'Fraid not at my end. I've not followed it, will dig back in when my PSA
warrants it.

I.P.

Hi Dale...As the name implies, "positron emission tomography" scans
for emitted positrons.  Its sensitivity is therefor dependent upon how
much of the positron source has been absorbed by the body or "target
organ."  One of the commonly used PET isotopes is 18F.  18F when used
as fluoride is readily incorporated into bone.  Hence PET is pretty
good when looking for bone mets.  In fact a relatively recent paper (J
Nucl Med. 2006 Feb;47(2):287-297; The Detection of Bone Metastases in
Patients with High-Risk Prostate Cancer: 99mTc-MDP Planar Bone
Scintigraphy, Single- and Multi-Field-of-View SPECT, 18F-Fluoride PET,
and 18F-Fluoride PET/CT: Even-Sapir E, Metser U, Mishani E, Lievshitz
G, Lerman H, Leibovitch I.) compared 4 different techniques in their
ability to detect bone mets.  The following table compares the
results:

                sensitivity    specificity   positive pv   negative
pv
planar BS       70%             57%           64%             55%,
spect BS        92%             82%           86%             90%,
18F PET        100%           62%           74%             100%
18F PET/CT  100%           100%         100%           100%

18F PET compares pretty well, but when you combine 18F PET and a CT
scan - well, you can't do better (BTW, 18F-Fluoride PET/CT bone scan,
which can identify bone metastases as well as scan lymph nodes, is
available at the  Dattoli Cancer Center & Brachytherapy Research
Institute, 2803 Fruitville Road, Sarasota, Florida 34237,
1-877-328-8654 www.dattoli.com).

However, if we are talking about diagnostic information before
treatment or in the early stages of recurrence, then it is not the
bones, but rather the prostate that we want to image and therein lies
the rub.  When organs are imaged with PET scans the 18F is often
introduced by attaching it to a deoxyglucose molecule.  The sugar
molecule accumulates in any tissue that metabolizes glucose.  But some
cancers, prostate included, do not metabolize sugars very rapidly
(e.g. PCa is "slow growing") and good signals are difficult to obtain
in such cases.  The abstract that I've included below, shows once
again that PET scans are not very useful in detecting small amounts of
PCa.  However, this continues to be an active area of investigation.
All that is needed is a fluorinated (or some other positron emitting
isotope) molecule that is rapidly taken up by the prostate...ron

BJU Int. 2007 Jun;99(6):1415-20

18F-choline and/or 11C-acetate positron emission tomography: detection
of residual or progressive subclinical disease at very low prostate-
specific antigen values (<1 ng/mL) after radical prostatectomy.

Vees H, Buchegger F, Albrecht S, Khan H, Husarik D, Zaidi H, Soloviev
D, Hany TF, Miralbell R.

Service of Radiation Oncology, University Hospital, Geneva,
Switzerland. Hansjorg.Vees@hcuge.ch

OBJECTIVES: To assess the value of positron emission tomography (PET)/
computed tomography (CT) with either (18)F-choline and/or (11)C-
acetate, of residual or recurrent tumour after radical prostatectomy
(RP) in patients with a prostate-specific antigen (PSA) level of <1 ng/
mL and referred for adjuvant or salvage radiotherapy.
PATIENTS AND METHODS: In all, 22 PET/CT studies were performed, 11
with (18)F-choline (group A) and 11 with (11)C-acetate (group B), in
20 consecutive patients (two undergoing PET/CT scans with both
tracers). The median (range) PSA level before PET/CT was 0.33
(0.08-0.76) ng/mL. Endorectal-coil magnetic resonance imaging (MRI)
was used in 18 patients. Nineteen patients were eligible for
evaluation of biochemical response after salvage radiotherapy.
RESULTS: There was abnormal local tracer uptake in five and six
patients in group A and B, respectively. Except for a single positive
obturator lymph node, there was no other site of metastasis. In the
two patients evaluated with both tracers there was no pathological
uptake. Endorectal MRI was locally positive in 15 of 18 patients; 12
of 19 responded with a marked decrease in PSA level (half or more from
baseline) 6 months after salvage radiotherapy.
CONCLUSIONS: Although (18)F-choline and (11)C-acetate PET/CT studies
succeeded in detecting local residual or recurrent disease in about
half the patients with PSA levels of <1 ng/mL after RP, these studies
cannot yet be recommended as a standard diagnostic tool for early
relapse or suspicion of subclinical minimally persistent disease after
surgery. Endorectal MRI might be more helpful, especially in patients
with a low likelihood of distant metastases. Nevertheless, further
research with (18)F-choline and/or (11)C-acetate PET with optimal
spatial resolution might be needed for patients with a high risk of
distant relapse after RP even at low PSA values.
PMID: 17428249

I don't know enough to give you a good answer.  I know PET was superceded by
PET/CT Scans, but I don't know if they have proven to be much better.