Positron Emission Tomography (PET) Mammography: A New Diagnostic Tool

Positron emission tomography (PET) mammography incorporates PET technology into a mammography unit that can detect lesions as small as 2 mm; this is two to three times smaller than lesions that can be detected by whole-body PET.[1]

How It Works

PET is a nuclear medicine technology best known for its role in cancer imaging. A small amount of a radioactive sugar molecule, 18 fluoro-2-deoxyglucose (FDG), is injected into the bloodstream and a scanner is used to detect and generate images that indicate areas of high-FDG uptake. Many cancers require more energy than normal cells and the FDG tracer preferentially accumulates in these cells. This allows cancers to be seen as “hot spots” on the PET scan. PET also guides therapy by assessing treatment response.

How It Fits Into Current Practice

PET mammography is also called positron emission mammography or PEM. Like whole-body PET imaging, it is an adjunct to conventional breast cancer imaging for disease staging or restaging, surgical planning, and for treatment evaluation. It is not intended for breast cancer screening or for assessing lymph node status. PET mammography is proposed for women who have breast lesions that are difficult to characterize, especially women with dense breast tissue and those at high risk for multi-focal or aggressive disease.[1]

Regulatory Status

The PEM Flex™ Solo II unit (Naviscan PET Systems, Inc.) received US Food and Drug Administration clearance in 2003 for general-purpose imaging. Unlike whole-body PET units, dedicated PET mammography units are not yet licensed in Canada. Toronto-based IMAGIN Diagnostic Centres, Inc. holds the Canadian distribution rights for PEM Flex.

Evidence

Currently, there is limited published evidence available. However, dedicated PET mammography is more sensitive than whole-body FDG PET imaging for detecting small lesions.[1] One prospective, non-randomized clinical trial with 77 patients reported that PET mammography had an overall accuracy of 88% to 92% compared with 71% for conventional imaging (p<0.001).[2] This was largely due to PET mammography performing better for very early-stage breast cancer that had not spread beyond the site of origin.

Cost

The cost of the PEM Flex Solo II unit was unavailable. The cost for each PET mammography scan will likely be similar to the cost of a whole-body PET scan since the infrastructure and radiopharmaceutical costs will be similar.

In Canada, the total cost for each whole-body FDG PET scan ranges from $1,231 to $7,869, depending on patient volumes, the cost of the FDG radiopharmaceutical dose, physician fees, capital infrastructure costs, operational costs, and the regulatory costs of a clinical trial application for FDG products that have not received a notice of compliance from Health Canada.[3] For out-of-province residents, Alberta and Manitoba charge approximately $1,250 and BC charges $1,500 per FDG PET scan. Private Canadian PET facilities charge patients approximately twice this amount. Physician professional fees range from $200 to $300 per case.

References

[1] Tafra L. Ann Surg Oncol 2007;14(1):3-13.
[2] Berg WA, et al. Breast J 2006;12(4):309-23.
[3] Chuck A, et al. Int J Technol Assess Health Care 2005;21(4):442-51.