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 775 records · Page 43Linked to original sources
PubMed1987

[Evaluation of coronary reperfusion for acute myocardial infarction by emission CT using technetium-99m pyrophosphate].

Twelve patients with acute transmural myocardial infarction (AMI) were treated with percutaneous transluminal coronary angioplasty (PTCA) following intracoronary thrombolysis using urokinase, and underwent technetium-99m stannous pyrophosphate (Tc-99m-PPi) imaging 9.2 +/- 2.1 hours after the onset of chest pain. The imaging was performed with emission computed tomography (ECT). Compared to planar imaging, this allowed more accurate detection of small myocardial infarcts and accurate measurements of infarcts irrespective of their location was also made. Early Tc-99m-PPi images were obtained to test the hypothesis that an early, abnormal Tc-99m-PPi image suggest successful reperfusion. The results were presented for two groups of patients: three with unsuccessful reperfusion (Group A) and nine with successful reperfusion (Group B). Eight of the nine patients with successful reperfusion had positive acute Tc-99m-PPi images. On the contrary, all the three patients for whom reperfusion failed had negative acute Tc-99m-PPi images. We also examined the feasibility of estimating infarct size using positive Tc-99m-PPi images in patients with successful reperfusion during the early phase of AMI. The Tc-99m-PPi uptake score (Tc-US) was used to measure infarct size in this study. Areas of increased Tc-99m-PPi uptake within myocardial infarcts were threshold at 60% of the peak activity. The Tc-US of each patient was obtained to sum the scores of all myocardial segments using a scoring system with a maximum score of 108. Using this method, Tc-US ranged from 2 to 39. The correlation of Tc-US with the peak serum creatine kinase level was significant (r = 0.91).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effects of altered physiologic states on clearance and biodistribution of technetium-99m MAG3, iodine-131 OIH, and iodine-125 iothalamate.

Technetium-99m mercaptoacetyltriglycine [( 99mTc]MAG3) is a new renal radiopharmaceutical with biologic properties similar to iodine-131 orthoiodohippuric acid [( 131I]OIH). MAG3 may be used as a replacement for [131I]OIH and/or [99mTc]DTPA. For this reason, we compared the effects of several potential adverse clinical conditions on the clearance and biodistribution of MAG3, OIH and a GFR marker. To simulate renal failure, five mice underwent bilateral renal pedical ligation. Twenty-four hours after surgery they were injected with MAG3 and OIH and killed 2 hr postinjection. Compared to sham operated controls, liver activity for MAG3 and OIH increased from 0.2% to 14.1% and 0.1% to 13.9%, respectively, while intestinal activity increased from 1.3% to 8.9% for MAG3 and 0.2% to 7.7% for OIH. Constant infusion studies were performed in rats to evaluate the effects of increased plasma organic acid levels, mannitol diuresis, dehydration, and acid/base imbalance on the clearance of OIH, MAG3, and [125I]iothalamate. No differences were noted between the OIH and MAG3 clearances following diuresis and dehydration and the differences involving acid/base imbalance were minimal. Dehydration depressed the clearance of [125I]iothalamate more than that of OIH or MAG3. Para-aminohippurate (PAH) infusion inhibited the clearance of MAG3 more than OIH supporting proximal tubular transport for MAG3; PAH had no effect on [125I]iothalamate. In summary HPLC purified MAG3 behaved similarly to OIH under adverse physiologic conditions and the data continue to support the use of MAG3 as a potential clinical substitute for OIH.

Acid-Base Imbalance↗
PubMed1985

Renal handling of technetium-99m DMSA in rats with proximal tubular dysfunction.

The renal handling of technetium-99m dimercaptosuccinic acid ([99mTc]DMSA) was studied in rats before and after treatment with Na-maleate (2 mmol/kg i.v.). In the control period, when measured 2 hr after the intravenous injection of [99mTc]DMSA, 39.9% of the injected dose was in the kidneys and 14.6% was in the bladder. After Na-maleate treatment, only 6.4% of the injected dose of [99mTc]DMSA was retained in the kidneys while 37.9% was found in the bladder. Subsequent studies revealed that Na-maleate produced a fall in the glomerular filtration rate, the effective renal plasma flow, and a generalized proximal tubular dysfunction. The latter was characterized by polyuria and an increased excretion of glucose, protein, albumin, calcium, and inorganic phosphate. It was concluded that proximal tubular dysfunction markedly alters the renal handling of [99mTc]DMSA. Whether this augmented urinary excretion is due to an inhibition of reabsorption or an enhanced cellular efflux of [99mTc]DMSA remains to be answered.

Animals↗
PubMed1986

Joint scintigraphy using technetium-99m pyrophosphate in experimental hemarthrosis.

To determine the validity of a method for induction of experimental hemarthrosis in dogs and for the nuclear imaging of hemarthrosis, serial technetium-99m pyrophosphate [( 99mTc]PYP) flow and blood-pool scans were performed monthly in eight dogs who received bi-weekly injections of autologous blood into their femoro-tibial joints (also called stifle joint). In four control dogs, one joint was injected with saline while the other joint received only a sham injection. In addition, two dogs received intra-articular injections of autologous blood into their right stifle joint and saline into their left stifle joint. These dogs were studied with 99mTcO4 joint scintigraphy at monthly intervals. The dogs were periodically taken out of the study and explored surgically. Pathologic examination of synovial tissue was performed. Serial radiographs were also obtained and correlated with the scan and surgical findings. There was a striking abnormal increase in blood-pool activity of [99mTc]PYP in the treated stifle joints, commencing at the first examination after 1 mo of blood injections and continuing for the length of the study. All radiographs showed only minimal joint space widening and some soft-tissue swelling. On pathologic examination, both grossly and microscopically, there was profuse pannus formation, with intense inflammatory infiltrate replacing much of the subsynovial fat. The scintigraphic findings correlated well with these pathologic findings. This study not only validates this method for simulating hemophilic hemarthrosis but also suggests that [99mTc]PYP joint scintigraphy is a simple, and noninvasive method for monitoring the early changes in hemophilic arthropathy and is superior to pertechnetate imaging for this disease process. Instead of the previously recommended delayed bone images, we recommend, in addition, flow studies to assess joint hypervascularity and immediate static images to visualize the synovium and joint capsule.

Animals↗
PubMed1987

Myocardial damage delineated by indium-111 antimyosin Fab and technetium-99m pyrophosphate.

Technetium-99m-labeled pyrophosphate and radiolabeled antimyosin antibodies are two infarct localizing agents with apparently different kinetics of localization. To determine whether these agents localize in a similar fashion in early acute myocardial necrosis, we studied the simultaneous distribution of 111In-labeled antimyosin and 99mTc-labeled pyrophosphate in dogs after intracoronary (i.c.) (n = 9) or intravenous (i.v.) (n = 9) administration of a mixture of these two agents in a reperfused infarct model. The mean infarct size (+/- s.d.) delineated by pyrophosphate [20.2 +/- 14.1 (i.v.), 29.8 +/- 12.3 (i.c.)] was larger than that by antimyosin [14.2 +/- 11.3 (i.v.) (p = 0.05), 20.0 +/- 11.8 (i.c.) (p = 0.05)] which was larger than that by triphenyl tetrazolium chloride [13.9 +/- 8.0 (i.v.) (p = 0.05), 15.3 +/- 6.5 (i.c.) (p = 0.05)]. This overestimation persisted whether the radiopharmaceuticals were administered by intracoronary or intravenous injections, although the latter with antimyosin was only slightly larger (TTC:AM = 13.9:14.2) (p = n.s.). There was a good correlation, however, between antimyosin and pyrophosphate delineated infarct sizes in dogs with intracoronary injection (y = 0.82x + 13.33, r = 0.79) or i.v. injection (y = 1.208x + 3.01, r = 0.97) of the mixture of the two agents. Since the images of the 111In and 99mTc activities were obtained consecutively by identical methods, the overestimation of infarct size by pyrophosphate cannot be due to differences in spatial resolution of the techniques used. The differences in the areas of myocardial damage delineated by pyrophosphate and antimyosin in our study most probably denote the area of viable but compromised myocardium.

Animals↗
PubMed1987

SPECT imaging of para-axial neurofibromatosis with technetium-99m DTPA.

Single photon emission computed tomography (SPECT) was used to study uptake of technetium-99m diethylenetriaminepentaacetic acid ([99mTc]DTPA) by para-axial neurofibromas in 13 patients. SPECT imaging led to better resolution of uptake in nine instances and detection of 12 lesions unsuspected on planar imaging (PI). Two false-positive instances and one false-negative instance of uptake are described. The planning of the surgical approach and placement of graft material for spinal fusion was assisted by SPECT in two patients. One patient with disability secondary to recurring abdominal pain had detection of the causative lesion by SPECT and subsequent relief of her symptoms following excision of the tumor. SPECT imaging of soft-tissue tumors of neurofibromatosis appears to have potential use in preplanning surgery on structural or cosmetic lesions, in the detection of occult lesions, and the monitoring of patients with neurofibromatosis at regular intervals.

Adolescent↗
PubMed1988

An evaluation of technetium-99m tin colloid--its value in the diagnosis of renal transplant rejection.

The value of the Technetium-99m tin colloid (TTC) scan in the diagnosis of renal transplant rejection occurring more than 1 month following transplantation was assessed. To our knowledge, use of this agent has not previously been reported. Gamma camera imaging was performed on 15 occasions in 14 patients in whom plasma creatinine was rising and in three patients in whom renal function was stable. Both a qualitative and a quantitative assessment of images was made. The radioactivity recorded over the graft at 12-16 min post injection was expressed as a percentage of that recorded at 0-4 min. In the nine patients in whom graft perfusion was adequate to allow interpretation of the TTC scan and in whom rejection was diagnosed by biopsy (six cases) or on clinical grounds (three cases), the index ranged from 45 to 153%. In two patients the graft was poorly perfused and the accumulation of TTC was predictably low despite the presence of rejection. In the seven patients with either a stable creatinine or with rising creatinine not due to rejection, the index ranged from 5 to 43%. Previously reported studies have shown that sulphur colloids may be of value in diagnosing graft rejection. This study suggests that Tc99m tin colloid may be regarded as a suitable alternative scanning agent and that some simplification of data collection and analysis can be achieved.

Colloids↗
PubMed1985

Electrophoretic analysis of different technetium-99m (SnCl2) methylene diphosphonate complexes.

Technetium-99m MDP was prepared from MDP kits from several different sources. The resulting [99mTc]MDP preparations were analyzed by electrophoresis. The results demonstrated the presence of at least four different 99mTc complexes in these preparations. Modified kit preparations were analyzed to show the effects of concentration and pH on formation of the impurities. The electrophoresis results were correlated with scintillation camera imaging studies in rabbits and suggest that hydrolysis of MDP to phosphate and methylphosphate results in formation of 99mTc complexes with poor biological behavior as bone scanning agents.

Animals↗
PubMed1988

Technetium-99m HM-PAO-SPECT study of regional cerebral perfusion in early Alzheimer's disease.

Regional cerebral perfusion was evaluated by single photon emission computed tomography (SPECT) using technetium-99m hexamethylpropyleneamine oxime ([99mTc]HM-PAO) in sixteen patients with Alzheimer's disease (AD) in early clinical phase and in 16 healthy elderly controls. In all patients transmission computed tomography (TCT) and/or magnetic resonance imaging (MRI) did not show focal brain abnormalities. Relative to normal subjects, AD patients showed significant reductions in cortical/cerebellar activity ratio: cortical perfusion was globally depressed with the largest reductions in frontal and posterior temporo-parietal cortices. Asymmetries of relative perfusion between cerebral hemispheres were also demonstrated when language was affected or visuospatial functions were unevenly impaired. In patients with early AD, SPECT provides functional information to be compared with clinical and psychometric data.

Aged↗
PubMed1988

[Study of myocardial perfusion at rest using technetium Tc 99m methoxy-isobutylisonitrile: comparison with labeled microspheres and thallium 201].

In order to evaluate the potential usefulness of 99m technetium (Tc)-methoxy-isobutyl-isonitrile (MIBI) as a myocardial perfusion tracer in man, its myocardial distribution at rest was compared with that of 201thallium (TI). Perfusion images obtained with 99mTc-labelled microspheres, whose myocardial distribution is exclusively coronary flow dependent, were used as reference. The study was performed on twelve patients (10 males and 2 females, mean age 55.4 +/- 6.4) with suspected effort angina and without a history of previous myocardial infarction. In the space of two weeks patients underwent rest and exercise 99mTc-MIBI myocardial scintigraphy, exercise-redistribution 201TI myocardial scintigraphy, 99mTc-labelled microsphere scintigraphy after microsphere injection in the left ventricle at rest during catheterization before performing left ventriculography and coronary angiography. The comparison with microsphere distribution was limited to rest 99mTc-MIBI scintigraphy and redistribution 201TI images. Single photon emission tomography (SPECT) was employed. SPECT was performed using a double-head Rotacamera with a 360 degrees rotation arc. Ninety projections of 20 seconds each were acquired; subsequently image reconstruction was performed using an iterative algorithm. To evaluate regional perfusion the left ventricular wall was divided into 18 segments; the uptake pattern of each segment was graduated according to a qualitative score (0: severe defect; 1: moderate defect; 2: normal uptake). The quality of tomographic myocardial 99mTc-MIBI and 99mTc-microspheres images was higher than that of 201TI tomograms in account of the different physical characteristics of the two radionuclides.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Renal arteriovenous transit times of technetium-radiolabeled chelates.

A noninvasive method was developed for quantitating the distribution of renal arteriovenous transit times of technetium-99m (99mTc) radiopharmaceuticals. Using this method, the characteristic transit times and amplitudes of the first two components of [99mTC] DTPA or MDP transit through the renal vasculature were calculated. The first component amplitude (A1) was evaluated for its ability to discriminate between 20 hypertensive patients with renovascular disease and 21 normotensive subjects. A1 was compared with three other quantitative indices: the ascending slope of the initial renal time-activity curve, the kidney-to-aorta slope ratio (K/A), and renal size. A1 nearly perfectly separated the hypertensive patients from the normotensive subjects; the ability of A1 to discriminate between these two groups is clearly superior to renal size, the initial renal slope, and K/A. We conclude that measurements of the intrarenal distribution of blood flow have distinct advantages over indices of renal blood flow that have been derived from scintillation camera measurements of 99mTc radiopharmaceuticals.

Humans↗
PubMed1987

Dissolution rate and transit times of technetium-99m DTPA-labeled tablets.

In this study we demonstrate that the dissolution rate and gastroduodeno-cecal transit time of radiolabeled tablets of theophylline can be determined in vivo using technetium-99m (99mTc). Six healthy male volunteers ingested a tablet containing 300 mg of theophylline mixed with 3.7 MBq of [99mTc]DTPA. Anterior and posterior scintigraphic views of the abdomen were collected serially over 8 hr, after which a 200-ml solution containing 37 MBq of [99mTc] pertechnetate was ingested in order to visualize the contours of the stomach. The in vivo activity contained in the tablet was calculated from the scintigraphic views after correction of background activity, radioactive decay, and depth attenuation. The dissolution rate of [99mTc] DTPA was also measured in vitro and compared with the dissolution rate of theophylline. The results showed close dissolution rates between [99mTc]DTPA and theophylline in vivo (T1/2 184 min and 176 min, respectively), and a faster early dissolution rate of [99mTc]DTPA in vitro (T1/2 92 min versus 156 min for theophylline). The mean gastroduodenal and duodenocecal times were 72 +/- 25 min (m +/- s.d.) and 245 +/- 15 min, respectively. Scintigraphic imaging of labeled formulations with 99mTc present useful applications in pharmaceutics and pharmacology.

Gastrointestinal Motility↗
PubMed1988

Hexakis (2-methoxy isobutylisonitrile) technetium-99m and thallium-201 chloride: uptake and release in cultured myocardial cells.

Hexakis (2-methoxy isobutylisonitrile) technetium-99m [(99mTc]MIBI), a new tracer of myocardial blood flow, was compared with 201TI CI in cultures of myocardial cells of newborn rats. The kinetics of uptake and release of both tracers were assessed in basal conditions and in the presence of 5 mM cyanide, an inhibitor of the respiratory chain, 0.1 mM iodoacetate, an inhibitor of glycolysis, 10 microM ouabain, an inhibitor of the Na-K ATPase, or with various pH values. The amplitude and frequency of contractions of the cells were also monitored in the same conditions. Results show that the washin and washout kinetics of [99mTc]MIBI are slower than 201TI(T1/2) of the washout curves were, respectively, of 28 min and 6 min). The kinetics of release of both tracers were not influenced by any of the inhibitors. There was a strong effect of the pH on the 201TI uptake only. Moreover 201TI uptake was decreased by 34% in the presence of cyanide plus iodoacetate. Otherwise the uptakes of 201TI and [99mTc]MIBI were not decreased by any of the drugs. The cellular contractility was significantly diminished by cyanide and it was abolished by cyanide plus iodoacetate. It is concluded that (a) impaired contractility can be associated with normal 201TI and [99mTc]MIBI kinetics in myocardial cells in culture, (b) that 201TI uptake may depend on the level of ATP devoted to the maintenance of membrane integrity, (c) that [99mTc]MIBI shows slower kinetics but is less sensitive to metabolic inhibitors than 201TI.

Animals↗
PubMed1988

Kinetic analysis of technetium-99m d,1-HM-PAO decomposition in aqueous media.

Technetium-99m-d,1-hexamethylpropyleneamine oxime [99mTc]d,1-HM-PAO) is a neutral-lipophilic chelate formed from a kit in high yield by stannous reduction of Na99mTcO4-. Of three methods used to analyze the purity of the 99mTc complexes, a single strip method using ether as the developing solvent was the most rapid and simple to perform. The lipophilic chelate converts to 99mTcO4- and other hydrophilic products with time and this limits the useful lifetime of the preparations. The rate of decomposition of [99mTc]d,1-HM-PAO increased in the presence of excess stannous ion and at pH greater than 9.

Chromatography, High Pressure Liquid↗
PubMed1987

Initial experience with technetium-99m HM-PAO brain SPECT.

Technetium-99m hexamethylpropyleneamineoxime ([99mTc]HM-PAO) brain single photon emission computed tomography (SPECT) was performed with a dual head rotating scintillation camera. Normal tracer distribution and side/side differences of counting rates were obtained in 11 healthy volunteers. Almost stable gray/white matter ratios were found (1.97-2.1) in one normal subject during 2 hr after tracer administration. Eighty-three investigated patients had the following diagnoses (in parentheses is percent of positive findings in each group): cerebral vascular disease 18 (94.4%), epilepsy 23 (82.6%), extrapyramidal disorders 8 (100%), dementia 12 (100%), headache 11 (63.6%), psychiatric disorders 11 (27.3%). In addition, SPECT was performed in 28 male volunteers during motor or visual imagery tasks and a significant increase (p = 0.035) of relative tracer deposition was observed in the left inferior occipital region during visual imagery when compared with motor imagery. The results indicate that [99mTc]HM-PAO SPECT is valuable for demonstrating pathologic and physiologic changes of the brain.

Adult↗
PubMed1987

Evaluation of the renal clearance of technetium-99m PAHIDA in dogs.

The renal clearance of the technetium-99m complex of para[(biscarboxylmethyl)-aminomethylcarboxyamino]hippuric acid ([99mTc]PAHIDA), has been previously studied in rodents and falls between that of [99mTc]DTPA (diethylenetriaminepentaacetic acid) and iodine-131 (131I) orthoiodohippuran (OIH). To investigate the effect of species variation, the plasma clearance of [99mTc]PAHIDA was investigated in dogs. The plasma disappearance of the renal agent approached that of [99mTc]DTPA and was significantly less than that of OIH. Despite the structural similarities of the PAHIDA ligand and aminohippurate, the [99mTc]PAHIDA complex undergoes little, if any, tubular secretion in the canine kidney.

Aminohippuric Acids↗
PubMed1986

Lung ventilation studies with technetium-99m Pseudogas.

Technetium-99m Pseudogas is an ultrafine near monodisperse aerosol of 0.12-microgram diam particle size. This report describes initial clinical experiences with 27 patients referred for investigation of suspected pulmonary embolism, and in whom Pseudogas ventilation images were compared with a high quality commercial aerosol. An additional group of ten patients with severe COPD was examined in a comparative trial of Pseudogas with 81mKr. Pseudogas was better than a conventional aerosol in reaching a diagnosis of pulmonary embolism using a simple blinded comparison with coded images. In addition, bronchial deposition was minimal unless COPD was severe. Moderately well patients had no difficulty inhaling the necessary activity in one or two breaths, and even severely ill and frail aged persons could accomplish the passive breathing maneuver in less than a minute. Clearance of Pseudogas was directly to the systemic circulation with a half-time of 10 min in normal subjects extending up to 100 min in patients with airways disease.

Adolescent↗