a distribution between the liver, spleen and bone of the same type as that seen with colloidal gold 198 without the dosimetric problems associated with the latter. Although it has a level of hepatic fixation which is less than that of certain sulphide complexes of technetium, the authors feel that it appears to provide a better relfection of the colloidopexic function of the liver.

Adult↗
PubMed1980

[The technetium-99-m-pyrophosphate scintigram in the assessment of the size of acute myocardial infarction: comparison with CK-(MB) curves mortality (author's transl)].

While the technetium-99m-pyrophosphate scintigram enables diagnostic proof of acute myocardial infarction, its use in the evaluation of the extent of infarction has not been clearly established. This study, in 30 patients with acute myocardial infarction was, thus, undertaken to assess the relationship between the findings of the technetium-99m-pyrophosphate scintigram, with respect to infarct area and uptake pattern, the infarct size, as determined from the total CK an CK-MB curves, and the mortality. The scintigraphically determined infarct areas ranged between 1.7 and 29.3 cm2; the 20.2 plus or minus 6.0 cm2 average for anterior wall infarction (n=18, range 7.4 to 29.3 cm2) was significantly greater (p smaller than 0.005) than the 8.3 plus or minus 5.3 cm2 average for inferior infarction (n=12, range 1.7 to 15.8 cm2). Correlation coefficients between the scintigraphically and enzymatically determined infarct sizes for the entire patient population ranged from 0.71 to 0.80. Anterior infarctions correlated more closely (0.66 to 0.84) than inferior infarctions (0.46 to 0.66). The technetium-99m-pyrophosphate uptake pattern was focal in 20 patients and ring-shaped (doughnut) in ten. Infarcts with focal uptake patterns were significantly smaller than those displaying a doughnut pattern (12.2 plus or minus 6.4 vs. 24 plus or minus 4.0 cm2, p smaller than 0.005). The infarct weight calculated from the CK-MC curve with application of individually determined disappearance rate for those infarcts displaying a focal uptake pattern was 34 plus or minus 29 grams while that associated with a doughnut uptake pattern was significantly greater at 86 plus or minus 25 grams (p smaller than 0.005). During the 18 -month observation period there were six deaths; the average scintigraphic infarct area of 22.8 plus or minus 3.6 cm2 in those who died was significantly greater (p smaller than 0.005) than that of the 13.8 plus or minus 8.2 cm2 of the survivors. Of the non-survivors, five had a doughnut uptake pattern and one displayed focal uptake. In the 24 survivors, a focal uptake pattern was found in 19 and a doughnut pattern in five. Conversely, 19 of the 20 patients with a focal uptake pattern survived while only five of the ten patients with a doughnut pattern were alive after 18 months. Thus, comparison with the enzymatically determined infarct weight as well as the mortality indicate that the technetium-99m-pyrophosphate scintigram yields clinically relevant data with regard to infarct size. Since no patient with an infarct area of less than 17 cm2 died within the 18-month observation period, designation of scintigraphically determined infarct size as small (smaller than 17 cm2) and large (larger than 17 cm2) was enabled. The corresponding cut-off point between large and small infarctions as determined enzymatically has been designated at 65 grams. Accordingly, agreement was found in 70% (14 of 20 patients) with scintigraphically small infarcts and in 80% (8 of 10 patients) with scintigraphically large infarcts...

Acute Disease↗
PubMed1982

Effects of concurrent drug therapy on technetium Tc-99m gluceptate biodistribution.

Drug interactions with technetium Tc-99m gluceptate resulting in altered biodistribution were studied using chart review and animal tests. Charts of nine patients who had abnormal gallbladder uptake of technetium Tc-99m gluceptate during a two-year period were reviewed to obtain data such as concurrent drug therapy, primary diagnosis, and laboratory values. Adult New Zealand white rabbits were then used for testing the biodistribution of technetium Tc-99m gluceptate when administered concurrently with possibly interacting drugs identified in the chart review--penicillamine, penicillin G potassium, penicillin V potassium, acetaminophen, and trimethoprim-sulfamethoxazole. Chart review revealed no conclusive patterns of altered biodistribution associated with other factors. The data did suggest the possibility that the five drugs listed above might cause increased hepatobiliary clearance of the radiopharmaceutical. Animal tests showed that i.v. penicillamine caused substantial distribution of radioactivity into the gallbladder and small bowel. Minimally increased gallbladder radioactivity occurred when oral acetaminophen and trimethoprim-sulfamethoxazole were administered concurrently. Oral and i.v. penicillins did not increase gallbladder activity. Penicillamine may cause substantial alteration of the biodistribution of technetium Tc-99m gluceptate.

Acetaminophen↗
PubMed1981

Preparation and characterization of two complexes of technetium with 2-mercaptocarboxylic acids.

We have synthesized the tetraphenylarsonium salts of oxotechnetium(V)bis-(2-mercaptopropionate) and oxotechnetium(V)bis-(2-mercaptohexadecanoate) containing macromolar quantities of the long-lived isotope technetium-99. The compounds were investigated by elemental analysis, paper electrophoresis, and infrared and ultraviolet-visual spectroscopy, proton nuclear magnetic resonance, and field-desorption mass spectrometry. The findings suggest that the technetium atom is coordinated by two sulfur and three oxygen atoms in a square pyramid, the two sulfur atoms and two of the oxygen atoms forming the base and the third oxygen atom the apex. The carboxyl oxygen coordinated to technetium will not be available for binding in vivo. This factor should be considered in the design of technetium 99m-labeled radiopharmaceuticals containing a mercapto group alpha to a carboxyl group.

Chemical Phenomena↗