Scintimammography is a nuclear medicine imaging test that uses a radioactive material (known as a radioactive isotope) and a special camera to take images of the breast. This test may also be called breast scintigraphy, breast specific gamma imaging (BSCI) or molecular breast imaging (MBI).
Breast cancer cells attract more radioactive material than normal or benign (non-cancerous) cells. This is because cancer cells divide and grow more rapidly. The radioactive isotope gathers in larger amounts in cancer cells because of this rapid growth.
Why scintimammography is done
Scintimammography is a second-line diagnostic tool that is used to find out more after a mammogram (the standard imaging test to diagnose breast cancer) or an ultrasound. It’s not used very often.
Scintimammography may be done to check breast lumps that do not show up clearly on a mammogram because of scar tissue or dense breast tissue. This test doesn’t need the breasts to be flattened as much to get images of the breast tissues, so it can be used on women with breast implants.
Scintimammography may also be used if mammography suggests that there are several tumours in the breast or to look for cancer in the lymph nodes in the armpit (called the axilla nodes).
If you’ve had other tests or treatments, you may need wait a little while to let tissues heal before having scintimammography. This test should not be done until:
- 2 weeks after a fine needle aspiration
- up to 6 weeks after a core needle or excisional biopsy
- 2 months after breast surgery or radiation therapy
Tissues that are healing may attract more radioactive isotope because they are growing more quickly. If you have a scintimammography too soon after these procedures, you may have inaccurate or incorrect results.
How scintimammography is done
You shouldn’t need to do anything special to prepare for scintimammography. Before the test, your healthcare team needs to know if you are pregnant or could be pregnant, or if you are breastfeeding. You should also tell them about any medicines you are taking, including:
- medicines that are part of your cancer treatment
- vitamins and herbal supplements
- allergy medicines
- medicines for any other medical conditions you have
Scintimammography is usually done in a hospital. The test takes about 45–60 minutes.
You will have a small amount of radioactive isotope injected into a vein in your arm. The most commonly used isotope is technetium-99 m (Tc-99m) sestamibi. Technetium-99m is also known by its brand name Miraluma, so this test may also be called Miraluma test. For a few moments after the injection you may have a metallic taste in your mouth.
You will be asked to sit in a chair next to the scintimammography machine. Each breast will be placed next to a special camera and compressed and firmly held in place with a flat plate. You will be asked to stay as still as possible while the test is being done.
The camera detects the radioisotope as it moves through the breasts. This information is sent to a computer. The computer creates images of the breast structure and tissues. At least 2 images are taken for each breast. More images may be needed if you have larger breasts.
Before you get dressed, the technologist will check the images to make sure they are clear enough for the radiologist (a doctor who specializes in using imaging techniques) to read. You may have to have the test repeated if the images aren’t clear or if a closer image of a certain area is needed.
After the scan, you don’t have to avoid other people. The radioactive material quickly loses its radioactivity. It passes out of the body through the urine or stool (feces). Depending on the type of radiopharmaceutical used, it may take a few hours or days to completely pass out of the body.
Drinking fluids after the procedure helps flush the radiopharmaceutical from the body. You may be given instructions to flush the toilet 2 times and to wash your hands thoroughly after urinating.
Potential side effects
The dose of x-rays or radioactive materials used in nuclear medicine imaging can vary widely. Dose depends on the type of procedure and body part being examined. In general, the dose of radiopharmaceutical given is small and people are exposed to low levels of radiation during the test. The potential health risks from radiation exposure are low compared with the potential benefits. There are no known long-term adverse side effects from such low-dose exposure.
You may develop some bleeding, soreness or swelling at the injection site. It’s possible to be allergic to the radiopharmaceutical, but this is extremely rare.
What happens if a change or abnormality is found
If an abnormality is found, the doctor will tell you if you need more tests.
Limitations of scintimammography
Scintimammography may not detect tumours less than 1 cm (1/2 inch) in diameter.
Activity from other organs, such as the heart or liver, may interfere with the test and affect the results.