If you have been diagnosed with breast cancer, your doctor may refer you for a PEM scan. PEM stands for positron emission mammography, a new and advanced application of positron emission tomography or PET scanning. For decades, PET has helped doctors diagnose and treat disease.
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, producing very sharp, detailed images of breast lesions – as small as 1.5 – 2mm, about the width of a grain of rice.
The images obtained with the PEM scanner identify areas of suspicion, giving physicians a “map” upon which they can base your treatment options and/or surgical plan. Armed with this information doctors can better determine candidates for breast-conserving surgery or lumpectomy.
Also, knowing the exact location and extent of the cancer guides doctors during surgery and helps assure that they remove all suspicious tissue and thereby avoid repeat surgeries. Your doctor may also use PEM during biopsy to guide the needle; to monitor treatment or to check for a recurrence of disease.
How PEM Works
Like PET, PEM is a nuclear
imaging technology. An accumulation of an injected radioactive
substance called a radiotracer in the cancerous tissue clearly
distinguishes cancer from healthy tissue.
PEM uses a radiotracer based on sugar (analog glucose). Cancer cells absorb and accumulate sugar faster than healthy tissue.
Essentially, PEM captures a “snapshot” of the cellular activity occurring at that moment within a mass of cancerous tissue. So not only does PEM reveal the size, shape and location of a suspicious mass; it is over 90%* accurate in identifying the mass as cancerous or not, based on its bio-active properties.
Preparing for a PEM Scan
Our office will provide specific instructions to prepare you for a PEM scan. To assure that you absorb the radioactive sugar properly, you will be instructed to not eat or drink anything other than water and non-diabetic medication six (6) hours before your appointment. These instructions may differ if you are diabetic or have low blood sugar (hypoglycemia).
Be sure to inform your doctor and clinic staff if you have either of these conditions. Generally, this will not prevent you from having a PEM scan. You should also bring a snack with you to the appointment to eat once the nurse or technician gives you permission to do so.
Other than food restrictions, it is recommended that you wear loose, comfortable clothing to your appointment. At some point during the preparation process, you will be asked to remove your top and bra and given a short hospital gown to wear during the scanning procedure.
The PEM Procedure: What to Expect
About one hour before the PEM scan, a nurse or technologist will take a drop of blood from your finger to test your blood sugar level. If it is within the acceptable range to perform the study, a small amount of radioactive sugar will be injected into your arm.
You will then be directed to a quiet room and asked to sit or lie comfortably still in a chair or recliner for about 60 minutes, giving your body ample time to absorb the radioactive sugar analog.
After an hour in the quiet room, you will be brought into the PEM scanning room and seated in a chair. The technologist will scan each breast separately, positioning each in the PEM scanner as for a mammogram but using far less pressure than a mammogram. Each breast will be gently immobilized for approximately 10 minutes per scan.
A typical PEM examination includes at least two (2) scans per breast. The entire procedure — including time in the quiet room - takes about two (2) hours; so be sure to arrange your day accordingly.
PEM Results
A PEM examination will be read by a radiologist, who will send a report to your physician within 24 to 48 hours after the PEM examination. Your doctor will then inform you of the results.
PEM Safety
The same radioactive sugar injected into your arm prior to a PEM scan is routinely used for other medical imaging procedures without negative reactions or side effects. The amount of radioactivity contained in the sugar injection is about the same as that for a PET or PET/CT scan, a technology that has been used safely for decades. The radioactivity in the sugar fades quickly and leaves no detectable trace after 24 hours.
PEM Location
Sacred Heart Center