Diagnostic imaging of the thyroid: methodology and normal patterns.

The diagnostic imaging of the thyroid is based on sonography and scintigraphy, which to-date play a unique role in the morphofunctional study of the thyroid gland. The high spatial resolution of sonography allows an accurate evaluation of the thyroid morphology, size and parenchymal structure. Color Doppler sonography allows a qualitative assessment associated with quantitative parameters of glandular vascularization. Furthermore, sonography is the simplest procedure to achieve an accurate, reproducible measurement of thyroid volume. Scintigraphy provides information unavailable by other methods on the regional thyroid function. The most common tracer for thyroid scintigraphy is 99mTc pertechnetate. 123I and 131I are essential for radioiodine uptake test. CT and MRI, while invaluable for other organs and apparatus, play a limited role in the diagnosis of thyroid disease.