The Preferred Method for Localizing Parathyroid Tumors
Sestamibi scanning is the preferred way in which to localize diseased parathyroid glands prior to an operation. This parathyroid scan was invented in the early 1990's and now is widely available at essentially every hospital in the United States (however, as you will read below... it is difficult to well). Sestamibi is a small protein which is labeled with the radio-pharmaceutical technetium99. This very mild and safe radioactive agent is injected into the veins of a patient with hyperparathyroidism (parathyroid disease) and is absorbed by the overactive parathyroid gland. Since normal parathyroid glands are inactive when there is high calcium in the bloodstream, they do not take up the radioactive particles. When a gamma camera is placed over the patient's neck an accurate picture will show the overactive gland. The picture below shows this camera. The picture on the right is the type of picture that is obtained from this camera. It shows radioactivity in the one bad parathyroid. This picture is a close-up of a patient's upper chest, neck, and lower face (the eyes would be just above the top of the picture and the heart would be just below the lower edge of the picture). You can see that the only structure in this person's neck and upper chest (the area in which parathyroids live) which is radioactive is a large overactive left lower parathyroid. The other 3 parathyroids are responding appropriately to the high blood calcium level by "going to sleep" and not producing any parathyroid hormone (see parathyroid function). Since the 3 normal parathyroids are NOT producing any hormone, they do not absorb radioactivity and therefore do not show up on this scan. Only the overactive parathyroid gland shows up...a very accurate test.
The Sestamibi scan will display the hyperactive gland which is causing hyperparathyroidism in about 90 percent (90% sensitivity) of all patients. If the Sestamibi does show the hyperactive gland it is almost always correct (98-100% specificity). It takes approximately two hours to perform the Sestamibi scan after it has been injected. Pictures of the neck and chest are usually taken immediately after the injection and again in 1.75 to 2.0 hours (shown above). Newer techniques allow for more complete two and three dimensional images to be obtained of a patient's neck. This technique is called SPECT scanning (Single Proton Emission Computerized Tomography) but it is usually not necessary.
NOTE: Most hospitals only perform one or two sestamibi scans PER YEAR, and thus the quality of these scans may be quite poor. This has been written about in the medial literature... If you have parathyroid disease, make sure you GO TO A PARATHYROID SPECIALIST! And, make sure you go to a hospital that does a lot of parathyroid Sestamibi scans (at least 50 per year).
This information was presented by the Norman Parathyroid Clinic which performs more than 500 sestamibi scans per year, and reviews over 700 scans per year performed at other institutions. The Norman Parathyroid Clinic has the world's larges experience in parathyroid localization and has developed many of the techniques used. For more information about the Norman Parathyroid Clnic, CLICK HERE.