Role of technetium-99m sestamibi scintimammography and contrast-enhanced magnetic resonance imaging for the evaluation of indeterminate mammograms

This study evaluated and compared technetium-99m sestamibi scintimammography (SMM) and breast magnetic resonance imaging (MRI) results in patients with indeterminate mammograms to determine whether either technique can improve the sensitivity and specificity for the diagnosis of breast carcinoma. From 123 consecutive patients who underwent physical examination, mammography, SMM, and histopathologic confirmation, a subgroup of 82 patients presenting with indeterminate mammograms was studied. Sixty-eight patients underwent contrast-enhanced MRI. SMM results were scored on the basis of the intensity and pattern of sestamibi uptake. MRI images were scored on the basis of signal intensity increase after administration of contrast material as well as the enhancement pattern and speed of gadolinium uptake. The results obtained with the two techniques were compared and related to the final histopathologic diagnoses. Considering indeterminate findings as positive, the sensitivity of SMM was 79% and the specificity, 70%. MRI displayed a sensitivity of 84% and a specificity of 49%. When indeterminate results were considered negative, the sensitivity and specificity of SMM were 62% and 83%, respectively. MRI revealed a sensitivity and specificity of 56% and 79%, respectively. The calculated sensitivities and specificities demonstrate the diagnostic limitations of both SMM and MRI in the evaluation of patients with indeterminate mammographic findings. Due to the higher specificity, SMM may be the preferred modality in the evaluation of selected patients with breast abnormalities. Received 16 April and in revised form 12 June 1997     

Breast cancer staging using technetium-99m sestamibi and indium-111 pentetreotide single-photon emission tomography

We evaluated the clinical usefulness of single-photon emission tomography (SPET) with technetium-99m sestamibi and indium-111 pentetreotide in breast cancer staging. Fifteen patients with clinical and/or mammographic findings suggesting T1-2N0-1 breast cancer were studied. SPET images were acquired 20 min after^99mTc-sestamibi injection and 4 and 24 h after¹¹¹In-pentetreotide injection. Patients underwent surgery the day after the later¹¹¹In-pentetreotide acquisition. Pathological examination showed 16 tumours in the 15 patients, with one bilateral carcinoma. The mean tumour diameter was 18.7 mm. Metastatic axillary involvement was found in 6/16 tumours, with a mean of five metastatic nodes per axilla. Both tracers correctly identified 15/16 primary tumours and five of the six cases of metastatic axillary node involvement. No difference between the tracers was observed in breast cancer staging.^99mTc-sestamibi seems to be the better tracer in terms of physical characteristics, execution time and cost-effectiveness. Our data suggest the future possibility of using nuclear medicine imaging to avoid axillary dissection in patients with T1 breast cancer.     

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.     

Detection of axillary lymph node metastases in breast carcinoma by technetium-99m sestamibi breast scintigraphy,ultrasound and conventional mammography

Axillary lymph node status is important in the staging of breast carcinoma. To evaluate the accuracy of technetium-99m sestamibi breast scintigraphy in detecting metastatic axillary lymph nodes as compared with other accepted imaging modalities, we performed^99mTc-sestamibi breast scintigraphy, conventional mammography and ultrasound in 36 patients with primary untreated breast carcinoma. With histopathology as the gold standard,^99mTc-sestamibi breast scintigraphy was found to yield true-positive results in 7 of 11 cases (64%) of axillary lymph node metastases and true-negative results in 18 of 20 cases (90%); it has an accuracy of 81%, a positive predictive value of 77.8% and a negative predictive value of 81.8%.     

Comparative myocardial uptake of technetium-99 m sestamibi and technetium-99m tetrofosmin one hour after stress injection

Technetium-99m sestamibi and ^99mTc-tetrofosmin are at present the preferred tracers for simultaneous assessment of myocardial perfusion and function by gated single-photon emission tomography (SPET). The aim of this work was to compare sestamibi and tetrofosmin myocardial uptake 1 h after stress injection. Consecutive unselected patients were studied either with sestamibi or with tetrofosmin on a random basis, until at least 100 patients had been enrolled for each gender and tracer. Stress was obtained by dipyridamole or exercise or combined dipyridamole + exercise; in the latter cases, exercise was sustained for at least 1.5 min after tracer injection. Injected activity was similarly adjusted to body weight. For each patient, imaging began 60–75 min after injection. All SPET projections were summed; due to the acquisition technology (”roving zoom”, i.e. a mobile zoom), the heart always appeared at the centre of the frame in all projections and in the sum image. Thus minimal lung background contamination could be assumed in an elliptic region of interest placed over the heart on the sum image. Three indexes were analysed: total myocardial counts (Sum), mean myocardial pixel (Mean) and maximum myocardial pixel (Max). Four patient groups were analysed: males with sestamibi or tetrofosmin (MS: n = 189 and MT: n = 157), females with sestamibi or tetrofosmin (FS: n = 101 and FT: n = 104). MS and MT groups were comparable for physical variables, maximum heart rate and stress type, as were the FS and FT groups. Sum, Mean and Max were significantly higher with sestamibi (P = 0.0001 by ANOVA). Comparing MS vs MT and FS vs FT, mean values ± SD were as follows: for Sum (kcounts) 750±184 vs 652±166, and 707±202 vs 594±189; for Mean (counts) 4517±1171 vs 4107±898, and 4908±1119 vs 4144±1025; and for Max (counts) 6471±1654 vs 5794±1312, and 7318±1886 vs 6152±1684. The mean gain with sestamibi was +15%, +10% and +12% in males, and +19%, +18% and +19% in females. Similar differences were found within each stress type subgroup. No gender-specific effect was found for Mean, so the overall mean gain was calculated for Mean: +13% for sestamibi vs tetrofosmin. These findings are consistent with other published smaller sample series. Possible differences between tracers with regard to residual activity in syringes were ruled out by an additional experiment. In summary, we found significantly higher myocardial counts with sestamibi than with tetrofosmin, in males as well as in females. Received 10 February and in revised form 27 July 1998     

Detection of radiation-induced myocardial damage by technetium-99m sestamibi scintigraphy

A prospective study was initiated to assess the side-effects of postoperative adjuvant radiotherapy in patients with left-sided early breast cancer. Twelve patients with early breast cancer were examined before and a year after radiotherapy. Echocardiography, ECG and bicycle ergometry stress test with technetium-99m sestamibi myocardial perfusion scintigraphic were carried out to assess changes in regional myocardial blood flow. Six of the 12 patients had new fixed scintigraphic defects after radiotherapy (as compared with the preradiation examination). The localization of the defects corresponded well with the irradiated volume of the left ventricle. These defects were probably due to microvascular damage to the myocardium. Neither ECG changes nor left ventricular segmental wall motion abnormalities could be detected by echocardiography. To our knowledge this study is the first to show that radiation-induced microvascular damage to the myocardium may be detected by perfusion scintigraphy. This may limit the use of scintigraphy in diagnosing coronary artery disease in patients treated with thoracic radiotherapy. Long-term follow-up is necessary to assess whether the presence of microvascular damage is a prognostic sign for the development of radiation-induced coronary artery disease.     

A miniaturized rapid paper chromatographic procedure for quality control of technetium-99m sestamibi

A miniaturized rapid paper chromatographic technique (MRPC) for quality control of a technetium-99m sestamibi preparation was developed and compared with the manufacturer's and Hung et al. techniques. The MRPC system involves the use of 6.0×0.5 cm Whatman 3MM paper strip developed in ethyl acetate. The procedure was completed within 3 min while that of the manufacturer and Hung techniques took 30–35 and 4 min respectively. The R_f range of^99mTc-sestamibi using MRPC was 0.55–0.75 while that of the other two techniques was 0.9–1.0. The results indicate that MRPC can be used to separate^99mTc-sestamibi from any^99mTc contaminant that migrates with the solvent front. The MRPC is a fast and effective chromatographic technique for routine quality control testing of^99mTc-sestamibi preparation.     

Optimization of X-ray mammography and technetium-99m methoxyisobutylisonitrile scintimammography in the diagnosis of non-palpable breast lesions

The purpose of this study was to evaluate the contribution of technetium-99m methoxyisobutylisonitrile (MIBI) scintimammography to the early diagnosis of breast cancer in 78 patients with non-palpable breast lesions detected by mammography. In all cases biopsy was indicated and they were classified into three groups according to the mammographic findings: high (28), intermediate (30) and low (20) mammographic probability of malignancy. Histological diagnosis confirmed 37 benign and 41 malignant lesions. In the high-probability group ^99mTc-MIBI scintimammography changed the four false-positives into true negatives at the expense of two false-negatives; in the intermediate group it changed nine of the 17 false-positives into true-negatives at the expense of one false-negative, and in the low-probability group it changed five of the 16 false-positives into true-negatives without false-negatives. Applying scintimammography to patients included in the intermediate and low-probability groups together, 14 of the 33 mammographic false-positives were changed into true-negatives with 1 false-negative; thus, 41% of the unnecessary biopsies would have been avoided. When MIBI scintimammography was applied to the low-probability group, the negative predictive value was 100% and the unnecessary biopsies would have been reduced by 31%. Received 10 November 1997 and in revised form 19 January 1998     

In vivo detection of multidrug-resistant (MDR1) phenotype by technetium-99m sestamibi scan in untreated breast cancer patients

Technetium-99m sestamibi is a transport substrate recognised by the multidrug-resistant P-glycoprotein (Pgp). To test whether^99mTc-sestamibi efflux is enhanced in breast carcinomas overexpressing Pgp, we determined the efflux rates of^99mTc-sestamibi and Pgp levels in tumours from 30 patients with untreated breast carcinoma. Patients were intravenously injected with 740 MBq of^99mTc-sestamibi and underwent a 15-min dynamic study followed by the acquisition of static planar images at 0.5, 1, 2 and 4 h. Tumour specimens were obtained from each patient 24 h after^99mTc-sestamibi scan and Pgp levels were determined using¹²⁵I-MRK16 monoclonal antibody and in vitro quantitative autoradiography. All breast carcinomas showed high uptake of^99mTc-sestamibi and data from region of interest analysis on sequential images were fitted with a monoexponential function. The efflux rates of^99mTc-sestamibi, calculated from decay-corrected time-activity curves, ranged between 0.00121 and 0.01690 min⁻¹ and were directly correlated with Pgp levels measured in the same tumours (r=0.62;P<0.001). Ten out of 30 breast carcinomas (33%) contained 5 times more Pgp than benign breast lesions and showed a mean concentration of 5.73±1.63 pmol/g of tumour (group A). The remaining 20 breast carcinomas had a mean Pgp concentration of 1.29±0.64 pmol/g (group B), equivalent to that found in benign breast lesions.^99mTc-sestamibi efflux from tumours of group A was 2.7 times higher than that observed in tumours of group B (0.00686±0.00390 min⁻¹ vs 0.00250±0.00090 min⁻¹,P<0.001). The in vivo functional test with^99mTc-sestamibi showed a sensitivity and a specificity of 80% and 95%, respectively. In conclusion, the efflux rate of^99mTc-sestamibi may be used for the in vivo identification of the multidrug resistant (MDR1) phenotype in untreated breast cancer patients.     

Localization of ectopic parathyroid glands using technetium-99m sestamibi imaging: Comparison with magnetic resonance and computed tomographic imaging

The aim of the study was to compare the accuracy of technetium-99m sestamibi imaging for localization of ectopic parathyroid glands in patients with hyperparathyroidism with that of magnetic resonance (MR) and computed tomographic (CT) imaging. Eleven patients with primary (n=3) or secondary (n=8) hyperparathyroidism were studied with^99mTc sestamibi parathyroid imaging CT and MR imaging. Images of the neck were acquired at 10 min and 2–3 after tracer injection. The three patients with primary hyperparathyroidism and five patients with secondary hyperparathyroidism underwent parathyroidectomy. The ectopic glands were confirmed by histopathological examination of the resected specimens. In respect of 20 parathyroid glands in the eight patients explored surgically, the sensitivity and specificity of sestamibi imaging were 70% (14/20) and 88%, respectively, those of CT, 40% (8/20) and 88%, and those of MR imaging, 60% (12/20) and 88%. Of these patients, three had parathyroid adenomas while five had hyperplasia (17 glands). Sestamibi imaging localized eight ectopic parathyroid glands, which were surgically confirmed (six were located in the thymus and two in the mediastinum). In one patient explored surgically, the ectopic gland was located outside the field of the MR coil. Although the remaining three cases of secondary hyperparathyroidism were not confirmed surgically, these patients demonstrated sestamibi uptake in five parathyroid glands, including three ectopic glands. MR images demonstrated abnormal parathyroid glands in the same regions as sestamibi imaging. Our data indicate that^99mTc-sestamibi imaging should be used initially to localize the ectopic parathyroid glands in patients with hyperparathyroidism for anatomical guidance prior to MR or CT imaging.     

Comparison of dynamic MR imaging of the breast and sestamibi scintimammography for evaluation of indeterminate mammographic lesions

The aim of this study was to compare Tc-99m sestamibi scintimammography and dynamic contrast-enhanced MR imaging for the evaluation of indeterminate mammographic lesions. Forty patients with questionable mammographic findings were included in a prospective study. Thirty lesions were non-palpable. Mean lesion size was 1.6+/-0.7 cm (range 0.5-3.5 cm). Scintigraphy was considered as malignant when focal tracer accumulation was present. In MR imaging, lesions were classified according to their signal intensity time course: no enhancement or steady enhancement with low signal intensity (M0); steady enhancement with high signal intensity (M1); or rapid enhancement with plateau (M2) or washout (M3). Lesions classified as M2 or M3 were considered as suspicious for malignancy. Histopathologic evaluation was performed in 24 lesions. In 16 cases lesions were classified as benign from follow-up examinations (mean 24 months). Malignancies were proven in 14 patients (9 invasive carcinomas, 5 ductal carcinoma in situ). Sensitivity of MR imaging was 12 of 14 (86%) and sensitivity of scintimammography was 8 of 14 (57%). One of 26 benign lesions was false positive at MR imaging. Scintigraphy showed no false-positive results. In conclusion, magnetic resonance imaging provided high accuracy in evaluation of indeterminate mammographic lesions. Sensitivity of scintimammography was too low in detecting small carcinomas.     

Washout and redistribution between immediate and two-hour myocardial images using technetium-99m sestamibi

The aim of this study was to assess whether a clinically relevant change in myocardial sestamibi activity could be documented within the first 120 min following injection (p.i.). In 17 patients planar anterior imaging of the heart was performed 5 min and 120 min p.i. During this time interval, mean decay-corrected myocardial activity declined to 77.9%±9.7% after stress and to 85.7%±7.9% after injection at rest (P<0.05). In 19 patients with angiographically documented coronary artery disease, single-photon emission tomography was performed 5 min and 120 min after injection at maximum stress. For analysis, sestamibi activity was scored semiquantitatively in six left ventricular segments. Furthermore, sestamibi uptake was assessed quantitatively using a circumferential profile method. In 35 of 114 segments the score improved within 120 min p.i. (early fillin); in these segments relative sestamibi activity rose from 69.9%±22.5% to 74.5%±20.8% (P<0.01). In five patients this early fill-in was the only sign of exercise-induced hypoperfusion. In 7 of 114 segments the score deteriorated 120 min p.i. (early tracer washout); in these segments relative sestamibi activity declined from 85.6%±9.9% to 80.1%±10.7% (P<0.02). In three of four patients with early tracer washout the corresponding coronary artery was significantly narrowed. In conclusion, a global myocardial sestamibi washout was registered within the first 120 min after injection. A fill-in of initial defects as well as an early tracer loss could be detected in a relevant number of patients with chronic coronary artery disease during the first 2 h p.i. In these patients the extent of detected reversible perfusion abnormality depends on the chosen time interval between injection and imaging. The results of this study suggest that exercise imaging should be started immediately after injection.     

Scintimammography with technetium-99m tetrofosmin in the diagnosis of breast cancer and lymph node metastases

The aim of the study was to evaluate the possible role of scintimammography (SMM) with technetium-99m tetrofosmin in breast cancer. Thirty-three patients with breast disease and ten normal controls were included in the study. Planar scintigraphic images in supine anterior, prone lateral and lateral views, with the patient lying in lateral recumbency, were acquired. A qualitative analysis evaluating both breasts and lymph nodes was performed. All breast lesions were verified after surgery and/or by fine-needle aspiration. In 8 of the 33 patients, mammography was inconclusive because of mastectomy or dense breasts. For mammography, a sensitivity of 95.6%, a specificity of 66.7% and an accuracy of 89.6% were obtained. At SMM, 26 out of 28 malignant lesions (average size 2.8 cm, range 0.4–12 cm), including two recurrences, were detected with a 92.8% sensitivity, a 100% specificity and a 95.1% accuracy. The smallest detectable carcinoma measured 0.6 cm. Two false-negative results on SMM were found in a 0.4-cm intraductal carcinoma and in the only mucinous papillary carcinoma in our series. With regard to lymph node analysis, 11 out of 12 axillary metastases (sensitivity=91.6%) were detected. A false-positive result, yielding a specificity of 92.3% was also obtained. A metastatic involvement of the internal mammary chain was observed. No uptake was seen in 11 benign mammary lesions or at the level of the breast and axilla when neoplastic involvement was absent. In conclusion, SMM with^99mTc-tetrofosmin is an effective technique for the evaluation of primary breast carcinomas, recurrences and lymph node metastases.     

A comparative study of technetium-99m sestamibi and technetium-99m tetrofosmin single-photon tomography in the detection of nasopharyngeal carcinoma

The intention of this prospective study was to compare the diagnostic potential of technetium-99m sestamibi (MIBI) and a novel radiotracer,^99mTc-Tetrofosmin (Tetro), for the assessment of primary nasopharyngeal carcinoma (NPC) and the differentiation of residual disease from post-therapy changes. A total of 38 patients underwent MIBI and Tetro single-photon emission tomography (SPET) imaging at initial presentation (n=22) or following therapy (n=16). The findings were correlated with computed tomography or magnetic resonance imaging (MRI) on a site-by-site basis. Tumour/background (Tm/Bkg) ratios were obtained on coronal sections. Biopsy (nine patients) and/or 12- to 24-month clinical follow-up data were available in the post-therapy group. All primary disease sites were accurately detected by both imaging studies. Although there was no statistical difference between the two imaging techniques in the detection of primary disease, MIBI was superior to Tetro in the detection of regional lymph node metastases (sensitivity: 95% vs 79%). Tetro and MIBI SPET were true-positive in all patients (n=7) with proven residual/recurrent diseuse. In nine patients who had no evidence of residual/recurrent tumour, MRI was false-positive in five while Tetro and MIBI SPET were false-positive in two and three patients, respectively. Tm/Bkg ratios were 1.7 in all false-positive cases except one. Tetro, MIBI and MRI had specificities of 78%, 67% and 44%, and accuracies of 87.5%, 81% and 69%, respectively. The results of Tetro and of MIBI SPET were rot statistically different from one another with regard to the prediction of residual/recurrent or metastatic NPC.     

The role of technetium-99m methoxyisobutylisonitrile scintigraphy in the differential diagnosis of cold thyroid nodules

Various diagnostic techniques have been successfully used in the clinical management of cold nodules; however, the decision on whether to employ surgery or a conservative treatment is not always easy. This study was designed to appraise the diagnostic value of technetium-99m methoxyisobutylisonitrile (MIBI) scintigraphy in the assessment of cold nodules detected using ^99mTc-pertechnetate. Fifty-two patients were included in the study. All had already been selected for surgery, based on their clinical and laboratory findings, including fine-needle aspiration biopsy. The total number of cold nodules on ^99mTc-pertechnetate scans was 59. The thyroid scan was performed 20-40 min after i.v. injection of 400 MBq of ^99mTc-MIBI. Uptake of MIBI in thyroid nodules was compared with that in the surrounding normal thyroid tissue, and a score of between 0 and 3 was assigned to each nodule as follows: 0, cold; 1, decreased; 2, equal; 3, hot. Definitive histology revealed nodular goitre in 24 cases, adenoma in 19, thyroiditis in 1, differentiated cancer in 12, medullary cancer in 2, and anaplastic cancer in 1. None of the degenerative nodules were hot on MIBI scan, while the adenomas showed a variety of MIBI imaging patterns, most frequently the score 3 pattern. In the diagnosis of differentiated thyroid cancer the sensitivities of score 3 and score 2+3 MIBI uptake patterns were 83% (10/12) and 100%, respectively. The score 3 MIBI uptake pattern had a specificity of 100% and a positive predictive value of 100% with respect to thyroid (benign and malignant) neoplastic diseases, whereas a specificity of 72% and a positive predictive value of 43% were observed in the detection of differentiated cancer. After a cold nodule had been detected using ^99mTc-pertechnetate, a second scan with high MIBI uptake increased by 7.8 times the probability that this nodule would be a differentiated cancer. In conclusion, ^99mTc-MIBI scintigraphy is a useful method in the differential diagnosis of cold thyroid nodules if the primary aim is to differentiate degenerative from neoplastic diseases rather than to differentiate benign from malignant nodules. High MIBI uptake considerably increases the probability of a differentiated thyroid cancer and facilitates immediate surgical removal, while decreased uptake actually excludes it. We suggest a combination of fine-needle aspiration biopsy and MIBI scan as a routine diagnostic approach to cold thyroid nodules. Received 12 January and in revised form 18 March 1999     

Time course of technetium-99m sestamibi myocardial distribution in dogs with a permanent or transient coronary occlusion

The influence of duration of coronary occlusion and reperfusion on technetium-99m hexakis-2-methoxyisobutylisonitrile (^99mTc-sestamibi) myocardial redistribution between necrotic, salvaged and non-ischaemic myocardium was investigated in dogs submitted either to a 90-min or a 24-h permanent left descending coronary artery occlusion (groups 1 and 2) or to a 90-min occlusion followed by 30 min, 6 h or 22.5 h of reperfusion (groups 3, 4 and 5). In all groups, ^99mTc-sesta-mibi and radiolabelled microspheres were injected at 45 min of occlusion. After delimiting the area at risk and the infarct by Evans blue perfusion and triphenyltetrazolium chloride staining, radioactivity of heart slices from normal, viable-ischaemic and necrotic myocardium was measured in a gamma counter. A significant (P<0.001) linear relationship between ^99mTc-sestamibi distribution and myocardial blood flow was observed in the area at risk of groups 1 (r=0.92), 2 (r=0.84), 3 (r=0.90), 4 (r=0.93) and 5 (r=0.58). In all groups, the mean percentage of ^99mTc-sestamibi uptake in the ischaemic over normal zone overestimated significantly (P<0.05) the mean percentage of the ratio in myocardial blood flow measured with microspheres (group 1: 13.3±1.4 vs. 7.7±1.2; group 2: 15.9±2.0 vs 5.6±1.2; group 3: 14.9±1.6 vs 6.2±1.0; group 4:20.9±1.7 vs 10.9±1.8; group 5: 51.0±2.7 vs 14.0±2.0). This overestimation of blood flow by ^99mTc-sestamibi approximated a ratio of 2 after brief (90 min) or sustained (24 h) occlusion and after 30 min or 6 h of reperfusion, but increased to almost 4 in group 5 with prolonged (22.5 h) reperfusion, indicating a significant redistribution of the tracer. In this group, redistribution was more pronounced in the viable-ischaemic zone as indicated by a ^99mTc-sestamibi uptake vs the normal zone of 66.5%±5.5% (P<0.05) as compared to 31.5%±3.3% in the necrotic zone, whereas the uptake in the necrotic zone of the 24 h permanently occluded group averaged 22.1%±3.4%. We conclude that upon 6 h of reperfusion, ^99mTc-sestamibi myocardial distribution is still flow dependent, with a net overestimation of the ischaemic myocardial blood flow. Prolonged reperfusion redistributes the tracer to the viable and necrotic myocardium in a 2:1 ratio. In these conditions, reperfusion may be overestimated and infarct size underestimated.     

Tc-99m sestamibi parathyroid imaging in a rare case of parathyroid lipoadenoma

Parathyroid lipoadenoma is an unusual cause of primary hyperparathyroidism. Only a few earlier reports have documented parathyroid imaging in diagnostic studies of parathyroid lipoadenoma. Our case was a 27-year-old man, who was originally diagnosed with primary hyperparathyroidism. He underwent a Tc-99m sestamibi dual-phase parathyroid imaging study, which revealed a right-inferior parathyroid hyperfunctional lesion. The first operation removed a lesion of 1.5 cm in diameter in the area, and parathyroid lipoadenoma was diagnosed by pathology. However, hypercalcemia persisted. One week later, a Tc-99m sestamibi whole-body scan and another dual-phase imagining were performed, which demonstrated a residual lesion in the inferior part of the right thyroid region, while no ectopic lesion was found. A second surgery was performed and pathological diagnosis was confirmed as parathyroid lipoadenoma again. Our case demonstrated that although hyperfunctional parathyroid lipoadenoma is rare, Tc-99m sestamibi parathyroid imaging is reliable in locating the lesion for surgical purposes. And Tc-99m sestamibi imaging is useful in reoperative and persistent hyperparathyroidism situations as well.     

Adenosine technetium-99m sestamibi single-photon emission tomography for the assessment of jeopardized myocardium early after acute myocardial infarction

This study investigated the value of technetium-99m sestarnibi scintigraphy in identifying patients at risk for post-infarct ischaemia (=jeopardized myocardium), especially within the reperfused infarct region. In 51 patients with a recent (99mTc-sestamibi single-photon emission tomography (SPET) and dobutamine stress echocardiography (DSE) were performed and correlated with the presence of significant coronary artery stenosis [% diameter stenosis (DS) >50%] on quantitative coronary angiography. Regional perfusion activity was analysed semiquantitatively (score 0–4) on a 13-segment left ventricular model. DSE was used for the estimation of the infarct size (low-dose DSE) and for concomitant evaluation of ischaemia (high-dose DSE). A reversible perfusion defect within the infarct region was observed in 20 of the 37 patients with a significant infarct-related lesion (sensitivity of 54%) and only in one patient without a significant infarct-related lesion (specificity of 93%). Further analysis revealed that the scintigraphic assessment of jeopardized myocardium was fairly good in patients with a moderate (DS 51%–64%) infarct-related stenosis but was inadequate in patients with a severe (DS65%) infarct-related stenosis (sensitivity of 80% vs 36%,P<0.01), while the echocardiographic detection of ischaemia was not influenced by stenosis severity (sensitivity of 73% in both subgroups). This scintigraphic under-estimation of jeopardized myocardium was mainly related to a severely impaired myocardial perfusion under baseline conditions, as was evidenced by a significantly more severe rest perfusion score in the infarct region in patients with a severe stenosis as compared to those with a moderate stenosis (average score: 1.5±0.7 vs 2.1±0.6,P<0.01), while infarct size on echocardiography was similar for both subgroups. It may be concluded that early after an acute myocardial infarction, adenosine^99mTc-sestamibi SPET may underestimate reperfused but still jeopardized myocardium, particularly in patients with a severe infarct-related stenosis. In these patients the evaluation of the ischaemic burden on rest-stress scintigraphy is hampered by the presence of a severely impaired myocardial perfusion in resting conditions.     

Exercise gated planar myocardial perfusion imaging using technetium-99m sestamibi for the diagnosis of coronary artery disease: an alternative to exercise tomographic imaging

Single-photon emission tomography (SPET) using technetium-99m labelled myocardial tracers (e.g.^99mTc-sestamibi) has become one of the most popular myocardial imaging methods for the diagnosis of coronary artery disease (CAD). This prospective study was designed to evaluate the diagnostic performance of^99mTc-sestamibi exercise gated planar myocardial imaging by comparison with both visual and quantitative analyses of SPET. The study was conducted in 115 consecutive patients with known or suspected CAD, including 54 patients with a previous myocardial infarction (MI), referred for exercise testing prior to coronary angiography. Multi-gated planar imaging and SPET were performed after bicycle exercise. The end-diastolic (ED) and SPET images were visually scored (SVi). Myocardial uptake was quantitated on SPET slices using maximum count circumferential profiles (SQu) and defect extent was measured by comparison with gender-matched data sets obtained from 27 controls (<5% likelihood of CAD). CAD was defined as coronary artery stenosis >50% and/or regional wall motion abnormality. The cut-off criteria for positivity of the three procedures were determined from receiver operating characteristic (ROC) curves derived from the data of patients without previous MI. The area under the ROC curves was similar for ED, SVi and SQu. This was confirmed by the analysis of sensitivity performed using the ROC curve-derived cut-off criteria, in patients with or without previous MI. SVi was more sensitive than ED in identifying the diseased vessel(s) (ED: 41% vs SVi: 80%;P<0.0005) but ED was more specific in this respect (ED: 79% vs SVi: 61%;P<0.0005). We conclude that visual analysis of ED images obtained from gated^99mTc-sestamibi stress planar imaging is a valuable alternative to SPET imaging for the diagnosis of CAD. SPET is, however, more accurate for the evaluation of the disease extent and localization and therefore remains the method of choice for the assessment of myocardial perfusion.     

Scintimammography with technetium-99m methoxyisobutylisonitrile: comparison with mammography and magnetic resonance imaging

The aim of the study was to compare the diagnostic accuracy of scintimammography with technetium-99m methoxyisobutylisonitrile (MIBI; SMM) in the detection of primary breast cancer with that of mammography (MM) and magnetic resonance imaging (MRI). Fifty-six patients with suspected lesions detected by palpation or MM were included in the study. Within the 4 weeks preceding excisional biopsy, MM and MRI were performed in all patients. Between 5 and 10 min after the injection of 740 MBq^99mTc-MIBI, SMM in the prone position was performed. In the total group of 56 patients, 43 lesions were palpable, while 13 were non-palpable but were detected by MM. Breast cancer was confirmed by histopathology in 27 of the patients (22 palpable and 5 non-palpable carcinomas). The tumour size ranged from 6 to 80 mm in diameter. For non-palpable lesions, the sensitivity of SMM, MM and MRI was 60%, 60% and 100%, respectively, while the specificity was 75%, 25% and 50%, respectively. For palpable breast lesions, all methods showed high sensitivity (SMM 91%, MM 95%, MRI 91%) but SMM demonstrated significantly higher specificity (SMM 62%, MM 10%, MRI 15%). In two mammographically negative tumours (dense tissue), SMM showed a positive result. In comparison to MRI, one additional carcinoma could be diagnosed by SMM. It may be concluded that for palpable breast lesions, the diagnostic accuracy of SMM is superior to that of MM and MRI. Through the complementary use of SMM it is possible to increase the sensitivity for the detection of breast cancer and multicentric disease. In patients in whom the status of a palpable breast mass remains unclear, SMM may help to reduce the amount of unnecessary biopsies.