Molecular Breast Imaging a Useful Adjunct to Mammography

Molecular breast imaging (MBI), also known as breast-specific gamma imaging (BSGI), is a comparatively new form of breast cancer detection performed by injecting the patient in the arm with a specialized tracer and then obtaining images of the tracer distribution using detectors. The imaging procedure is similar to that of mammography, but with significantly less compression, and each image takes between 5–10 minutes to obtain.

Earlier research has established that it can detect tumors overlooked by mammography, especially in patients with dense breast tissue; however, this new research, published in the February 2013 issue of the European Journal of Nuclear Medicine and Molecular Imaging, is the largest analysis conducted to date.

Dr. Yu Sun, from the department of breast surgery, Guangxi Cancer Hospital, Affiliated Cancer Hospital of Guangxi Medical University (Nanning City, Guangxi, People’s Republic of China) and his research team evaluated hundreds of peer-reviewed articles published on this modality to determine the validity of the scientific methodology used in each study. Nineteen articles containing 3,093 patients met their precise criteria for inclusion. Their meta-analysis determined that MBI detected 95% of the tumors overall and that it was particularly useful in: cancers smaller than 1 cm; an early stage cancer called ductal carcinoma in-situ (DCIS); and a type of cancer called lobular carcinoma, which is difficult to detect with mammography with sensitivities of 84%, 88%, and 93%, respectively.

The smallest malignancy identified by MBI was 1 mm and it was able to detect breast cancer in four of every 100 women who had a negative mammogram. The authors also noted that MBI was as sensitive as breast MRI in the detection of breast cancer, but provided higher specificity (80%) meaning fewer positive findings in women without disease. Moreover, the MBI procedure can be performed for approximately one-third the cost of breast magnetic resonance imaging (MRI) and is useful for patients who cannot have an MRI study. Their findings also suggested that similar to breast MRI, MBI can detect additional tumors in six of every 100 women who have only one cancer seen by mammography and ultrasound and that it may be useful to help monitor the response of tumors to chemotherapy in patients who are receiving their chemotherapy before breast surgery.

Although the MBI procedure does expose the patient to some radiation, the radiation dose patients receive is similar to that of other diagnostic imaging studies routinely used in medical imaging and there are several researchers looking to reduce the dose even further in to expand its use into breast cancer screening.

The authors concluded, “Current evidence suggests that BSGI is an extremely useful adjunct to mammography for its ability to identify breast cancer with a high diagnostic performance.”

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Guangxi Medical University