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OBJECTIVE: To assess the potential role of conventional sonography and colour flow Doppler (CFD) sonography (CFDS) in the differential diagnosis of toxic multinodular goitres. SUBJECTS AND METHODS: We investigated 55 patients with untreated hyperthyroidism (24 with typical toxic diffuse goitre of Graves' disease (Group A); 26 with multinodular goitre (Group B); and five with single toxic adenoma (Group C); 22 euthyroid subjects (12 with non-toxic multinodular goitre (Group D) and ten normal subjects (Group E)) were included as controls. In all cases free thyroxine, free tri-iodothyronine, TSH, TSH receptor antibodies (TRAb), anti-thyroperoxidase antibody, anti-thyroglobulin antibodies and anti-thyroid microsomal antibodies were determined and a [(99m)Tc]pertechnetate thyroid scan was performed. RESULTS: Patients with toxic multinodular goitre displayed two different CFDS patterns: 18 patients (Group B-1) had nodules with normal vascularity surrounded by diffuse parenchymal hypoechogenicity with markedly increased CFD signal and maximal peak systolic velocity (PSV) (a pattern similar to Group A patients with Graves' disease); eight patients (Group B-2) had increased intra- and perinodular CFD signal and PSV with normal extranodular vascularity (a pattern similar to that found in Group C patients with single toxic adenoma). Patients of Group B-1 showed a proportion of clinically evident thyroid ophthalmopathy, positive TRAb and other thyroid autoantibodies similar to that observed in Group A patients, while no evidence of thyroid autoimmunity was found in Group B-2. Sixteen out of 18 (89%) patients from Group B-1 displayed a scintiscan pattern of diffuse uneven radionuclide distribution, while seven out of eight (87.5%) of those from Group B-2 had localized uptake in multiple discrete nodules. Taken together, these data strongly suggest that Group B-1 mostly represents patients with the multinodular variant of Graves' disease, while Group B-2 represents patients with non-autoimmune toxic multinodular goitre. CONCLUSIONS: This study shows that combined conventional sonography and CFDS may easily distinguish nodular variants of Graves' disease from non-autoimmune forms of toxic multinodular goitre and confirms the clinical usefulness of this technique in the first-line evaluation of hyperthyroid patients.

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 Hurthle 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.