**11. Imaging**

Thyroid ultrasonography is a useful tool to support the diagnosis, and classical sonographic findings are present in 20-95% of affected individuals (63). Furthermore, their presence is related to subclinical hypothyroidism and levels of thyroid autoantibodies (64,65), and ultrasonography has been used for the follow-up of patients (66). Thyroid ultrasonography is usually heterogeneous because of fibrosis and hypoechogenic areas, it is not necessary for diagnosis but it is recommended to conrm the presence of a thyroid nodule, solitary or multiple nodule can be detected both hypothyroid or euthyroid patients. During disease progression, reduced echo levels develop gradually, reflecting either reduction of colloid content and increased intrathyroidal blood flow or lymphocytic tissue infiltration, which induces diffuse fibrosis (64). The appearance of thyroid gland on ultrasonography may be normal at diagnosis, but characteristic changes evolve over time. Vlachopapadopoulou et al. studied 105 children, the time needed for 30%, 50%, and 70% of children to demonstrate an abnormal thyroid sonographic pattern has been detected 4, 7, and 14 months, respectively. Important factors accelerating sonographic changes have been demonstrated as goiter, hypothyroidism, and seropositivity for both anti-TPO and anti-Tg autoantibodies (67).
