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PubMed1988

Specific and stable labeling of antibodies with technetium-99m with a diamide dithiolate chelating agent.

Technetium-99m labeling of antibodies has been suboptimal because of low affinity adventitious binding, nonspecific labeling, and loss of immunoreactivity. The diamide dithiolate ligand system (N2S2) forms highly stable, well-defined tetradentate complexes with Tc(V). Antibodies and their fragments have been labeled by conjugation of preformed 99mTc-4,5-bis(thioacetamido)pentanoate active ester to protein amine groups to give a chemically known 99mTc-N2S2 complex covalently linked to antibody. Evaluations of the 99mTc-N2S2-bound antibodies and their fragments have shown high stability and retained immunoreactivity.

Animals↗
PubMed1995

Radiometal labeling of recombinant proteins by a genetically engineered minimal chelation site: technetium-99m coordination by single-chain Fv antibody fusion proteins through a C-terminal cysteinyl peptide.

We describe a method to facilitate radioimaging with technetium-99m (99mTc) by genetic incorporation of a 99mTc chelation site in recombinant single-chain Fv (sFv) antibody proteins. This method relies on fusion of the sFv C terminus with a Gly4Cys peptide that specifically coordinates 99mTc. By using analogues of the 26-10 anti-digoxin sFv as our primary model, we find that addition of the chelate peptide, to form 26-10-1 sFv', does not alter the antigen-binding affinity of sFv. We have demonstrated nearly quantitative chelation of 0.5-50 mCi of 99mTc per mg of 26-10-1 sFv' (1 Ci = 37 GBq). These 99mTc-labeled sFv' complexes are highly stable to challenge with saline buffers, plasma, or diethylenetriaminepentaacetic acid. We find that the 99mTc-labeled 741F8-1 sFv', specific for the c-erbB-2 tumor-associated antigen, is effective in imaging human ovarian carcinoma in a scid mouse tumor xenograft model. This fusion chelate methodology should be applicable to diagnostic imaging with 99mTc and radioimmunotherapy with 186Re or 188Re, and its use could extend beyond the sFv' to other engineered antibodies, recombinant proteins, and synthetic peptides.

Amino Acid Sequence↗
PubMed1998

Design and characterization of alpha-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination.

alpha-Melanocyte stimulating hormone (alpha-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind alpha-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, D-Phe7-alpha-MSH4-13 analog. Structural analysis of the Re-peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate-metal-thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re-peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re-alpha-MSH analog. Characterization of the second-generation Re-peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of alpha-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties.

Amino Acid Sequence↗
PubMed2004

Cold bone defect on granulocytes labelled with technetium-99m-HMPAO scintigraphy: significance and usefulness for diagnosis and follow-up of osteoarticular infections.

We wished to determine the frequency and significance of cold bone defect on granulocytes labelled with technetium-99-m-hexamethylpropyleneamine oxime (99mTc-HMPAO-PMN) in non-spinal bone infection. Cold bone defect was investigated as part of a retrospective review during a 2-y period. Patients who had possible osteoarticular infection underwent bone scintigraphy combined with 99mTc-HMPAO-PMN for diagnosis and follow-up. Osteomyelitis was confirmed by isolation of the responsible pathogen. Among 210 patients who had possible infection, 17 (8%) demonstrated a cold bone defect. The site of cold bone defect was for all patients the hip. All 17 patients had proven bacterial orthopaedic hardware-related infection. The single causative micro-organism was staphylococcus. Whatever the outcome, cold bone defect was constant regardless of follow-up equal to or longer than 18 months. These data suggest that this uncommon scintigraphic pattern is an indication of an infectious process similar to increased uptake.

Adult↗
PubMed2001

Hepatic technetium-99m-mebrofenin iminodiacetate scans and serum gamma-glutamyl transpeptidase levels interpreted in series to differentiate between extrahepatic biliary atresia and neonatal hepatitis.

UNLABELLED: Hepatic technetium-99m-mebrofenin iminodiacetate (99mTc-mebrofenin IDA) scans and serum gamma-glutamyl transpeptidase (GGTP) have high sensitivity for extrahepatic biliary atresia (EHBA). This study was based on the hypothesis that the interpretation of results of 99mTc-mebrofenin IDA scans and serum GGTP levels in series would result in a reduction of the false positivity observed with these tests individually. The aetiology of neonatal cholestasis in 132 study patients was: 25% (33/132) EHBA, 45.5% (60/132) neonatal hepatitis (NH) with an identifiable cause and 19.7% (26/132) idiopathic NH. Of the various clinical, biochemical and imaging parameters that were significantly different between patient groups, sensitivity for EHBA was: serum GGTP > or = 150 IU l(-1) (100%), 99mTc-mebrofenin IDA scans (100%), pale stools (82.8%) and total serum bilirubin > or = 12 mg dl(-1) (66%). However, specificity ranged from 48.5 to 79%. Of the 63 patients who had non-excreting IDA scans, operative cholangiograms could be avoided on the basis of a specific aetiological diagnosis of NH, made concurrently, in only 9 infants. The rest (54) underwent operative cholangiograms; 21 (39%) of these had patent biliary trees and therefore underwent the procedure unnecessarily. If serum GGTP (< 150 IU l(-1)) had been used as a screen after IDA scanning in these 54 patients, operative cholangiograms could have been avoided in another 12 patients and thereafter only 9/42 (21%) of the operative cholangiograms would have been considered unnecessary. CONCLUSION: A diagnostic algorithm is proposed wherein serum GGTP level (at a cut-off level that maintains 100% sensitivity for EHBA) is used in series with non-excreting 99mTc-mebrofenin IDA scans (for patients with no specific aetiological label). This strategy reduces the false positivity of individual tests.

Algorithms↗
PubMedDate not supplied

Is technetium-99 (Tc-99) radiologically significant?

According to radiological protection authorities the radioisotope technetium-99 (Tc-99) is not 'radiologically significant' to humans or other species. The Sellafield plutonium reprocessing plant discharges large amounts of Tc-99 into the Irish Sea; by the year 2015 a total of about 3,000 tera-becquerels of Tc-99, weighing about 5 tonnes, will have been discharged. This article considers the effects of Tc-99 on the environment. After discharge, Tc-99 travels large distances in the ocean. Levels of Tc-99 in Norwegian coastal waters increased by ten times between 1991 and 1996. Tc-99 becomes concentrated offshore in seaweed, winkles and mussels. A concentration factor of 120,000 has been reported in seaweed and one of 650,000 has been measured in the green gland of lobster. It may be necessary to reassess the risk to human health following the ingestion of the relevant isotopes, including Tc-99, because of the possibility of radiation induced genomic instability, as well as the cancer risk. The committed effective doses used to determine permitted levels of intake of these isotopes should be increased and the authorized limits for the discharge of radioactive wastes from Sellafield reduced. Authorized limits of the discharge of radioactivity should be based on Contaminated Food Intervention Levels rather than Generalized Derived Limits as they are now.

England↗
PubMed1994

Personnel protection during aerosol ventilation studies using radioactive technetium (Tc99m)

Two commercially available nebulizing devices used for ventilation studies were evaluated. The nebulizers use radioactive Technetium-99m (Tc99m), a potential source of room air contamination. Ambient air concentrations of Tc99m were monitored, as were the exposures of department personnel not performing ventilation studies. Room surfaces and air vents were examined to determine the extent of contamination in the examination room. Personnel were evaluated for contamination on clothing, hair, and airways when hospital lab coats and latex gloves were the only protective apparel used. Though the maximum permissible concentration of 4 x 10(-5) microCi/c3 was not exceeded, preliminary results indicated levels as high as 11,000 disintegrations/min in the nasal passages of personnel. These findings clearly demonstrate the need for more effective personal protective devices. Personnel contamination resulted primarily from the patient, due to an inability to maintain a proper oral seal on the nebulizer mouthpiece. Conventional hospital surgical masks were ineffective in reducing internal deposition to tolerable levels. By comparison, levels were reduced by 19% (p > 0.10) through use of methods such as simple body substance isolation techniques and high-efficiency disposable respirators. Levels approaching 50 disintegrations/min or less were obtainable (p < 0.001), and overall levels of Tc99m were reduced by 78%.

Aerosols↗
PubMed2002

Comparison of technetium-99m methoxyisobutylisonitrile scintimammography and ultrasonography in the diagnosis of breast cancer in patients with mammographically dense breast.

The main purpose of this study was to compare the utility of technetium-99m methoxyisobutylisonitrile (Tc-99m sestamibi) scintimammography with that of ultrasonography for diagnosis of breast cancer in 32 female patients with indeterminate mammographic probability of malignancy because of mammographically dense breast. All breast masses were removed and histopathological diagnosis was obtained in all cases. The results showed 20 of 24 cases of breast carcinoma detected on Tc-99m sestamibi scintimammography. Only one out of eight patients with benign breast lesion had abnormal scintimammographic finding. Ultrasonography diagnosed 22 of the 24 cases of breast carcinoma. However, five out of eight patients with benign breast lesion had positive ultrasonographic findings. In differentiating malignant and benign breast tumors in mammographically dense breast, the diagnostic sensitivities were 83 and 92%, specificities were 88 and 38%, and accuracies were 84 and 78% for Tc-99m sestamibi scintimammography and ultrasonography, respectively. Ultrasonography showed a nonsignificantly higher sensitivity (p < 0.05), but lower specificity, with more false-positive diagnoses made on ultrasonography. Due to its higher sensitivity, ultrasonography is more suitable for screening breast masses. However, Tc-99m sestamibi scintimammography exhibited significantly higher specificity (p < 0.05) and accuracy in detecting malignant breast tumors in the current study. We conclude that Tc-99m sestamibi scintimammography is a safe and useful diagnostic method for detection of breast cancer in patients with nondiagnostic mammogram because of mammographically dense breast.

Adult↗
PubMed2002

Long-term intravenous calcitriol in secondary hyperparathyroidism: the role of technetium-99m-MIBI scintigraphy in predicting the response to treatment.

BACKGROUND: Despite the effectiveness of intravenous calcitriol in suppressing parathyroid hormone secretion in patients with uremic hyperparathyroidism, 50% of the patients remain refractory to this treatment. There are conflicting reports regarding the factors that can predict the response to treatment. Technetium-99m-MIBI scintigraphy was found to be correlated with functional activity of the parathyroid gland. METHODS: We, retrospectively, evaluated 16 chronic hemodialysis patients, who were maintained on i.v. calcitriol for 36 months or longer, and who had MIBI scan either at the start of, or within the first 6 months of starting calcitriol. Nine patients had a positive uptake (+ve group), and 7 patients had a negative uptake (-ve group). All patients had an elevated iPTH (iPTH > 300 pg/ml) at the start of treatment. RESULTS: The percentage reduction of iPTH in the (-ve) and the (+ve) groups was 65% versus 45% at 12 months, and 65% versus 10% at 36 months respectively. In long-term follow-up of 36 months, all the patients in the (-ve) group responded to calcitriol; while 8 of the 9 patients (89%) in the (+ve) group didn't respond. The difference in response between the 2 groups was statistically significant (p<0.001). CONCLUSION: We conclude that MIBI scan is a reliable technique in predicting the response to treatment with i.v. calcitriol in patients with secondary hyperparathyroidism.

Adult↗
PubMed1980

Monitoring of airborne contamination during the handling of technetium-99m and radioiodine.

Measurements have been made using an air sampler to measure airborne radioactivity produced during the routine handling of large activities of technetium-99m, iodine-125 and iodine-131. The results indicate that 99Tcm can be safely handled in environments without direct exhaust of the ventilated air but that 125I and 131I should always be handled in a ventilated environment such as a fume cupboard or a down-draught work-station of the total-exhaust type. Monitoring of thyroid uptake proves to be the most reliable means of monitoring airborne contamination by these radionuclides, but burdens and radiation doses for typical procedures are well within the maximum permissible limits of the Code of Practice for the Protection of Persons from Ionizing Radiation arising from Medical and Dental Use.

Air Pollution, Radioactive↗
PubMed1999

Simultaneous technetium-99m/thallium-201 SPECT imaging with model-based compensation for cross-contaminating effects.

Simultaneous acquisition of dual-isotope SPECT data offers a number of advantages over separately acquired data; however, simultaneous acquisition can result in cross-contamination between isotopes. In this work we propose and evaluate two frameworks for iterative model-based compensation of cross-contamination in dual-isotope SPECT. The methods were applied to cardiac imaging with technetium-99m-sestamibi and thallium-201, and they were compared with a subtraction-based compensation method using a cross-talk estimate obtained from an auxiliary energy window. Monte Carlo simulations were performed to carefully study aspects of bias and noise for the methods, and a torso phantom with cardiac insert was used to evaluate the performance of the methods for experimentally acquired data. The cross-talk compensation methods substantially improved lesion contrast and significantly reduced quantitative errors for simultaneously acquired data. Thallium image normalized mean square error (NMSE) was reduced from 0.522 without cross-talk compensation to as low as 0.052 with model-based cross-talk compensation. This is compared with a NMSE of 0.091 for the subtraction-based compensation method. The application of a preliminary model for cross-talk arising from lead fluorescence x-rays and collimator scatter gave promising results, and the future development of a more accurate model for collimator interactions would probably benefit simultaneous Tc/Tl imaging. Model-based compensation methods provide feasible cross-talk compensation in clinically acceptable times, and they may ultimately make simultaneous dual-isotope protocols an effective alternative for many imaging procedures.

Drug Interactions↗
PubMed1998

Transfer across the human gut of environmental plutonium, americium, cobalt, caesium and technetium: studies with cockles (Cerastoderma edule) from the Irish Sea.

Our previous studies have indicated lower values of the gut transfer factor ('f1 values') for plutonium and americium in winkles (Littorina littorea) than adopted by ICRP. The present study was undertaken primarily to investigate whether this observation extends to other species. Samples of cockles (Carastoderma edule) from Ravenglass, Cumbria were eaten by volunteers who provided 24 h samples of urine and faeces. Urine samples indicated f1 values for cockles which were higher than for winkles; for plutonium these ranged overall up to 7 x 10(-4) with an arithmetic mean in the range (2-3) x 10(-4), and for americium up to 2.6 x 10(-4) with an arithmetic mean of 1.2 x 10(-4). Limited data based on volunteers eating cockles from the Solway suggest that f1 values for americium may be greater at distance from Sellafield. The measured values compare with 5 x 10(-4) used by the ICRP for environmental forms of both elements, which would appear to provide adequate protection when calculating doses from Cumbrian cockles. Data for other nuclides were obtained by analysing faecal samples from the volunteers who ate the Ravenglass cockles. Cobalt-60 showed an f1 value in the region of 0.2, twice the value currently used by ICRP. For 137Cs, variabilities were indicated in the range 0.08 to 0.43, within the ICRP value of f1 = 1.0. Technetium-99 gave f1 values up to about 0.6, in reasonable conformity with the ICRP value of 0.5.

Americium↗
PubMed2001

The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in suspected recurrent breast cancer.

The aim of this study was to determine the role of technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy in the evaluation of recurrence and metastases in breast cancer patients with mastectomy and/or radiotherapy. A prospective study was designed to assess the accuracy of 99mTc-MIBI scintigraphy in 36 patients (mean age 49 years) with suspected recurrent breast cancer. The scintigraphic studies were correlated with radiological findings and/or with histopathology. At 10-15 min after 740MBq 99mTc-MIBI injection, standard planar images were obtained in prone lateral and anterior supine views and then single-photon emission computed tomography (SPECT) imaging was performed. A whole body imaging was also performed to demonstrate distant metastatic lesions. Totally 52 lesions were evaluated which 19 of them in 9 patients were malignant, while 33 lesions in 27 patients were benign. The sensitivity was 33%, 88% and the specificity was 96%, 93% for planar and SPECT imaging, respectively in loco-regional lesions. Overall, the sensitivity and the specificity of MIBI imaging including whole body were 89%, 81%, in other conventional radiological imaging methods were 95%, 65%, respectively. 99mTc-MIBI scintigraphy using SPECT imaging may provide useful complementary information in patients with suspected recurrence breast cancer.

Adult↗
PubMed2001

Technetium-99m-tetrofosmin would be a substrate for multidrug resistance-associated protein (MRP): comparison between a leukemia cell line with high MRP gene expression and its parental cell line.

UNLABELLED: The kinetics of cellular accumulation and retention of technetium-99m-tetrofosmin (99mTc-TF) were investigated in wild type HL60/WT cell line and in its doxorubicin-resistant HL60/DOX cell line with multidrug resistance-associated protein (MRP), but without P-gp overexpression, to determine whether 99mTc-TF is a substrate for MRP. METHODS: The accumulation and washout of 99mTc-TF were observed in both cell lines at 37 degrees C. The effect of verapamil on the kinetics was also assessed. RESULTS: 99mTc-TF net accumulation was significantly lower in HL60/DOX (1.35 +/- 0.23%) than in HL60/WT (12.79 +/- 0.47%) at 60 min (P < 0.001). Three minutes after exchanging the incubation solution to the tracer-free medium, only 18.20 +/- 0.34% of 99mTc-TF remained in HL60/DOX, whereas 84.74 +/- 0.65% did in HL60/WT (P < 0.001). In the presence of 10 microM verapamil, 99mTc-TF net accumulation in HL60/DOX was 302% of the control and the washout was significantly delayed. CONCLUSION: 99mTc-TF would be a substrate for MRP and 99mTc-TF may be used as a functional imaging agent of MRP in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Preparation and in vitro and in vivo evaluation of technetium-99m-labeled folate and methotrexate conjugates as tumor imaging agents.

The cell-membrane folic acid (FA) receptors are known to be responsible for cellular accumulation of FA and FA analogs, such as methotrexate (MTX), and are overexpressed on several tumor cells. Folate, as well as antifolates (i.e., MTX), possess high affinity for the folate-receptor positive cells and tissues and were deemed useful for diagnostic imaging. We have prepared and evaluated technetium-99m (99mTc)- labeled FA and MTX analogs using MAG3 and MAG2 chelating agents in an attempt to develop folate-receptor targeting radiopharmaceuticals. Folate and MTX-conjugates after labeling with 99mTc by ligand exchange method displayed high in vitro stability in human plasma. In vitro cell binding and internalization on MCF-7 and MDA-MB-231 cells indicated the affinity and specificity of the radioconjugates toward human breast cancer cells. In mice, all radioconjugates showed rapid clearance from the blood and excretion mainly through the renal/urinary pathway, with some elimination by way of the biliary route. There was no significant accumulation of radioactivity observed in other organs, with the exception of the intestines. Uptake in the breast tumor was moderate in nude mice. These findings could be of potential diagnostic interest in designing and developing FA/MTX-based radiopharmaceuticals for tumor imaging.

Chromatography, High Pressure Liquid↗
PubMed1991

Technetium 99m radiolabeling of aerosolized drug particles from metered dose inhalers.

To assess mechanisms of bronchodilation and effectiveness of metered dose inhalers, it may be useful to determine sites of drug deposition in the lung. To establish suitable test aerosols, two brands of metered dose inhalers containing bronchodilator (Brethaire, Proventil) were radiolabeled with technetium ( 99mTc) and tested to determine if the distribution of radioisotope in the aerosol was representative of the distribution of agonist activity. Cascade impaction was used to determine the particle size distribution of the radioisotope and drug aerosols by assaying each state of the cascade using scintillation and HPLC techniques. Possible influences of the radiolabeling method and delivery techniques on the particle distribution were assessed by analyzing distributions from nonradiolabeled inhalers using HPLC. For these drugs, there was an excellent correlation between the distribution of radioactivity and the drug within the captured aerosol (Brethaire r = 0.994, Proventil r = 0.998, 20 - 200 consecutive puffs). Distributions were close to log-normal and differences in mass median aerodynamic diameter (MMAD) between the radioisotope and agonist activities were not significant (Brethaire, MMAD +/- sigma g, radiolabel vs drug = 4.7 +/- 2.1 mum, vs 4.4 +/- 1.7 mum, and Proventil, 2.5 +/- 2.1 mum, vs 2.4 +/- 2.0 mum. Non-labeled inhalers produced similar drug distributions (Brethaire, 4.2 +/- 1.8 mum, and Proventil 2.0 +/- 1.9 mum). Pausing between actuations resulted in slightly smaller distributions (Brethaire, 3.6 +/- 1.8 mum, Proventil 1.8 +/- 1.8 mum, 20 puffs-60 sec pauses) but the differences were not significant. In addition, to search for multimodal distributions and assess the accuracy of the MMAD measurement via our cascade impactor (Delron), we also measured the distribution of the mass of material within the aerosols using a weight-sensitive cascade (California Measurements). Using the latter device (1 puff), the mass distributions of both aerosols were similar to the values obtained from the puffs with pauses (Brethaire 3.8 +/- 2.3 mum, Proventil 1.4 +/- 2.2 mum). Multi-modal distributions were not found. By all assessments, the distributions were nearly log-normal with drug activity well described by the radiolabel.

Bronchodilator Agents↗
PubMed1997

Value of combined technetium-99m hydroxy methylene diphosphonate and thallium-201 imaging in detecting bone metastases from thyroid carcinoma.

Detectability of bone metastases from differentiated thyroid carcinoma by technetium-99m hydroxymethylene diphosphonate ([99m]Tc-HMDP) bone scan is considered to be poor. Thallium-201 (201Tl) is also widely used for detecting metastatic lesions. Our present study was aimed at the evaluation of the combined use of (99m)Tc-HMDP and 201Tl imaging in successful detection of bone metastases from differentiated thyroid carcinoma. Twenty-seven thyroidectomized thyroid cancer patients (19 females, 8 males; 12 papillary type, 15 follicular type) with 77 bone lesions were included in this retrospective study. All of these patients received ablative doses of radioiodine. Thyroidal origin of the lesions was proved by positive iodine-131 (131I) uptake. In 131I-negative lesions, histological proof or absence of tumor markers other than thyroglobulin was considered when computed tomography (CT) and/or magnetic resonance imaging (MRI) suggested metastatic nature of the lesions. Of the 77 lesions, 58 (75.3%) were positive and 19 were negative in the (99m)Tc-HMDP bone scintigraphy, whereas 53 lesions (68.9%) could be detected by 201Tl scintigraphy. However, within the 19 (99m)Tc-HMDP-negative lesions, 14 showed abnormal accumulation of 201Tl, and within the 24 201Tl negative lesions, 19 were positive in (99m)Tc-HMDP scan. This resulted in a combined sensitivity of 93.5%. Our present study concludes that combined (99m)Tc-HMDP and 201Tl imaging is a sensitive and effective method for detecting bone metastases from thyroid carcinoma.

Adenocarcinoma, Follicular↗
PubMed1998

Diagnostic value of technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy in detecting thyroid cancer metastases: a critical evaluation.

Technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy has recently been used in clinical application for detecting thyroid cancer metastases, its role being considered supplementary to serum thyroglobulin (Tg) measurements and radioactive iodine (131I) whole-body scans (WBS). The present retrospective study was designed to elucidate the role of 99mTc-MIBI scans in localizing metastatic lesions by assessing sensitivity and specificity of the scan results obtained in a group of 68 thyroidectomized thyroid cancer patients. Presence or absence of thyroid cancer was judged with other diagnostic modes including serum Tg measurements, 131I WBS, bone scans, chest x-rays, computed tomography (CT), ultrasonography, histopathology, and evolution of disease during follow-up. All scans were read on lesion basis for detecting neck, lung, and bone metastases and also on region basis, namely head-neck, chest, and abdomen-pelvis-extremities (ab-p-ex) areas. The sensitivity of detection was 94.4% (17/18) for neck, 78.4% (40/51) for lung, and 92.8% (64/69) for skeletal lesions. Positive predictive value (PPV) and negative predictive value (NPV) were 96.3% (26/27) and 97.7% (43/44) for head-neck; 94.7% (71/75) and 50.0% (12/24) for chest; 100.0% (25/25) and 93.1% (54/58) for ab-p-ex regions, respectively. For all scan sites taken together, PPV and NPV were 96.1% (122/127) and 86.5% (109/126), respectively. In conclusion, the present study reveals that 99mTc-MIBI can be proposed as a first-line diagnostic agent for the follow-up protocol of thyroid cancer patients, although the ability to detect small lung metastases is somewhat limited.

Adult↗