Scintimammography breast scintigraphy
Scintimammography is a form of ‘nuclear medicine breast imaging‘. It is scintigraphy of a breast.
It involves injecting a radioactive tracer into the patient. The tracer will accumulate differently in cancerous versus non-cancerous tissues, and can therefore help determine whether cancer is present.
This page is still very useful, but getting a little bit old. So I have created a newer version with more up-to-date information on Scintimammography.
Nuclear medicine breast imaging may also be used for women who have particularly dense breast tissue, limiting the sensitivity of a breast X-ray. Scintimammography is also sometimes used to investigate large and palpable breast abnormalities, as they are often more difficult to scan using conventional mammography or ultrasound. Additionally, scintimammography is employed for women with breast implants, or when multiple tumors are suspected.
Lymphoscintigraphy
It may also be used to check the axillary lymph nodes (for a sentinel lymph node biopsy), or to help differentiate between possible tumors and scar tissue remaining from a previous mastectomy.
Determining the extent of breast cancer with nuclear medicine helps determine the best treatment option, such as breast conserving surgery (lumpectomy) or breast removal. Mastectomy is usually the best course of action if multiple tumors are present.
Scintimammography might also be suggested for women who show no visible or palpable mass on mammogram or ultrasound, but have more than two significant risk factors.
99m Tc-Sestamibi Scintimammography
Scintimammography, is sometimes called ‘99m Tc-Sestamibi Scintimammography‘ when the tracer they inject is “Sestamibi“, and the radioactive atom is ‘Technicium 99m‘.
Size limits
Scintimammography is usually not indicated for a breast lesion of less than 1 cm. For a primary breast lesion of greater than 1 cm, scintimammography has an estimated sensitivity of 85%, specificity of 89%, a positive predictive value of 89%, and a negative predictive value of 84%, which are really very good indicators. The sensitivity for detection of axillary node metastasis is about 77%, with a specificity of about 89%.
Statistical definitions
By way of definition, for breast cancer statistics ‘sensitivity‘ refers to the ability of a test to identify the presence of disease. ‘Specificity‘ is the ability of the test to determine the absence of disease. The ‘positive predictive value‘ is the probability that a positive test will truly identify the presence of disease, while the ‘negative predictive value‘ is the probability that a negative test will truly identify the absence of disease.
A Geiger counter measures scintillation, which refers to ionizing radiation. So Scinti – graphy means making an image showing where radiation is coming from.
Here are a few Q&A…
- Why is scintimammography done? It may be used in some women to assess breast abnormalities after a mammogram. It also may be done to check breast lumps that to not show up clearly on a mammogram because of scar tissue from previous surgery or radiation therapy, dense breast tissue, and breast implants. Also, when multiple tumors are seen in the breast, and to scan the lymph nodes in the armpit (axilla) to see if they contain cancer.
- What are some side effects of scintimammography? Some potential side effects include bleeding, soreness or swelling that may develop at injection site. And allergic reactions to the radio pharmaceutical may occur, but is extremely rare.
- What are some limitations of scintimammography? Activity from the other organs, such as the heart or liver, may interfere with the test and effect the scintimammography results. Scintimammography may not detect very small tumors, such as those less than 1 cm in diameter.
- How is scintimammography performed? Nuclear medicine imaging of the breast is usually performed on an outpatient basis. The procedure requires approximately 45-60 minutes to perform. Prior to imaging, you will be injected with a small amount of radiotracer. One breast at a time will be placed next to the BSGI gamma camera and compressed with a flat plate, similar to a screening mammogram. Some machines have a gamma camera that is placed on each side of the breast. Each image takes about 10 minutes to acquire. Two images of the breasts are obtained and more images may be taken depending on the size of the breast or if a potential abnormality is identified. Therefore, the exam takes roughly around 40-60 minutes in most cases.
References
- Taillefer, R. The Role of 99mTc-Sestamibi and Other Conventional Radiopharmaceuticals in Breast Cancer Diagnosis. Seminars in Nuclear Medicine 29 (1): 16-40, Jan. 1999.
- Taillefer R. Clinical Applications of 99mTc-Sestamibi Scintimammography. Seminars in Nuclear Medicine 35: 100-115, 2005.
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