Role of technetium-99m sestamibi in localisation of thyroid cancer metastases

Technetium-99m sestamibi (MIBI) is a routinely used myocardial perfusion imaging agent. We have studied groups of patients with differentiated thyroid carcinoma, in order to evaluate the usefulness of this agent in localising regional neck and nodal disease and metastases. There are three groups of patients. Group 1 consisted of patients with known nodal disease or metastases (22 patients) and with raised serum thyroglobulin levels (Tg). Group 2 comprised patients with normal I-131 scans and normal Tg levels (nine patients). Non-thyroid malignancies (six patients) comprised an additional group 3. In group 1, the MIBI scan showed 47 sites of metastases, while the I-131 scan revealed 49 sites. The MIBI scan was positive in two patients where the I-131 scan was negative, while in two other patients, the MIBI study was negative whereas the I-131 scan was positive. In group 2, 6/9 patients had no disease, 2/9 had thyroid remnants, and 1/9 had a fresh primary lung tumour, unrelated to the earlier thyroid cancer. All of them had normal MIBI scans. In group 3, two patients with lung cancer and two with breast cancer and metastases had normal MIBI scans. A further two patients with nasopharyngeal cancer (NPC) had mildly increased MIBI localisation in neck nodes and bone metastases. In summary, Tc-99m sestamibi appears to be as good as I-131 in search for thyroid carcinoma metastatic spread, especially nodal disease and this tracer does not localise well in the primary or metastases of other cancers.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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.     

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

Mitoxantrone (MIT) is a new anthraquinone anticancer agent. We treated 14 patients with locally advanced breast cancer, 3 of which were inflammatory breast cancers, by pre-operative arterial injection of MIT. The treatment protocol was MIT 12 mg/m2 injected into both the internal mammary and the subclavian arteries with oral administration of 5'-DFUR 1,200 mg/day for 20 days. After 2 courses, all tumors were decreased over 50% in size. Down-staging was obtained in all of 8 cases. Mastectomy could be carried out on all patients, without microscopically residual tumor cells. Preoperative arterial injection of MIT might be the treatment of choice for locally advanced breast cancer to perform down-staging, however the survival benefit has remained equivocal. These preliminary results are encouraging to further studies.     

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: 0=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 201Tl 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.     

Thallium-201, technetium-99m-tetrofosmin and iodine-131 in detecting differentiated thyroid carcinoma metastases

The purpose of this study was to asses the detectability of differentiated thyroid carcinoma (DTC) metastases by 99mTc-tetrofosmin and to compare the results of 99mTc-tetrofosmin with 131I and 201Tl. The reliability of 201Tl and 99mTc-tetrofosmin scanning during suppression therapy also has been studied. METHODS: A prospective study was performed on 41 patients (30 females, 11 males) with DTC (30 papillary, 11 follicular) who had undergone total thyroidectomy and received an average dose of 117 mCi (4329 MBq) of radioiodine for ablation of postsurgical residual thyroid tissue. All patients (n = 41) had 201Tl, 99mTc-tetrofosmin or 131I whole-body imaging after discontinuation of thyroid hormone replacement (thyroxine-off group). Eight of 14 patients with distant metastases also were imaged when they were on thyroxine therapy both with 201Tl and 99mTc-tetrofosmin (thyroxine on-and-off group). Radiologic studies (chest radiography, CT and MRI), serum thyroglobulin assays and histopathologic examinations were performed to clarify the presence of metastases with positive uptake on any of three radionuclide studies. RESULTS: In 26 of 41 patients all three scans were negative. These patients also clinically didn't show any evidence of metastases. Fourteen patients were considered to have distant metastases on the basis of clinical, radiologic and histopathologic findings. The sensitivities of 201Tl, 99mTc-tetrofosmin and 131I in diagnosing distant metastases were comparable (0.85, 0.85 and 0.78, respectively). Iodine-131 was much more sensitive than 201Tl and 99mTc-tetrofosmin for demonstrating residual thyroid tissue after surgery (1.00, 0.33 and 0.33, respectively). The only false-positive case involved radioiodine uptake in a tuberculoma. Thyroxine-on images of 8 patients with distant metastases showed no difference from their thyroxine-off images regarding the site, number and uptake of metastases. CONCLUSION: Technetium-99m-tetrofosmin and 201Tl imaging are highly sensitive for detecting differentiated thyroid carcinoma metastases and do not require prior withdrawal of thyroid hormone suppressive therapy.     

Role of technetium-99m sestamibi myocardial imaging in the emergency department evaluation of chest pain

The use of technetium-99m sestamibi myocardial imaging is rapidly becoming a state of the art methodology for the emergency department evaluation of patients with chest pain. The following case report represents the first emergency department sestamibi scan ordered at the University of Mississippi Medical Center and is used to discuss the logistics and indications for such tests. A general guideline for ordering sestamibi scans has been developed for use in the emergency department.     

Tc-99m sestamibi scintigraphy in multiple myeloma

Tc-99m sestamibi imaging was performed in two patients with multiple myeloma. Focal areas of increased uptake in one patient and diffuse skeletal uptake in the second patient were found. Tc-99m sestamibi appears to identify bone marrow and osteolytic involvement in multiple myeloma.     

Technetium-99m sestamibi tomographic evaluation of residual ischemia after anterior myocardial infarction

OBJECTIVES: This study investigated the value of sestamibi scintigraphy in assessing residual ischemia after anterior myocardial infarction. BACKGROUND: Serial imaging with sestamibi, the uptake and retention of which correlate with regional myocardial blood flow and viability, has been used to estimate salvaged myocardium and risk area after acute infarction. We recently documented that recovery of perfusion and contraction in the infarcted area may continue well after the subacute phase, suggesting myocardial hibernation. Some underestimation of viability in the setting of hibernating myocardium by sestamibi imaging has been reported. METHODS: We studied 58 patients in stable condition after Q wave anterior infarction. Regional perfusion and function were quantitatively assessed by sestamibi tomography and two-dimensional echocardiography at 4 to 6 weeks and at 7 months after infarction. In sestamibi polar maps, abnormal areas with tracer uptake > 2.5 SD below our reference values were computed at rest and after symptom-limited exercise. On two-dimensional echocardiography the ejection fraction and extent of rest wall motion abnormalities were assessed by a computerized system. All patients had coronary angiography between the two studies. RESULTS: At 7 months the extent of rest sestamibi defect was significantly reduced in 40 patients (69%, group 1) and unchanged in 18 (31%, group 2). Rest wall motion abnormalities and ventricular ejection fraction significantly improved in group 1 but not in group 2. Underlying coronary disease, patency of the infarct-related vessel and rest sestamibi defect extent at 5 weeks were comparable between the two groups. At 7 months, an increase in the reversible (stress-rest defect) tracer defect was observed in group 1 (p < 0.05) despite a smaller stress-induced hypoperfusion (p < 0.05). Reversible sestamibi defects and stress hypoperfusion were unchanged in group 2. In 38 (95%) of 40 group 1 patients, the area showing reversible sestamibi defects at 7 months matched the area showing fixed hypoperfusion at 5 weeks. CONCLUSIONS: The reduction in the rest tracer uptake defect that can occur late after infarction may affect the assessment of ischemic burden by sestamibi imaging early after anterior myocardial infarction.     

Preoperative parathyroid gland localization with technetium-99m sestamibi in secondary hyperparathyroidism

Technetium-99m sestamibi scintigraphy has become a valuable tool in locating parathyroid glands in patients with primary hyperparathyroidism. The aim of this study was to evaluate its usefulness in secondary hyperparathyroidism. Twenty patients were injected intravenously with 740 MBq of 99mTc-sestamibi and images were obtained at 15 min and 2 h post injection. All patients underwent parathyroid ultrasonography (US) as well as bilateral surgical neck exploration and 64 parathyroid glands were removed. US revealed at least one enlarged gland in 15/20 patients (75%), while 99mTc-sestamibi scintigraphy showed focal areas of increased uptake in at least one gland in 17/20 patients (85%). When imaging results for all glands were evaluated according to surgical results, sensitivity was 54% for parathyroid scintigraphy and 41% for US, and specificity was 89% for both imaging techniques. There was a discrepancy between the two imaging modalities in 28 glands (35%). The mean surgical weight of US-positive glands (1492+/-1436 mg) was significantly higher than that of US-negative glands (775+/-703 mg) (P<0.05). However, there were no significant differences in weight between sestamibi-positive and sestamibi-negative glands. When only sestamibi-positive glands were considered, a positive correlation between uptake and weight was found (r=0.4, P<0.05). In conclusion, parathyroid US and 99mTc-sestamibi scintigraphy are complementary imaging techniques in the preoperative localization of abnormal parathyroid glands in patients with secondary hyperparathyroidism. The limited sensitivity of the techniques means that patients will still require bilateral neck exploration; therefore routine preoperative parathyroid scanning in renal patients is not justified.     

Technetium-99m biliary imaging in pediatric surgical problems

The results of scintigraphic imaging of the hepatobiliary system with 99mTc-PIPIDA (IDA derivative p-isopropylacetanilidoiminodiacetic acid) in forty children are reported. 99mTc-PIPIDA imaging is a noninvasive, rapid, safe examination that provides both functional and anatomical information about the hepatobiliary system. Although interpretation is limited by elevated direct serum bilirubin, this agent allows diagnostic information to be obtained with direct serum bilirubin levels up to 8 mg/dl.     

Use of exercise technetium-99m sestamibi SPECT imaging to detect residual ischemia and for risk stratification after acute myocardial infarction

The clinical presentation, electrocardiographic findings, and technetium-99m sestamibi single-photon emission computed tomography (SPECT) imaging results of 134 consecutive patients who underwent nuclear exercise testing within 14 days of an acute myocardial infarction (AMI) were correlated with cardiac events over a 15 +/- 10-month follow-up. Whereas only 23 patients (17%) had chest pain and 31 (23%) had ischemic ST-segment depression during exercise, 94 (70%) had ischemia on SPECT (p < 0.001). On follow-up, 13 patients experienced a cardiac event: 7 were rehospitalized for unstable angina, 3 had recurrent AMI, and 3 died of cardiac causes. Ischemia on the sestamibi images identified 11 of these patients (85%), whereas chest pain identified only 3 (23%, p = 0.006), and electrocardiographic ischemia identified only 4 (31%, p = 0.017). The presence of either ischemia as seen on SPECT or defects in multiple vascular territories identified 12 patients (92%) with an event, including all who had cardiac death. By Cox regression analysis of clinical, stress, and image parameters, the number of ischemic defects on SPECT was the only significant correlate of a future event (chi-square = 4.62, p = 0.03), and patients with > or = 3 reversible sestamibi defects had an event rate of 38%. The extent of ischemia as seen on nuclear imaging remained a strong correlate (p = 0.008) of an event in the 54 patients (40%) who had received thrombolytic therapy. Thus, exercise technetium-99m sestamibi SPECT after AMI frequently reveals residual ischemia, and is better than clinical data, symptoms, and stress electrocardiographic data in identifying patients who will have a subsequent cardiac event.     

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.     

Better visualization of retinoblastoma metastases with Tc-99m sestamibi versus Tl-201

Tc-99m sestamibi has been shown to accumulate in several primary malignant tumors, but data regarding its use in the detection of distant metastases are limited. Despite its physical limitations, Tl-201 now has a definite place in the routine evaluation of certain primary and metastatic tumors. This report describes the value of Tc-99m sestamibi and its superiority to Tl-201 in the visualization of distant metastases in a 2-year-old girl with bilateral retinoblastoma. Three sites of soft tissue and bone metastasis were demonstrated by Tc-99m sestamibi imaging. Of these metastases, the one in the parieto-occipital region showed evident Tl-201 uptake, while the other two in the right arm and chest wall showed only slightly increased uptake, which could hardly be spotted without the confirmation of a later Tc-99m sestamibi scan. The scintigraphic findings were confirmed with histopathologic examination. Tc-99m sestamibi scan is effective and superior to Tl-201 in the detection of distant soft tissue and bone metastases from retinoblastoma.     

Brain metastases in patients with differentiated thyroid carcinoma

We present a retrospective review of six patients who developed brain metastases in our series of 649 with differentiated thyroid carcinoma seen at the Royal Marsden Hospital between 1936 and 1991. Prognosis was poor, with survival 1-19 months from the diagnosis of brain metastases in five patients. One patient remains alive at 18 months. A dosimetric approach may help to individualize and optimize treatment.     

Clinical experience with technetium-99m stannous polyphosphate for myocardial imaging

Myocardial imaging with technetium-99m stannous polyphosphate was performed on 46 patients. Eleven patients had no cardiac disease, 22 had acute myocardial infarction, and 13 had stable arteriosclerotic heart disease. Distinct patterns of myocardial activity were noted: (1) the patients with no obvious cardiac disease showed no cardiac activity; (2) stable arteriosclerotic heart disease showed faint, ill-defined cardiac activity, primarily in the anterior or inferior aspect of the left ventricle; (3) acute myocardial infarction showed intense, focal, well-defined activity, with a shape that characterized the location of the infarct.