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. PEM may also be ordered during a 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 for your patient to prepare them for a PEM
scan. To assure that they absorb the radioactive sugar properly, the patient
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).
The patient should inform us
if they have either of these conditions. Generally, this will not
prevent the PEM scan. The patient should also bring a snack to eat once the nurse or technician gives them
permission to do so.
Other than food restrictions, it is
recommended that the patient wear loose, comfortable clothing to the
appointment.
The PEM Procedure: What to Expect
About
one hour before the PEM scan, a nurse or technologist will take a drop
of blood from the finger to test blood sugar levels. If it is
within the acceptable range to perform the study, a small amount of
radioactive sugar will be injected into the arm.
The patient is then directed to a quiet room and asked to sit or lie comfortably still
in a chair or recliner for about 60 minutes, giving the body ample
time to absorb the radioactive sugar analog.
After an hour in
the quiet room, the patient 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 and sent within 24 to 48 hours.
PEM Safety
The
same radioactive sugar injected into the 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.
