Nuclear medicine studies are performed using radioactive isotopes to help aid in the diagnosis and treatment of certain diseases. The tests are completely safe and minimal doses of radiation are used; in fact, the amount of radiation to the patient is seldom more than that of a typical x-ray exam.

Nuclear medicine exams are unique. Unlike other diagnostic modalities, they are able to demonstrate the anatomy and function of organs. Some of the most common procedures in nuclear medicine are bone scans, stress tests, lung scans and gallbladder scans.

Purpose

• Bone scans are performed to locate bone abnormalities or damage, such as bone cancer, fractures, infection and arthritis.
• Nuclear stress tests are performed primarily to assess for narrowing or blocked arteries. This test will determine if the heart muscle is getting the blood supply it needs to function properly.
• Lung scans are commonly done to detect pulmonary embolisms (blood clots) in the lungs.
• Gallbladder (HIDA) scans are specifically done to determine gallbladder function.

How to Prepare
Your ordering doctor will discuss the procedure to be performed and any preparations you must follow.

Procedures

Bone Scan
A technologist will inject a radioactive tracer intravenously. The tracer enters your bloodstream and eventually is absorbed by all bones. You will be instructed to return for the scan approximately three hours later to allow for adequate absorption of the tracer.

Nuclear Stress Test
This is a lengthy exam that involves multiple technologists and departments. An intravenous (IV) line will be inserted into your arm and you will be injected with a small dose of a radioactive substance called Cardiolite. Images of your heart are obtained approximately 30 minutes afterwards for 15 minutes. Upon completion of the "resting" scan, you will be taken to another department where the exercise portion of the test is performed. During treadmill exercise, you will be monitored by a cardiologist and an EKG technician. You will exercise until a predetermined heart rate is achieved.

At this point, you will be injected with a second dose of Cardiolite by the nuclear medicine technologist. After a brief recovery period, you'll return to the nuclear medicine department for a final set of images-"stress" scan.

Lung Scan
This exam consists of two portions- ventilation (air flow) and perfusion (blood flow). You will inhale a radioactive gas called Xenon for approximately 3 minutes. The ventilation study is performed to detect any respiratory abnormalities such as asthma or chronic obstructive pulmonary disease (COPD). Upon completion of the ventilation study, you will be injected with a radioactive tracer that mimics the blood flow to the lungs. This perfusion study is performed to detect pulmonary emboli (blood clots) in the lungs.

Gallbladder Scan (HIDA or Hepatobiliary Scan)
This test requires you to fast overnight. You will be injected with a radioactive tracer which clears from circulation by hepatic cells of the liver and is secreted into bile. You will be imaged sequentially for approximately one hour. At this time, gallbladder and small bowel activity should be demonstrated; if not, the scan will continue. Typically, if gallbladder or small bowel activity is not visualized by four hours, the exam is ended. If a gallbladder ejection fraction is indicated, you will be given an additional injection of cholecystokinin (CCK). This is an agent administered by the radiologist that stimulates the gallbladder to contract. This injection is based on your weight and administered over a three-minute period. This adds an additional 30 minutes of imaging time to the scan. An abdominal ultrasound must be done sometime prior to this exam to confirm the absence of gallstones. The technologist will process the images to determine an actual percentage of gallbladder function (EF). A 40% or higher ejection fraction is considered normal.

Results
The images will be interpreted by a radiologist. A detailed report will be sent to your ordering physician who will then discuss the results with you.