[Echotomography and color-Doppler in the diagnosis of thyroid carcinoma]

Abstract

Ultrasound examination of the thyroid gland is used extensively in the diagnosis of thyroid carcinoma: it is easy and rapid to perform and widely available. Ultrasound enables easy identification of the image of disease foci within the gland, especially when high frequency probes (7.5-10 MHz) are used. Thyroid nodules are subdivided on the basis of their echostructure into hypoechoic solid, isoechoic solid, and hyperechoic solid, mixed, and liquid. In neoplastic pathologies, a hypoechoic echostructure is not pathognomonic of malignancy but must be regarded with suspicion, especially if it is an isolated nodule in a male patient and continues to grow during suppressive therapy. In fact, thyroid neoplasms evidence a hypoechoic echostructure in 60-70% of the cases, while a hyperechoic echostructure is present in only 2-4%. Only 15-25% of neoplasms appear as isoechoic nodules; a mixed echostructure is rarely (5-10% of the cases) seen. Color-Doppler patterns are classified into four types: I) nodules without internal or perinodular vascularization; II) nodules with vascularization confined to extranodular tissue; III) nodules with significant intra- and perinodular vascularization; IV) increased vascularization (or "thyroid inferno"). The vast majority of thyroid carcinoma (90%) presents type III vascularization. We therefore suggest the routine use of ultrasonography and color-Doppler studies in conjunction with fine-needle aspiration cytology for the diagnostic evaluation of thyroid carcinoma.