FAQ PET
- What does PET stand for?
- Is PET different than Nuclear Medicine?
- What is PET used for?
- How does it work?
- What does PET show that CT or MRI doesn't?
- Is a PET scan uncomfortable for the
patient?
- What about patient prep?
- Is PET scanning covered by insurance?
1. What does PET stand for?
PET is short for Positron Emission Tomography. PET scanning is
a diagnostic imaging technique which utilizes positron emitting
radioisotopes and a sophisticated radiation detection device, the
scanner, which looks similar to a CT scanner.
2. Is PET different than Nuclear Medicine?
Both PET and Nuclear Medicine use radioisotopes to generate images
which represent various functions within the body, but PET requires
a specialized imaging device that is different than a standard Nuclear
camera.
3. What is PET used for?
PET scanning is mainly used in oncology work-ups for the detection
and characterization of tumors, but it also has application in neurology
and cardiology.
4. How does it work?
The positron emitting isotope (F-18) is connected to a glucose
molecule to make a radiopharmaceutical called FDG. After being injected
through a vein in the patient's arm, FDG preferentially accumulates
in malignant cells because they have a higher than normal metabolism
and, therefore, a higher than normal glucose utilization. The scanner
creates a picture of the FDG distribution. A malignant tumor will
appear brighter (or "hotter") than a benign structure.
5. What does PET show that CT or MRI doesn't?
CT and MRI show abnormal structures but they usually do not characterize
it as benign or malignant. In general, PET and Nuc Med images portray
function whereas CT and MRI portray anatomy.
6. Is a PET scan uncomfortable for the patient?
The exam begins with an intravenous injection but otherwise it
is a straightforward and painless. There are no side effects from
the FDG. After injection, the patient is asked to sit quietly in
a comfortable reclining chair for 45 minutes. The actual scan requires
the patient to lie still for approximately 45 minutes.
7. What about patient prep?
The patient must not eat for several hours before the exam in order
to avoid elevated blood glucose levels. This is because the technique
is based upon the abnormal glucose utilization of malignant cells
and we want those cells to be hungry for glucose. Drinking water
prior to the exam is encouraged.
8. Is PET scanning covered by insurance?
Yes it is. Because of the high cost, though, most
insurance carriers require prior approval or they have published
a list of approved indications. Medicare has approved the following
indications.
| |
| Clinical Indication |
Diagnostic
Setting |
| 1. Breast Cancer |
Initial staging; advanced local regional disease,
re-staging; know or suspected reoccurrence, completion
of therapy, monitoring response to therapy |
| 2. Single Pulmonary Nodule |
Characterization of malignant potential in nodule
less than 4 cm |
| 3. Lung Cancer
— Non Small Cell |
Diagnosis, staging, restaging |
| 4. Esophageal
Cancer |
Diagnosis, staging, restaging
|
| 5. Colorectal Cancer |
Diagnosis, staging, restaging |
| 6. Lymphoma |
Diagnosis, staging, restaging
|
| 7. Melanoma |
Diagnosis, staging, restaging; not covered for
regional lymph node evaluation |
| 8. Head + Neck
Cancers |
Diagnosis, staging, restaging;
not covered for CNS and thyroid cancer |
| 9. Breast Cancer |
Staging, restaging, treatment monitoring |
| 10. Myocardial
Viability |
Metabolic assessment for myocardial
viability |
| 11. Refractory Seizures |
Metabolic brain imaging for pre-surgical evaluation
refractory seizures |
|
|
