|
When to do a PET
Timing
in life is everything. Here are some factors to consider when ordering
a PET or
PET/CT scan. If you have any questions in regards to PET or PET/CT
in relation to any
of the below treatment situations, please do not hesitate to call
us.
I. Chemotherapy:
A. During therapy:
1.
Continuously administered - PET/CT can be done any time. PET/CT
in this case
measures
both tumor cell death and suppression of remaining viable cell activity
2.
Cyclic administration - best time to do PET/CT is 1-3 days before
next cycle begins.
B. At completion of planned regimen:
1.
4-6 weeks following last chemotherapy (or 1-2 days before additional
therapy
would be employed).
II. Radiation therapy and chemoradiation therapy:
A. As primary therapy:
1.
At 3-4 weeks after completion - assess adequacy of therapy (is all
the hyper-
metabolism
abated? If not, more therapy is needed). Exceptions based on
chemotherapy
protocol.
2.
At 3-4 months - verify completeness of response.
III. Surgery:
A. Prior to surgery - 1-3 days prior
to procedure.
B. After surgery - 1-2 weeks preferred,
but can be sooner.
IV. Bone marrow stimulants - by stimulating increased production
of circulating cells in the bloodstream the uptake of FDG in the
precursor cells increases 5-10 fold:
A. Procrit - wait 1-2 days after administration
before doing a PET/CT scan.
B. Neupogen - wait 7-10 days after
administration before a PET/CT scan.
C. Neulasta - wait 10-17 days after
administration before performing a PET/CT scan.
V. Caveats:
A. General answers - the above answers
may not fit every clinical situation. Often, timing
of PET/CT
scanning needs to be individualized. The referring physician should
call and
discuss the
patient's care with an MRP physician.
B. Evolution of cancer therapy - timing
of PET scanning must continue to evolve as the
treatment
of cancer evolves.
C. The above information is based
upon Metro Region PET Center's clinical experience
from reading
more than 19,000 PET scans. Research for evidence based decisions
is
currently
ongoing. |
