Positron Emission Mammography (PEM) Technology Installed

In late July, Inland Imaging installed the Inland Northwest’s first Positron Emission Mammography (PEM) unit at its Women’s Imaging Center located at the Sacred Heart Hospital Doctor’s Building.

A relatively new form of breast imaging technology, PEM allows for detecting very small areas of cancer that, in some cases, may be difficult to image with traditional methods of imaging. This technology provides Radiologists, Breast Surgeons, Medical Oncologists and Nuclear Medicine Specialists with a powerful tool to characterize the scope of cancer by measuring glucose metabolism.

The PEM unit, a major capital investment, was purchased by Inland Imaging after garnering input from area physicians as to the value associated with providing this advanced diagnostic capability. “Adding the PEM unit to our list of modalities will help us to more accurately evaluate breast abnormalities that may represent or be associated with breast cancer. In many cases, PEM provides unique and valuable information that will enable the physician and their patient to make a more informed decision as to their course of treatment” said Dr. Judd, a breast imaging radiologist at Inland Imaging.

PEM is similar to PET in that an intravenous injection of radioactive glucose analog, called FDG, is administered to the patient. The FDG accumulates in glucose-avid cells. The FDG collects in both inflammatory and cancerous cells because they have a higher metabolic
rate than normal cells. The glucose analog maintains its presence within the cell, permitting PET or PEM imaging.

PEM, like PET, is considered “functional imaging.” Both modalities create an image based on the presence and distribution of radiotracer in glucose-avid cells. As compared to whole body PET scanners , the PEM exam captures localized images of the breast, “finding” smaller breast lesions through better spatial resolution, reduced attenuation, and higher coincident counts in the imaging process.

Benefits of PEM

PEM imaging is of particular value for patients who:

• have a history of breast cancer
• have dense breast tissue
• had a inconclusive diagnosis

PEM may also have value for patients who:

• Have a high lifetime risk of breast cancer (>20-25% risk, BRCA genetic mutations, or prior chest radiation treatment)

It is important that patients understand that PEM is used as a secondary tool for problem solving and does not replace a standard screening mammogram or other breast imaging techniques such as ultrasound, diagnostic mammography, or breast MRI. After a suspicious area appears on a screening mammogram, the resolution capability and flexible configuration of PEM technology enables a more definitive diagnosis, thus assisting physicians in determining an appropriate treatment plan for their patient.

The PEM system boasts resolution capability of between 1.5 and 2.0 millimeters – about the size of a grain of rice. Studies show that PEM sensitivity and specificity for characterizing lesions is greater than 90% AND has a positive predictive value of 92% for identifying breast cancer. Correlatively, the number of false negatives are reduced by the use of PEM.

A PEM test may be ordered for patients with newly diagnosed breast cancer. It is a strong tool for determining the local extent of disease prior to surgery. In some cases, PEM technology can significantly alter patient management and treatment.

PEM also serves as a legitimate alternative for patients who are not candidates for breast MRI exam. For patients with certain kinds of medical implants, claustrophobia, or obesity, PEM offers similar results to breast MRI. Women with dense breast tissue, where tumors can be hard to spot, can use PEM as an alternate imaging option.

Added Dr. Judd, “We are excited by this technology. Introducing PEM will provide more data which, when combined with other information previously gathered, will aid in breast treatment and overall patient management.”