Scintigraphy
Thyroid and Parathyroid Scintigraphy
Thyroid and parathyroid scintigraphy are nuclear medicine imaging techniques used to evaluate the function and structure of the thyroid and parathyroid glands.
Thyroid Scintigraphy
Thyroid scintigraphy is used to assess thyroid nodules, hyperthyroidism, and thyroid cancer metastases. It involves the use of radioactive tracers such as:
Technetium-99m pertechnetate (Tc-99m) – Commonly used because it is taken up by thyroid tissue similarly to iodine.
Iodine-123 (I-123) – Preferred for functional assessment since it reflects true iodine metabolism.
Iodine-131 (I-131) – Used mainly for post-treatment imaging in thyroid cancer.
Indications:
Differentiation of hot (hyperfunctioning) vs. cold (non-functioning) nodules
Evaluation of hyperthyroidism (e.g., Graves' disease, toxic multinodular goiter)
Post-thyroidectomy follow-up in thyroid cancer patients
Findings:
Hot nodule – Increased uptake, usually benign.
Cold nodule – Decreased uptake, warrants further evaluation for malignancy.
Diffuse increased uptake – Seen in Graves’ disease.
Patchy uptake – Seen in toxic multinodular goiter.
Parathyroid Scintigraphy
Parathyroid scintigraphy is used to detect parathyroid adenomas or hyperplasia in cases of primary or secondary hyperparathyroidism. The most commonly used radiopharmaceutical is Tc-99m sestamibi, which is preferentially taken up by hyperfunctioning parathyroid tissue.
Findings:
Parathyroid adenoma – Persistent focal uptake on delayed images.
Parathyroid hyperplasia – Multiple areas of uptake.
Ectopic parathyroid tissue – Identified in unusual locations (e.g., mediastinum).
Comparison of Thyroid vs. Parathyroid Scintigraphy
Feature | Thyroid Scintigraphy | Parathyroid Scintigraphy |
|---|---|---|
Tracer | Tc-99m pertechnetate, I-123, I-131 | Tc-99m sestamibi |
Purpose | Evaluate thyroid function and nodules | Detect parathyroid adenomas or hyperplasia |
Findings | Hot/cold nodules, diffuse uptake patterns | Persistent focal uptake for adenomas |
Additional Imaging | SPECT/CT in some cases | SPECT/CT often used for localization |
General Safety Instructions After Scintigraphy:
After undergoing scintigraphy, patients are exposed to a small amount of radioactive material. Although the radiation dose is generally low and safe, there are still some precautions to minimize exposure to others, especially vulnerable individuals (pregnant women, children, and immunocompromised individuals).
Hydration & Frequent Urination
Drink plenty of water for 24–48 hours to help flush the radioactive tracer out of your body.
Urinate frequently, and always wash your hands thoroughly afterward.
Avoid Close Contact with Others
Keep a safe distance (about 1 meter or more) from pregnant women, infants, and young children for at least 24 hours.
Limit physical contact, such as hugging or holding children, especially if a high-dose tracer was used.
Personal Hygiene
Wash your hands thoroughly after using the restroom.
If sweating excessively, consider changing your clothes more frequently to avoid residual contamination.
Special Precautions for Breastfeeding Mothers
If you are breastfeeding, you may need to pause breastfeeding for a specific period, depending on the type of tracer used. Consult your doctor for exact recommendations.
Restroom Use
Flush the toilet twice after use for the first 24 hours.
Men should sit while urinating to minimize contamination from splashes.
Radiation Detectors in Public Places
Some airports, hospitals, and border controls have radiation detectors. If traveling within a few days of your scan, carry a medical certificate or inform security personnel if needed.
Follow-Up & Additional Scans
If further imaging or procedures are required, follow your doctor’s instructions regarding timing and precautions.