PEM (Positron Emission Mammography)

PEM (Positron Emission Mammography)

NuclearWomen suspected of having or diagnosed with breast cancer may be referred to Florida Hospital for a PEM scan. PEM stands for positron emission mammography, a specialized form of PET (positron emission tomography) for imaging breasts. Unlike large PET systems that can scan a person's entire body, PEM systems are small and scan a single breast at close range. This produces very clear, detailed images that enable doctors to see cancers when they are still very small and determine the exact size, location and extent of cancer deposits in the breast.  

At Florida Hospital, PEM plays an important role in the diagnosis, treatment and monitoring of breast cancer. With PEM, doctors are better able to:

  • Plan a patient's treatment and/or surgery
  • Determine a patient's suitability for lumpectomy or breast-conserving surgery
  • Remove tumors or cancerous tissue more completely and thereby avoid repeat surgeries
  • Guide the needle during biopsy
  • Monitor treatment and check for a recurrence of the disease

PEM is a nuclear imaging technology that records chemical activity in the breast. What doctors see in a PEM image that distinguishes cancer from healthy tissue is the accumulation of a mildly radioactive substance that has been injected into the cancerous tissue. This substance called a radiotracer, is usually glucose (sugar) based. Cancerous cells and tumors absorb, accumulate and metabolize sugar faster than healthy tissue and appear as bright spots on the scan. Basically, PEM captures a picture of the biochemical activity occurring within a tumor or cancerous tissue. So it not only reveals the size, shape and location of a suspicious mass; it confirms whether the mass is cancerous or not.


The radioactive properties of the tracer used during PEM scanning is very low, exposing patients to no more radiation than some x-ray procedures. These tracers have been routinely used for decades without negative reactions or serious side effects. Pregnant women and nursing mothers are cautioned and advised to talk with their doctor or our staff before having a PEM test, as radioactivity can pass from mother to developing fetus or to nursing infants through breast milk.  After the exam, the radioactivity dissipates quickly and leaves no detectable trace after 24 hours. 

Extra care and planning are also required for patients with diabetes and hypoglycemia (low blood sugar), because of the sugar-based radiotracer. These conditions don't necessarily exclude a woman from having a PEM scan; however they do require special consideration and individualized instruction.  

What to Expect

Before the Test

Your doctor will provide specific instructions before your appointment. In preparation for a PEM scan, the following general guidelines will apply:

  • To assure that your body absorbs the radioactive sugar properly, do not eat or drink anything except water for four to six hours before your exam. Do not even chew gum. You may want to bring a snack with you to eat after the exam, once the nurse or technician gives you permission to do so.
  • Unless instructed otherwise, take all prescribed medications on the day of your appointment. If you have been advised not to take medications on an empty stomach, you may eat a few soda crackers with your medicine four to six hours before your exam.
  • If you are diabetic or have low blood sugar (hypoglycemia), please inform our clinical staff in advance, so we can consult with your physician to determine the safest way to prepare you for your exam.
  • For your convenience, wear a two-piece outfit to your appointment. You will need to undress from the waist up. It is best not to wear a necklace; you'll be asked to remove it.
  • If you are or think you might be pregnant or are currently breastfeeding, let your doctor and our imaging services staff know.

During the Test

Prior to your exam, a nurse or technologist will inject a small amount of radioactive sugar into your arm. You will then be directed to sit quietly and very still for about 60 minutes, giving the tracer sufficient time to circulate through your body. You will then be led to a room with the PEM scanner.

Throughout the procedure you will be seated in a special chair with a breast positioned in the scanner as for a mammogram (only using much less compression than a mammogram) to immobilize the breast. Each breast is scanned separately; typically two scans per breast at 10 minutes per scan. The entire procedure, including time in the quiet room, takes about two hours; so plan your day accordingly.

After the Test

You may leave as soon as your exam is completed. Unless you have received special instructions, you may eat, drive, resume normal activity and exercise and take all prescribed medications. Drink plenty of water and fluids throughout the day after the exam and empty your bladder frequently to flush the glucose tracer from your system.

If you are a nursing mother, discontinue breast-feeding for the amount of time specified by your doctor or our medical staff. In the interim, pump your breasts and discard the milk.

PEM Results

Once obtained, your PEM image remains an electronic file. Florida Hospital has the most sophisticated network, viewing stations and software for processing, transmitting, reviewing and storing these electronic images.

One of our physicians, a specialist in nuclear medicine and breast imaging, will examine and interpret your scan and create a report of his/her findings that will be sent to your doctor. Your doctor will present the results and discuss them with you.    


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