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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↗
PubMed1999

Myositis ossificans demonstrated by positive gallium-67 and technetium-99m-HMDP bone imaging but negative technetium-99m-MIBI imaging.

Gallium-67-citrate and 99mTc-diphosphate bone imaging agents are localized in myositis ossificans, a tumor-like benign soft-tissue mass that makes it impossible to differentiate between malignant tumor and the infection/inflammatory process. We present such a myositis ossificans patient whose bone and 67Ga-citrate imagings showed increased uptake in the left thigh and two foci of the right gluteal region leading to inconclusive results. Technetium-99m-MIBI imaging showed the absence of substantial uptake in these regions. ACT scan confirmed myositis ossificans. The lack of 99mTc-MIBI uptake in myositis ossificans means that 99mTc-MIBI imaging may be useful in the differential diagnosis.

Aged↗
PubMed1992

Technetium-99m-MIBI uptake in benign and malignant bone lesions: a comparative study with technetium-99m-MDP.

The potential of hexakis (methoxyisobutylisonitrile) technetium (1) (MIBI) for the imaging of various bone pathologies and for assessment of effectiveness of therapy were investigated in a prospective study. MIBI was evaluated in comparison to MDP bone scans in 73 bone lesions (31 benign, 42 malignant). With MIBI, all but six malignant lesions were clearly visualized and the mean lesion/contralateral (L/C) ratio (2.21 +/- 1.17) was significantly higher than that of benign counterparts (1.26 +/- 0.40) (p less than 0.0005). No such significance was detected on corresponding MDP bone scans (4.86 +/- 3.48 versus 3.11 +/- 1.52). Ten cases with malignant tumor underwent both pre- and post-therapy MIBI evaluation and it was demonstrated that radiotherapy and/or chemotherapy significantly inhibited MIBI uptake. Moreover, post-therapeutic MIBI uptake was a good reflection of the effectiveness of therapy as confirmed by histopathological evaluation. Thus, with a strikingly higher uptake in malignant bone lesions MIBI might have good potential for the detection of malignant bone pathologies as well as for assessing tumor response to therapy.

Adolescent↗
PubMed1990

Kit preparation of technetium-99m-mercaptoacetyltriglycine: analysis, biodistribution and comparison with technetium-99m-DTPA in patients with impaired renal function.

Technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) was prepared by a frozen solution method, enabling the preparation of kits yielding a product substantially free of lipophilic impurities (96% 99mTc-MAG3). However, biliary activity was not completely eliminated as HPLC-purified 99mTc-MAG3 was also excreted by that route. Sequential 99mTc-DTPA and 99mTc-MAG3 renal scans were performed in 15 patients with renal dysfunction, including renal transplant recipients. In all cases, the 99mTc-MAG3 kit preparation provided superior images to 99mTc-DTPA at all levels of renal function due to a higher target-to-background ratio and a plasma clearance twice as fast as 99mTc-DTPA. Interpretation of delayed 99mTc-MAG3 images, however, was complicated by biliary excretion which will limit quantitative estimates of renal clearance. A 99mTc-MAG3 kit is likely to be of value in renal transplant assessment and in cases of significant renal impairment but would not appear to offer major advantages over 99mTc-DTPA in routine renal imaging.

Chromatography, High Pressure Liquid↗
PubMed1989

Cardiac blood-pool scintigraphy using technetium-99m DTPA-HSA: comparison with in vivo technetium-99m RBC labeling.

We performed cardiac blood-pool scintigraphy using technetium-99m diethylenetriaminepentaacetic acid human serum albumin [( 99mTc] DTPA-HSA), a newly developed blood-pool agent, in 31 patients with various heart diseases and evaluated its clinical usefulness in comparison with the conventional in vivo 99mTc red blood cell (RBC) labeling. Excellent cardiac blood-pool images were obtained by [99mTc]DTPA-HSA method. Biodistribution studies showed higher accumulation of [99mTc]DTPA-HSA than that of 99mTc RBC in the lungs and liver, but similar count ratios of the cardiovascular blood pool to whole body between the two methods. In ECG-gated end-diastolic images, no quantitatively significant difference was observed in left ventricular target-to-background ratios between these two methods. Left ventricular ejection fraction (LVEF) calculated by [99mTc]DTPA-HSA MUGA method was correlated well with that by contrast LVEF (r = 0.91). No side effects were observed in any patient. In conclusion, cardiac blood-pool scintigraphy using [99mTc] DTPA-HSA is readily performed by single i.v. injection and useful for the assessment of cardiac function.

Adult↗
PubMed1987

Comparison of technetium-99m MAG3 kit with HPLC-purified technetium-99m MAG3 and OIH in rats.

Technetium-99m (99mTc) mercaptoacetylglycylglycylyglycine (MAG3) in high (greater than or equal to 95%) radiochemical purity is prepared from lyophilized kits containing benzoylMAG3, sodium tartrate, lactose, and stannous chloride by adding sodium [99mTC]pertechnetate and heating the contents briefly. Constant-infusion renal whole-blood clearance obtained with [99mTc] MAG3 kits was compared with that obtained with high performance liquid chromatography (HPLC) pure [99mTc]MAG3 and with co-infused iodine-131 (131I) iodohippurate (OIH) in anesthetized rats. Average renal whole-blood clearance of [99mTc]MAG3 from kits was 3.9 +/- 0.4 ml/min/100 g body weight (mean +/- s.e.m. n = 5) and that for HPLC-pure [99mTc]MAG3 was 4.6 +/- 0.3 (n = 3). Renal whole-blood clearance ratios for [99mTc]MAG3 to co-infused iodine-131 (131I) OIH were greater than unity for both kit formulation (1.7 +/- 0.1) and HPLC-pure [99mTc]MAG3 (1.9 +/- 0.2). Differences in these two measures were not significant. Plasma binding (determined from blood drawn at the end of the infusion) of [99mTc]MAG3 prepared from both kits (75 +/- 2%, n = 4) and HPLC-separation (76 +/- 4%) were greater than that of [131I]OIH in corresponding plasma samples (31 +/- 1% and 32 +/- 2%) respectively). Renograms performed in anesthetized rats revealed no statistically significant differences between kit-prepared [99mTc]MAG3 and [131I]OIH in terms of time-to-peak renal activity (5.0 +/- 1.7 min, n = 6; and 2.2 +/- 0.2 min, n = 3, mean +/- s.e.m. for [99mTc]MAG3 and [131I]OIH, respectively), in terms of time to fall to half-maximal activity (15.3 +/- 2.4 min and 9.6 +/- 2.1 min, respectively), or in terms of fraction of peak radioactivity in right kidney (0.53 +/- 0.01 for both substances). To assess possible interference from hepatobiliary uptake and excretion in renal failure, radioactivity in liver regions of interest was followed by gamma camera scintigraphy for 30 min after intravenous injection of [131I]OIH and kit and HPLC-purified [99mTc]MAG3 in anesthetized rats rendered anephric by ligating renal peduncles. Liver activity was 25% of total for both preparations of [99mTc]MAG3 and was 22% of total for [131I]OIH. There were no significant differences among the substances.

Animals↗