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 iodine (RAI) ablation is an option, especially in patients with distant metastasis, tumours larger than 4 cm, or extra-thyroidal disease extension. Ultrasound examination is usually adequate in evaluating primary tumours and cervical lymph nodes. Preoperative cross-sectional imaging with CT or MRI is indicated if there is a concern for local invasion that may alter the patient’s staging as well as surgical approach (Figs. 4, ,55 and 6)6) . Some thyroid primaries may be small, diffuse, or multifocal and therefore may be occult on imaging (Fig. 4) . In patients with known thyroid malignancies, a non-enhanced exam is preferred due to