What is a sestamibi or parathyroid scan?
Thyroid and parathyroid surgeons might order this scan or X-ray to help identify abnormal or enlarged parathyroid glands. It is not used for diagnosing hyperparathyroidism, but mainly for surgical planning, and is accurate in about 80% of cases. The thyroid and parathyroid glands have a strong affinity for the sestamibi(radiotracer) that is injected and with time the thyroid loses or washes out the sestamibi. The parathyroid glands hold onto the tracer longer, especially if they are enlarged or abnormal. Over a span of about 2 hours, photos or X-rays are taken to evaluate the patient for parathyroid disease. This helps determine which of the 4 parathyroid glands is hypercellular or enlarged. When a single gland is identified on the parathyroid scan, Dr. Brady, with 15 years of experience in the Austin area, offer the MIP (minimally invasive parathyroidectomy) for patients and it is done on an outpatient basis. It is also helpful in identifying ectopic parathyroid glands or those that are not in the normal anatomic positions. Some of these glands can even be in the chest, upper neck, or next to the esophagus.
What if my sestamibi scan is normal or negative for any abnormal parathyroid glands?
If a parathyroid or sestamibi scan is normal, it does not mean that a patient does not have a parathyroid problem. Thyroid nodules, thyroid cancers, and Hashimoto’s thyroiditis can all cause a scan to be inaccurate or not show the abnormal parathyroid gland. Some may also have multiple (more than one) abnormal parathyroid glands occurring in 15%-20% of patients with hyperparathyroidism. Also, if a patient has had prior thyroid or parathyroid surgery, their scan can be negative. Finally, the patients with small abnormal parathyroid glands cannot always be seen on X-ray.
What is a SPECT scan? What is a 4D CT scan of the neck?
This is a sestamibi scan with single photon emission computed tomography (SPECT), or basically a CT scan of the neck using sestamibi tracer also. A 4D CT scan of the neck is a detailed computed tomography with use of IV contrast or dye with the 4th dimension being time. It can help identify a lymph node from a parathyroid gland by monitoring blood flow in real time.