The usefulness of 99mTc-SestaMIBI scan in the diagnostic evaluation of thyroid nodules with oncocytic cytology

Abstract

Objective: To assess the relevance of 99m Tc-SestaMIBI (MIBI) scan in the diagnostic evaluation of thyroid nodules with oncocytic cytology. Subjects and methods: Twenty-four patients with a single (or prevalent) 'cold' solid nodule with Hü rthle cells (HC) at fine needle aspiration cytology (FNAC) were studied. Cytological diagnosis of oncocytic metaplasia (OM) or HC tumor (HCT) was made when HC on the smear were comprised 10-75%, or . 75%. Nodules concentrating MIBI at early and late (2 h after washout) stages were considered MIBI-positive. In all cases histological findings were obtained after total thyroidectomy. Results: FNAC was malignant or suspect for malignancy in 16 cases (six HCT and 10 OM) and not suspect in eight (two HCT and six OM). Histological examination revealed 14 malignant tumors (11 HCT and three OM), and 10 benign thyroid lesions (three HCT and seven OM). Sensitivity of FNAC for malignancy was 92.8% and specificity was 70.0%; HCT were identified by FNAC in only 35.7% and OM in 70.0% of cases. No significant difference in MIBI positivity was found between malignant and benign thyroid nodules. The highest percentage of MIBI positivity was found in HCT (78.5%), but MIBI-positive nodules were also observed in thyroid lesions with HC metaplasia (40.0%). Conclusions: MIBI scintiscan has no value in differentiating malignant from benign HC thyroid neoplasias. Most HCT are MIBI-positive, but this scan is not sufficiently specific to differentiate true HC neoplasias from other thyroid lesions showing HC at FNAC, although an MIBI-negative scan strongly supports the absence of true HCT.

99mTc-MIBI Imaging in the Presurgical Characterization of Thyroid Follicular Neoplasms: Relationship to Multidrug Resistance Protein Expression

“…Our findings showed that visual and semiquantitative 99m Tc-MIBI scintiscans were not specific enough to differentiate benign oncocytic lesions from malignant ones; most oncocytic lesions, both benign and malignant, were characterized by a significantly increased uptake or retention of 99m Tc-MIBI at 2 h, in agreement with other studies (22,(25)(26)(27). Therefore, we do not advise exposing patients to 99m Tc-MIBI scintigraphy when the cytologic result is oncocytic follicular neoplasm.…”

“…Observations that 99m Tc-MIBI scintigraphy is often positive in both benign and malignant oncocytic thyroid lesions (22,(25)(26)(27) prompted us to investigate whether its diagnostic accuracy could be increased when the nononcocytic thyroid follicular neoplasms were in advance separated (by cytologic examination) from the mitochondria-rich oncocytic ones. This study was prospectively conducted on a series of 51 cases of follicular neoplasms using both visual and semiquantitative 99m Tc-MIBI analyses.…”

“…Particularly, differentiated thyroid carcinoma has been reported to intensively accumulate and persistently retain 99m Tc-MIBI (18)(19)(20)(21)(22)(23)(24). However, discrepant results have been reported about the usefulness of 99m Tc-MIBI scanning in identifying thyroid carcinoma, especially in mitochondria-rich oncocytic lesions (22,(25)(26)(27).…”

Parathyroid hormone in washout fluid seems to be superior to cytology for localization of the lesion in MIBI-negative patients with primary hyperparathyroidism

“…Despite its high sensitivity (71%-93%) and high specificity (90%), the small size of parathyroid adenomas, oxyphilic cell content, degree of apoptosis, or necrosis may lessen MIBI uptake and lead to false negative results (13)(14)(15). Hypermetabolic thyroid lesions such as toxic thyroid adenomas and oncocytic tumors may retain MIBI and yield false positive results (16).…”

The usefulness of 99mTc-sestaMIBI thyroid scan in the differential diagnosis and management of amiodarone-induced thyrotoxicosis

“…Tc-sestaMIBI (MIBI) is a well-known lipophilic monovalent cation that shows an increased uptake in epithelial cells containing high numbers of mitochondria (18)(19)(20). For this reason, increased retention of MIBI is currently employed to detect hyperfunctioning parathyroid tissue (21,22) and may be observed in benign or malignant thyroid tumours, especially of oncocytic nature (23). Increased MIBI retention has also been described in hyperfunctioning thyroid tissue (toxic adenoma or toxic diffuse goitre) (24,25) and this phenomenon is believed to be the consequence of increased mitochondria number in hypermetabolic cells (26,27).…”