PET Scan Technology
In the treatment of cancer, early detection
is key. Physicians at Pennsylvania Hospital have
a powerful diagnostic tool, Positron
Emission Tomography (PET), that is helping
them not only make a diagnosis sooner, but also
determine the best course of treatment.
The PennPET Center at Pennsylvania Hospital opened in March 2003.
As part of Pennsylvania Hospital's comprehensive cancer program,
PET is a valuable step in the early stages of diagnosis and treatment.
PET is only appropriate for certain cancers such as lung, lymphoma,
and head and
neck. Patients should also check insurance coverage as it may
be limited to only certain conditions.
When used, it can precisely locate a tumor, detect if it is benign
or malignant and even determine a patient's response to chemotherapy
and/or radiation. For patients who have already been diagnosed with
cancer, a PET scan can determine the source and extent of the cancer
and can often eliminate the need for additional diagnostic procedures.
“The availability of PET to the patients and physicians of
Pennsylvania Hospital is representative of the strong commitment on
the part of this institution to cancer treatment,” according
Bruce Kneeland, chair of the department of radiology.
PET imaging changes patient management in 30% to 40% of cases because
of its sensitivity to the presence of early metastatic deposits not
seen with other imaging modalities. This is especially true for involvement
of lymph nodes before they have become sufficiently enlarged to be
detected by computerized
tomography (CT) or magnetic
resonance imaging (MRI), as well as the skeleton. In patients
who have undergone treatment, PET imaging can also frequently detect
lymph nodes involved by tumor from fibrosis.
A PET scan works by measuring the body's metabolic activity.
The PET scan procedure begins with a simple injection of FDG (fluorideoxyglucose),
a radiopharmaceutical about one hour before the scan. The FDG is metabolized
by the body and emits signals, which are picked up by the PET scanner.
A computer then reassembles the signals into images. Cancer cells
show up more brightly on the scan because they are more metabolically
active than non-cancerous cells. Results are usually ready within
48 hours of the procedure.
A PET scan differs from other imaging systems such as CT or MRI because
it shows how the body is functioning. It can often identify abnormal
activity, such as tumor growth, before it is visible on an MRI or
CT, which looks at the structure of the body.
With the advent of image “fusion” techniques, which have
just become available at Pennsylvania Hospital,PET
images can be directly superimposed on CT images allowing a comparison
of the metabolic changes seen with PET and the changes in structure
seen with CT. According to Dr.
Gary Greene, chief of the section of nuclear medicine, this provides
greater accuracy than either modality. And an
improved diagnosis can make all the difference.
For more information on the PET Scan Center at Pennsylvania Hospital,
call 1-800-789-PENN (7366). You can also request
an appointment online.