Technetium-99m tetrofosmin and technetium-99m sestamibi imaging of multiple metastases from differentiated thyroid carcinoma

A 79-year-old male with follicular thyroid carcinoma metastasizing to the lung, bone and lymph nodes was subjected to whole-body scintigraphy using technetium-99m tetrofosmin and^99mTc-sestamibi. Both agents delineated the metastatic lesions and the two image qualities were comparable. We believe that^99mTc-tetrofosmin and^99mTc-sestamibi images may be helpful in localizing metastatic foci and substitute for thallium-201 in the follow-up of patients with differentiated thyroid carcinoma.     

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. Received 19 April and in revised form 1 August 1999     

Technetium-99m HL91 uptake as a tumour hypoxia marker: relationship to tumour blood flow

Technetium-99m HL91 (HL91) is a potential agent for imaging hypoxic tissue in vivo. To elucidate the relationship between hypoxia and blood flow in a tumour, dual-tracer autoradiography with HL91 and carbon-14 iodoantipyrine (IAP) was performed in a tumour-bearing rat model. The distribution of each tracer was analysed visually and semiquantitatively. In the tumours with central necrotic areas, HL91 uptake was marked around the necrotic areas whereas IAP uptake was marked at the periphery of the tumours, around the areas of marked HL91 uptake. Normalized HL91 uptake (%HL91) was highest in the low normalized IAP uptake (%IAP) fraction in the non-necrotic areas. There was a weak negative correlation between %HL91 and %IAP in the non-necrotic areas (r = –0.322, P<0.0001). In tumours with few or no necrotic areas, HL91 uptake was heterogeneous throughout the tumours, while IAP uptake predominantly occurred at the periphery of the tumours. %HL91 was higher in the inner two-thirds of the tumour than in the outer third. There was again a weak negative correlation between %HL91 and %IAP (r = –0.354, P<0.0001). This study confirmed that high HL91 uptake is related to low blood flow. The marked HL91 uptake around the necrotic region suggests the presence of chronic hypoxia in a tumour. Received 10 September and in revised form 20 October 1998     

Technetium-99m methoxyisobutylisonitrile localizes an ectopic ACTH-producing tumour: case report and review of the literature

Extensive investigation including whole-body examinations with computed tomography and magnetic resonance imaging did not detect the suspected ectopic ACTH-producing tumour in a patient with advanced Cushing's syndrome and hypokalemic alkalosis. Gamma camera examination with technetium-99m methoxyisobutylisonitrile (MIBI) depicted the tumour, which was localized in the anterior neck and mediastinum. This was later verified by surgery. ^99mTc-MIBI is normally used for myocardial scintigraphy. Its accumulation is unspecific and merely reflects metabolic activity. Despite this, the present case shows that examination with this agent can provide important information with regard to tumour localization in a given situation, thereby serving as a complement to other imaging modalities. The current literature on ^99mTc-MIBI for tumour diagnosis is reviewed. Correspondence to: H. Jacobsson     

The value of Tc-99m-tetrofosmin scintigraphy in the assessment of P-glycoprotein in patients with malignant bone and soft-tissue tumors

P-glycoprotein (Pgp) overexpression has been shown to be correlated with resistance to chemotherapy in patients with malignant bone and soft-tissue tumors. The aim of our study was to investigate the role of 99mTc-tetrofosmin as a functional imaging agent reflecting Pgp expression in these tumors. METHODS: Twenty eight patients with various malignant bone and soft-tissue tumors were studied. Radionuclide angiography with 99mTc-tetrofosmin was done first and planar images were acquired at 15 min and 90 min postinjection. Vascular phase was evaluated visually on dynamic images, metabolic state was evaluated both visually and quantitatively on planar images. Quantitative analysis was performed by the calculation of tetrofosmin uptake in the lesion against background and percent washout rate (WR%) of the tracer. Immunohistochemical analysis of Pgp was performed on biopsy specimens and the degree of expression was graded from 0 to 3. RESULTS: There was a positive correlation between the Pgp score and the washout rate of tetrofosmin (r = 0.73, p = 0.000). The mean washout rate of tetrofosmin from the lesions with Pgp expression (31.81 +/- 6.72) was found to be significantly higher than those of without Pgp expression (21 +/- 3.49) (p = 0.000). No statistically significant correlation was found between 15 min and 90 min uptake ratios (UR) of tetrofosmin and Pgp score (r = -0.10, p = 0.6 and r = -0.21, p = 0.2, respectively). When the cut-off value of 24.5 (according to ROC-analysis) for the washout rate was used to discriminate the lesions with and without Pgp expression, the test yielded a sensitivity value of 87.5% with a specificity of 100%. CONCLUSIONS: In malignant bone and soft-tissue tumors, 99mTc-tetrofosmin uptake were not related to Pgp overexpression. Pgp overexpression was found to be correlated with the washout rate of the tracer. 99mTc-tetrofosmin scintigraphy with washout analysis may not only be a useful method for evaluating Pgp overexpression but also its function.     

Technetium-99m methoxyisobutylisonitrile single-photon emission tomography in hepatocellular carcinoma

Nine lesions in eight patients with hepatocellular carcinoma (HCC) were studied using single-photon emission tomography (SPET) and technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) to evaluate the pattern of uptake of ^99mTc-MIBI in the lesions and the relation between the uptake pattern and the histopathology of HCC. All the lesions were diagnosed as HCC by percutaneous needle biopsy. Four of the nine lesions showed positive uptake of ^99mTc-MIBI, while the other five showed negative uptake. All of the lesions which showed positive uptake were of the compact type. Of the five lesions that showed negative uptake, four were of the trabecular type while one was of the compact type. These results suggest that the patterns of ^99mTc-MIBI accumulation in HCC are divided into positive and negative types and that these uptake patterns are associated with the tissue structure of HCC. Received 10 August and in revised form 15 August 1997     

Technetium-99m sestamibi uptake in human breast carcinoma cell lines displaying glutathione-associated drug-resistance

An in vitro study was designed to evaluate the uptake of sestamibi (MIBI) in P-glycoprotein (Pgp) and glutathione-associated (GSH) multidrug-resistant (MDR) cell lines. MIBI uptake was studied in various human breast carcinoma cell lines, i.e. in wild-type (MCF7/wt) cells, in adriamycin-resistant (MCF7/adr) cells which express Pgp and in melphalan-resistant (MCF7/mph) cells with increased levels of GSH. The effects of buthiomine sulphoximine (BSO) and verapamil on MIBI uptake were also studied in the MCF7/mph and MCF7/adr cells respectively. The cells were incubated for 1 h with a dose of 0.1 MBq thallium-201 and technetium-99m MIBI. Both MIBI and²⁰¹Tl uptakes were higher for MCF7/mph cells than for the other cells studied. The mean MIBI uptake in MCF7/adr cells was significantly lower than that in MCF7/wt cells (1.9%±0.5% vs 3.1%.0.6%;P <0.01). Verapamil treatment increased the MIBI uptake in MCF7/adr cells (to 2.6%.0.3%;P <0.05). Treatment of MCF7/mph cells with BSO resulted in a significant reduction in GSH content (from 243.2±81.1 nmoUmg protein to 17.6±4.4 nmol/mg protein;P <0.001). However, MIBI uptake in BSO-treated and untreated MCF7/mph cells was similar (4.43%±0.5% and 5.93%±1.7%, respectively;P >0.1). This study suggests that the uptake of MIBI is not diminished by glutathione-associated drug resistance and that MIBI uptake in a tumour sample does not necessarily indicate that a cancer is sensitive to drugs.     

Comparison of99mTc(V)-DMSA,201Tl and99mTc-MIBI imaging in the follow-up of patients with medullary carcinoma of the thyroid

Radionuclide scanning with tumour-seeking agents such as pentavalent technetium-99m dimercaptosuccinic acid [^99mTc(V)-DMSA], thallium-201 and technetium-99m sestamibi (MIBI) has been reported to be useful in the detection of medullary thyroid carcinoma (MTC). We undertook a study in 14 MTC patients to determine the comparative imaging potential of²⁰¹Tl, MIBI and^99mTc(V)-DMSA in the detection of recurrent or metastatic MTC. All patients underwent total thyroidectomy and had persistently elevated serum calcitonin levels after the surgery. Scintigraphic studies were carried out 20 min after the injection of 111 MBq of²⁰¹Tl or 555 MBq of MIBI and 2 h following the injection of 370 MBq of^99mTc(V)-DMSA. All scintigraphic findings were correlated with contemporaneous CT or MRI studies. CT, MRI and bone scans showed 42 (26 bone, 16 soft tissue) metastatic sites in 11 of the 14 patients. In the remaining three patients no lesions were detected during diagnostic evaluation.^99mTc(V)-DMSA showed all of the soft tissue metastases but could not show two bone lesions. On the other hand, MIBI imaging was false-negative in 22 (52%) sites and²⁰¹Tl was false-negative in 34 (80%) sites. Overall, lesion detection sensitivities for^99mTc(V)-DMSA, MIBI and²⁰¹Tl were 95%, 47% and 19% respectively. We conclude that^99mTc(V)-DMSA is clearly superior to MIBI and²⁰¹Tl in the follow-up of MTC patients.     

Assessment of tumour necrosis and detection of mediastinal lymph node metastasis in bronchial carcinoma with technetium-99m sestamibi imaging: comparison with CT scan

Thirty-eight patients with four major types of bronchial carcinoma were studied to evaluate technetium-99m sestamibi imaging in the assessment of tumour necrosis and the detection of hilar and mediastinal lymph node metastasis. Quantitative analysis was also performed to ascertain whether tumour uptake values correlate with histological types of bronchial carcinoma. Of the patients, 34 showed tumour uptake on planar imaging (n = 38) and 27 on single-photon emission tomography (SPET) (n = 29), the overall sensitivity in the localisation of primary tumour being 89% with planar imaging and 93% with SPET. Four types of tumour uptake pattern were identified: (1) focal uptake, (2) focal uptake with a central hypoactive focus, (3) ring-like uptake and (4) no uptake (negative uptake). Tumour necrosis was diagnosed in 12 patients based upon histopathology (n = 2) and density measurements and type of contrast enhancement on computed tomography (CT) scan (n = 12). Defective tumour uptake was seen in 11 of these patients on planar images (focal uptake with a central hypoactive focus, n = 7; ring-like uptake, n = 2; and no tumour uptake, n = 2) and in 12 patients on SPET (focal uptake with a central hypoactive focus, n = 7, ring-like uptake, n = 3, and no uptake, n = 2). Hilar and mediastinal lymph node involvement was detected in ten patients on CT scan, nine on planar images and 11 on SPET. A total of 26 metastatic lymph nodes were detected on CT scan; 24 of these were seen on planar, and all 26 on SPET images. SPET disclosed five further lymph nodes with metastasis, all of which were confirmed by histopathological examination of the surgical material (n = 3). The sensitivity in establishing the hilar and mediastinal disease was 90% on planar images, and 100% on SPET slices, but when the number of lymph nodes was taken into account, these values were 62% and 100%, respectively. Also, brain metastases were detected with SPET in three patients. The results of quantitative analysis of tumour uptake did not differentiate between squamous cell carcinoma and adenocarcinoma. We conclude that ^99mTc-sestamibi, particularly with SPET imaging, is potentially useful in the follow-up of patients with bronchial carcinoma by differentiating residual or recurrent disease from postradiotherapy necrosis, and is as sensitive as CT scan in the detection of hilar and mediastinal lymph node metastasis.     

Technetium-99m tetrofosmin imaging in patients with subacute thyroiditis

We studied the significance of technetium-99m tetrofosmin scintigraphy in patients with subacute thyroiditis (SAT). Six patients with SAT, who had painful goitre with thyrotoxicosis, underwent ^99mTc-pertechnetate scintigraphy and ^99mTc-tetrofosmin imaging during the acute and recovery stages of SAT. The thyroid uptake ratio of tetrofosmin was compared with the clinical parameters associated with SAT. ^99mTc-pertechnetate scintigraphy showed markedly reduced uptake in the thyroid during the acute stage of SAT, suggesting that the appropriate metabolic pathway is not functioning. Conversely, ^99mTc-tetrofosmin images showed diffuse increased uptake in the thyroid region on early and delayed imaging. Tetrofosmin images in the acute stage and in the recovery stage of SAT showed different clearance curves for tetrofosmin uptake. The uptake ratio assessed as thyroid uptake/background (T/B) correlated with the serum C-reactive protein concentration. In conclusion, ^99mTc-tetrofosmin uptake may reflect the inflammatory process associated with SAT, and thus this tracer may have potential as a marker of disease activity and severity. Received 20 May and in revised form 10 July 1998     

Prognostic value and quality of life in patients with normal rest thallium-201/stress technetium 99m-tetrofosmin dual-isotope myocardial SPECT

BACKGROUND: The prognostic value of normal dual-isotope single photon emission computed tomography (SPECT), with technetium 99m-tetrofosmin for the stress images, is not well known. Furthermore, thallium-201 cross talk in the Tc-99m window may reduce the defect severity of the Tc-99m images. METHODS AND RESULTS: In a consecutive series of 610 patients, 246 patients with normal rest and stress SPECT images by means of visual semiquantitative analysis were included. The patients' pre-test likelihood of coronary artery disease was determined, based on age, sex, symptoms, and the results of stress electrocardiography. Quality of life was assessed by using a mailed self-administered general quality-of-life questionnaire. We compared the mean scores (8 dimensions) of our study population with the scores of 1063 control subjects, sampled randomly out of the inhabitant register of a Dutch city. The mean follow-up period was 25+/-3 months. Compared with the control group, patients in our study scored lower (less perceived health) for all dimensions of the SF-36 (P<.05), suggesting a selection of symptomatic or otherwise diseased patients. The primary cardiac event rate was 0.4% per year. The cardiac events occurred in patients with an intermediate-to-high pre-test likelihood of disease and negative or nondiagnostic exercise electrocardiographic results. In a subset of patients with a high pre-test likelihood of coronary artery disease (more than 85%), the primary cardiac event rate was 0.7% per year. CONCLUSIONS: Patients with normal results on dual-isotope myocardial perfusion scintigraphy, performed with Tc-99m-tetrofosmin for the stress images, have an excellent prognosis. Furthermore, our results suggest that Tl-201 cross talk in the Tc-99m window may be low and functionally and clinically unimportant.     

Comparison of technetium 99m-tetrofosmin and thallium-201 single photon emission computed tomographic imaging for the assessment of viable myocardium in patients with left ventricular dysfunction

Background  Tetrofosmin is a new technetium 99m-labeled myocardial perfusion agent that has demonstrated favorable imaging characteristics in recent clinical trials. However, it is not certain whether ^99mTc-tetrofosmin compared with thallium 201 would underestimate myocardial viability in regions with left ventricular dysfunction. Methods  To this end 15 patients (mean age 52±7 years) with coronary artery disease and left ventricular dysfunction (ejection fraction 35%±8%) documented on angiography underwent both quantitative rest-redistribution ²⁰¹TI and rest ^99mTc-tetrofosmin single photon emission computed tomography imaging. Results  Of 240 total segments on rest-redistribution ²⁰¹TI protocol 139 (58%) segments had irreversible ²⁰¹TI defects. Of these segments 79 (57%) had only mild to moderate reduction of ²⁰¹TI uptake (51% to 85% of normal uptake), whereas the remaining 60 (43%) had severely reduced tracer uptake (≤50% of normal uptake). On ^99mTc-tetrofosmin protocol 180 (75%) segments had abnormal ^99mTc-tetrofosmin uptake; of these segments 120 (67%) had mild to moderate reduction of ^99mTc-tetrofosmin uptake, whereas 60 (33%) had severely reduced activity. Among hypokinetic regions concordance between ²⁰¹TI and ^99mTc-tetrofosmin regarding myocardial viability with a cutoff point of 50% of peak activity was obtained in 28 (90%) of 31 segments (K′=0.80), leaving only 3 of 31 regions discordant (p=NS). Similarly, among akinetic or dyskinetic regions concordance between the two tracers regarding myocardial viability was achieved in 54 (93%) regions (K′=0.75), leaving only 4 of the 58 regions discordant (p=NS). Conclusions  These data show that when the severity of uptake was considered within abnormal segments, a similar amount of ²⁰¹TI viable regions were observed by ^99mTc-tetrofosmin. Thus these two agents may provide comparable information about myocardial viability when quantitative analysis of defect severity is performed.     

Tc-99m-tetrofosmin scintigraphy in a primary giant cell tumor of bone with pulmonary metastases

Giant cell tumor (GCT) is usually considered to be a benign entity. In rare cases, pulmonary metastases can be observed. This report documents the 99mTc-tetrofosmin scan findings of a conventional GCT of the femur and developed pulmonary nodules. The lung lesions were felt to be an example of benign metastases. According to our review, this is the first case in the literature demonstrating tetrofosmin accumulation in a GCT of bone and its pulmonary metastases.     

Comparison of uptake of99mTc-MIBI,99mTc-tetrofosmin and99mTc-012 into human breast cancer cell lines

Technetium-99m hexakis-2-methoxyisobutylisonitrile (MIBI),^99mTc-tetrofosmin and^99mTc-Q12 were all introduced for myocardial imaging but found additional applications as they are taken up by different tumours, enabling imaging of these lesions in patients. The aim of this study was to compare the uptake characteristics of these compounds in vitro in the human adenocarcinoma breast cell lines MCF-7 and ZR-75. It was shown that^99mTc-MIBI had the highest cellular uptake (15.9%±0.5% dose/mg protein after 60 min in MCF-7, and 14.2%±0.4% dose/mg protein in ZR-75), followed by^99mTc-tetrofosmin (6.8%±0.6% dose/mg protein in MCF-7, and 8.2%±0.2% dose/mg protein in ZR-75) and^99mTc-Q12 (3,2%±0. I% dose/mg protein in MCF-7, and 3.5%±0.3% dose/mg protein in ZR-75 cells). For all three compounds tenfold differences in specific activity did not influence total cell-associated radioactivity. Uptake of^99mTc-MIBI and^99mTc-tetrofosmin was obviously lower at 4° C than at 37° C, whereas^99mTc-Q12 uptake showed only slight temperature dependence. When uptake was compared in cells grown to different cell densities (1 mg/ml cellular protein versus 0.3 mg/ml), no differences in uptake were detected when uptake was corrected for the amount of cellular protein present in the dishes. Furthermore, for all compounds it was shown that cellular radioactivity decreased rapidly after washing. Apart from the differences in cellular uptake of the three compounds after 60 min, no differences in residual cellular radioactivity after washing were found between the different compounds when expressed as a percentage of their 60-min uptake, suggesting that the efflux process of the radiolabelled compounds was similar. The differences in cell-associated activity after 60 min were thus presumably caused by differences in uptake. It was concluded that of the Tc-labelled compounds tested,^99mTc-MIBI had the highest cellular retention in both human breast tumour cell lines. However, for imaging in vivo not only radioactivity in the target organ is important, but also the ratio of radioactivity in the target versus that in the background. Therefore, further studies in vivo need to be performed to investigate which compound is the optimal imaging agent     

Technetium-99m sestamibi brain single-photon emission tomography for detection of recurrent gliomas after radiation therapy

Technetium-99m sestamibi (MIBI), an alternative radiopharmaceutical for myocardial perfusion imaging, has also been proposed for use as an imaging agent for various tumours, including breast cancer, lung cancer, lymphomas, melanomas and brain tumours. After routine radiation therapy, deteriorating clinical status or treatment failure may be due to either radiation-induced changes or recurrent tumour. Computed tomography and magnetic resonance imaging offer imperfect discrimination of tumour viability and radionecrosis. Against this background we undertook a retrospective study of 35 malignant glioma patients in whom clinical deterioration had occurred, in order to clarify the value of ^99mTc-MIBI SPET in identifying tumour recurrence. SPET was performed 15 min after intravenous injection of 1110 MBq ^99mTc-MIBI. The images were obtained with a dual-headed gamma camera using a fan-beam collimator. Transverse, coronal and sagittal views were reconstructed. Intense MIBI uptake was found in 31 patients. This uptake was correlated with tumour recurrence as proved by histology and/or rapid, fatal evolution of these cases. The statistical analysis performed on this population of patients with MIBI uptake revealed a group of patients with a long mean survival and a group with a short mean survival. Two subgroups were found within each of these groups, according to the functional index ratio (tumour uptake/pituitary gland uptake ratio). No MIBI uptake was found in four patients who are still alive and can be considered to be disease-free. In those cases showing MIBI uptake, death occurred an average of 6.69 months following brain SPET. According to our results, the specificity and sensitivity of ^99mTc-MIBI brain SPET seem to be high. Moreover, this technique is more accurate than computed tomography or magnetic resonance imaging for discriminating between tumour recurrence and radionecrosis. Received 9 April and in revised form 9 July 1998     

Technetium-99m teboroxime scintigraphy

In order to evaluate the clinical value of a new myocardial perfusion tracer, a series of 30 patients (25 male, 5 female, mean age 56 years) referred for thallium 201 stress/redistribution scintigraphy has been studied using stress/rest (n = 7) or rest/stress (n = 23) protocols with technetium 99m teboroxime (Cardiotec SQUIBB). In all cases coronary artery disease was known or highly probable, with a history of myocardial infarction in 18 cases. Medical treatment was not discontinued at the time of stress testing, and coronary angiography was available in 27 patients. Exercise tests for both tracers were carried out on a bicycle ergometer during the same day, and the levels of exercise achieved for the ²⁰¹Tl study were very similar to those achieved for 99^mTc-teboroxime. Studies performed in three planar projections were evaluated using a model with four territories septal and anterior assumed to correspond to the left anterior descending artery, lateral and lateroposterior (left circonflex), inferior and posterior (right coronary artery) and apex. Classification of results was normal, ischaemic, infarcted and infarcted with ischaemia. On comparison with the ²⁰¹Tl results, agreement was found in 86% (37/43) of normal regions and in 82% (63/77) of abnormal regions. Relative to documented coronary artery lesions (27 patients), sensitivity and specificity of ²⁰¹Tl and ^99mTc-teboroxime for exact correspondence between arteries and territories were respectively: ²⁰¹Tl: sensitivity 64%, specificity 60%; ^99mTc-teboroxime: sensitivity 62%, specificity 77%. These results, obtained in a given clinical context, indicate the ability of Cardiotec to evaluate myocardial perfusion with a significant saving in time, since the complete study duration (stress and rest) was: ²⁰¹Tl, 4 h 35 min±21 min; ^99mTc-teboroxime, 1 h 52 min ±29 min. Nevertheless, the high liver uptake was responsible for 68% of non-evauble inferior segments and the limited acquisition time makes the applicability of SPET questionable.     

Technetium-99m tetrofosmin imaging in thyroid diseases: comparison with Tc-99m-pertechnetate,thallium-201 and Tc-99m-methoxyisobutylisonitrile scans

Technetium-99m tetrofosmin is a lipophilic phosphine used for myocardial perfusion imaging. Biodistribution studies have shown significant thyroid uptake of tetrofosmin and preliminary reports have suggested that tetrofosmin imaging may be of value in patients with thyroid cancer. In this study, tetrofosmin whole-body scintigraphy was performed in 35 patients with evidence of thyroid diseases. All patients underwent laboratory evaluation of thyroid function as well as^99mTc pertechnetate scan, thallium-201 (n=16)^99mTc-methoxyisobutylisonitrile (MIBI) (n=19) whole-body studies. Thyroid images were semi-quantitatively analysed by a 4-point score: O=no significant uptake; 1=uptake increased as compared to background activity, but inferior to normal thyroid tissue; 2=uptake equal to normal thyroid tissue; 3=uptake superior to normal thyroid tissue. Pathology examinations were obtained. A total of 41 thyroid nodules were detected, of which 15 were goitre nodules, 13 adenomas and 13 malignant lesions. In goitre nodules, concordant results of tetrofosmin and pertechnetate uptake (score 1 or 0) were observed in the majority of lesions (87%). In function adenomas (n=10), both tetrofosmin uptake and pertechnetate uptake were score 3. In non-function adenomas (n=3), tetrofosmin uptake was score 3, while pertechnetate uptake was score 0. In six malignant lesions, tetrofosmin uptake was score 3, while pertechnetate uptake was score 0; in the other seven lesions, where a prevalence of goitre abnormalities was observed, results of tetrofosmin and pertechnetate uptake were similar (score 0 or 1). In seven (70%) of the ten patients with malignant nodules, whole-body tetrofosmin images showed increased abnormal uptake in a total of 28 extra-thyroid tumour sites, as subsequently confirmed by other techniques. When tetrofosmin images were compared to 201T1 and^99mTc-MIBI scans, concordant results were observed in all cases. In conclusion, tetrofosmin imaging may be particularly useful to characterize and stage patients with malignant thyroid nodules; it shows similar results to thallium but provides better image quality. Comparable findings were observed between tetrofosmin and MIBI studies. Thus, tetrofosmin may be an alternative to thallium and MIBI in the aforementioned patients.     

Technetium-99m-tetrofosmin radionuclide mammography in the diagnosis of malignant breast tumors

BACKGROUND: Technetium-99m (99mTc) tetrofosmin scintigraphy is a new imaging method for the diagnosis of various malignancies, such as lung, thyroid, and most frequently breast neoplasms. The aim of this study was to evaluate the diagnostic reliability of 99mTc-Tetrofosmin breast scintigraphy in the detection of malignant breast disease. METHODS: 99mTc-Tetrofosmin scintimammography (SMM) was performed in 28 patients with 30 breast lesions suspicious for malignancy. Standard mammography (MM) was also done. After surgery, the results of SMM and MM were compared to definitive histopathological findings as the "gold standard". After intravenous injection of radiotracer, SMM was performed in prone and supine views of the thorax, using large field-of-view Gamma camera. RESULTS: The results of SMM were interpreted visually and semiquantitatively, and evaluated as positive or negative. Sensitivity, specificity and accuracy, positive (PPV) and negative predictive value (NPV) were obtained in relation to histopathology. After comparing the results of SMM and MM, SMM was proved more sensitive (95% for SMM vs. 80% for MM), while the specificity of both methods was similar. CONCLUSION: The results of this study indicate that the contribution of SMM as a nuclear medicine procedure has its place in the diagnostic protocol for patients suspected of malignant breast cancer.     

Technetium-99m dextran: a promising new protein-losing enteropathy imaging agent

The purpose of this study was to evaluate technetium-99m dextran (^99mTc-Dx; molecular weight 81000) as a prospective protein-losing enteropathy (PLE) imaging agent. Twenty-two patients with diseases commonly associated with PLE and 12 healthy control subjects underwent intravenous^99mTc-Dx scintigraphy. All of the 22 test patients showed significant radiotracer accumulation in the intestines within 3–4 h post injection. The focal, regional or generalised nature of the enteropathy and involvement of the large or small intestine could be identified in most cases. Four of the 12 apparently healthy subjects also showed minimal accumulation in the abdominal area occurring late in the study period. This could have been physiological, related to food habits or due to unsuspected intestinal worms. We attribute the high sensitivity of^99mTc-Dx to its relatively fast blood (background) clearance. The radiotracer may have several other advantages over^99mTc-labelled human serum albumin in imaging PLE.     

Technetium-99m-hexakis-2-methoxyisobutylisonitrile scintigraphy and multidrug resistance-related protein expression in human primary lung cancer

Objective The occurrence of multidrug resistance (MDR) is a major cause of resistance to chemotherapeutic agents in patients with lung cancer, in part owing to the overexpression of MDR-related proteins. Technetium-99m-hexakis-2-methoxyisobutylisonitrile (^99mTc-MIBI) has been shown to be a substrate for some MDR-related proteins. The aim of this study is to evaluate the role of ^99mTc-MIBI scintigraphy for functional imaging of MDR-related protein phenotypes. Methods To determine the correlation between ^99mTc-MIBI scintigraphy and the expression level of P-glycoprotein (Pgp), multidrug-resistance protein (MRP), and glutathione-S-transferase Pi (GSTπ), 26 patients (17 men and 9 women, median age 57.5 years) with primary lung cancer were investigated. Following intravenous administration of 925 MBq ^99mTc-MIBI, single-photon emission computed tomography (SPECT) and computed tomography (CT) were performed at 15 min and 2 h. On the basis of the fused images, tumor to background (T/B) ratio of both early and delayed images, and washout rate (WR%) of ^99mTc-MIBI were calculated. The immunohistochemical staining of Pgp, MRP, and GSTπ was performed, and the expression level was semiquantitated using a pathoimage analysis system. The imaging results were compared with the status of Pgp, MRP, and GSTπ expression. Results The WR% of ^99mTc-MIBI showed a significant positive correlation with Pgp expression (r = 0.560, P = 0.003), as no correlation was observed between WR% and MRP or GSTπ (r = 0.354, P = 0.076; r = 0.324, P = 0.106). Neither early T/B nor delayed T/B correlated with the expression level of Pgp, MRP, and GSTπ. WR%, Pgp, and GSTπ expression showed significant differences between squamous cell carcinoma (group A) and adenocarcinoma (group B). There was no significant difference among Pgp, MRP, and GSTπ expression levels in any cases (P > 0.05). Conclusions Our data confirmed that ^99mTc-MIBI scintigraphy is useful for determining the MDR caused by Pgp in patients with primary lung cancer.