How to Prepare for Surgery
People who have already been diagnosed with primary hyperparathyroidism, then undergo one or more imaging studies to localize the enlarged parathyroid(s) in preparation for surgery to treat their hyperparathyroidism.
Tc-99m Sestamibi Scan
The sestimibi parathyroid scan is a very useful tool to find the enlarged parathyroid(s) and is the most commonly used localization test. Here at the University of Wisconsin, we also use Tc-99m sestamibi with SPECT (single photon emission computed tomography) imaging which detects a single gland 80-90% of the time. The advantages of Tc-99m sestamibi are its availability, the ability to obtain 3-D anatomic information, and the ability to evaluate for adenomas outside of the neck at the same time. When Tc-99m sestamibi is combined with ultrasound, the combined sensitivity is > 90%.
It is performed in Radiology and takes about 2 hours. First, an injection of radioactive dye is given in your arm. Then a scanner will take a picture of the neck region. You will then be asked to come out of the machine and wait about 90 minutes. At that time, additional pictures will be taken. Enlarged parathyroid(s) look more white on the second pictures when compared to the first pictures taken. There will be no pain during the exam.
Ultrasound is being used more now compared to previous years. Ultrasound is noninvasive and inexpensive. However, it also is very operator dependent. It is very important that the person performing the ultrasound knows where to look for the abnormal glands. Ultrasound is good for identifying glands in the neck, but often cannot see lesions located either deep in the neck or in the chest. Ultrasound shows in great detail where a lesion is, but it does not show function. Sometimes it can be difficult to distinguish a parathyroid from a thyroid nodule or a lymph node. When ultrasound is combined with Tc-99m sestamibi, the combined sensitivity is >90%.
It is performed in Radiology or by your surgeon and takes 10 – 30 minutes. High frequency sound waves create pictures of your parathyroid(s) and other neck structures. These high-frequency sound waves cannot be heard during the exam. Ultrasound does not use x-rays or special dyes, and is most often painless. You will be asked to lie on a table in a darkened room. A gel will be applied to your skin on your neck. A small, hand-held device called a transducer will be placed over your skin. This is the device that creates the images and displays them on a computer monitor. You may feel some mild pressure from the transducer.
When done correctly, computerized tomography (also referred to as a CT or CAT scan) can be a very helpful tool to find the enlarged parathyroid(s). A CT scan is a special computer that makes detailed pictures of your internal organs and bones through the use of x-rays. Traditional CT scans are not very good at identifying parathyroid glands, but newer techniques using special parathyroid protocols and contrast in an intravenous catheter are showing promise in localizing parathyroid glands both in the neck and chest.
A CT scan is performed in Radiology and takes about 30 minutes. A small plastic catheter is placed in a vein in your arm to give IV contrast, a clear dye liquid. For the scan you will lie on a table. You will be placed on a table that can move in and out of the scanner. During the scan you will hear the machine make a humming noise. You may be asked to hold your breath for short amounts of time. The contrast injection will be placed in your IV line during the scan. When the contrast is given, you will have a brief feeling of heat throughout your body. You may also have a metallic taste in your mouth. While you receive the IV contrast, it is very common to feel as if you have urinated when this has not really occurred. This feeling is very brief and often lasts about one minute. The machine and room are very large, with a large open space. People who are claustrophobic often do not have problems during the scan. There will be no pain during the scan
Prior to surgery, Sarah Schaefer NP will meet with you and perform a presurgical physical to make sure you are in good health for your operation. Additional testing, like blood work, an electrocardiogram (heart test), or a chest x-ray may be performed. Instructions for your surgery including what to expect and how to prepare will also be discussed.