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Question About Scans and Low PSA

Posts: 21
Joined: Dec 2011

My question is are results from the use of C11 Pet scans with low PSA values determined simply by a matter of probability with high GL being the greater probability?  I noticed Dr Eugene Kwon reporting C11 Choline Pet scan results on patients having a PSA of 0.

How do you determine when to use these types of scans - particularly after having already gone through treatment (surgery or radiation) and with a low PSA?  Is it incorrect to assume that these types of scans should only be used when the PSA rises to predetermined value?

VascodaGama's picture
Posts: 3427
Joined: Nov 2010


In my opinion, our main purpose in undertaking the C11 PET/CT exam is to locate the cancer. We know that we got it because of an increasing PSA or symptoms, and want to tackle it the best way possible with the intent of “killing” it for good (with surgery or radiation), or, in the impossibility of cure, at least have a better diagnosis of one’s status. If cancer is found in an organ or in a place restrictive to operation then one can avoid those treatments and chose a palliative way that best fits his preferences.

In other words, the exam should be done when the conditions are propitious for a positive result avoiding false negatives to the maximum extent, but not too late that would allow the bandit to spread freely. We should look for the highest probability in detecting the bandit.

Through experiences and trials we know that the traditional CT, MRI and Bone scintigraphy scans are not reliable in small size PCa lesions, however, the combination of PET/CT have shown better results when using particular contrast agents. From trials it was found that some contrasts have better outcomes (positive results) depending on the grade of the cancer (Gleason) the level of the PSA (size) and spread (location). C11 and F18 choline and the novel tracer PSMA seem to be the best choice but the 18F FDG (fluorodeoxyglucose) is practical in symptomatic osseous lesions. The best level in terms of PSA for all the tests is above 2.0 with the new tracer PSMA improving the possibility of detection in levels above 1.2.

Dr. Eugene Kwon may have his own particular threshold table he trusts to be good but such level of PSA=0.0 is not judged as a proper marker in trials worldwide.

I would recommend you to draw conclusions after reading the details in these links;




Best wishes for peace of mind.



Old Salt
Posts: 838
Joined: Aug 2014

Why don't you ask Dr Kwon what the rationale is for doing the scan(s)?

Is it possible you are in a clinincal trial?

hopeful and opt...
Posts: 2338
Joined: Apr 2009

Another place for advanced pet ct scan  using c11 acetate is in Arizona, Dr. Fabio Almeida runs this one..




Also UCLA does this pet scan as well.


As Vasco mentioned in order to be a candidate, your PSA has to be high enough so that the tests can be effective.


As I understand you have to pay out of pocket

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