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Breast Specific Gamma Imaging
By Eithne Burke, M.D.
Molecular-based imaging of the breast, or breast-specific gamma
Currently 25 millicurie of Tc-99m Sestamibi are injected intravenously,
imaging, uses a functional approach to imaging breast pathology,
and imaging begins immediately. Both breasts are imaged in the
rather than the anatomic approach, on which mammography and
cranio-caudal (CC) and mediolateral-oblique (MLO) projections,
ultrasound are based.
mirroring the mammographic views. The study takes about 45
minutes and is performed with the patient comfortably seated with
Mammography remains the mainstay for breast cancer screening
minimum breast compression. Its cost is significantly less than MRI.
and diagnosis; however, it has well-documented limitations, resulting
in limited sensitivity and specificity. At least 15 percent of breast
cancers are mammographically occult. Additionally, differentiation
of benign from malignant lesions is limited with both mammography
and ultrasound.
Breast-specific gamma imaging (BSGI) is proving a valuable, evolving
adjunct tool in the diagnosis of breast cancer. BSGI utilizes the
functional difference between tumor and normal cells that results in
different levels of radiotracer uptake, independent of tissue density.
The development of gamma cameras, uniquely configured for breast
imaging, with images mirroring the standard mammographic views,
has resulted in significantly improved detection of small, less than 1
centimeter breast cancers, with reports of 1 millimeter cancers being
detected.
There is no patient preparation for this study. As the images, like
those in magnetic resonance imaging (MRI), are adversely affected
by high-circulating estrogen levels, the procedure should be
performed between Day three and Day 10 of the menstrual cycle.
Figure 1, 2, and 3: Patient with palpable mass. Right breast marked with bb.
Proven invasive ductal carcinoma.
BSGI clearly demonstrates a focal hot spot correlating with the carcinoma.
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The Triangle Physician
Breast tissue is very dense, and it is difficult to see the mass with mammography.