Table 1 Definitions of suspicious US features (the, so-called, US patterns), in contrast to US patterns speaking for a benign nature of lesion [1].
Calcifications | - assessed especially as the presence of microcalcifications, also their coexistence with other forms of calcifications (e.g. dystrophic), in contrast to the absence of calcifications (the latter suggesting benign nature of lesions); |
|---|---|
Orientation | - “taller-than-wide” shape on transverse and longitudinal planes, in contrast to all other shapes; |
Doppler | - the presence of increased irregular chaotic central blood flows; this group includes also hypoechoic lesions when accompanied by a total absence of blood flow; in contrast to the peripheral, subcapsular blood flow (suggesting benign lesions); |
Echogenicity | - hypoechogenicity, defined as “darker” than normal thyroid echogenicity, and described as similar to the echogenicity of muscles surrounding the gland, especially sternocleidomastoid muscles; |
Halo | - uneven thickness of halo (outer shell that surrounds the lesion) or absence of halo, in contrast to thin halo, regularly surrounding the lesion; |
Echostructure (composition) | - solid lesions, also mixed lesions with cystic portion not exceeding 10% of the volume, in contrast to mixed lesions with cystic parts greater than 10% of total volume, as well as to lesions with solely cystic composition; |
Largeness (size) | - the size of lesion greater than 3 cm in diameter, in contrast to smaller lesions; |
Margin | - poorly defined and irregular, sometimes infiltrated border, in contrast to a well-differentiated regular margin; |
Augmentation | - the enlargement of lesion by at least 20% in two dimensions, i.e. at least 50% by volume (for the lesion in diameter of less than 10 mm - minimum 2 mm in two dimensions) in a period of time shorter than 1.5 years [2, 3]; |
Lymph node invasion | - the presence of lymph nodes, suspicious in US evaluation and of the size larger than 5-8 mm in the smallest dimension [3]. |