Thyroid and Parathyroid
- 1.Ultrasound is the preferred imaging modality in the initial evaluation of all thyroid nodules and helps evaluate:
Size, location, and number of nodules and their characteristics (cystic, solid, mixed)
Status of opposite lobe to differentiate solitary nodule from multinodular goiter. This will aid in risk stratification for malignancy
For guided FNAC in non-palpable nodules as well as to direct the needle to representative area (solid component) in palpable nodules
Presence of metastatic cervical nodes in malignancies
Monitor progression of benign nodules in patients kept on observation
Follow up post-thyroidectomy in Ca thyroid
During evaluation of metastatic papillary carcinoma in patients presenting with cervical lymphadenopathy with no detectable primary to identify the presence of any thyroid nodule and possible primary.
Technetium thyroid scan is indicated in the evaluation of patients with hyperthyroidism.
CT/MR is not indicated in routine evaluation of thyroid swelling but is mandatory to confirm substernal extension, tracheal/vascular compression in locally invasive thyroid malignancies and in the evaluation of the superior medistinum in medullary carcinomas. In the evaluation of very large benign nodules where trachea is not palpable, CT may help identify involved lobe and guide surgery. It is important to remember that CT may miss subclinical thyroid nodules which may often be picked up on USG. CT is also useful in the evaluation of recurrent thyroid cancer.
Radioactive iodine scan is used in the postsurgery follow-up of Ca thyroid while CT/PET-CT is reserved for patients with rising thyroglobulin levels and normal USG and RAI scan.
PET-CT scan may be indicated in evaluation of dedifferentiated, non-radioiodine avid recurrent thyroid cancers.