Inclusion Criteria:

- The presence of a single nodule or dominating nodule;

- A solid or mixed echo-structure with less than 20% fluid volume;

- A lesion volume between 5 and 18 ml (greatest diameter > 3.0 cm and <= 4 cm);

- Thyroid hormone and TSH serum levels within the normalcy value;

- 2 cytologically negative examinations for suspected neoplasia (British Thyroid
Association, Second class THY)within the last six months;

- Calcitonin values within the normalacy value;

- Anticoagulant treatment suspension and antiaggregation treatment suspended for at
least 72 hours.

Exclusion Criteria:

- Hyperfunctioning lesion (99mTc scintigraph);

- Autoimmune thyreopathy or elevation of autoantibodies;

- Active anticoagulant treatment or antiaggregation treatment.