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PubMed1996

Discordant technetium-99m-MIBI and technetium-99m-HMPAO uptake of recurrent occipital meningioma on brain SPECT images.

Technetium-99m-HMPAO and 99mTc-MIBI brain SPECT, MRI, CT and cerebral angiogram were studied in a patient with recurrent occipital meningioma. MRI and CT of the head showed right cerebral hemispheric tumor masses involving parasagittal, temporal and parietoccipital areas. The angiograms showed an intense vascular tumor blush in recurrent mass lesions supplied by the following arteries: the meningeal branch of the right external carotid artery, the right middle cerebral artery, the right anterior cerebral artery and the right posterior cerebral artery. Although demonstrable 99mTc-MIBI lesions mass exactly corresponded to CT and MRI (T-1) findings, mass lesions exhibited a mismatch between 99mTc-MIBI (increased uptake) and 99mTc-HMPAO (absent uptake) brain SPECT images. Technetium-99m-MIBI images, rather than 99mTc-HMPAO brain SPECT, resulted in the correct pathological diagnosis of recurrent meningioma.

Aged↗
PubMed2001

Evaluation of thyroid nodules with technetium-99m MIBI and technetium-99m pertechnetate.

BACKGROUND: Most thyroid centers use fine-needle aspiration (FNA) and technetium-99m pertechnetate for the preoperative assessment of thyroid nodules. This approach is sufficient in most cases other than follicular neoplasm, and follicular carcinoma is more common than papillary carcinoma in developing countries such as in our center. Technetium 99m-methoxyisobutylisonitrile (MIBI) proposed for myocardial perfusion was also found to be taken up by a variety of tumors including thyroid cancer. METHODS: We evaluated MIBI uptake of nodular thyroid disease and compared it with pertechnetate scan, FNA, and histologic findings for the differentiation of malignant thyroid nodules from benign lesions. Seventy-one patients were included in the study. Three-phase pertechnetate scintigraphy was completed after a single injection of 150 MBq. Perfusion/uptake mismatch (uniform perfusion with cold uptake) was regarded as positive for malignancy, whereas perfusion/uptake match (cold perfusion with cold uptake) was regarded as negative. After 1 week, 400 MBq of MIBI was injected, images were obtained at 20 minutes and 2 hours, and evaluated semiquantitatively by use of a 4-point (0-3) scoring system. MIBI scans were considered positive if there was uptake superior to normal thyroid tissue on early and delayed images (score = 3). In the following days and weeks, all patients underwent FNA followed by surgery. RESULTS: Histopathologic diagnosis revealed a total of 23 thyroid carcinomas, 21 (91%) and 19 (83%) were positive on MIBI and pertechnetate, respectively. Of the 48 patients with benign nodules, 11 (23%) and 29 (60%) were positive on MIBI and pertechnetate, respectively. The specificity of MIBI, pertechnetate, and FNA is 77%, 40%, and 90%, respectively. CONCLUSIONS: In combination with FNA and three-phase pertechnetate scan, MIBI could be helpful in preoperative assessment of thyroid nodules. Intense MIBI activity increases the probability of thyroid cancer, whereas reduced activity drastically decreases the probability of malignancy.

Adolescent↗
PubMed1980

Localization of technetium 99m-ethylenediamine-N,N'-bis(alpha-2-hydroxy-5-bromophenyl)acetic acid and technetium 99m-N-(2-mercapto-1-oxopropyl)glycine in hepatobiliary system.

Two radiopharmaceuticals, technetium 99m-N-(2-mercapto-1-oxopropyl)glycine (99mTc-I) and technetium 99m-ethylenediamine-N,N'-bis(alpha-2-hydroxy-5-bromophenyl)acetic acid (99MTc-II), were prepared and evaluated in dogs, rabbits, and rats. Both agents gave good scintigraphic images of the liver and gallbladder in dogs. The cumulative amount of 99mTc-I and 99mTc-II excreted in the bile of dogs and the physiological disposition data in rats revealed slight, inconclusive differences in their distributions. However, the scintigraphic images and physiological disposition data in rabbits revealed gross differences in the distribution pattern of the two agents. The observed similarities in the biliary excretion of both agents in dogs and rats were attributed to the fact that these species are relatively good biliary excretors, and both agents therefore were excreted extensively. However, rabbits, which are poor biliary excretors relative to dogs and rats, excreted 99mTc-II more extensively than 99mTc-I because of the favorable molecular characteristics of 99mTc-II.

Amino Acids, Sulfur↗
PubMed1993

Comparative scanning of thyroid nodules with technetium-99m pertechnetate and technetium-99m methoxyisobutylisonitrile.

Thyroid imaging was performed using technetium-99m methoxyisobutylisonitrile and technetium-99m pertechnetate in 58 patients. The 99mTc-pertechnetate scans showed a total of 77 nodules: 60 cold, 13 hot and 4 of normal activity. There was no 99mTc-MIBI accumulation in 46.4% of 99mTc-pertechnetate cold nodules; 27 (45%) of these nodules showed 99mTc-MIBI uptake with the same intensity as the surrounding normal tissue, and five (8.6%) became hot with 99mTc-MIBI. Of the 99mTc-pertechnetate hot nodules 11 (84.6%) could not be differentiated from the normal extranodular tissue on the 99mTc-MIBI scan. The histopathology of 34 surgically removed nodules proved that increased, normal or decreased 99mTc-MIBI accumulation is not specific for thyroid malignancy and that the 99mTc-MIBI uptake depends mainly on the viability of thyroid tissue.

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↗
PubMed1995

A quantitative approach to technetium-99m ethyl cysteinate dimer: a comparison with technetium-99m hexamethylpropylene amine oxime.

To develop non-invasive regional cerebral blood flow (rCBF) measurements using technetium-99m ethyl cysteinate dimer (99mTc-ECD) and single-photon emission tomography (SPET), the same graphical analysis as was described in our previous reports using technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) was applied to time-activity data for the aortic arch and brain hemispheres after intravenous injection of 99mTc-ECD. Hemispherical brain perfusion indices (BPI) for 99mTc-ECD showed a highly significant correlation (n = 22, r = 0.935, P = 0.0001) with those for 99mTc-HMPAO in 11 patients who underwent both tracer studies. Using both linear regression line equations between 99mTc-ECD BPI and 99mTc-HMPAO BPI and between 99mTc-HMPAO BPI and mean cerebral blood flow (CBF) values obtained from a xenon-133 inhalation SPET method in a previous study, 99mTc-ECD BPI was converted to 133Xe CBF values (y = 2.60 chi + 9.8). Then raw SPET images of 99mTc-ECD were converted to rCBF maps using Lassen's correction algorithm. In this algorithm, the correction factor alpha was fixed to 1.5, 2.6 and infinite. In the comparison of rCBF values for 99mTc-ECD SPET with those for 99mTc-HMPAO SPET in 396 regions of interest in the aforementioned 11 patients, the fixed correction factor alpha of 2.6 gave nearly the same rCBF values for 99mTc-ECD (50.1 +/- 16.9 ml/100 g/min, mean +/- SD) as for 99mTc-HMPAO (49.9 +/- 17.3 ml/100 g/min). In conclusion, the same non-invasive method as has been used in 99mTc-HMPAO studies is applicable to a 99mTc-ECD study for the measurement of rCBF without any blood sampling.

Adult↗
PubMed1999

A head-to-head comparison between technetium-99m-tetrofosmin and technetium-99m-MIBI scintigraphy to evaluate suspicious breast lesions.

The aim of this study was to assess the diagnostic value of technetium-99m-tetrofosmin and technetium-99m-MIBI in a head-to-head comparison. Both radiopharmaceuticals are routinely used for detecting breast cancer. In a prospective, open, diagnostic trial, the two radiopharmaceuticals were administered randomly on different days to the same 101 women suffering from 103 breast tumours. Planar images and single photon emission computer tomography (SPET) were performed. After histological examination of the tumours, sensitivity, specificity and positive and negative predictive value were compared. 99mTc-tetrofosmin and 99mTc-MIBI showed low sensitivity in planar images (44% vs 46%, respectively). SPET improved sensitivity (70% vs 69%, respectively). Specificity in planar images was 83% and 87%, and it was even lower using SPET (70% vs 78%, respectively). Positive predictive value in planar images was 76% vs 81%, and it was not changed by SPET. Negative predictive value was low in planar images (54% vs 57%, respectively), but it was improved by using SPET (65% vs 67%, respectively). In conclusion, 99mTc-tetrofosmin and 99mTc-MIBI scintigraphy show similar diagnostic value in assessing suspicious breast lesions.

Adult↗
PubMed1984

Biological studies of a new class of technetium complexes: the hexakis(alkylisonitrile)technetium(I) cations.

This study describes the preparation and synthesis of a new class of cationic technetium compounds, the hexakis(alkylisonitrile)technetium(+ 1) complexes, at both carrier added and no carrier added concentrations in aqueous media from pertechnetate. Biological distribution and imaging data in animals indicate that certain members of this class may be effective for cardiac imaging in man. The usefulness of these lipophilic water-soluble species for labeling mammalian cells is also reported.

Animals↗
PubMed1999

Preparation and characterization of technetium complexes with Schiff base and phosphine coordination. 1. Complexes of technetium-99g and -99m with substituted acac2en and trialkyl phosphines (where acac2en = N,N'-ethylenebis[acetylacetone iminato]).

A series of 23 technetium(III) complexes of the type [TcL(PR3)2]+, where L represents a tetradentate Schiff base ligand in the equatorial plane and PR3 represents the axial phosphine ligands, are reported. Full ligand syntheses and characterizations are included. The technetium complexes were prepared with 99mTc to study the organ distribution in guinea pigs at 5 and 60 min postinjection. Four prototypical complexes of the series were also prepared with either 99gTc or 99gTc/99mTc (designated as carrier-added) to allow macroscopic characterization. Equivalence of the 99gTc and 99mTc complexes was demonstrated by dual detection high performance liquid chromatography (HPLC) techniques. The development of a one-step preparation from the standard two-step method is discussed for some complexes. Biodistribution data are related to structure and lipophilicity. None of the complexes in the series exhibited a tendency for in vivo reduction. Myocardial uptake was favorable for a number of complexes. The optimal agent from this series for further imaging development was chosen based on myocardial uptake, rapid blood and liver clearance, and ability to be formulated as a one-step kit.

Animals↗
PubMed2004

Technetium-99m-L,L-ethylenedicysteine renal scan as a single-modality investigation for the evaluation of renal morphology and function: a comparative study with technetium-99m-dimercaptosuccinic acid.

AIM: To evaluate whether cortical scars can be detected using the summed images of technetium-99m-L,L-ethylenedicysteine (99mTc-L,L-EC) renal dynamic scan, and to compare the results with technetium-99m-dimercaptosuccinic acid (99mTc-DMSA) scan. To evaluate the inter-observer variability for 99mTc-L,L-EC and 99mTc-DMSA scan reporting. METHODS: One hundred and three patients were initially included in the study; 21 were excluded, five due to a single functioning kidney and 16 due to impaired renal function (serum creatinine>2.5 mg.dl(-1)). Eighty-two patients (39 females, 43 males), including 31 children, with a mean age of 33.4+/-11.3 years (range, 4 months to 74 years), underwent both 99mTc-DMSA and 99mTc-L,L-EC scintigraphy within a period of 14 days. 99mTc-L,L-EC images were regrouped into 2 min image sets, and the initial 2 min summed image (cortical phase) was used for the evaluation of scars. Three independent observers analysed both images separately on different days without being aware of the identity and clinical details of the patients. Their 99mTc-L,L-EC findings were compared with the consensus 99mTc-DMSA scan findings taken as reference. RESULTS: The overall sensitivity of 99mTc-L,L-EC scans was 93% and the specificity was 96%. The inter-observer variability was 0.91 for 99mTc-L,L-EC and 0.94 for 99mTc-DMSA scan reporting, using the weighted kappa analysis at P<0.05. CONCLUSIONS: 99mTc-L,L-EC is an excellent single-modality comprehensive investigational agent for renal morphology, function and outflow tract evaluation with the added advantages of lower cost, convenience and low radiation exposure to the patient.

Adolescent↗
PubMed1975

Technetium-99m-methylene diphosphonate--a superior agent for skeletal imaging: comparison with other technetium complexes.

Methylene diphosphonate (MDP) was formulated as a complex of 99mTc for skeletal imaging. This agent was compared with three other bone-seeking technetium agents: ethane-1-hydroxy-1, 1-diphosphonate (EHDP), pyrophosphate, and polyphosphate. In tissue radioassay experiments in rodents, the technetium complexes of MDP and EHDP were similar, but skeletal concentration with both of these agents was higher than that with pyrophosphate or polyphosphate. The total-body retention of MDP and EHDP complexed with 95mTc was studied in beagle dogs for 35 days by excretion measurements and total-body counting and compared with polyphosphate and pertechnetate. The long-term retention was greater for MDP. The 5-day cumulative fecal excretion of 95mTc was low when administered as EHDP or polyphosphate complexes and negligible when administered as MDP complex. In six human volunteers the blood clearance of 99mTc-mdp was similar to that of 18F and significantly faster than that of 99mTc-EHDP. Pyrophosphate cleared from the blood much faster than polyphosphate but slower than the diphosphonates. The urinary excretion of the MDP complex was greater than for EHDP within the first 2-3 hr after injection. The 24-hr urinary excretion of pyrophosphate and polyphosphate complexes was not as complete as for the diphosphonates. All four 99mTc complexes proved satisfactory for clinical imaging studies. The MDP complex produced images of superior quality as early as 2 hr after administration, attributable to its more rapid clearance from the blood and soft tissues. On the contrary, a longer interval of 3-4 hr after injection was usually needed for 99mTc-EHDP; pyrophosphate and polyphosphate complexes regularly required a waiting period of 4 hr. Comparitive radiation dose estimates were made based on the available biologic distribution data for these 99mTc skeletal-localizing agents.

Animals↗
PubMed1986

Uptake of hexakis(t-butylisonitrile) technetium (I) and hexakis(isopropylisonitrile) technetium (I) by neonatal rat myocytes and human erythrocytes.

The uptake mechanism of two potential cardiac imaging agents [99mTc]hexakis(t-butylisonitrile) technetium (I) (TBI) and [99mTc]hexakis(isopropylisonitrile) technetium (I) (IPI) has been studied using neonatal rat myocytes and human erythrocytes. Uptake of these complexes was rapid, of greater magnitude than seen previously for 42K, and was unaffected by either 0.15 mM ouabain or 10 mM KCI. Both [99mTc]isonitrile complexes had a high affinity for the membranes of the myocytes and erythrocytes. The data suggest that the uptake is not dependent on the membrane Na+/K+ ATPase but may be related to the lipophilicity of these agents as evidenced by the rapidity, tenacity, and quantity of the binding observed.

Animals↗
PubMed1997

Comparison of technetium-99m-MIBI and technetium-99m-tetrofosmin uptake by musculoskeletal sarcomas.

UNLABELLED: Technetium-99m-MIBI was initially developed for heart studies but it can also be used to depict tumors, predict multidrug resistance and evaluate chemotherapy. Recently, 99mTc-tetrofosmin, which exhibits similar physical properties, has been launched for heart studies. Tumor uptake and prediction of multidrug resistance have also been reported regarding the latter tracer. A comparison of these two tracers regarding the detectability of musculoskeletal sarcoma has been made. METHODS: Twenty patients with musculoskeletal sarcoma of the extremities or pelvis underwent planar examination after the administration of 99mTc-MIBI and 99mTc-tetrofosmin with an interval of 2-7 days. The tumor activity was compared with one ipsilateral and one contralateral background region. RESULTS: There was a small, but not significant, difference in favor of 99mTc-MIBI with regard to both background regions. CONCLUSION: Technetium-99m-MIBI and 99mTc-tetrofosmin can both be used to visualize musculoskeletal sarcomas. The choice may depend on which agent is used routinely for myocardial studies in the laboratory.

Adolescent↗
PubMed1988

Comparison of technetium-99m pyrophosphate and technetium-99m DTPA aerosols for SPECT ventilation lung imaging.

Although [99mTc] diethylenetriaminepentaacetic acid (DTPA) is currently the most widely used radioaerosol, rapid alveolar clearance limits its usefulness for single photon emission computed tomography (SPECT) ventilation lung imaging. Previous research has shown that [99mTc]phosphate compounds have high alveolar deposition and slow clearance and thus provide suitable aerosols for pulmonary ventilation studies. We have compared the pulmonary retention and blood levels of [99mTc]pyrophosphate (PYP) and [99mTc]DTPA in eight normal nonsmoking male volunteers. These two radioaerosols have comparable pulmonary deposition. Technetium-99m PYP, however, has a much slower pulmonary clearance which allows sufficient time (20 or more minutes) for SPECT data acquisition using a single-headed rotating gamma camera. While the radiation absorbed dose to the lungs for [99mTc]PYP (0.31 rad/mCi) is greater than for [99mTc]DTPA (0.11 rad/mCi), it is at a clinically acceptable and safe level.

Administration, Inhalation↗
PubMed1998

Adsorption of technetium-99m tetrofosmin and technetium-99m furifosmin on plastic syringes.

Some groups have reported that adsorption of radiopharmaceuticals on disposable plastic syringes can reach levels of almost 50%. This high loss of radioactivity stimulated us to carry out similar studies. Our measurements were done in combination with patient studies. Therefore, we used 2-ml syringes, all of the same brand. The radioactivity in the syringe was measured immediately before and after injection. a total of 500-600 MBq technetium-99m labelled tetrofosmin or technetium-99m furifosmin was administered to 48 patients using four different injection techniques (n = 6 for each technique with each tracer): with needles, 1 min blood incubation at 22 degrees C, 10 or 30 min after preparation of the tracer; with butterflies, 1 min blood incubation at 22 degrees C, 10 or 30 min after preparation of the tracer. Neither in syringes nor in needles or butterflies did more than 7% of the initial radioactivity remain. The entire residual activity in syringe plus needle or syringe plus butterfly together never exceeded the 9% limit. Furthermore, in a pilot study we measured the remaining radioactivity in the vial; here, too, we found no more than 14% of total radioactivity. These findings indicate that total retention of radioactivity during elution and application of 99mTc-tetrofosmin and 99mTc-furifosmin with material used in our setting does not approach relevant amounts.

Adsorption↗
PubMed1998

Technetium-99m-tetrofosmin for parathyroid scintigraphy: comparison to thallium-technetium scanning.

UNLABELLED: The efficacy of 99mTc-tetrofosmin for the detection of parathyroid lesions was investigated prospectively in patients with hyperparathyroidism referred for surgical treatment. METHODS: Twenty-seven patients with primary and 18 with tertiary hyperparathyroidism were studied. Twelve patients had undergone one or more previous neck explorations. Static imaging with 201Tl was performed first, immediately followed by a 30-min 99mTc-tetrofosmin dynamic study. Delayed views of up to 3 hr postinjection were also obtained. Technetium-99m-pertechnetate was used for thyroid delineation. The tetrofosmin/99mTc-pertechnetate subtraction scan (TF/TC), the single-tracer washout technique and the thallium/technetium subtraction (TL/TC) were compared. Quantification of relative uptakes of tracers in the thyroid and abnormal parathyroids was accomplished by measuring activity within regions of interest. Kinetics of tetrofosmin in the thyroid and abnormal parathyroids were studied by evaluating the plots of the parathyroid to thyroid ratios against time as well as by calculation of the half-clearance times from the slow component of the time-activity curves. RESULTS: The overall sensitivity, specificity and accuracy of TF/TC and TL/TC were 76%, 92% and 83% and 52%, 85% and 65%, respectively. The respective sensitivities were 87% and 70% for adenomas and 72% and 46% for hyperplasia. The parathyroid-to-thyroid activity ratios of tetrofosmin were significantly higher than those of thallium (p < 0.001). The tetrofosmin single-tracer washout study was less accurate than the subtraction technique (overall sensitivity and specificity, 70% and 69%, respectively). The washout properties of tetrofosmin in abnormal parathyroids were not substantially different from those in the thyroid, with a few exceptions (p = 0.4). No correlation of half-clearance times with parathyroid size, degree of early uptake, parathyroid hormone levels or histology could be established. Comparing adenomas to hyperplasia in respect to tetrofosmin retention, a statistically significant difference was observed (p = 0.005). CONCLUSION: Technetium-99m-tetrofosmin is suitable for parathyroid imaging. The kinetic properties of this agent in parathyroid and thyroid tissues do not warrant differential washout protocols. The diagnostic impact of the observed difference in tetrofosmin kinetics between parathyroid adenomas and hyperplasia requires further investigation.

Adenoma↗
PubMed1993

Technetium-99m mercaptoalbumin as a potential substitute or technetium-99m labelled red blood cells.

Technetium-99m labelled red blood cells (99mTc-RBCs) are far superior to 99mTc-labelled human serum albumin (99mTc-HSA) for radionuclide ventriculography, but their labelling is more complex, time consuming and risk bearing (in vitro labelling) or suffers from interference by some medications (in vivo labelling). We have now modified HSA by the introduction of mercapto groups with the purpose of preparing stable and practical 99mTc-mercaptoalbumin with long retention in the vascular system, that could replace 99mTc-RBCs. HSA was incubated with N-succinimidyl S-acetylthioacetate (SATA) or N-succinimidyl 2,3-di(S-acetylthio) propionate (SATP) to introduce a chain containing one or two protected sulfhydryl groups on some of the lysine amino groups. After purification by size-exclusion chromatography (SEC), the mercapto groups were deprotected by incubation at alkaline pH or by treatment with hydroxylamine. The reaction products were used with or without SEC purification for direct or exchange labelling experiments with 99mTc at neutral pH. SEC-HPLC was used to determine labelling yields and to isolate pure 99mTc-mercaptoalbumin. Stable 99mTc-mercaptoalbumin complexes could be formed in 90%-95% yield after coupling albumin with SATA or SATP in all molar ratios used followed by deacetylation in one of the mentioned conditions. The most favourable results were obtained after reaction of SATA or SATP with HSA in a 25:1 ratio and deprotection with NH2OH. The stability of the resulting 99mTc-mercaptoacetyl-albumin (99mTc-MA-HSA) and 99mTc-dimercaptopropionyl-albumin (99mTc-DMP-HSA) and their retention in vivo in plasma of mice and rabbits are clearly higher than that of conventional 99mTc-HSA preparations. 99mTc-DMP-HSA approaches the behaviour of 125I-HSA quite well in both animal species. A preliminary study with 99mTc-DMP-HSA in a volunteer showed a retention in the vascular compartment almost identical to that of 99mTc-RBCs and clearly higher than that of a common 99mTc-HSA preparation. The results indicate that these 99mTc-mercaptoalbumins and especially 99mTc-DMP-HSA are very promising as a practical alternative to 99mTc-RBCs.

Animals↗