engleski

The role of 99mtc-methoxyisobutylisonitrile scintigraphy in the differential diagnostics of thyroid nodules

Introduction: 99mTc-methoxyisobutylisonitrile (MIBI) is a well known tumor imaging agent. Its retention within tumor cell mitohondria is related to perfusion and to the magnitude of the electrical gradient, reflecting cell viability. Aim: The aim of this study was to evaluate the diagnostic role of 99mTc-MIBI scintigraphy in the differential diagnostics of thyroid nodules. Patients and methods: A total of 159 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 thyroid scintigraphy was performed 20, 60 and 120 min after i.v. injection of 555 MBq (15 mCi) of 99mTc-MIBI. Positive 99mTc-MIBI scintigraphy was considered when it was increased uptake in the nodule, in the early and delayed images, compared with that in surronding thyroid tissue. These data were compared to the final histopathological results. Results: Histology revealed thyroid malignancy in 91/159 (57.2%) patients [76 cases (84%) of papillary carcinoma, 5 cases (6%) of follicular carcinoma, 2 cases (2%) of Hürthle cell carcinoma, 7 cases (8%) of medullary carcinoma and 1 case of Non Hodgkin lymphoma] and benign conditions in 68/159 (43%) [32 cases (47%) of follicular adenoma, 5 cases (7%) of Hürthle cell adenoma, 4 cases (6%) of lymphocitic thyroiditis, 22 cases (32%) of nodular goitre, 2 (3%) cysts and 1 (2%) old haemathoma]. 99mTc-MIBI scintigraphy was diagnostic in 66/159 (42%) patients and non-diagnostic in 93/159 (58%) patients, 50/159 (31%) patients with negative 99mTc-MIBI scan had a final histological diagnosis of malignancy [48 cases (96%) of papilary carcinoma, 1 case (2%) of medulary carcinoma, 1 case (2%) of Non Hodgkin lymphoma]. 80% (40/50) of these patients had nodules less than 1.5 cm in diameter and there was no cases of follicular carcinoma. 43/159 (27%) patients with positive 99mTc-MIBI scan had a final histological diagnosis of benign conditions - 22 cases (51%) of follicular adenoma, 5 cases (12%) of Hürthle cell adenoma, 14 cases (33%) of nodular goitre and 2 cases (5%) of lymphocitic thyroiditis. Sensitivity was 45% and positive predictive value 49%. Results: We found that 99mTc-MIBI could provide useful information for the diferential diagnostics of thyroid nodules in combination with ultrasound guided fine-needle aspiration biopsy, which remeins "gold standard" in the differential diagnostics of thyroid nodules.

: 99mTc-methoxyisobutylisonitrile; thyroid nodules; Osijek

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