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At least 19 recordsLinked to original sources
PubMed1998

The influence of generator eluate on the radiochemical purity of 99Tcm-sestamibi prepared using fractionated Cardiolite kits.

The reconstitution of fractionated Cardiolite kits with sodium 99Tcm-pertechnetate eluted from a wet-column 99Mo/99Tcm generator results in a preparation that contains elevated amounts of a polar radiochemical impurity, which is normally present in only trace amounts when such kits are reconstituted with eluate from a dry-column generator. A consequence of this impurity, which appears to be an organotechnetium compound, is that it causes a positive bias in several quality control methods for 99Tcm-sestamibi, including that recommended by the manufacturer. This impurity was isolated, and its biodistribution determined in Wistar rats. Two alternative methods for the preparation of 99Tcm-sestamibi from fractionated Cardiolite kits using eluate from a wet-column generator were investigated. A rapid procedure, based on a C18 solid phase extraction (SPE) cartridge, for measuring the radiochemical purity of 99Tcm-sestamibi samples, which had been prepared using fractionated Cardiolite kits, was developed and compared with two other methods including high-performance liquid chromatography (HPLC). Over a radiochemical purity range of 49-98%, the values obtained using our quality control method deviated from those obtained using HPLC by 1.1 +/- 1.3% (n = 26). In contrast to some of the rapid quality control methods assessed in our investigation, the SPE technique was not biased by the presence of the organotechnetium impurity.

Animals↗
PubMed2001

Comparing 18-fluoro-2-deoxyglucose positron emission tomography with a combination of technetium 99m tetrofosmin single photon emission computed tomography and computed tomography to detect recurrent or persistent nasopharyngeal carcinomas after radiotherapy.

BACKGROUND: The diagnostic accuracy of combined computed tomography (CT) and technetium 99m tetrofosmin (Tc-TF) single photon emission computed tomography (SPECT) of head and neck to differentiate recurrent or residual nasopharyngeal carcinomas (NPCs) from benign lesions after radiotherapy was evaluated and compared with positron emission tomography (PET) with 18-fluoro-2-deoxyglucose (FDG). METHODS: Four months after radiotherapy, 36 patients with NPC underwent Tc-TF SPECT and CT of head and neck to differentiate recurrent or residual NPC from benign lesions. Histopathologic examinations were performed on nasopharyngeal biopsies of all 36 patients. RESULTS: Based on the biopsy results, the sensitivity, specificity, and accuracy of Tc-TF SPECT were 64%, 96%, and 86%, respectively, for differentiation of recurrent or persistent NPC from benign lesions. For CT and FDG-PET, the sensitivity, specificity, and accuracy were 73%, 88%, and 83% and 100%, 96%, 97%, respectively. For the 27 patients with NPC whose Tc-TF SPECT and CT results were congruent, the combination of Tc-TF SPECT and CT had the same sensitivity, specificity, and accuracy (100%, 96%, and 96%) as FDG-PET. For the nine patients with NPC with incongruent Tc-TF SPECT and CT results, FDG-PET correctly differentiated two benign lesions from seven recurrent/residual NPCs. CONCLUSIONS: Although, FDG-PET is the best tool for detecting recurrent or residual NPC, combined congruent Tc-TF SPECT and CT results achieved the same accuracy as FDG-PET. Therefore, we concluded that FDG-PET could be considered only when Tc-TF SPECT and CT give incongruent results.

Adolescent↗
PubMed2001

New and efficient routes to biomolecules substituted with cyclopentadienyltricarbonylrhenium and -technetium derivatives.

The small, compact, robust, and nonpolar units of [CpM(CO)3] (M = Re, Tc) coupled with biomolecules may be considered as bioorganometallic entities of potential interest in the field of medicinal chemistry. However, the short half-life of useful radionuclides (186Re t1/2 = 3.7 d, 188Re t1/2 = 16.8 h, 99mTc t1/2 = 6 h), the risks inherent in their use, and their cost have led chemists to search for novel synthetic strategies that allow the rapid introduction of the [CpM(CO)3] moiety as a late step in the course of synthesizing the target molecule. The present paper describes different strategies recently reported in the literature to tackle this problem.

Breast Neoplasms↗
PubMed1996

Neutrophil trafficking into inflamed joints in patients with rheumatoid arthritis, and the effects of methylprednisolone.

OBJECTIVE: To investigate the trafficking of circulating blood neutrophils and synovial fluid neutrophils in rheumatoid arthritis (RA) patients and the influence of a 1,000-mg intravenous pulse of methylprednisolone succinate (MP). METHODS: Neutrophils were isolated from the circulation and from the knee synovial compartments of subjects with RA. Circulating neutrophils were labeled with technetium-99 hexametazime (99mTc-HMPAO) and reinjected intravenously. Synovial fluid neutrophils were labeled from indium-111 oxine and reinjected into the knee from which they were isolated. Gamma camera images were obtained at intervals up to 24 hours post MP. Each patient had a baseline study (no MP) and a study in which MP was administered either 4 hours before (2 patients), 10 minutes before (1 patient), or 30 minutes to 1.5 hours after (6 patients) injection of the radiolabeled neutrophils. Subsequent analysis allowed quantitation of the neutrophil uptake into and clearance from the knee as a function of time. RESULTS: Nine patients who had not received glucocorticoids in the previous 3 months were studied. MP significantly decreased neutrophil ingress in 13 of the 16 knees studied (almost total inhibition in 5 knees), and this occurred within 1.5 hours of MP administration in all except 1 knee. At 24 hours after MP administration, there was a significant increase in visual analog scale (VAS) scores for well-being and significant decreases in scores on the modified Health Assessment Questionnaire (P<0.05), tender joints (P<0.005), VAS for pain (p<0.005), and generalized stiffness (P<0.005), as well as a decrease in the C-reactive protein level (P<0.05). MP had no effect on neutrophil egress (2 patients). Two additional patients who were receiving oral glucocorticoids were studied. One of them was clinically unresponsive to oral prednisolone, and MP had no effect on neutrophil ingress. The other patient showed no neutrophil ingress during the baseline study. This was confirmed by the presence of a noninflammatory synovial fluid at arthrocentesis. CONCLUSION: Neutrophil ingress into and egress from inflamed joints can be accurately monitored using radiolabeled neutrophils and quantitative gamma camera imaging. MP rapidly and substantially decreases neutrophil ingress into inflamed joints. In contrast, MP has no effect on neutrophil egress from the joint.

Aged↗
PubMed1998

Are technetium-99m-labeled myocardial perfusion agents adequate for detection of myocardial viability?

The noninvasive assessment of myocardial viability in patients with coronary artery disease and depressed left ventricular function has proven clinically useful for identifying those patients with ischemic cardiomyopathy who benefit most from coronary revascularization. Thallium-201 (201Tl) imaging at rest has been the radionuclide imaging technique most often utilized for distinguishing viable myocardium from scar. However, new technetium-99m (99mTc) perfusion agents such as 99mTc-sestamibi and 99mTc-tetrofosmin have emerged as alternatives to 201Tl for imaging of regional myocardial perfusion. Whether these new agents, which have better physical properties for imaging with a gamma camera than 201Tl, are valid for use in assessing myocardial viability is still uncertain. Recent clinical studies have demonstrated that these agents, when imaged using quantitative SPECT, can identify patients with myocardial hibernation who exhibit improved regional systolic function following revascularization. Experimental laboratory studies have shown that the uptake of 99mTc-sestamibi and 99mTc-tetrofosmin in ischemic myocardium is only slightly lower than the uptake of 201Tl. These 99mTc-labeled agents remain bound intracellularly in mitochondria of viable myocytes under conditions of myocardial stunning and short-term hibernation, producing severe myocardial asynergy. With respect to determination of viability, the inferior wall region is at times problematic since attenuation of 99mTc-sestamibi and 99mTc-tetrofosmin is greatest in this area. Demonstration of preserved systolic thickening on ECG-gated SPECT images is indicative of viability in the instance of decreased regional 99mTc counts due to attenuation and not scar. Administration of nitrates prior to tracer injection improves the sensitivity for identifying viable myocardial segments using rest imaging with 99mTc-sestamibi or 99mTc-tetrofosmin. Thus, it appears that the new 99mTc perfusion imaging agents can be successfully employed for the determination of myocardial viability in the setting of severe regional dysfunction and chronic coronary artery disease. The greater the myocardial uptake of these agents in the resting state, the greater the probability of improved systolic function after coronary revascularization.

Animals↗
PubMed2002

99mTC-tetrofosmin scintigraphy in lung carcinoma staging and follow-up evaluations.

BACKGROUND: 99mTC-tetrofosmin recently has emerged as a new radiopharmaceutical for cancer visualization. In this study, the authors have investigated, for the first time in a comprehensive way, its ability to assess lung carcinoma dissemination and progression. METHODS: A 99mTC-tetrofosmin scan was incorporated into the pretreatment and posttreatment diagnostic workup of all lung carcinoma patients seen in a second referral institution for a province of 500,000 inhabitants during the years 1998 and 1999. Sixty-one patients, strongly suspected of lung carcinoma were photon-scanned; 21 of them were rescanned after completion of their front-line treatment. Eleven patients eventually underwent surgery, and 3 others underwent mediastinoscopy. Both planar and single photoemission computed tomography thoracic views were obtained. Images for the whole body also were acquired. RESULTS: All 57 patients whose lung carcinoma was pathologically confirmed showed accumulation of the radiotracer (100% sensitivity). However, three of the four nonmalignant lesions were also 99mTC-tetrofosmin positive. 99mTC-tetrofosmin scan was highly sensitive for the detection of the T0-T2 disease (97% sensitivity) and highly specific for the N0-N1 disease (83% specificity). In the 16 pathologically staged mediastina, sensitivity, specificity, and accuracy rates were 73%, 100%, and 81%, respectively. 99mTC-tetrofosmin scan correctly detected most skeleton (9 of 10) and brain (5 of 7) metastases. The treatment response evaluation made with 99mTC-tetrofosmin corresponded to the clinical estimate in almost half of the sample. CONCLUSIONS: This study shows that 99mTC-tetrofosmin scan is a relatively accurate method for lung carcinoma evaluation. The authors' preliminary data exclude, however, that noninvasive diagnostic efficiency might be substantially increased by a scintigraphy with 99mTC-tetrofosmin. More studies are needed for a better understanding of the real value of this technique.

Adult↗
PubMed1989

Technetium-99m-iminodiacetic acid organic anions: review of biokinetics and clinical application in hepatology.

Technetium-99m-labeled iminodiacetic acid analogs are a new class of organic anions, taken up and secreted by hepatocyte into hepatic bile by a carrier-mediated organic anion pathway. They provide a new dimension in the assessment of pathophysiology and morphology of the hepatobiliary system. The amount of uptake and the rapidity of its elimination from the liver is dependent upon the structural configuration of the agent as well as the functional integrity of the hepatocyte and the patency of the biliary system. The clinical areas for application are wide and include most of the hepatobiliary diseases. Technetium-99m-iminodiacetic acid, an agent well suited for both planar and single photon tomographic scintigraphy, is ideal for early diagnosis prior to anatomical changes in the hepatobiliary system. The data collection directly from the liver provides quantitation of both regional and global liver diseases. The count-based method for measuring gallbladder emptying overcomes the theoretical disadvantages of geometric tests. Biokinetics and current clinical application of six of the 99mTc-iminodiacetic acid agents are reviewed, and the potential future clinical and research areas of application are indicated.

Anions↗
PubMedDate not supplied

Gd-EOB-DTPA enhancement pattern of hepatocellular carcinomas in rats: comparison with Tc-99m-IDA uptake.

The enhancement pattern of chemically induced hepatocellular carcinomas (HCCs) after intravenous administration of the hepatobiliary magnetic resonance (MR) contrast agent gadolinium-EOB-DTPA (ethoxybenzyl-diethylenetriaminepentaacetic acid) was compared with the uptake pattern of technetium-99m-labeled iminodiacetic acid (IDA), a hepatobiliary radioactive tracer. The hepatocyte uptake of both the contrast agent and the scintigraphic agent has been shown to be driven by the organic anion transporter. The tumors enhanced less than the liver after Gd-EOB-DTPA administration, whereas the Tc-99m-IDA uptake of differentiated HCCs exceeded that of the liver at 30 minutes and 3 hours after administration. The enhancement pattern of a differentiated HCC with Gd-EOB-DTPA does not mirror that seen with Tc-99m-IDA.

Animals↗
PubMed1992

Physiological modeling of disposition of potential tumor-imaging radiopharmaceuticals in tumor-bearing mice.

Radiopharmaceuticals have great potential in the early detection of human tumors. Three potential 99mTc-labeled platinum compounds based on cisplatin have been synthesized and tested in tumored mice. This report presents the analysis of the disposition data obtained after a single intravenous injection with an empirical, physiologically based pharmacokinetic model. The radioactivity of each radiopharmaceutical after administration was measured in blood, urine, and 15 tissues, including tumor. Parameters included in the model were tissue volumes (experimentally determined), tissue blood flows (determined from literature values), tissue:blood extraction ratios (determined by nonlinear least-squares regression with MULTI-FORTE), and clearance terms (also determined by nonlinear least-squares regression). Data were weighted by the reciprocal of the square of the observed values. Good fits to the experimental data were obtained. As expected, the compound producing the best tumor:blood profile (3) also had the highest tumor extraction ratio (6.2 versus 2.0 and 1.3 for 1 and 2, respectively). Total body clearance values for the radioactivity associated with the three compounds 1-3 were calculated to be 0.09, 0.04, and 0.016 mL/min, respectively. Analysis of data with such an empirical, physiologically based model may assist future development of suitable tumor-imaging agents.

Animals↗
PubMed1999

Axillary metastases of an occult primary carcinoma of the breast-discovered only by 99mTc-tetrofosmin scintigraphy.

Recent reports consider 99mTc-tetrofosmin scintigraphy to be a powerful new diagnostic tool for discriminating malignant from benign breast disease. We report on a woman suffering from histologically confirmed axillary metastases of a primary unknown, occult carcinoma, whose origin was suspected within the breast. All the diagnostic procedures performed to discover any lesion failed or were inconclusive. The primary cancer was clearly visualized, however, in the right breast by means of 99mTc-tetrofosmin scintigraphy. Conclusion. We suggest that 99mTc-tetrofosmin scintigraphy is a powerful method to detect breast cancer, especially when other diagnostic imaging procedures are inconclusive.

Axilla↗
PubMed1999

99m-Tc-tetrofosmin scintigraphy and breast cancer.

BACKGROUND: 99m-Tc-tetrofosmin holds significant interest among medical oncologists because of its high positive predictive value (>90%) in pilot trials, exceeding sensitivity and specificity rates of mammography. Objective. Our objective was to assess the diagnostic accuracy of 99m-Tc-tetrofosmin whole-body scintigraphy in outpatients. PATIENTS AND METHODS: Thirty-one patients with an abnormal mammograph (n = 22) or follow-up patients (n = 9), 7 of whom were known to have metastatic disease, were included. Tracer (550 MBq) was injected into the cubital vein. Whole-body planar and single photon emission computed tomography images of regions of interest were obtained. Histology, computed tomography (CT), or magnetic resonance imaging (MRI) were performed to confirm scintigraphic results. Correlation between scintigraphy and CT or MRI was assessed by two independent radiologists. Accuracy, sensitivity, and specificity rates for the diagnosis of local and distant breast cancer lesions were given. RESULTS: Of the 22 first-visit patients, 15 had breast cancer, and 7 had no evidence of any malignant disease. Of all patients examined (n = 31), 21 had distant metastases. Breast tumors were correctly diagnosed in 14/15 patients (93%), with only 1 false-negative result. Extrahepatic metastatic lesions (n = 16) were correctly diagnosed in 14 (88%) patients, whereas the method was not suitable for the diagnosis of liver metastases. CONCLUSION: Tetrofosmin scintigraphy has shown very high detection rates of breast tumors and of metastatic lesions and is therefore a valuable option in breast cancer diagnosis.

Adult↗
PubMed1993

Comparison of simultaneous 99mTc-HMPAO and 111In oxine labelled white cell scans in the assessment of inflammatory bowel disease.

Forty-seven patients, 29 with chronic inflammatory bowel disease (IBD) and 18 with presumed irritable bowel syndrome, including one with uncomplicated diverticular disease, were studied with simultaneous technetium-99m hexamethylpropylene amine oxime and indium-111 oxine labelled leucocyte scans performed at 1, 3 and 24 h. Twenty-seven patients with IBD had active disease as judged by clinical and laboratory criteria and all of these had positive scans with both agents. No false positive studies were obtained. The 1-h 99mTc-HMPAO WBC scans showed the same distribution to disease as the 3-h 111-In WBC scans, with no difference in intensity (P < 0.92); they showed more extensive disease (P < 0.02) and more intense uptake (P < 0.001) than did the 1-h 111-In scans. The 3-h 99mTc-HMPAO WBC scans showed more extensive disease (P < 0.002), with greater intensity (P < 0.0005), than did the 3-h 111In WBC scans. Physiological bowel activity on 3-h 99mTc-HMPAO WBC scans was present in 12 patients but was faint and did not interfere with assessment of disease extent and activity. It is concluded that in terms of isotope availability, radiation dosimetry and image quality, 99mTc-HMPAO is the agent of choice in detecting active IBD, with localization of disease possible at 1-h after re-injection and optimal resolution and definition of disease extent at 3 h. A negative scan reliably excludes active disease.

Adult↗
PubMed1986

The scintigraphic evaluation of myocardial infarction and regional ventricular performance using technetium-99m hexakis (t-butylisonitrile) technetium (I) (TBI): a new myocardial imaging agent.

Technetium-99m hexakis (t-butylisonitrile) technetium (I) (99mTc-TBI) is a new myocardial perfusion imaging agent. To determine its potential in the evaluation of myocardial infarction, 15 patients with suspected or confirmed acute infarction were studied by bedside imaging in the coronary care unit. Good-quality planar scintigrams in multiple projections were obtained in 13 patients. Gated perfusion studies were performed in 14 patients, and for comparison 13 of these were restudied 24-72 h later by standard gated equilibrium blood pool radionuclide ventriculography. Conventional and planar scintigraphic criteria for myocardial infarction (acute or old) agreed in 12 (92%) patients (k = 0.81, p less than 0.05). All the infarctions detected by scintigraphy were associated with electrocardiographic Q-waves. Localization of infarction by the electrocardiogram and scintigraphy exhibited moderate agreement (k = 0.49, p less than 0.1). Regional wall motion analysis by standard radionuclide ventriculography and gated 99mTc-TBI scintigraphy were in complete agreement for 25 (64%) of 39 left ventricular segments (k = 0.35, p less than 0.05). However, in 7 other segments, associated with areas of infarction, regional wall motion abnormalities were noted only on gated 99mTc-TBI scintigraphy. Therefore, 99mTc-TBI scintigraphy can readily provide data on regional myocardial perfusion and wall motion, permitting detection and localization of areas of myocardial infarction. The superior imaging properties, ready availability and low cost of 99mTc point to the considerable potential value of 99mTc-TBI in assessing patients with suspected or confirmed myocardial infarction.

Adult↗
PubMed1988

Evaluation of six new 99mTc-IDA agents for hepatobiliary imaging.

IDA derivatives of three substituted benzothiazol, and two substituted chlorophenyl and one substituted pyrazoline compounds have been labeled with 99mTc and screened with four rat models with hepatocellular dysfunction manifesting varying degrees of change of liver architecture and hepatocellular damage associated with an active parenchymal destruction, fatty metamorphosis and cirrhosis. Organ distribution studies at 1 h postinjection have been compared in normal and diseased animal models for each agent labeled with 99mTc and with 99mTc-Disofenin (Disida) and Lidofenin (Hida) and 131I-Rose Bengal. From the data obtained with the six new IDA derivatives, the distribution kinetics of 99mTc-Arclophenin, (N-N'-2-benzoyl-4-chlorophenyl)carbamoylmethyl) imino diacetic acid (Phenida), are closely comparable to 99mTc-Disofenin in all animal models. Crossover patient studies (n = 14) for clinical evaluation of 99mTc-Arclophenin vs 99mTc-Disofenin indicate the close similarity of the 2 agents with regard to blood pool retention, gross liver/heart ratios and liver washout, suggesting Arclofenin as a suitable agent for hepatobiliary function studies. The impaired hepatocellular animal models presented should serve for fast screening of hepatobiliary agents and enable comparison of a series of closely related compounds.

Adult↗
PubMed1987

Animal and human studies of a new 99mTc labelled phosphine-isocyanide complex with possible applications to radionuclide ventriculography.

A new 99mTc-phosphine-isocyanide complex with the general structure [99mTc (DEPE)2(CNR)2]+ has been synthesised and tested in animals and one human. In three animal species (rat, rabbit, dog), the complex is an efficient myocardial imaging agent, while in humans it remains in the blood pool. The complex is 100% protein bound in animals and humans, but whereas in humans it is attached to a 51.5 kdalton protein (probably prealbumin), in rabbits it appears to be bound to a larger macromolecule (M.W. greater than 100 kdalton). The efficiency of the complex for blood pool labelling was tested in a human volunteer and compared with the standard in vivo red cell labelling technique with stannous pyrophosphate. A satisfactory radionuclide angiogram could be performed with less than 370 MBq of the complex. The count rate for the complex (cps/MBq) was 15% higher than that obtained with the labelled red cells and the absence of splenic activity was notable. In humans this complex appears to be an efficient blood pool labelling agent which might be useful for radionuclide ventriculography.

Animals↗
PubMed1989

Quality control of 99mTc-labeled dextran for lymphoscintigraphy.

99mTc-labeled dextran has been suggested as a lymphoscintigraphic agent. However, quality-control results from previous studies have been controversial. In this study, the optimal concentration of stannous ion and pH value were determined to obtain maximal labeling. Paper and thin-layer chromatography showed total labeling efficiency as high as 98.4%. Anthrone test of the supernatant of the segments from thin-layer chromatographic strip was performed. Colorimetric determinations verified that dextran was found in the same locations as the peak radioactivity.

Chromatography, Paper↗
PubMed1989

Uptake and release of two new Tc-99m labeled myocardial blood flow imaging agents in cultured cardiac cells.

Two new neutral lipophilic 99mTc labeled molecules, chloro (methylboron (1-)-tris[1,2-cyclohexane-dionedioxime (1-)]-N,N',N'',N''',N'''',N''''') (SQ 30217) and Bis [1,2-cyclohexanedione dioximato (1-)-0]-[1,2-cyclohexane-dione dioximato (2-)-0] borato (2-N,N',N'',N''',N'''',N''''')-chloro Tc (SQ 32014), were studied in cultures of beating myocardial cells of newborn rats. The uptake and release kinetics, the effects of various pH levels of the medium, and the effects of three metabolic inhibitors, i.e., ouabain, cyanide and iodoacetate were assessed. Results show that T1/2 of uptake were less than 2 min with both tracers, and T1/2 of release were 12 and 13 min with SQ 32014 and SQ 30217, respectively. The intra/extracellular tracer concentrations was about 15 times higher with SQ 30217 than with SQ 32014. Intracellular concentration was decreased for both tracers at high pH levels, and was only moderately modified otherwise, including in the presence of the metabolic inhibitors. It is concluded that both tracers present very interesting properties for myocardial blood flow imaging, although a higher contrast should be expected with SQ 30217 than with SQ 32014.

Animals↗
PubMed1988

Comparison of delayed hepatobiliary imaging using 99mTc-Sn-N-pyridoxyl-5-methyltryptophan and 67Ga-citrate imaging for diagnosis of hepatocellular carcinoma.

Images were obtained both with a biliary agent, 99mTc-Sn-N-pyridoxyl-5-methyltryptophan (99mTc-PMT), and with 67Ga-citrate in 40 cases of hepatocellular carcinoma and in 43 cases of other hepatic diseases and results were compared. Positive results were obtained by delayed 99mTc-PMT imaging in 25 (63%) of 40 cases of hepatoma: the hepatic tumor showed increased uptake in 18 cases (45%) and equilibrated uptake in 7 cases (18%). Positive 67Ga-citrate imaging was found in 28 (70%) of the 40 cases of hepatoma: increased uptake was seen in 24 cases (60%) and equilibrated uptake in 4 cases (10%). Of 15 cases of hepatoma giving negative results in the 99mTc-PMT study, 7 cases (47%) took up 67Ga-citrate, and 6 of these showed increased 67Ga-citrate uptake by the hepatic tumors. A certain relation existed between the degree of histological differentiation of hepatomas and the intensity of 99mTc-PMT uptake by those tumors, while such a histological correlation was denied for 67Ga-citrate uptake by the tumors. Delayed 99mTc-PMT imaging is preferable to 67Ga-citrate imaging for increasing the specificity of diagnosis of hepatoma. 67Ga-citrate should be used in those cases that do not give positive results with 99mTc-PMT.

Carcinoma, Hepatocellular↗