According to a study published in the American Journal of Roentgenology (AJR) in January 2012, Molecular Breast Imaging (MBI), also known as Breast-Specific Gamma Imaging or BSGI, can detect cancers missed by the two most common breast imaging studies, mammography and ultrasound. To clearly differentiate between benign from malignant tissue after mammography, phycians perform BSGI/MBI. In this procedure a patient receives a pharmaceutical tracing agent that is absorbed by all the cells in the body. Due to their increased rate of metabolic activity, cancerous cells in the breast absorb a greater amount of the tracing agent than normal healthy cells and generally appear as dark spots on the BSGI/MBI image.

In the study published in AJR, Breast-Specific Gamma Imaginghad the highest overall sensitivity (91%) for breast cancer detection, significantly higher than that of mammography and ultrasound, 74% and 84% respectively. In addition, BSGI was more effective than ultrasound in contributing to patient management when the results of these studies changed the diagnosis provided by mammography.

In this multi-center study of 1042 patients at four institutions, BSGI had an outstanding overall sensitivity of 91% and negative predictive value (NPV) of 96%. The BSGI procedures were conducted with a high-resolution gamma camera, the Dilon 6800? (Dilon Diagnostics, a brand of Dilon Technologies Inc.). For patients who had adjunctive imaging procedures with results discordant from those for mammography, BSGI provided higher diagnostic accuracy than ultrasound (77% vs 35%). The group of patients with indeterminate mammograms (BI-RADS 0) received the greatest benefit from use of BSGI. For the BI-RADS 0 patients, BSGI was significantly more likely to contribute to patient management than ultrasound, it was less likely to be negative in cancerous lesions and was less likely to be positive in benign lesions. Interestingly 85% of the patients included in this study had dense breast tissue.

More effective
The lead author, Jean M. Weigert, a radiologist atBradley Memorial Hospital in New Britain, CT, noted: “BSGI continuously proves to be a very important diagnostics tool in our facility. In the recently published article BSGI indicated a change in patient management for a greater number of patients, and was typically more effective than ultrasound because of improved specificity and positive predictive values.”

No radiation
Ultrasound does not involve an exposure to radiation. BSGI involves the injection of a dose to the patient that is comparable with or lower than that of other diagnostic imaging procedures. According to RadiologyInfo.org, a website co-developed by the American College of Radiology and Radiological Society of North America, “…there are no known long-term adverse effects from such low-dose exposure.” Like mammography, the benefits of BSGI greatly outweigh the risks due to radiation exposure.

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For more information:
Weigert JM, Margaret L. Bertrand ML, Lanzkowsky L, Stern LH, Kieper DA. Results of a Multicenter Patient Registry to Determine the Clinical Impact of Breast-Specific Gamma Imaging, a Molecular Breast Imaging Technique. AJR January 2012 vol. 198 no. 1 W69-W75.

Picture credit: Dilon Diagnostics, a brand of Dilon Technologies Inc.

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