Computed tomography of the thyroid bone, before it loops posteriorly and inferiorly to the hyoid bone. Then it continues its descent into the infra-hyoid portion of the neck, anterior to the trachea, thyroid cartilage, and thyroid membrane. Any thyroid residual along the descent course may lead to the development of ectopic thyroid glands. Thyroid carcinomas, thyroiditis, and goiter may develop within any ectopic thyroid tissue. Thyroid scanning with technetium-99 m (Tc99m) plays an important role in detecting orthotopic and ectopic thyroid tissue. Both CT scans and US can help detect ectopic tissue when a lesion demonstrates imaging and enhancement characteristics of thyroid tissue. The absence
Computed tomography of the thyroid is required for patients less than 35 years old with nodules measuring more than 1 cm in the axial plane. The cutoff size for further evaluation is raised to 1.5 cm for patients more than 35 years old. This recommendation should be applied to the largest thyroid nodule in cases of multiple thyroid nodules. Incidentally discovered heterogeneous and enlarged thyroid glands should undergo dedicated ultrasound if the patient has no limited life expectancy or serious comorbidities. Primary thyroid carcinomas include papillary, follicular, medullary, and anaplastic carcinomas. Lymphoma and metastasis of other primary malignancies to the thyroid gland represent a minority