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PubMed1992

[The adenosine test in association with 99m-technetium sestamibi tomoscintigraphy in the diagnosis of coronary pathology].

BACKGROUND: The exogenous adenosine is able to provoke a coronary vasodilation, which is the same as the one provoked by the papaverine and greater than the one provoked by the dipyridamole. We report our experience in using exogenous adenosine in association with technetium-99m-sestamibi tomoscintigraphy for a diagnostic test on the coronary artery disease (CAD). METHODS: We considered 22 patients (18 male and 4 female, mean age 57 years) affected by angiographically demonstrated coronary artery disease (stenoses > or = 50%). Adenosine was infused at a dosage of 0.070 mg/kg/min for 3 minutes and, if well tolerated, the dosage was increased to 0.140 mg/kg/min; in the third minute of the major dosage the radioisotope was injected. The myocardial perfusion imaging at rest was evaluated on the following day. RESULTS: The test was completed on 21 of the 22 patients, and 20 of the latter were subjected to the maximal dosage of the adenosine infusion. Clinically irrelevant adverse effects were observed in 20 cases; only one patient developed a II degree type 1 AV block. Angina occurred in 19 patients. Coronary angiography demonstrated significant stenosis of 35 vessels: the left anterior descending (LAD) in 14 patients, the left circumflex (LCx) in 8 and the right coronary artery (RCA) in 13. In detecting CAD, the test in our study demonstrated a sensitivity of 85% in the LAD disease, of 89% in the LCx disease and of 77% in RCA disease. CONCLUSIONS: The adenosine infusion associated with technetium-99m-sestamibi tomoscintigraphy demonstrated an elevated incidence of adverse effects which are of short duration and clinically irrelevant. The method was shown to be highly sensitive in detecting the CAD.

Adenosine↗
PubMed1992

Technetium-99m-diphosphonate, gallium-67 and labeled leukocyte scanning techniques in tibial nonunion.

On the technetium-99m bone scan the vast majority of nonunion cases show an intense tracer uptake at the fracture site, as do fractures undergoing normal healing. Therefore static bone scintigraphy usually does not contribute to the diagnosis of nonunion. One of the main causes of delayed fracture healing is infection. Increased blood flow and blood pool as demonstrated during the first and second phases of a 3-phase bone scan are consistent with an inflammatory reaction but are not pathognomonic for infection. A gallium-67 scan is indicative of infection if Ga-67 uptake exceeds Tc-99m uptake on the bone scan. The most specific tracers for infection however are leukocytes labeled with indium-111 or technetium-99m.

Citrates↗
PubMed2003

[Preparation of liposome-mediated 99m-technetium-labeled antisense oligonucleotides of c-myc mRNA].

To explore the preparation method of liposome-mediated 99m-technetium-labeled antisense oligonucleotides of c-myc mRNA and lay foundations for antisense imaging and treatment, antisense oligonucleotides (DNA) with 15 bases and di-functional chelate, hydrazino nicotinamide derivatives, were synthesized. After DNA combined with chelate, they were labeled with 99m-technetium to form compounds, 99mTc-chelate-DNA (99mTc-DNA), and were purified through Sep-Pak reverse column(C18, Waters) by using methanol and water as eluent. The leaching curve was made; the labeling efficiency was calculated. The products were then encapsulated with cation liposome to form liposome-mediated 99mTc-DNA. The radiochemical purity and stability of the liposome-mediated 99mTc-DNA were tested through strip chromatography. The labeling efficiency was 63.37% +/- 3.51% at the radioactive concentration of 1480 MBq, 62.52% +/- 3.69% at that of 740 MBq, 59.82% +/- 5.12% at that of 592 MBq. There were no significant differences between these labeling efficiencies. The radiochemical purity was 96.47% +/- 3.01%. The liposome-mediated radiolabeled antisense oligonucleotides were stable after incubation with water or serum. Therefore liposome-mediated radiolabeled antisense oligonucleotides could be obtained through hydrazino nicotinamide derivatives as di-functional chelate and liposome as vector.

DNA, Antisense↗
PubMed2004

The value and throughput of rest Thallium-201/stress Technetium -99m sestamibi dual-isotope myocardial SPECT.

Myocardial perfusion scintigraphy is an established method in cardiology for the diagnosis and evaluation of coronary artery disease (CAD). Thallium-201 and Tc-99m sestamibi myocardial perfusion imaging has been widely accepted as non-invasive diagnostic procedure for detection of CAD, risk stratification and myocardial viability assessment. But, standard Tl-201 redistribution and same day or 2-day rest/stress Tc-99m sestamibi protocols are time-consuming. Hence, the dual isotope rest thallium-201/stress technetium-99m sestamibi gated single-photon emission tomography protocol has gained increasing popularity for these applications. Combining the use of thallium-201 with technetium-99m agents permits optimal image resolution and simultaneous assessment of viability. Dual-isotope imaging may be separate or simultaneous acquisition set-up. The more rapid completion of these studies is appreciated as an advantage by patients, technologists, interpreting and referring physicians, nurses and hospital management. Simultaneous imaging has the potential advantages of precise pixel registration and artifacts, if present, are identical in both thallium and sestamibi, and require only one set of imaging. Also, there are some disadvantages of spillover of activity from the Tc-99m to the Tl-201 window. Fortunately, despite this problem it can be overcome. Separate acquisition dual isotope also has some disadvantages. Difference in defect resolution in attenuation and scatter between T-201 and Tc-99m sestamibi potentially results in interpretation problems. But, studies about cost-effectiveness of dual isotope imaging showed that some selective elimination of the rest studies may decrease the cost of the nuclear procedures and should be considered in the current care health system.

Coronary Artery Disease↗
PubMed2006

Tissue-targeting lead generation and optimization from random and directed screening of technetium-99m labeled tripeptide complex libraries in vivo.

BACKGROUND: Screening libraries against a molecular target in vitro are idealized models that cannot reflect the real state in vivo where biomolecules coexist and interact. C-terminal amide tripeptides labelled with Technetium-99m can provide a unique noninvasive approach to trace a large number of compounds in vivo. METHODS: The C-terminal amide tripeptide libraries were synthesized on Rink Amide-MBHA resin using iterative and pooling protocol. Technetium (V) oxo core [TcO(3+)] was bound to each tripeptide via 4 deprotonated nitrogen atoms to form a library of 8000 (99m)Tc tripeptoid complexes. The radiocombinatorial screening (RCS) in vivo was carried out on SD rats and A549 tumour bearing mice. RESULTS: Signals of tissue distribution and metabolism of libraries were recorded by counting or imaging and tissue targeting leads identified by both random and directed RCS. Among them, (99m)Tc RPA, (99m)Tc VIG and (99m)Tc RES had specific tissue targeting in kidney, liver and tumour respectively. The percent injected dose per gram tissue of (99m)Tc labelled leads in their target tissue was highly structure dependent. Because the nontarget tissue binding and the metabolism of (99m)Tc tripeptoid sublibraries were simultaneously monitored successfully by RCS, the interference of background activity was limited to the lowest level. Optimization of renal function agent from the labelled libraries was carried out by directed screening. (99m)Tc DSG was finally identified the most promising agent for renal function studies. CONCLUSIONS: RCS in vivo is a powerful tool for the discovery of tissue targeting drugs. The potential screening bias is probably the major limitation of labelled libraries.

Animals↗
PubMed1991

Technetium-labelled autologous lymphocytes: clinical protocol for radiolabelling using a high concentration and low volume of 99Tcm-exametazime.

Little clinical work has been performed using technetium-labelled lymphocytes due to the difficulty of effecting an imaging dose of technetium on the small number of lymphocytes available. We have successfully labelled lymphocytes using a high concentration and low volume of 99Tcm-exametazime. In eight readings from three patients and two volunteers, the labelling efficiency was 27% (4 S.D.). The radiolabel was stable in plasma in vitro up to 4 h. Viability of the lymphocytes as determined by trypan blue exclusion was greater than 95%.

Blood Specimen Collection↗
PubMed1991

Use of technetium-99m-MAG3 for renal scintigraphy after angiotensin-converting enzyme inhibition.

Technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) was tested in 82 hypertensive patients submitted to renal scintigraphy 1 hr after oral premedication with 50 mg of Captopril. Baseline studies were obtained only for those patients showing abnormal findings in the provocative study. All patients underwent renal arteriography. Sensitivity and specificity for the detection of renal artery stenosis (RAS) greater than 50% were 89% and 91%, respectively. After Captopril administration, tracer parenchymal transit time increased significantly in ischemic kidneys (334 +/- 93 sec in baseline conditions versus 468 +/- 96 sec after Captopril, p less than 0.001) but not in kidneys with no RAS or RAS less than 50% (243 +/- 46 sec versus 271 +/- 95 sec, p = ns). False-positive responses were mostly bilateral and associated with a marked decrease in blood pressure. Technetium-99m-MAG3 is an effective compound for detecting RAS greater than or equal to 50% with Captopril renal scintigraphy. Performing the provocative test as a first step considerably reduced the number of scintigraphic studies required.

Administration, Oral↗
PubMed1991

[Technetium-99m-pyrophosphate myocardial scintigraphy in polymyositis--a case report].

A patient with polymyositis who had cardiac involvement underwent myocardial scan with technetium-99m-pyrophosphate. We used Activity Index for evaluating myocardial uptake of technetium-99m-pyrophosphate, which correlated with the degree of serum creatine phosphokinase elevation. Our findings indicate that these examinations may be helpful for identifying patients who have cardiac involvement and evaluating their response to the treatment with corticosteroids or immunosuppressants.

Cardiomyopathies↗
PubMed1991

Technetium-99m nanocolloid scintigraphy in rheumatic inflammation in children.

Technetium-99m HSA (human serum albumin) is a nanometer-sized albumin-based inert colloid, which has a specific ability to accumulate in inflamed soft tissue lesions. With a particle size smaller than 30 nm, Tc-99m HSA spills into the extravascular space in the sites of inflammation because of the changed capillary permeability. The conventional tracer in joint scintigraphy, technetium-99m methylene diphosphonate (Tc-99m-MDP) is a boneseeking compound, which strongly accumulates in the epiphyseal area of growing bones. This makes the estimation of the inflammatory process in the joints of growing children difficult. The nanocolloid compound has not this disturbing tendency. This fact makes the joint scans more specific and the detection of inflammatory lesions is easier especially in children. In our study Tc-99m HSA is used for the detection of rheumatic inflammation in children with juvenile rheumatoid arthritis. We examined 24 children with juvenile rheumatoid arthritis, age 3-19 years, 20 girls and 4 boys, who all had clinically active inflammation in the joints or in the tendon sheets. The uptake pattern of nanocolloid parallels the severity of the inflammatory process in periarticular tissues and tendon sheets. In suspicious cases, the comparison with the contralateral area helps in the detection of the lesion. Therefore, when investigating paired joints, the scintigraphy of symmetrical parts is necessary.

Adolescent↗
PubMed1991

The chemical identity of pentavalent technetium-99m-dimercaptosuccinic acid.

The tumor-targeting radiopharmaceutical known as pentavalent technetium-99m-meso dimercaptosuccinic acid (DMSA) has been studied by a variety of techniques in order to elucidate its structure and chemical behavior. The radiopharmaceutical is identical with a chemically characterized sample of [99TcO(DMSA)2]- when studied by mobility methods including thin-layer chromatography, reversed-phase high-performance liquid chromatography, gel filtration, and electrophoresis. The technetium is pentavalent and coordinated by an oxo-ligand and four thiolate sulfurs of two DMSA ligands. No-carrier-added preparations consist of mixtures of three stereoisomers of the square pyramidal, mononuclear complex. The isomers arise from differing orientations of the carboxylate groups in the DMSA ligands and may be designated syn-endo, syn-exo, and anti. All three isomers are significant components of the radiopharmaceutical, raising the question of which are tumor-specific. The carboxylate groups in the complex are almost completely ionized at pH 7, thus the average charge on the complex at this pH approaches -5.

Chromatography, High Pressure Liquid↗
PubMed1991

Use of technetium-labeled red blood cell scintigraphy in the detection and management of gastrointestinal hemorrhage.

The effectiveness of technetium 99m-labeled red blood cell scintigraphy in localizing hemorrhage, directing surgical intervention, and screening patients for arteriography was determined in 103 patients. The radionuclide scan result was compared to the bleeding site determined by arteriography, endoscopy, or surgery. Eighty-five patients had a bleeding site identified; 18 patients did not and were excluded. Thirty-one scans were performed in 29 patients for upper gastrointestinal hemorrhage. Five positive scans incorrectly localized an upper gastrointestinal bleeding site, although two scans localized the site, for a scan sensitivity of 8%. Fifty-nine scans were performed in 56 patients with lower gastrointestinal bleeding. Fifteen scans were positive, three incorrectly localizing the hemorrhage. Seventy-four percent of the patients with lower gastrointestinal hemorrhage documented by arteriography, endoscopy, or surgery had negative scans for bleeding. The radionuclide scan sensitivity for lower gastrointestinal bleeding was 23%. Surgery was required in 18 patients for bleeding, 11 of whom had negative scans for bleeding. In seven surgical patients with positive scans, in no instance did the scan direct the surgical intervention. Eighteen patients underwent scintigraphy and arteriography; nearly one half of the patients with negative scans for bleeding had positive localizing arteriograms, although almost one half of the patients with positive scans for bleeding had negative arteriograms. Scintigraphy failed to localize hemorrhage in 85% of the patients. Technetium 99m-labeled red blood cell scintigraphy did not direct surgical intervention, nor did it adequately screen patients for arteriography.

Adult↗
PubMed1977

Pancreatic scanning using retrograde injection of technetium-99m-labeled compounds.

With increased clinical availability of endoscopic retrograde pancreatography, a method for retrograde injection of radionuclides into the pancreas became available. A dog model was developed to evaluate resolution and toxicity of retrograde imaging prior to human use. Two groups of technetium-99m-labeled compounds were used. The first included ionic carriers--pertechnetate and pyrophosphate--and the second included particulate carriers--sulfur colloid and albumin microspheres. Parenchymal visualization, absorption patterns, and toxicity in dogs were studied. The results suggest that pyrophosphate, sulfur colloid, and albumin microspheres would all be feasible technetium carriers for use in humans.

Animals↗
PubMed1990

Staging non-small cell carcinoma of the lung using technetium-99m-labeled monoclonal antibodies.

A technetium-labeled monoclonal antibody was administered to 52 patients with non-small cell lung carcinoma, either to stage the mediastinum preoperatively or to detect distant metastases. Results from planar and tomographic imaging are compared to CT and histologic confirmation. Differences in detection rates and predictive values between imaging modalities are discussed. The authors conclude that imaging with a technetium-labeled monoclonal antibody is safe and accurate and may be useful for staging patients with either operable or inoperable non-small cell lung cancer.

Adult↗
PubMed1991

Combined technetium radioisotope penile plethysmography and xenon washout: a technique for evaluating corpora cavernosal inflow and outflow during early tumescence.

Combined technetium radioisotope penile plethysmography and xenon washout is a new technique that measures both corporal arterial inflow and venous sinusoidal outflow during early tumescence in patients with erectile dysfunction. Fourteen patients were studied using 99mTc-RBCs to measure inflow and 133Xe or 127Xe in saline to measure outflow. Tumescence was induced by injecting papaverine intracorporally. Peak corporal rates corrected for outflow (r = 0.88) and uncorrected for outflow (r = 0.91) and change in volume over 2 min centered around peak flow [corrected] (r = 0.96) all correlated with angiography. Outflow measurements did not correlate with intracorporal resistance. Thus, outflow rates alone could not be used to predict venous sinusoidal competence. Normal inflow rate is greater than 20 ml/min; probable normal 12-20; indeterminate inflow 7-12; and abnormal inflow less than 7 ml/min. Technetium-99m radioisotope penile plethysmography and xenon washout can be performed together and both provide a method for simultaneously evaluating the relationship between corporal inflow and outflow rates in patients with erectile dysfunction.

Adult↗
PubMed1977

[Incorporation of radioactive calcium and technetium pyrophosphate in to bones].

A method is given for simultaneous in vivo measurement of mineral and collagen metabolism of the bone. Accretion rates of 47-calcium as a chlorid into the bone are representative for bone mineralisation and of 99m-technetium labelled pyrophosphate for collagen metabolism. Compartmental models used for analysis are presented. Bone accretion rates are given in mg, or mMol respectively per unit time for the skeleton, by computation of the specific activity of 47-calcium and 99m-Technetium pyrophosphate and rational bone accretion as registered by total body profile scanning technique. The results obtained in five normal volunteers are presented.

Apatites↗
PubMed1990

Myocardial redistribution of technetium-99m-methoxyisobutyl isonitrile (SESTAMIBI).

To determine whether technetium-99m-hexakis-2-methoxyisobutyl isonitrile (SESTAMIBI) remains fixed in the myocardium following its initial uptake or undergoes time-related redistribution, anesthetized dogs underwent occlusion of the anterior descending coronary artery for 6 min, followed by 3-hr reperfusion. Technetium-99m-SESTAMIBI and thallium-201 (201Tl) were injected intravenously after 1 min occlusion and regional myocardial blood flow was measured with radioactive microspheres. Tomographic imaging of Tc-SESTAMIBI revealed a perfusion defect with slight but definite filling in over 2 hr. Quantitative analysis indicated a significant rise in the nadir and decrease in the width of the defect in circumferential profile curves. After 3-hr of reperfusion, Tc-SESTAMIBI activity in the previously ischemic area was always greater than the activity of microspheres injected during coronary occlusion (mean normalized values, 0.32 versus 0.11, p less than 0.0001). Our results indicate that following transient ischemia and reperfusion, Tc-SESTAMIBI clearly undergoes myocardial redistribution, although more slowly and less completely than 201Tl.

Animals↗
PubMed1990

SPECT imaging of pediatric brain tumor with hexakis (methoxyisobutylisonitrile) technetium (I).

Technetium-99m-Hexamibi [Hexakis (methoxyisobutylisonitrile) technetium (i)] was developed as a myocardial perfusion agent with biologic properties similar to those of thallium-201 (201TI). As 201TI has recently been observed to be of value for the diagnosis of brain tumors when used in conjunction with single-photon emission computed tomography (SPECT) imaging technology, the possibility that the biologic similarity of the two radiopharmaceuticals extended to their affinity for tumors was tested. A 5-yr-old female patient with a brain stem astrocytoma showed marked focal uptake of 99mTc-Hexamibi at the site of tumor recurrence as defined by biopsy and prior 201TI/SPECT study. Tumor-to-normal cortex radioactivity ratios for the 99mTc-Hexamibi/SPECT study were 132:1 and the spatial resolution of the 99mTc-Hexamibi images was high. This observation suggests that 99mTc-Hexamibi merits further study as a potential agent for SPECT imaging of human brain tumors.

Astrocytoma↗
PubMed1979

Radiation decomposition of technetium-99m radiopharmaceuticals.

Technetium-99m radiopharmaceuticals are shown to be subject to autoradiation-induced decomposition, which results in increasing abundance of pertechnetate in the preparation. This autodecomposition is catalyzed by the presence of oxygen, although the removal of oxygen does not prevent its occurrence. The initial appearance of pretechnetate in the radiopharmaceutical is shown to be a function of the amount of radioactivity, the quantity of stannous ion used, and the ratio of Tc-99m to total technetium in the preparation.

Diphosphates↗