Up to 70% Reduction in Radiation Dose Achievable for Positron Emission Mammography Imaging

Radiation a patient receives from positron emission mammography (PEM) may be reduced by as much as 70% without altering image quality.

The study's findings were presented at the American Association of Physicists in Medicine (AAPM) 52nd annual meeting in Philadelphia (PA, USA) in August 2010 by researchers from the University of Washington (Seattle, USA).

PEM scanners are high-resolution breast PET systems that show the location as well as the metabolic phase of a lesion. The metabolic image helps clinicians to make the optimal cancer care decision by providing an unprecedented ability to differentiate between benign and malignant lesions, what researchers term specificity. PEM is different from X-ray mammography in that it is currently not used as a screening modality, instead is utilized to confirm extent of disease in a patient already diagnosed with a primary breast cancer.

"We have several tools to help us make better patient care choices. Mammography is our primary screening tool. PEM is used in women with known breast cancer in order to plan treatment,” said Wendie Berg, M.D., a breast-imaging radiologist based in Lutherville (MD, USA). "Radiation for treatment of breast cancer uses doses which are roughly 5,000 times higher than a diagnostic PEM study. Minimizing radiation dose is still important for any patient, and we can likely cut the dose of PEM in half, but the benefit to proper treatment exceeds the still low risk from the radiation dose of PEM.”

Dr. Lawrence MacDonald, research assistant professor in the department of radiology at the University of Washington, and his team presented findings of a study to detect lesions with very low doses of radiation using the Naviscan PEM scanner. Early results using phantom images suggest that PEM lesion detection can be reduced down to approximately 3 mCi injected dose of 18FDG or three to four times lower than the dose typically used in clinical practice, while maintaining lesion detectability. These results are the basis of an ongoing clinical trial at Swedish Cancer Institute (Seattle, WA, USA) with the goal of determining the optimized dose levels of FDG required to produce high quality PEM images in patients with breast cancer.

"Naviscan believes that the radiation dose to patients who undergo PEM can be cut at least in half, if not more as suggested by the University of Washington study,” said Judy Kalinyak, M.D., medical director, Naviscan, Inc. "Our site in Japan is already injecting 5 mCi of FDG compared to the 10 mCi in the US and a recently published abstract in the Journal of Nuclear Medicine further validates the reduction in dose down to 5 mCi.”

Results from a recent presentation at the Society of Nuclear Medicine on findings from an U.S. National Institutes of Health (NIH; Bethesda, MD, USA)-sponsored clinical study comparing PEM with breast magnetic resonance imaging (MRI) further demonstrate PEM's clinical appropriateness. This multisite study of hundreds of women with newly diagnosed breast cancer revealed that PEM demonstrated a 6% improvement in specificity at comparably high sensitivity, and also recommended fewer unnecessary biopsies. These results are particularly significant for women who cannot tolerate an MRI exam and require an alternate imaging tool.

The Naviscan PEM scanner is currently installed and available in breast and imaging centers throughout the United States and other parts of the world. The company is the first to obtain U.S. Food and Drug Administration (FDA)-clearance for a high-resolution PET scanner designed to image small body parts and for breast biopsy image guidance.

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University of Washington
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