Computed tomography of the thyroid ,88 and and9).9). CT scans are also the most sensitive diagnostic tool for the detection of pulmonary micro-metastases. Many of the neck US features that are considered as suggestive signs of disease recurrence are also applicable to CT examination. These signs might include sizable rounded nodules in the thyroid bed, fine calcifications, or cystic change. In cases of elevated thyroglobulin with negative neck US and iodine whole body scintigraphy (WBS), fluorodeoxyglucose (FDG) positron emission tomography (PET) is the next modality of choice. Dedifferentiated thyroid carcinoma usually has avid FDG-PET uptake and a negative radioiodine scan, typically does not respond to
Computed tomography of the thyroid region, or within the parotid gland substance (Fig. 17). The origin of lateral ectopic thyroid tissue is not fully understood. Although this is controversial, some authors suggest that it might have originated from lateral thyroid anlagen (ultimobranchial bodies) that failed to fuse with the median anlage during caudal migration. A thyroglossal duct cyst (TDC) is a duct remnant between the foramen cecum and thyroid isthmus. Most TDCs are located below the hyoid bone and in the midline. The more caudal the cyst, the more likely it will be off midline within 2 cm (Fig. 19 and and20).20). On a CT