Finding the Tumors: Octreoscan

Neuroendocrine tumors can be small and they can spread anywhere in the body. That makes them hard to find. There are many tests that doctors can use to find these tumors, but Roswell Park is the only place in Western New York with an Octreoscan, an important tool for locating these tumors.

An Octreoscan is a test that can indicate the extent of tumors and show where they are. This information helps your doctor plan your treatment.

How does an Octreoscan work?

You will be given a small amount of radioactive material — called a tracer — that is usually injected into a vein in your arm or hand. The tracer quickly moves to and collects in specific organs where it sends signals, or gamma rays. The medicine used in this exam is designed to bind to neuroendocrine tumors that have certain proteins called somatostatin receptors on the surface of the cancer cells.

A special camera (called a gamma camera) can detect the energy emitted by the tracer and identify the sites in your body where the drug has accumulated. These areas will appear on the scan and help your doctor to evaluate your medical condition.

Are there any concerns with this test?

Don’t let the words “nuclear” or “radioactivity” scare you. These tests are designed to expose you to the least amount of radiation possible. The drug that will be used during this procedure is prepared with exceptional care and has been approved by the U.S. Food and Drug Administration. However, there is always a chance that you may have a reaction to the drug. It is important to tell your doctor or the person conducting the exam of any unusual reactions or feelings that you may have during or after the exam.

Important risk information
Be sure to talk with your doctor before having this test if you:

  • Have serious kidney problems
  • Receive nutritional fluids through a tube in your vein (called total parenteral nutrition)
  • Take octreotide acetate (Sandostatin®)
    • Important information for those who take octreotide (Sandostatin®) injections: This test must be done as far away from your last injection as possible. If you are on long-acting octreotide, the scan should be done 4 weeks after your last injection. If you are on short-acting/immediate-release octreotide, the scan should be 1-2 days after your last injection.
  • Are being tested for a possible tumor in your pancreas
  • Are pregnant, trying to become pregnant or breast feeding

Side effects are rare (seen in less than 1 percent of the patients studied) and may include: dizziness, fever, flush, headache, low blood pressure, changes in liver enzymes, joint pain, nausea, sweating and weakness. A very small number of patients have reported a slow heartbeat or reduced hematocrit and hemoglobin levels. The safety and effectiveness of this procedure have not been determined in patients under 18 years old.

How do I prepare for the test?

Water: Unless your doctor tells you otherwise, you should drink extra water the day before your exam and for two days after. The more often you urinate, the faster you remove the excess materials not used by your body for the scan. In patients with good kidney function, most of the radioactivity (85 percent) usually will be removed from the body within 24 hours.

Medications: Tell your doctor about any medications you are taking, including octreotide acetate, over-the-counter medications and supplements. He or she may decide to temporarily discontinue certain medications before the exam.

Laxative: You may be asked to take a mild laxative before your scan. This can help the doctor see your abdomen more clearly.

Diet: There are no dietary restrictions prior to this test.

What can I expect?

There are several parts to this test. Here is a basic description of what you can expect.

Injection: During your first appointment, the technologist will insert a tube called an intravenous (IV) line into a vein in your arm or hand. You may feel a slight prick and a small amount of tracer will be injected. The technologist will also explain the test, answer questions and give you instructions for taking a laxative (usually the evening before your second scan). You may be in normal contact with your family and friends after the injection. Also, you may eat, drink, bathe and use the toilet without any special precautions.

Waiting period: The tracer will be allowed to circulate for 4 to 24 hours before your first scan is performed. During this time, the drug will collect in the area or areas of interest to your doctor. You will be told when to return for your scan.

Scans: After the waiting period, you will return to be scanned up to three times. The technologist will ask you to lie on your back on the exam table. A gamma camera will move over and around you to take the images. A number of pictures will be taken at different locations on your body. Scan times are usually at 4 hours, 24 hours and possibly 48 hours after your injection. This timing may vary. Each scan may take up to one hour or longer to perform. During the test, you will need to remain as still as possible. This will help prevent the images from blurring, which can make it difficult for the doctor.

How long does the test take?

The entire test may take place over several days. Ask your doctor or the technologist performing the exam to discuss your specific exam timing.

Is there anything special I need to do after the test?

The radioactive tracer usually does not stay in the body for very long. Before your test, ask your doctor for specific instructions regarding resuming normal activities.