Factors impacting the choice between gallium 68 and fluorine 18 PSMA PET tracers, including half-lives, institutional capabilities, access to resources, detection rates, reimbursement constraints, and potential differences in interpretation.
Naveen Kella, MD: Given all the data and guideline recommendations, would you typically use one…PSMA [prostate-specific membrane antigen] PET [positron emission tomography] tracer over another?
Shadi Abdar Esfahani, MD, MPH: It's a little tough to answer this question right now based on…the data that we have. There are not a lot of head-to-head comparisons of the 2 compounds. But I would say, we all practice in different institutions, in different centers, and we have certain capabilities and also access to the resources that we could have. So, I would say it really depends on the institution and also the setting. Obviously, with the gallium 68–labeled compounds, there's a 68-minute half-life and with the fluorine-18, there is 109-minute half-life of the compound. So, in terms of the scheduling for patients, this is something that we need to consider based on the recommended dose that needs to be delivered to the patient.
The other [aspect] is based on the institution's capabilities of making the compounds in-house, or if they need to have it delivered from the suppliers around them. So again, depending on the resources inside the institution and around the institution, then the availability of these compounds is...right now the major point to just consider in general. If we have both [compounds] available...again, based on the data that we have…they function very well. And I would say the detection rate, the sensitivity and the specificity of the PSMA-targeted PET scans are much better than the conventional CTs and even the bone scans. So, I would say that there is not a major difference if we have both compounds available to us.
In terms of the CMS reimbursement, we would love to have access to any kind of compound. Right now, it is only gallium 68–labeled PSMA 11. So that's also another consideration if the patient is being evaluated for the eligibility for receiving the…treatment. And also, the other major point to just have in mind is in terms of the overall nature of the fluorine-18 and the fact that it may have some higher background bone uptake in some cases, and also the pitfalls. We need to consider that the fluorine 18–labeled compounds may show some more benign findings to have uptake. And this is our responsibility as…radiologists and nuclear medicine physicians and…clinicians to know more about what is a true positive and what is just a normal biodistribution of the compound, or [it] could be just a benign finding that has uptake.
Naveen Kella, MD: Great. Thanks for that great answer.
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