The thyroid is easy to visualize on CT scan because of its high iodine content. The presence or absence of calcification is not helpful in this regard. Nuclear medicine plays a key role. I recently returned from a meeting in which the speaker felt that the three largest nodules should be biopsied to exclude carcinoma. 131-Iodine is used to treat hyperthyroidism and to ablate the thyroid after cancer surgery.
Laboratory tests are important in diagnosing thyroid disease.
Ultrasound also plays a key role. It can distinguish cystic from solid lesions. It can guide biopsy. Look for assymetries and deviation of midline structures.