[Thyroid ultrasonography--considerations and progress in routine diagnostic examinations].

Thyroid ultrasonography is becoming increasingly important because it is easy to perform non-invasively and provides much more information than other imaging devices such as CT and MRI. It is possible to infer the causes of diffuse goiter and thyrotoxicosis by the internal echo level and blood flow analysis. The combination of B mode and color Doppler imaging is also useful for the diagnosis of thyroid nodules. Malignant B mode findings include an irregular shape, indistinct border, hypo and inhomogeneous internal echo, and fine calcification. New diagnostic criteria for thyroid nodules and a flow chart for the selection of indications of aspiration biopsy cytology have been developed by the Japan Association of Breast and Thyroid Sonology. Recent improvements in thyroid ultrasonography include 3D imaging, contrast agents and tissue elasticity imaging. 3D ultrasonography and contrast agents have made it possible to display vascular structures more accurately. Tissue elasticity imaging is expected to play an important role in the diagnosis of thyroid carcinomas since it evaluates tissue stiffness objectively. Tissue elastography may be useful for the differentiation of follicular adenomas from follicular carcinomas, which is still one of the most difficult clinical challenges for all endocrinologists. It also provides detailed information on the efficacy of thyroid interventions. New combinations with tissue elastography and other imaging devices are under development.