Medical Policy: 06.01.22
Original Effective Date: August 2006
Reviewed: July 2018
Revised: July 2017
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This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Scintimammography, also know as nuclear medicine breast imaging, refers to the use of radiotracers with nuclear medicine imaging as a diagnostic tool for abnormalities of the breast. Breast specific gamma imaging (BSGI) also known as molecular breast imaging (MBI) refers to specific types of imaging machines that are used in conjunction with scintimammography to improve diagnostic performance.
These modalities have been proposed primarily as adjuncts to mammography and physical examination in patients who have palpable masses or suspicious mammograms as a technique to improve patient selection for biopsy. It has been suggested scintimammography has the potential to reduce unnecessary invasive biopsies by differentiating benign from malignant lesions. Breast specific gamma imaging (BSGI) or molecular breast imaging (MBI) have been suggested for evaluating suspected recurrence in patients who are at high risk, for patients in whom breast MRI is indicated but who are not candidates due to contraindications, and among patients in whom breast imaging is technically difficult, such as those with radiodense breast tissue.
Scintimammography is performed while the patient is lying prone and the camera positioned laterally, which increases the distance between the breast and the camera. Scintimammography using conventional imaging modalities has relatively poor sensitivity in detecting smaller lesions (< 15 mm), because of this relatively poor resolution BSGI/MBI were developed to address this issue.
Breast-specific gamma imaging (BSGI) and is also sometimes referred to as “molecular breast imaging (MBI)” is a scintimammography examination that uses a special breast optimized gamma camera. This is performed while the patient is seated in a position similar to that of mammography, and the breast is lightly compressed. The detector head(s) is immediately next to the breast, increasing resolution, and images can be compared with mammographic images.
BSGI/MBI uses high-resolution gamma cameras. These cameras, specially designed to image the breast, offer improved signal-to-noise ratio and improved spatial resolution to produce high-contrast images of small lesions. The dedicated breast cameras facilitate imaging from several angles to more closely resemble the cranial-caudal and medial-lateral-oblique mammographic views. This imaging takes approximately 45 minutes.
Note: The term molecular breast imaging (MBI) may be used in different ways, sometimes for any type of breast imaging involving molecular imaging, including positron emission mammography (PEM), and sometimes is limited to imaging with a type of breast specific gamma camera.
The primary radiopharmaceutical used is technetium-sestamibi (MIBI). MIBI accumulates in tissues with increased mitochondrial activity, such as rapidly growing tumors. After intravenous injection, MIBI rapidly (within two minutes) accumulates within breast tumors and slowly, over the courses of hours is “washed out” out of the cells by P-glycoprotein receptor, allowing imaging to be performed immediately after injection, but also allowing ample time for clinicians to perform all desired views and data collection.
Sentinel lymph node (SLN) procedure is now a widely used method of lymph node staging in selected invasive breast cancers (unifocal, size < 2 cm, clinically N0, without previous treatment). Complete axillary clearance is no longer needed if the SLN is negative. One main pitfall is the failure to visualize SLN, resulting in incorrect tumor staging, leading to suboptimal treatment or axillary recurrence. Operative gamma cameras have therefore been developed to be used preoperatively and intra-operatively to optimize the SLN visualization and the quality control of surgery.
Based on the peer reviewed literature mobile gamma cameras for preoperative and intra-operative sentinel lymph node detection are in development. Current evidence consists of small studies with inconsistent results. Also, this has not shown improved diagnostic performance in comparison with standard gamma probes.
Positron emission mammography (PEM) is a new imaging modality that has higher resolution than PET-CT and can be performed on patients unable to have an MRI scan. PEM uses a pair of dedicated gamma radiation detectors placed above and below the breast and mild breast compression to detect coincident gamma rays after administration of fluorine-18 fluorodeoxyglucose (18F-FDG), the positron-emitting radionuclide used in whole-body PET studies for the detection of metastatic disease. Whereas PEM has high imaging sensitivity for breast lesions, its clinical utility requires further investigation. PEM cannot provide the anatomical detail that is provided by MRI. A disadvantage of PEM is the radiation exposure. Radiation doses from positron emission mammography (PEM) are 15 to 30 times higher than the dose from digital mammography.
The American College of Radiology includes PEM in two sets of Appropriateness Criteria: one on breast screening and the other on the initial diagnostic work-up of breast microcalcifications. In the first, PEM is given a rating of 2 (1, 2, 3=usually not appropriate) for its use in screening women at high or intermediate risk of breast cancer and a 1 for screening women at average risk of breast cancer. It also assigns a relative radiation level of 10 to 30 mSv. It also notes that “Radiation dose from BSGI and PEM are 15-30 times higher than the dose of a digital mammogram, and they are not indicated for screening in their present form.” In the second set of appropriateness criteria, PEM was assigned a rating of 1 (usually not appropriate) for the initial work-up of all 18 variants of microcalcifications. The authors note “The use of magnetic resonance imaging (MRI), breast specific gamma imaging (BSGI), positron emission mammography (PEM), and ductal lavage in evaluating clustered microcalcifications has not been established…. In general, they should not be used to avoid biopsy of mammographically suspicious calcifications.”
The SBI Position Statement ‘Use of Alternative Imaging Approaches to Detection of Breast Cancer’ states that “often predicated on the increased vascularity associated with cancer, techniques to detect increased heat production, oxygen consumption, electrical impedance, light absorption, microwave transmission, and nitrous oxide production have indicated changes in the breast containing cancer that may assist in detection or diagnosis. While many of these approaches have received FDA approval for safety, such techniques remain either experimental or investigational, given the lack of standard techniques that can be uniformly applied and paucity of sufficient research to substantiate reliability of results. None of these tests have been shown to reduce mortality among tested women in randomized controlled trials.”
Current evidence does not support the routine use of breast scintigraphy (eg, sestamibi scan) or ductal lavage as screening procedures.
Mammography is the recommended method for breast cancer screening of women in the general population. However, mammography alone does not perform as well as mammography plus supplemental screening in high risk women. Therefore, supplemental screening with MRI or ultrasound is recommended in selected high risk populations. Screening breast MRI is recommended in women at high risk for breast cancer on the basis of family history or genetic predisposition. Ultrasound is an option for those high risk women who cannot undergo MRI. Recent literature also supports the use of breast MRI in some intermediate risk, and ultrasound may be an option for intermediate risk women with dense breasts.
There is insufficient evidence to support the use of other imaging modalities, such as thermography, breast specific gamma imaging (BSGI), positron emission mammography (PEM), and optical imaging, for breast cancer screening, and they are not indicated for screening in their present form.
The Society of Nuclear Medicine (SNM) released 2010 Practice Guideline for Breast Scintigraphy with Breast Specific y-Cameras, which lists potential indications and cites references for each indication but does not provide a systemic review of the literature, including assessment of study quality. The guideline is based on consensus, and most of it is devoted to procedures and specifications of the examination, documentation and recording, quality control and radiation safety.
A 2013 TEC Assessment by the Blue Cross Blue Shield Association evaluated the use of BSGI, MBI, or scintimammography with breast-specific gamma camera as a diagnostic modality for screening to detect breast tumors and concluded that there is no evidence of improved health outcomes
There is limited evidence on the use of scintimammograpy including breast specific gamma imaging (BSGI)/molecular breast imaging (MBI), including positron emission mammography (PEM) for screening geno typical women who have an elevated risk of breast cancer or in geno typical women with factors that limit the sensitivity of mammography. Also, the relatively high radiation dose currently associated with BSGI/MBI has prompted the American College of Radiology to recommend against the use of BSGI/MBI for screening. The consideration of the potential use of BSGI/MBI for screening geno typical women with dense breasts or at high risk of breast cancer should await the development of a lower dose regimen, and if warranted, larger higher quality studies with study populations representative of patients encountered in clinical practice. A large quality head-to-head comparison of BSGI/MBI and MRI would be needed, especially for geno typical women at high risk of breast cancer, because MRI, alternated with mammography, is currently the recommended screening technique.
Scintimammography including Gamma Imaging of the breast and axilla, Molecular Breast Imaging (MBI), including Positron Emission Mammography (PEM) is considered investigational for all indications, including but not limited to:
While recent studies have produced promising observations, patient populations were small and highly select. Larger, multicenter studies are needed to validate the potential of scintimammograpy including breast specific gamma imaging (BSGI)/molecular breast imaging (MBI) as an adjunct screening or diagnostic modality and to further identify the subset of patients for whom this technology will improve net health outcomes and contribute to clinical management. While BSGI is promising for use in the preoperative assessment of disease extent in breast cancer patients, the available data are limited and this technique cannot be used for screening or to exclude breast cancer in patients with suspicious breast masses or abnormal mammography. Therefore, scintimammography including BSGI/MBI is considered investigational.
The use of positron emission mammography (PEM) is considered investigational for all indications.
Preoperative or intraoperative sentinel lymph node detection using handheld or mounted mobile gamma cameras is considered investigational.
Based on the peer reviewed literature mobile gamma cameras for preoperative and intra-operative sentinel lymph node detection are in development. Current evidence consists of small studies with inconsistent results. Also, this has not shown improved diagnostic performance in comparison with standard gamma probes. Therefore, preoperative or intraoperative sentinel lymph node detection using handheld or mounted mobile gamma cameras is considered investigational.
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