When to do a PET
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
A. During therapy:
Continuously administered - PET/CT can be done any time. PET/CT
in this case
both tumor cell death and suppression of remaining viable cell activity
Cyclic administration - best time to do PET/CT is 1-3 days before
next cycle begins.
B. At completion of planned regimen:
4-6 weeks following last chemotherapy (or 1-2 days before additional
would be employed).
II. Radiation therapy and chemoradiation therapy:
A. As primary therapy:
At 3-4 weeks after completion - assess adequacy of therapy (is all
abated? If not, more therapy is needed). Exceptions based on
At 3-4 months - verify completeness of response.
A. Prior to surgery - 1-3 days prior
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.
A. General answers - the above answers
may not fit every clinical situation. Often, timing
scanning needs to be individualized. The referring physician should
patient's care with an MRP physician.
B. Evolution of cancer therapy - timing
of PET scanning must continue to evolve as the
of cancer evolves.
C. The above information is based
upon Metro Region PET Center's clinical experience
more than 19,000 PET scans. Research for evidence based decisions