Info about PET scans
PET stands for positron emission tomography. A PET scan is an imaging
technique that is useful for detecting and monitoring the treatment of
breast cancer. It is different from an X-ray, mammogram, CAT scan,
MRI, or bone scan and can detect cancer in certain situations where these
other types of scans do not. Certainly all of these other types of
scan have their utility, but the PET scan represents an important additional
tool for diagnosis and monitoring. A PET scan works as follows: one
is asked to fast for several hours before the scan so that one’s blood
sugar level drops considerably. Just prior to the scan one will be
sedated so as to be able to relax and lay still as much as possible during
the scan. Then a radioactively marked sugar is injected into the
blood stream. This is somewhat like a bone scan in that a radioactive
injection is also utilized. The level of radioactivity is very low
and is not viewed as a significant health risk; certainly not significant
relative to the risk represented by having cancer. This radioactively
marked sugar circulates in the blood and is taken up by any tissue in the
body that is metabolically active, and thus needing energy. Thus
the radioactive sugar accumulates in metabolically active tissue.
Radioactive decay of this sugar then occurs and is recorded to form an
image. The type of radioactive decay that occurs results in repeated
events where an electron and positron are created that fly apart in exactly
opposite directions. The sensors that surround the person being scanned
detect these emissions. The point where the decay took place can
be determined because it must be on the line between the two detecting
sensors and the exact position can be determined by the time difference
between detection of the positron and the electron. For example,
if they arrive at the same time, then the radioactive decay happened exactly
half way between the sensors. Certainly ones heart is active and
thus it glows. But the heart can be readily identified as a heart.
The same is true for certain other always active organs. On
the other hand, breast tissue and even muscle tissue (when relaxed) should
not be active and thus not light up in a PET scan. Cancer tumors
will often glow because they are growing rapidly, whereas the surrounding
tissue may be quite benign and not glow at all. Basically the hungry
cancer cells suck up the radioactive sugar and are marked for imaging.
I have personally seen that a PET scan can clearly detect cancer in situations
where an X-ray, mammogram, CAT scan and bone scan showed nothing.
Dulce had been suffering unexplained pain for months and these other scans
were all negative. When she finally had a PET scan it showed activity
around her lung (which had just collapsed) and intense activity in multiple
lymph nodes in her chest, neck and upper abdomen. And yet a CAT scan
of the same area only a week prior showed all of these points to look normal.
I would strongly recommend that cancer patients utilize a PET scan to determine
the spread of their cancer and to monitor the effectiveness of their treatments.
Kevin...
Dulce’s PET scans were done in Seattle by
Dr. David Mankoff
Nuclear Medicine Department
University of Washington Medical Center
Seattle, Washington
Tel: (206) 548-4240 Fax: (206) 548-4496
Dulce’s oncologist in Seattle was:
Dr. Julie Gralow
Oncology Department
University of Washington Medical Center
Seattle, Washington
Tel: (206) 543-9598 Fax: (206) 616-8553
PET scanners are made by:
GE Medical Systems - Americas
Nuclear Medicine / PET Marketing
3000 North Grandview Boulevard
Waukesha WI 53188
Wisconsin, USA
Tel: 1 800 643 6439
Fax: (414) 548 2317
Web: www.ge.com/medical/nuclear/
Siemens Medical Systems, Inc.
Nuclear Medicine Group
2501 North Barrington Road
Hoffman Estates, IL 60195-5203
Tel: (847) 304-7700
Fax: (847) 304-7707
Web: www.sms.siemens.com/nmg/