Shared insight into FDA-approved PSMA PET imaging tracers, highlighting similarities and differences between gallium 68 and fluorine 18 compounds.
Naveen Kella, MD: I’d like to follow up with the available FDA-approved PSMA PET imaging tracer options. Can you talk to us about similarities and differences between them?
Shadi Abdar Esfahani, MD, MPH: Certainly. Right now in the United States, we have 2 compounds that we could order and use for our patients with prostate cancer. One is a gallium 68–based compound, PSMA 11.... And the other is a fluorine 18–labeled compound.... They are pretty much the same in terms of their use and their detection ability…for the site of the primary disease and also the metastatic disease. I would say that in terms of the comparison, it’s a little bit about the compounds and…how they are being made.
With the gallium 68 compounds, usually an institution requires a gallium generator to be able to make it in house. And if not, then we would need some suppliers from outside to deliver the dose to us so that we can inject and scan the patients. The gallium 68 has a 68-minute half-life. In terms of the timing of the delivery or for compounding it and then making it completely ready to be injected to the patient and then getting the scan done, this is the half-life that we need to have in our mind for the scan. For the fluorine 18–labeled compounds, fluorine 18 is being made by the cyclotron. For making the compound, there needs to be a cyclotron available either within the institution or a supplier has to make the compound and deliver it. The fluorine 18 has a half-life of about 109 or 110 minutes. This is the timeline and the period of time that we need to consider when we want to order it, schedule our patients, inject them, and…get the scan done.
I would say this is basically the major…difference between these 2 compounds…. And obviously, based on the availabilities of the of the suppliers around each institution or imaging facility or cancer center and also based on what each institution has, then the use and the frequency of the use and the way that our providers can order them would be a little different.
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