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PubMed1982

Iminodiacetate complexes of technetium: an electrochemical study.

Iminodiacetate complexes of technetium are used extensively in diagnostic medical imaging, but their chemical structure and properties are yet uncertain. We studied formation of technetium-99 complexes with diethylenetetraminepentaacetate (DPTA), ethylenediaminetetraacetate (EDTA), N-(2-acetamido)iminodiacetate (ADA), and N-(2,6-dimethylphenylcarbomoylmethyl)iminodiacetate (HIDA) by tast (sampled DC) polarography, reverse-pulse polarography, controlled-potential coulometry, and amperometric titration. The products, often mixtures, varied with reaction conditions and ligand; this can explain apparent contradictions in previous studies.

Edetic Acid↗
PubMed1983

Sensitivity of technetium-99m-pyrophosphate scintigraphy in diagnosing cardiac amyloidosis.

To determine the value of technetium-99m-pyrophosphate myocardial scintigraphy in the diagnosis of amyloid heart disease this procedure was prospectively performed in 20 consecutive patients with biopsy-proven primary amyloidosis. Eleven patients had echocardiographic abnormalities compatible with amyloid cardiomyopathy, 9 of whom had congestive heart failure. Diffuse myocardial pyrophosphate uptake was of equal or greater intensity than that of the ribs in 9 of the 11 patients with echocardiograms suggestive of amyloidosis, but in only 2 of the 9 with normal echocardiograms, despite abnormal electrocardiograms (p less than 0.01). Increased wall thickness measured by M-mode echocardiography correlated with myocardial pyrophosphate uptake (r = 0.68, p less than 0.01). None of 10 control patients with nonamyloid, nonischemic heart disease had a strongly positive myocardial pyrophosphate uptake. Thus, myocardial technetium-99m-pyrophosphate scanning is a sensitive and specific test for the diagnosis of cardiac amyloidosis in patients with congestive heart failure of obscure origin. It does not appear to be of value for the early detection of cardiac involvement in patients with known primary amyloidosis without echocardiographic abnormalities.

Aged↗
PubMed1991

Comparison of indium-111 antimyosin antibody and technetium-99m pyrophosphate localization in reperfused and nonreperfused myocardial infarction.

Recent imaging studies suggest that technetium-99m (Tc-99m) pyrophosphate yields a considerably larger estimate of myocardial infarct size than does indium-111 (In-111) monoclonal antimyosin antibody. To determine whether Tc-99m pyrophosphate may be taken up by reversibly injured myocytes, particularly in the setting of coronary reperfusion, the tissue localization of Tc-99m pyrophosphate and antimyosin antibody was compared in 11 dogs 24 to 68 h after anterior descending coronary artery occlusion (4 dogs with permanent occlusion, 7 with reperfusion). Technetium-99m pyrophosphate and In-111 antimyosin antibody content was determined in serial 2 to 3 mm wide endocardial and epicardial samples taken through the infarct zone in multiple short-axis left ventricular slices. The number of samples with increased In-111 antimyosin antibody (defined as greater than or equal to mean + 2 SD of normal) was not significantly different from that with increased Tc-99m pyrophosphate. This was true in both reperfused and nonreperfused infarcts. However, the intensity of uptake of Tc-99m pyrophosphate exceeded that of In-111 antimyosin antibody, particularly in the border zones of reperfused infarcts, and the area with moderate to marked increase in tracer uptake (greater than or equal to 2 times normal) was significantly larger with Tc-99m pyrophosphate than In-111 antimyosin antibody (p less than 0.001). A specific zone of abnormal Tc-99m pyrophosphate with normal In-111 antimyosin antibody content could not be identified. Histologic evidence of myocardial necrosis was found in virtually every sample with increased In-111 antimyosin antibody, Tc-99m pyrophosphate, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Right ventricular myocardial infarction diagnosed by 99 m technetium pyrophosphate scintigraphy: clinical course and follow-up.

Out of 178 consecutive patients with acute inferior wall myocardial infarction submitted to technetium-99 m pyrophosphate scintigraphy, 49 (27.5%) were found to have concomitant right ventricular infarction. Gated blood pool scans showed right ventricular abnormalities in 21 out of 26 patients who were submitted to this investigation (right ventricular asynergy: 16 cases; right ventricular dilatation: eight cases; decreased right ventricular ejection fraction: 16 cases). Complications were common in the acute stage. Shock was noted in 19 cases (eight related to bradycardia, three related to relative hypovolaemia and eight instances of true cardiogenic shock). Atrial fibrillation (seven patients), ventricular fibrillation (eight patients) and severe atrioventricular conduction disorders (13 patients) were also frequent. In spite of this, the in-hospital mortality was low: three deaths occurred (6.1%), one from heart failure, two others from posterior septal rupture. All patients were followed up for one year or more. Six additional deaths were noted (three from left cardiac failure, two from recurrent anterior wall infarction and one from massive pulmonary embolism). Clinical assessment, haemodynamic measurements and gated blood pool scans showed significant improvement of right ventricular function with return to normal in those cases with small right ventricular infarcts as judged from technetium-99 m pyrophosphate scintigraphy. In spite of the complications seen in the initial period, patients with a right ventricular infarction have a good overall prognosis and the long-term outcome, primarily determined by the left-sided lesions, is often favourable.

Adult↗
PubMed1984

Emission computed tomography with technetium-99m pyrophosphate for delineating location and size of acute myocardial infarction in man.

Emission computed tomography with technetium-99m pyrophosphate was used to delineate the location and estimate the size of myocardial infarcts in 20 patients with documented acute myocardial infarction. Tomography was performed after planar imaging within 2-5 days after the onset of infarction. A series of transaxial, frontal, and sagittal tomograms were reconstructed from 32 views imaged from the left side of the patient's chest with a rotating gammacamera. Infarct volume was measured from the tomographic images by computerised planimetry and was compared with the cumulative release of creatine kinase MB isoenzyme. The planar images showed discrete myocardial uptake in 13 of the 20 patients and diffuse uptake throughout the cardiac region in the remaining seven. In contrast, the tomographic images clearly delineated discrete myocardial uptake by avoiding confusion of myocardial activity with that of surrounding structures, particularly bones, in all patients. For the 10 patients whose infarct size was assessed by analysis of the creatine kinase MB curve there was a close correlation between infarct volume estimated by tomography and by cumulative creatine kinase MB release. Thus emission computed tomography can provide a three dimensional map of technetium-99m pyrophosphate distribution within the heart and is thus able accurately to localise and estimate the size of myocardial infarcts in man.

Adult↗
PubMed1980

Evaluation of focal defects on technetium-99m sulfur colloid scans with new hepatobiliary agents.

In 3,600 patients evaluated with technetium-99m sulfur colloid for metastatic liver disease, 40 had equivocal scans due to a solitary defect in the interior margin of the right lobe. In these patients, the authors differentiated the gallbladder fossa from a metastatic focus using one of two new hepatobiliary agents: technetium-99m labeled pyridoxylideneglutamate and paraisopropylacetanilido iminodiacetic acid. In 31 patients, the focal defect filled with radioactive bile, showing that the solitary defect in the radiocolloid scan was a prominent gallbladder fossa. On laparoscopic biopsy, eight of nine patients whose focal defects were not due to the gallbladder were found to have metastatic disease. The ninth patient had carcinoma of the gallbladder. The need for laparoscopic biopsy was obviated in a majority (78%) of the patients by identifying the gallbladder fossa.

Adult↗
PubMed2001

Intrathoracic splenosis: superiority of technetium Tc 99m heat-damaged RBC imaging.

Intrathoracic splenosis is a rare diagnosis that is usually made following an invasive procedure. Although radiographic and CT findings are nonspecific, these findings combined with a history of splenic injury should suggest the possibility of this diagnosis. We present a patient with intrathoracic splenosis diagnosed on the basis of a technetium Tc 99m heat-damaged RBC scan following false-negative technetium Tc 99m sulfur colloid scan results.

Diaphragm↗
PubMedDate not supplied

A new method of functional scintiphotosplenoportography using technetium-99m-DTPA-galactosylated human serum albumin.

BACKGROUND/AIMS: We investigated whether a new method for scintiphotosplenoportography using technetium-99m-DTPA-galactosylated human serum albumin could visualize the portal venous system and simultaneously assess hepatic function. METHODOLOGY: Thirty-two patients underwent scintiphotosplenoportography, including 4 with metastatic tumor in an otherwise normal liver, 5 with chronic hepatitis, 9 with cirrhosis, and 14 with both hepatocellular carcinoma and cirrhosis. The tracer (3 mg, 185 MBq) was injected into the spleen under ultrasonic guidance. Hepatic function was evaluated using the receptor index and the index of blood clearance, both calculated by regions of interest for liver and for heart. Spleen-to-liver times were calculated by subtracting peak activity times over the spleen from those over the portal vein. RESULTS: Correlations of blood clearance and receptor indices with plasma retention rate of indocyanine green at 15 min (respectively, r = 0.616, P < 0.0005 and r = -0.669, P < 0.0001), prothrombin time (r = -0.605, P < 0.0005 and r = 0.710, P < 0.0001), the hepaplastin test (r = -0.526, P < 0.005 and r = 0.605, P < 0.0005), serum albumin (r = -0.488, P < 0.005 and r = 0.640, P < 0.0001), and serum cholinesterase (r = -0.600, P < 0.0005 and r = 0.671, P < 0.0001) were significant. Blood clearance and receptor indices also were significantly related to clinical stage, underlying liver disease, features of radioisotopic images, and presence of esophagogastric varices (P < 0.01). Additionally spleen-to-liver time reflected progressive hepatic damage. CONCLUSIONS: Our new method of scintiphotosplenoportography using technetium-99m-DTPA-galactosylated human serum albumin can assess hepatic function and portal hemodynamics simultaneously. Results correlate with accepted, conventional diagnostic techniques. This method represents a potent new method for evaluating the hepatic system.

Adult↗
PubMed1989

Technetium-99m HM-PAO-labeled leukocytes in detection of inflammatory lesions: comparison with gallium-67 citrate.

Forty-three patients with suspected benign, inflammatory, or infectious diseases were imaged with [99mTc]HM-PAO-labeled leukocytes and [67Ga]citrate. Technetium-99m leukocytes showed 22 true-positive, no false-positive, 19 true-negative, and two false-negative findings and [67Ga]citrate 23, 7, 12 and 1, respectively. The sensitivity, specificity, and accuracy values with 99mTc leukocytes were 92%, 100%, and 95%, and with [67Ga]citrate 96%, 63%, and 81%. Technetium-99m leukocyte scintigraphy has a promising future in comparison with [67Ga]citrate because of the ready availability of [99mTc]HM-PAO, the good image quality, more rapid results (within few hours), and the lower radiation exposure to the patient with 99mTc leukocytes. The usefulness of 99mTc leukocytes in chronic osteomyelitis needs further evaluation.

Abdomen↗
PubMed1988

Demonstration of reperfusion after thrombolysis with technetium-99m isonitrile myocardial imaging.

Technetium-99m isonitrile myocardial perfusion imaging was employed in a patient undergoing thrombolytic therapy with recombinant tissue plasminogen activator for acute anteroseptal myocardial infarction. Technetium-99m isonitrile does not demonstrate significant myocardial redistribution after intravenous injection. The imaging agent was administered in the emergency room, prior to the initiation of thrombolytic therapy. The initial area at risk for infarction was visualized on images obtained after the patient had been effectively treated. Imaging performed 5 days later, after repeat injection of [99mTc]isonitrile, showed a smaller myocardial perfusion defect indicating salvage of myocardium. Thus, this technique offers promise as a noninvasive means of assessing the area at risk, the success of reperfusion, and the presence of salvaged myocardium, early in the course of acute myocardial infarction.

Fibrinolytic Agents↗
PubMed1988

Quantitation of renal function with technetium-99m MAG3.

The technetium-labeled hippuran analog [99mTc]MAG3 was compared with [131I]hippuran in 50 patients using a quantitative renal function protocol that includes: (a) estimation of effective renal plasma flow by a single-injection, single-sample plasma clearance method, (b) determination of relative function of right and left kidney from the initial count rate over each kidney, and (c) comparison of recovered urine activity with plasma disappearance. This protocol is suitable for routine clinical use, and, in fact, has been used heavily at our clinic for a number of years. By slight modification of the formulas, the results obtained with [99mTc]MAG3 agreed well with those using [131I]hippuran. We conclude that [99mTc]MAG3 can be substituted for [131I]hippuran in the quantitative protocol, with the better image quality and lower radiation dose (in abnormals) of a technetium-labeled agent.

Humans↗
PubMed1985

[Study of space-occupying lesions in the liver using technetium-99m tin colloid and indium-113m chloride].

Liver scanning with radiocolloids is an important method to determine the presence, the position and the size of space-occupying lesions in the liver. Unfortunately, this information is nonspecific and it is not possible to distinguish between tumours, abscesses or cysts. Thirty-six patients in whom a definite diagnosis of hepatoma, amoebic liver abscess or echinococcus cyst had been made were examined with technetium-99m tin colloid and indium-113m chloride. The amoebic liver abscesses were avascular, showed a hyperaemic area surrounding the abscess and appeared smaller on the indium than on the technetium scan. The hepatomas showed greater vascularity and absence of the hyperaemic area. Cysts were avascular, did not show a hyperaemic rim and the size was equal on both scans. The experience of the observers had an influence on the accuracy of interpretation of the scans; experienced observers made a correct diagnosis in 73% of cases. It is suggested that simultaneous 99mTc tin colloid and 113mIn-chloride scans provide additional specificity in the differential diagnosis between hepatoma, amoebic liver abscess and echinococcus cysts.

Adult↗
PubMed1985

Mechanism of renal concentration of technetium-99m glucoheptonate.

Seventy female Sprague-Dawley rats were studied to determine the mechanism of tubular localization and the effects of commonly encountered changes in hydration and acid-base balance on renal uptake and urinary excretion of technetium-99m glucoheptonate ([99mTc]GHA). The in-vivo protein binding and protein-free plasma clearance of [99mTc]GHA also were quantitated. Twenty additional rats were studied to determine the effects of PAH competition and probenecid blockade on renal uptake of [99mTc]dimercaptosuccinic acid (DMSA) in comparison with their effects on [99mTc]GHA localization. Kidney uptake of [99mTc]GHA averaged 11.17 +/- 0.49 (s.e.)% of the injected dose in control animals. This varied slightly among groups but was significantly reduced by probenecid blockade and para-aminohippuric acid (PAH) competition to 4.08 +/- 0.55 (p less than 0.005) and 2.39 +/- 0.14 (p less than 0.005), respectively. Technetium-99m DMSA was not affected in its renal accumulation by these maneuvers. The total plasma clearance of [99mTc]GHA was lower than iodine-125(125I)iothalamate but the clearance of the protein free supernate was higher, raising a possibility of some tubular secretion. Acidification of the urine which has been shown to reduce [99mTc]DMSA uptake appeared to have no effect on [99mTc]GHA. Hepatic uptake was minimal in all groups averaging less than 1% injected dose. These data demonstrate that renal accumulation of [99mTc]GHA is blocked by probenecid and PAH suggesting that it is actively concentrated in the proximal tubule by enzyme systems similar to those involved in PAH and hippuran transport. It appears that [99mTc]GHA uptake measures a different aspect of kidney function than [99mTc]DMSA.

Acid-Base Imbalance↗
PubMed1987

Utility of technetium Tc 99m pyrophosphate bone scanning in cardiac amyloidosis.

Thirty-four patients with amyloidosis proved by biopsy specimen were studied using technetium Tc 99m pyrophosphate scintigraphy to assess its utility in the diagnosis of amyloid heart involvement. Of 14 patients studied retrospectively, only three had intense uptake judged to be diagnostic of cardiac amyloidosis. In a prospective analysis of 20 patients with amyloidosis, all of whom had evidence of cardiac involvement by two-dimensional echocardiography, 17 had abnormal scans. Fourteen of the 17 scans had only 1+ or 2+ uptake, a finding that also was present in 15 of the 20 control patients (without amyloid heart disease). Only three of the 20 patients with cardiac amyloidosis had intense uptake that was considered unequivocal and diagnostic of amyloidosis. Of the five patients with biopsy specimen proof of endomyocardial amyloidosis, only one had intense uptake and one had no uptake. When intense uptake of technetium Tc 99m pyrophosphate is found in the heart of a patient, amyloidosis is highly likely. The technique, however, is not sufficiently sensitive to warrant routine screening of patients with amyloidosis or cardiomyopathies. Cross-sectional echocardiography is superior to pyrophosphate scintigraphy for recognition of cardiac amyloidosis.

Aged↗
PubMed1988

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

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

Animals↗
PubMed1987

Leukocyte labeling with technetium-99m tin colloids.

Triple density gradients of metrizamide in plasma (MP) were used to characterize label distribution in human leukocyte preparations incubated with 99mTc tin colloids. Less than 50% of the cell-associated radioactivity was specifically bound to leukocytes when heparinized blood was rotated with stannous fluoride colloid ([Tc]SFC). Labeling efficiency in leukocyte rich plasma (LRP) averaged 44%, of which greater than 90% was specifically bound to leukocytes. MP-gradient analysis also revealed that leukocyte labeling did not occur with stannous chloride colloid, nor when citrate was present during rotation with [Tc]SFC. When citrate was added after labeling to "solubilize" unbound [Tc]SFC, radiocolloid was removed from the leukocytes, indicating that the mechanism of [Tc]SFC labeling is adherence rather than phagocytosis. Technetium-labeled neutrophils exhibited normal in vitro chemotaxis and no lung uptake in vivo. Technetium-labeled mononuclear leukocytes, on the other hand, exhibited prolonged lung transit in vivo. Neither [Tc]SFC cell preparation showed signs of in vivo reoxidation to pertechnetate.

Humans↗
PubMed1987

Technetium-99m radiopharmaceutical preparation by surface adsorbed stannous ions.

A method of producing technetium-99m (99mTc) radiopharmaceuticals is described, where reduction of pertechnetate occurs through stannous ions adsorbed on the surface of an infusion catheter. This leads to radiopharmaceuticals containing microgram quantities of stannous ions and that, therefore, results in minimal blood-pool labeling and essentially the elimination of tin colloids. Other advantages of the method include a reduction in quantities of ligand required and the possibility to mass produce the "tinned" catheters as technetium "reduction" kits. A wide variety of 99mTc radiopharmaceuticals have been prepared in high yield. Excellent biodistribution in several of these is demonstrated.

Adsorption↗
PubMed1980

Scintigraphic evaluation of primary bone tumors. Comparison of technetium-99m phosphonate and gallium citrate imaging.

A prospective investigation of two different radionuclide imaging techniques for the skeleton--technetium-99m phosphonate and gallium-67 citrate--was carried out prior to biopsy in fifty-five patients with primary bone tumors of the extremities and limb girdles. The study showed that the technetium-99m phosphonate scans were not useful in separating benign from malignant lesions or in defining reliably the local extent of malignant tumors. Gallium scans were more accurate in delineating the local extent of malignant tumors and may provide better indentification of benign tumors.

Bone Neoplasms↗