Methoxyisobutylisonitrile Scintigraphy Research Articles

Could Negative Tc-99m-Methoxyisobutylisonitrile (MIBI) Scintigraphy Obviate the Need for Surgery for Bethesda III and IV Thyroid Nodules?

In about 20% of all cases, the fine needle aspiration cytology (FNAC) results are equivocal, delivering the two common categories of indeterminate cytology, Bethesda III and IV. The observed rates of malignancy vary widely among institutions, with the urgent need for a more precise risk stratification. 99mcTc methoxyisobutylisonitrile scintigraphy (MIBI) is less expensive than molecular testing and has been shown to have a high negative predictive value. For this reason, the results of MIBI scintigraphy in adult patients with indeterminate FNAC were collected, and correlated with the final pathology reports of surgical specimens. Patients receiving FNAC, MIBI scintigraphy and surgery for sonographic suspicious hypofunctional thyroid nodules between 2015 and 2019 at the University Hospital of Cologne, Germany were identified. Sensitivity, specificity, positive predictive and negative predictive value of MIBI scintigraphy were calculated. Seventy-eight patients with sonographic suspicious hypofunctional thyroid nodules underwent surgery after interdisciplinary case discussion of both FNAC and MIBI results. In 49 (62.5%) cases, FNAC consisted of Bethesda III and IV results. In 39 (79.6%) of these cases, MIBI scintigraphy resulted in mismatch and intermediary results, but in only 4 (10.2%) of these cases was a carcinoma diagnosed. The negative predictive value of MIBI scintigraphy was 90–100%, respectively. Relying on the negative predictive value of MIBI match results might have obviated the need for surgery in 20.4% cases; one papillary microcarcinoma, however, would have been missed. MIBI scintigraphy has an underused potential for improving the diagnostic precision of hypofunctional thyroid nodules.

Diagnostic value of ultrasonograpy and 99mTc-MIBI scintigraphy for preoperative localization of parathyroid adenomas

Aim: The primary treatment of primary hyperparathyroidism (PHPT) is parathyroidectomy. With its shorter operative time and healing period, lesser general anesthesia duration, lesser hypoparathyroidism risk and better cosmetic results minimally invasive parathyroidectomy is the most commonly performed contemporary surgical procedure. However, in order for this procedure to be successful, it is important to know the location of the parathyroid adenoma. The purpose of this study was to determine the diagnostic value of Ultrasonography (USG) and technetium methoxyisobutylisonitrile scintigraphy (99mTc-MIBI) in the preoperative localization of parathyroid adenoma. Materials and Methods: Fifty-two patients diagnosed with parathyroid adenoma were included in the study. Preoperative parathyroid USG and 99mTc-MIBI were performed on all patients. All patients’ preoperative serum calcium, phosphorus, parathormone and Vitamin D levels, parathyroid USG and 99mTc-MIBI, intraoperative parathyroid lesion location and histopathological examination results were recorded. Results: Patients aged between 22 and 81 (51.7±15.6) were eventually enrolled. When USG was used alone, the site of the adenoma was correctly determined in 26 of the 52 patients with a sensitivity of 52% and a positive predictive value of 92.8%. When scintigraphy was performed alone, the site of the adenoma was correctly identified in 39 of the 52 patients. Sensitivity was thus 76.4% and positive predictive value 97.5%. When USG and scintigraphy were assessed together, adenoma location was correctly identified in 45 of the 52 patients. Sensitivity for the two tests employed together was 88.2% and positive predictive value was 97.8%. Conclusions: Due to the high sensitivity of combined use of USG and 99mTc-MIBI, we recommend the two tests to be assessed together before parathyroid surgery.

Causes of false negatives in technetium-99m methoxyisobutylisonitrile scintigraphy for hyperparathyroidism: influence of size and cysts in parathyroid lesions.

The aim of this study was to elucidate the causes of false-negative cases of technetium-99m methoxyisobutylisonitrile scintigraphy (MIBI) for hyperparathyroidism. Consecutive MIBI examinations performed in 154 patients between April 2011 and March 2017 were retrospectively reviewed. Sensitivities of MIBI, CT and US were calculated. The effects of serum calcium, phosphorus, PTH, weight of parathyroid lesions, use of NSAIDs and Ca-channel blocker (CCB), presence of cyst in parathyroid lesions, and a number of lesions observed by MIBI were investigated. Seventy-nine patients (21 men and 58 women), ranging from 18 to 88years of age (mean ± SD: 57.6 ± 15.3years), who underwent parathyroidectomy, were included. MIBI and preoperative US were performed in the 79 patients and single-phase parenchymal contrast-enhanced CT (CE-CT) was performed in 55 patients. A total of 120 parathyroid proliferative nodules were detected by MIBI and US, and 92 lesions were detected by CE-CT. In the lesion base, MIBI detected 82 out of the 120 lesions (sensitivity = 68.3%), US detected 103 out of the 120 lesions (sensitivity = 85.8%), CE-CT detected 63 out of the 92 lesions (sensitivity = 68.5%), and MIBI plus CE-CT detected 72 of the 92 lesions (sensitivity = 78.3%). A significant difference in the sensitivity was found between US and MIBI (P < 0.01), and between US and CT (P < 0.01). In the patient base, MIBI detected 67 out of the 79 patients (sensitivity = 84.8%), US detected 74 out of the 79 patients (sensitivity = 93.7%), CE-CT detected 45 out of the 55 patients (sensitivity = 81.8%), and MIBI plus CE-CT detected 52 out of the 55 patients (sensitivity = 94.5%). No significant difference was observed in any of the comparisons. A significant difference was observed in lesion weight (P < 0.01), single or multiple lesions (P = 0.02), and presence of cyst (P < 0.01) between the MIBI false-negative (n = 38) and the true-positive groups (n = 82). The presence of cyst in parathyroid proliferative lesions as well as small size and multiple number of parathyroid lesions contribute to false negative in parathyroid MIBI scan.

Thoracoscopic surgical case of an ectopic mediastinal parathyroid adenoma detected by chance: a case report

BackgroundEctopic mediastinal parathyroid tumor (EMPT) is a rare cause of primary hyperparathyroidism (PHPT); it is difficult to resect using the cervical approach. We describe a case of using video-assisted thoracic surgery (VATS) for EMPT resection.Case presentationA 67-year-old woman with a history of postoperative thyroid cancer had no symptoms. She was diagnosed with PHPT and underwent thyroid cancer surgery. She had serum calcium and intact parathyroid hormone (PTH) levels of 11.1 mg/dL and 206 pg/mL, respectively. Chest computed tomography showed a 10-mm nodule in the anterior mediastinum. Technetium-99 m methoxyisobutyl isonitrile scintigraphy showed an abnormal uptake lesion in the anterior mediastinum. She was diagnosed with PHPT caused by EMPT and underwent VATS. The pathological examination confirmed parathyroid adenoma. Her serum calcium and intact PTH levels were normal from 15 min after tumor resection. She has had no recurrence of EMPT.ConclusionsThe VATS approach was effective for the resection of EMPT.

Effect of trifluoperazine on Tc-99m sestamibi uptake in patients with advanced nonsmall cell lung cancer.

Objective:The aim of this study was to investigate whether there is an effect of trifluoperazine on Tc-99m methoxyisobutylisonitrile (MIBI) uptake in patients with advanced nonsmall cell lung cancer (NCLC).Materials and Methods:A total of 23 patients with biopsy-proven advanced NCLC who had no previous history of chemo-radiotherapy, underwent baseline dual phase planar, single photon emission computed tomography and whole body Tc-99m MIBI scintigraphy performed at 20 and 120 min. After oral administration of trifluoperazine (5 mg, 2 times a day, for 5 days), dual phase Tc-99m MIBI scintigraphy was repeated. For each patient, and for both studies, regions of interest were drawn over the tumor area (T) and over the normal lung area (L) on the contralateral side in transverse slices where tumor was visualized clearly. Then, early and delayed T/L ratios and washout rate (WR) were calculated.Results:Tc-99m MIBI was accumulated in the cancer tissue in all of the patients. Delayed ratio after the oral administration of trifluoperazine (DR2) was significantly higher (P = 0.039) than delayed ratio before trifluoperazine (DR1). We found no significant differences of early ratio before trifluoperazine (ER1) and early ratio after trifluoperazine (ER2), and washout rate before (WR1) and washout rate after trifluoperazine (WR2).Conclusion:In patients with advanced NCLC, trifluoperazine treatment in addition to chemotherapy might be useful. However, our results need to be confirmed in larger series of patients.

Combined Tc-99m sesta MIBI scintigraphy and Ultrasonography in preoperative detection and localization of parathyroid adenoma

PurposeTo evaluate the role of combined high resolution ultrasonography and technetium Tc-99m methoxyisobutylisonitrile (MIBI) parathyroid scintigraphy in preoperative detection and localization of parathyroid adenoma, for better operative outcome. Patients and methods40 patients were included in this study, 25 of them were females and 15 were males, with age ranging between 31 and 75 (mean 46±15). All patients presented with some of symptoms of hyperparathyroidism with venous blood sampling showed elevated parathyroid hormone (PTH). Parathyroid imaging was evaluated by ultrasonography, double phase Tc-99m MIBI parathyroid scintigraphy with surgical findings and results of clinical follow-up as a reference standard. ResultsAmong the 40 patients, Ultrasonography correctly identified 35 adenomas (87.5%) and MIBI scintigraphy identified 34 adenomas (85%), but when both modalities were applied together, 37 adenomas were correctly detected (92.5%).Minimally invasive parathyroidectomy under local anesthesia with unilateral incision was successfully performed in 34 (85%) patients. ConclusionsAccurate localization of adenomas should be obtained prior to surgery for minimal invasive surgical procedure. In this study, combined ultrasonography and Tc-99m MIBI improved localization of parathyroid adenomas.

Qu’attend le chirurgien de la scintigraphie au sestaMIBI ?

Nowadays, the incidence of hyperparathyroidism is increasing (about 3%). Its revealing aspect and its surgical treatment have changed these past few years. They evolved into mini-invasive approaches which lead to a more accurate gland resection, respecting the healthy ones. The interest of methoxy-isobutyl-isonitrile (MIBI) scintigraphy is now well established and contributes to this evolution. Different categories of hyperparathyroidism (primary, secondary, tertiary, sporadic vs. familial, adenoma vs. carcinoma) have been separated to evoke the consensual surgical indications. SestaMIBI scintigraphy always follows a cervical sonogram and can be associated, in some cases, with a scannography. It only has to be performed in case of a surgery treatment and exclusively helps in topographic diagnosis. However, it remains a lot of false positive errors (nodular goitre, nodular or carcinomatous thyroids, lymphadenopathies) and some rare false negative errors (encountered in early hyperparathyroidism). The major interest of MIBI scintigraphy is its help in the topographic diagnosis of surgical hyperparathyroidism. It can detect parathyroid ectopias, multiglandular diseases, underlining the most pathological ones. It has become the most necessary examination in hyperparathyroidism pre-operative check-up and, in association with sonography and scannography, can lead to an accurate and mini-invasive surgical treatment.

Radioactive probe-guided parathyroidectomy for secondary hyperparathyroidism.

The value of gamma probes in the surgical treatment of secondary hyperparathyroidism (sHPT) was determined. We retrospectively analyzed the clinical data of 48 sHPT patients between May 2007 and September 2011. Preoperative (99)Tc(m)- methoxyisobutyl isonitrile (MIBI) scintigraphy and high-frequency ultrasonography were used for parathyroid localization. Thirty-five patients (group I) underwent conventional neck exploration and open parathyroidectomy. Thirteen patients (group II) underwent gamma probe-guided total parathyroidectomy and parathyroid transplantation. The two groups were compared in terms of the number of parathyroid resections, operative time, and postoperative changes in the blood levels of parathyroid hormone (PTH), calcium, and phosphate. The clinical manifestations, PTH and calcium levels, age distribution, and clinical characteristics did not differ between the two groups. The accuracy of preoperative (99)Tc(m)-MIBI scintigraphy (89.74%) for the diagnosis of hyperparathyroidism did not differ from that of ultrasonography (81.25%). However, the accuracy of (99)Tc(m)-MIBI scintigraphy (66.67%) for localizing hyperfunctioning parathyroids was significantly lower than that of ultrasonography (76.86%). The operation time was significantly longer in group I (120+/-25) min than in group II (90+/-30) min. The accuracy of parathyroid specimens were obtained in group I (2.5+/-0.5) than in group II (3.5+/-0.5). Compared with group I, group II showed a significant increase (15.4%) in the number of parathyroid resections. The PTH, calcium, and phosphate levels significantly decreased postoperatively in all patients. Intraoperative gamma probe examination confirmed that the excised specimen was parathyroid tissue and improved the accuracy of parathyroid resection. The parathyroidectomy rate was increased by 15.4% due to the use of these probes. However, the probes did not detect all ectopic parathyroids, and further research is required to clarify the underlying reasons.

A pilot study to examine the management of asymptomatic hyperparathyroidism in Japanese patients in accordance with the guidelines for asymptomatic PHPT proposed at the Third International Workshop in 2008.

Objective The treatment for asymptomatic primary hyperparathyroidism (PHPT) remains controversial. In 2008, the Third International Workshop on the Management of Asymptomatic PHPT proposed a set of guidelines for the management of asymptomatic PHPT. We therefore evaluated the application of the Workshop recommendations in Japanese patients with asymptomatic PHPT. Methods We analyzed each parameter of the guidelines in 87 Japanese patients with asymptomatic PHPT who underwent methoxy-isobutyl-isonitrile (MIBI) scintigraphy. Results Fewer than 10% of the patients were less than 50 years of age. The bone mineral density T-score was below -2.5 SD in 20 women (46.5% of all women analyzed) and in none of the men. The eGFR was <60 mL/min/1.73 m(2) in 17 patients. A majority of patients (43) satisfied only one parameter, while 25 patients satisfied none of the parameters. Furthermore, the MIBI-positive and surgically treated patients tended to satisfy a larger number of the parameters. The Workshop criteria and levels of PTH, daily Ca excretion, serum ALP and 1,25(OH)2 Vitamin D were further analyzed in relation to the findings of MIBI scans, and almost all of the parameters were found to be significantly correlated with the results of the MIBI studies. Conclusion Our results suggest the need to reassess the Workshop guidelines for the treatment of hyperparathyroidism in Japanese patients. It is desirable that MIBI scintigraphy be performed whenever possible, as this modality is anticipated to play an important role in determining whether or not surgery is appropriate.

An Incidentally Detected Breast Cancer on Tc-99m MIBI Cardiac Scintigraphy

Tc-99m methoxyisobutylisonitrile (MIBI) scintigraphy is generally used as a second-line diagnostic tool for obscured breast lesions. When the entire field of view is examined carefully, it is often possible to detect additional lesions unrelated to the initial intent and purpose of the examination. Herein we present a case of breast cancer incidentally detected by cardiac Tc-99m MIBI scintigraphy. An area of uptake was detected in the breast during a cardiac imaging test. Further evaluation of this lesion revealed a histopathological diagnosis of invasive ductal carcinoma of the breast. Sensitivity of this scintigraphic technique is not enough sufficient to use this test as a screening test for breast cancer, but it may provide supplemental information. Since it is not uncommon to find incidental lesions during imaging studies, examination of the image field may help clinicians find otherwise unrecognized or undiagnosed pathologies.

The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in predicting the therapeutic effect of chemotherapy against nasopharyngeal carcinoma

The authors prospectively evaluated the correlation between technetium-99m methoxyisobutyl isonitrile ((99m) Tc-MIBI) accumulation in tumors and response to induction chemotherapy in patients with nasopharyngeal carcinoma (NPC). Eighty-six patients with locally advanced NPC underwent single-photon emission computed tomography 15 minutes after an intravenous injection of 740 megabecquerels (20 mCi) (99m) Tc-MIBI before chemotherapy. The tumor uptake ratio (TUR) was calculated. Two weeks after the second cycle of combined chemotherapy with 5-fluorouracil (5-FU) and cisplatin (DDP), the tumor response rate was evaluated. The correlation between (99m) Tc-MIBI accumulation in tumors and response to chemotherapy with 5-FU/DDP was examined. Positive accumulation of (99m) Tc-MIBI in tumors was observed in 76 patients (88.4%). The tumor response was a complete response (CR) in 8 patients, a partial response (PR) in 68 patients, stable disease (SD) in 9 patients, and progressive disease (PD) in 1 patient. The response rate (CR and PR) to 5-FU/DDP chemotherapy in patients who had positive (99m) Tc-MIBI accumulation (tumor uptake ratio [TUR] >1.1) was higher than that in patients who had negative (99m) Tc-MIBI accumulation (TUR ≤ 1.1; 98.7% vs 10%; P < .001). Patients with negative (99m) Tc-MIBI accumulation were resistant to 5-FU/DDP chemotherapy. (99m) Tc-MIBI imaging in patients with NPC was capable of predicting tumor response to chemotherapy with 5-FU/DDP and can help in the selection of patients for induction chemotherapy.

Cinacalcet reduces vascular and soft tissue calcification in secondary hyperparathyroidism (SHPT) in hemodialysis patients

Management of secondary hyperparathyroidism (SHPT) in chronic kidney disease patients on hemodialysis (HD) can be challenging. Conventional treatments can lead to hypercalcemia and hyperphosphatemia, both of which are associated with vascular and soft tissue calcification and increased risk of cardiovascular disease. We report the effect of treatment with the Type II calcimimetic cinacalcet on vascular calcification in a HD patient with SHPT. A 40-year-old male with a 24-year history of kidney failure secondary to mesangial proliferative glomerulonephritis, commenced HD in October 2004 following chronic graft dysfunction. The patient was admitted to hospital with renal insufficiency and metabolic abnormalities. An anatomopathological study showed calcium (Ca) deposits in the alveolar septa, bronchial wall and pulmonary arterioles. Parathyroid methoxy isobutyl isonitrile (MIBI) scintigraphy revealed multiglandular parathyroid disease and an ectopic gland behind the sternal notch. Serum intact parathyroid hormone (iPTH) was repeatedly found to be > or = 2,500 pg/ml, and was accompanied by significant abnormalities in phosphorus (P) and Ca metabolism which were difficult to control. The patient was initially treated with sevelamer, low dose calcium carbonate, a low P and reduced protein diet and high doses of intravenous erythropoietin. In addition, he received HD with a high efficiency membrane for 4.5 hours, 4-times weekly. Treatment with cinacalcet was initiated at 30 mg/day and adjusted to achieve National Kidney Foundation Kidney Disease Outcomes Quality Initiative targets for iPTH, P, Ca and Ca-P product. One year following cinacalcet treatment, a chest x-ray showed a moderate reduction in Ca deposits, a bone X-ray showed a significant reduction in vascular calcifications, and parathyroid MIBI scintigraphy showed a disappearance of ectopic focus and minimal remains of glands. Significant reductions in calcemia were controlled by concomitant modifications to oral Ca supplementation, Ca concentration in the dialysis liquid, and administration of paricalcitriol. In the second year of treatment, iPTH was maintained within the target range, with moderate rises in P and stabilization of serum Ca. An echocardiogram showed an improvement in left ventricular hypertrophy. Chest and hand X-rays showed a progressive reduction in calcifications. Radiology showed an improvement in bone morphology, with reduced trabeculation and better cortical definition in the phalanx bones. In conclusion, the changes in iPTH, P and Ca associated with cinacalcet treatment were accompanied by reduced vascular and soft tissue calcification in this patient. There were no cardiovascular events and the patient experienced a marked improvement in quality of life.

Primary osteogenic sarcoma of breast detected on Tc-99m MIBI scintigraphy and Tc-99m MDP skeletal scintigraphy

A 64-year-old woman presented with a painless breast mass. Tc-99m methoxyisobutylisonitrile scintigraphy of both breasts showed a local area of abnormal uptake in the left breast in 5 min and 2 h. A skeletal scan showed very intense concentration of activity in the primary breast tumor in the left breast. A left mastectomy and an axillary dissection were performed. The predominant histologic type of the mass was an osteosarcoma, and the diagnosis of a primary osteogenic sarcoma of the breast was made. Primary osteogenic sarcoma of the breast is rare and represents less than 1% of all primary breast malignancies.

Dobutamine Modulated Tc-99m MIBI Scintigraphy in Secondary Hyperparathyroidism in Uremic Patients

The aim of this study was to determine if low-dose dobutamine infusion can enhance Tc-99m methoxy isobutyl isonitrile (MIBI) uptake of hyperfunctioning parathyroid glands of patients with secondary hyperparathyroidism (SHP). We studied 24 patients with chronic renal failure and SHP. Median age of the sample was 47.5 years. A single-tracer, double-phase technique was performed, acquiring planar images of the neck and thorax after the injection of 740 to 1110 MBq (20-30 mCi) of Tc-99m MIBI. After 2 to 7 days, the study was repeated after the infusion of low-dose dobutamine of 2.0 microg . kg . min for 60 minutes. The scan was considered positive for hyperfunctioning parathyroid tissue when an area of increased uptake that persisted on late imaging was found. Parathyroid-to-thyroid count rates (PT/T) were calculated for each abnormal focus. Hyperplasic parathyroid tissue was confirmed in 12 of 24 patients who underwent neck surgery whereas the remaining group had persistent or worsening disease, verified by clinical follow-up between 6 and 25 months after the nuclear studies (median: 12 months). An MIBI baseline study was positive in 21 of 24 patients (87%), whereas the dobutamine study was positive in all patients. Thirty-five abnormal foci were seen on baseline MIBI studies and 43 on dobutamine scans (1.46 +/- 1.02 vs. 1.79 +/- 0.88, mean +/- SD, respectively, P = 0.043). Dobutamine PT/T ratios were significantly higher than those from the baseline study (1.49 +/- 0.30 vs. 1.38 +/- 0.28, mean +/- SD, respectively, P = 0.0002, n = 43). We concluded that low-dose dobutamine Tc-99m MIBI scintigraphy has the potential of enhancing tracer uptake and retention in patients with SHP.

Utilidad del MIBI, la ecografía y la tomografía computarizada en el diagnóstico topográfico preoperatorio del hiperparatiroidismo

1. To assess the sensitivity of scintigraphy using methoxy isobutyl isonitrile (MIBI). 2. To compare its resolution with that of ultrasound (US) and computerized axial tomography (CAT). 3. To use its diagnostic reliability to determine whether selective approaches can be used to treat hyperparathyroidism (HPT). A study of 76 patients who underwent surgery for HPT between 1996 and 2005 was performed. MIBI scintigraphy and cervical US were used for whole-body scanning in all patients; CAT was used in 47 patients. Intraoperative and postoperative biopsies were used for final evaluation of the tests, after visualization and surgical extirpation. The results of scintigraphy were positive in 65 patients (85.52%). The diagnosis was correct in all of the single images. Multiple images were due to hyperplasia and parathyroid adenomas with thyroid disease (5.2%). Three images, incorrectly classified as negative (3.94%), were positive. The sensitivity of US was 63% and allowed detection of three MIBI-negative adenomas (4%). CAT was less sensitive (55%), but detected a further three MIBI-negative adenomas (4%). 1. The sensitivity of MIBI reached 89.46%. In the absence of thyroid nodules, MIBI diagnosed 100% of single lesions. Pathological thyroid processes produced false-positive results (5.2%) and there were diagnostic errors (4%). 2. MIBI scintigraphy was more sensitive than US and CAT. 3. Positive, single image scintigraphy allows a selective cervical approach. US and CAT may help to save a further 8% of patients (with negative scintigraphy).

Usefulness of Tc-99m methoxyisobutylisonitrile scintigraphy for evaluating congestive heart failure

Evidence is accumulating that technetium 99m methoxyisobutylisonitrile (MIBI) is not retained in the impaired myocardium. The purpose of this study was to determine whether the severity of congestive heart failure (CHF) can be evaluated by use of the washout rate (WR) of MIBI. Seventeen patients with CHF and ten healthy volunteers were enrolled in this study. MIBI and iodine 123 metaiodobenzylguanidine (MIBG) scintigraphy techniques were performed, and the WR was calculated. The blood was also sampled for the measurement of levels of brain natriuretic peptide, which is a powerful predictor of the severity of CHF. The WR of MIBI was higher in CHF patients (31.2%+/-6.3%) than in healthy volunteers (25.2%+/-4.7%) (P<.05). There were positive correlations between the WR of MIBI and brain natriuretic peptide levels (r=0.723, P<.0001) and a negative correlation between the WR of MIBI and the left ventricular ejection fraction (r=-0.545, P<.01). The WR of MIBI was correlated with that of MIBG (r=0.603, P<.01). MIBI scintigraphy is useful in evaluating the severity of congestive heart failure.

PET con 18FDG en pacientes con cáncer diferenciado de tiroides que presentan niveles elevados de tiroglobulina sérica y rastreos con 131I negativos

This study aimed to evaluate the role of Fluorine-18-fluorodeoxyglucose positron emission tomography (PET-FDG) in patients with elevated serum thyroglobulin (hTg) levels where thyroid cancer tissue does not concentrate radioiodine, rendering false-negative results on I-131 scanning. Whole-body PET imaging using FDG was performed in 54 patients (37 female, 17 male) aged 17-88 years: 45 with papillary tumors and 9 with follicular tumors who were suspected of having recurrent thyroid carcinoma due to elevated thyroglobulin levels (hTg > 2 ng/ml) under thyroid-stimulating hormone (TSH > or = 30 microIU/ml) in whom the iodine scan was negative. All whole body scans were obtained with diagnostic doses (185 MBq). Whole body PET imaging was performed in fasting patients following i.v. administration of 370 MBq FDG while the patients were receiving full thyroid hormone replacement. Before PET, 99mTc methoxyisobutylisonitrile scintigraphy (99mTc-MIBI) was done in 14 patients and morphologic imaging in 26 by CT scan. Positive PET results confirmed the presence of hypermetabolic foci in 25/54 patients (46.29 %). Positive findings were found for PET-FDG in patients with hTg levels higher than 10 ng/ml receiving full thyroid hormone replacement. 99mTc-MIBI demonstrated lesions in 7/14 patients (50 %). PET-FDG and 99mTc-MIBI had congruent positive results in 4/7 patients. All the lesions found by CT were detected by PET-FDG, while recurrent disease was found in 12/21 patients with previous negative CT. These results suggest that PET-FDG seems to be a promising tool in the follow-up of thyroid cancer and should be considered in patients suffering from differentiated thyroid cancer with suspected recurrence and/or metastases by elevated thyroglobulin levels, and negative I-131 whole body scans. PET-FDG might be more useful at hTg levels > 10 ng/ml.

Correlation of technetium-99m MIBI and thallium-201 retention in solitary cold thyroid nodules with postoperative histopathology.

A comparative prospective study of technetium-99m methoxyisobutylisonitrile (MIBI) and thallium-201 with early (15 min) and delayed (90 min for MIBI, 3 h for 201Tl) imaging in the differentiation of thyroid lesions is presented. Forty patients with cold thyroid nodules visualised on 99mTc-pertechnetate scan and with dyskaryotic or atypical epithelial cells verified by fine needle aspiration biopsy underwent MIBI and 201Tl scintigraphy at 3-day intervals. Subsequent thyroidectomies were carried out in all patients. Semiquantitative analysis was performed using a lesion to non-lesion ratio on early (ER) and delayed images (DR). Additionally, a retention index (RI) was calculated using the formula RI=(DR-ER) x 100/ER. The reproducibility of the method for the early and delayed measurements was tested by analysing intra- and inter-observer variability and repeatability coefficients. Histopathologically, the nodules were found to be well-differentiated thyroid cancer in 21 patients and benign in 19 patients. There was no significant difference in the ER between malignant and benign lesions for either 201Tl or MIBI (P>0.05). However, for both agents significant differences were found between malignant and benign lesions with regard to DR (P<0.01 for 201Tl and P<0.001 for MIBI) and RI (P<0.001 for both agents). Statistical comparison of the two agents showed no significant differences (P>0.05) except with regard to DR and RI in malignant nodules (P<0.05). A receiver operating characteristic analysis was performed to determine threshold levels for the differentiation of malignant from benign nodules. Following this analysis, ER, DR and RI levels of 1.03, 1.54 and 2 for MIBI and < or =1.42, 1.24 and 5 for 201Tl were selected. Using these threshold levels, the sensitivity, specificity and accuracy of the study were 90.5%, 36.8% and 65% for ER MIBI, 61.9%, 94.7% and 77.5% for DR MIBI, 95.2%, 89.4% and 92.5% for RI MIBI, 85.7%, 47.3% and 67.5% for ER 201Tl, 80.9%, 73.6% and 77.5% for DR 201Tl, and 90.5%, 94.7% and 92.5% for RI 201Tl. In conclusion, the DR for MIBI and 201Tl is superior to the ER in detecting malignant nodules, and the RI for both MIBI and 201Tl is more valuable than the DR in differentiating malignant from benign thyroid nodules.

The role of technetium-99m methoxyisobutylisonitrile scintigraphy in the planning of therapy and follow-up of patients with differentiated thyroid carcinoma after surgery.

The aim of this study was to investigate the possible role of technetium-99m methoxyisobutylisonitrile (MIBI) scan in planning post-surgical therapy and follow-up in patients with differentiated thyroid carcinoma (DTC). Four groups of DTC patients were considered: Group 1 comprised 122 patients with high serum thyroglobulin (s-Tg) levels and negative high-dose iodine-131 scan during follow-up who had previously undergone total thyroidectomy and 131I treatment. Group 2 consisted of 27 patients who had previously undergone total thyroidectomy and 131I treatment but were now considered disease-free; this group was considered as controls. Group 3 comprised 49 patients studied after total thyroidectomy but prior to 131I scan. Finally, group 4 consisted of 21 patients who had previously undergone partial thyroidectomy alone. MIBI scan, neck ultrasonography (US), and s-Tg measurements during suppressive hormonal therapy (SHT) were obtained in all patients. Neck and chest computed tomography (CT) or magnetic resonance imaging (MRI) was also performed in group 1 patients. In group 1, MIBI scan and US were very sensitive in detecting cervical lymph node metastases (93.54% and 89.24%, respectively). Furthermore, MIBI scan and US played a complementary role in several patients, yielding a global sensitivity of 97.84%. In contrast, CT/MRI sensitivity for cervical lymph node metastases was very low (43.01%). MIBI scan also showed a higher sensitivity than CT/MRI in detecting mediastinal lymph node metastases (100% vs 57.89%). Regarding distant metastases, MIBI scan provided results similar to those of conventional imaging (CT, MRI, 99mTc-methylene diphosphonate bone scan). In group 2, no false-positive cases were observed with MIBI scan (100% specificity). In group 3, MIBI scan correctly identified all the 131I-positive metastatic foci, except in two patients with micronodular pulmonary metastases that were visualised with 131I scan. In contrast, both MIBI scan and US showed low sensitivity (46.15% and 61.53%, respectively) compared with 131I scan in detecting thyroid remnants. s-Tg was increased in all patients with distant metastases but only in 56% of those with lymph node metastases. Furthermore, s-Tg was increased in 21.42% of patients with thyroid remnants alone (false-positive results). In group 4, MIBI scan was the only examination capable of detecting at an early stage a mediastinal lymph node metastasis in one patient. We conclude that the integrated MIBI scan/neck US protocol: (a) can be proposed as a first-line diagnostic procedure in the follow-up of DTC patients with high s-Tg levels and negative high-dose 131I scan, and (b) may be helpful in the follow-up of DTC patients who undergo partial thyroidectomy alone. Moreover, the combined MIBI scan/neck US/s-Tg protocol appears to be highly sensitive in identifying patients with metastatic disease after total thyroidectomy and prior to 1311 scan; consequently, it may play a prognostic role in distinguishing high-risk from low-risk DTC patients. However, due to the low sensitivity of MIBI scan and neck US in detecting thyroid remnants, this diagnostic approach cannot be used as a predictor of 131I scan results. Lastly, because of the high sensitivity of MIBI scan and neck US in revealing both functioning and non-functioning metastases, this integrated protocol might be helpful in the follow-up of high-risk DTC patients, particularly for the early detection of lymph node metastases in patients with undetectable s-Tg during SHT.

Parathyroid glands: combination of (99m)Tc MIBI scintigraphy and US for demonstration of parathyroid glands and nodules.

To determine the appropriate choice of imaging techniques for localization of nodular lesions of parathyroid glands. First, computed tomographic (CT), magnetic resonance (MR), ultrasonographic (US), and technetium 99m methoxyisobutyl-isonitrile (MIBI) scintigraphic images in 49 patients with primary hyperparathyroidism were retrospectively evaluated. A single-blind, prospective study that included 16 patients with primary hyperparathyroidism was then conducted. MR, US, scintigraphic, and color Doppler US images of the neck were obtained and analyzed. In the retrospective study, CT, MR imaging, and US had low sensitivity (13%, 17%, and 27%, respectively) and specificity (39%, 65%, and 65%, respectively). Scintigraphy had 57% sensitivity and 85% specificity. In the prospective study, the use of latest-generation MR and US equipment and the participation of experienced operators led to improved sensitivity and specificity for these techniques. The combination of US and scintigraphy resulted in improved sensitivity (96%), specificity (83%), and positive and negative predictive values (88% and 94%, respectively), relative to the results obtained with either method alone. Doppler US was of little help in the setting of small glands. The combination of (99m)Tc MIBI scintigraphy and US performed by well-trained operators with up-to-date instruments appeared to be the best diagnostic tool for the preoperative diagnosis of parathyroid disease.