Good News for PET Researchers: Radiotracer binding Is less sensitive to blood flow than previously thought

Gary Boas

In a Journal of Cerebral Blood Flow & Metabolism paper published last month, the Martinos Center’s Christin Sander and colleagues resolved a longstanding question in positron emission tomography studies.

PET has played a crucial role in receptor binding studies, shedding light on a range of biological questions and contributing in important ways to the development of new drugs. But there has always been an open question in these studies as to the potential effects of changes in blood flow on the delivery and washout of PET radiotracers. This is significant because any such changes during measurements could, in theory, influence accurate quantification of receptor binding.

Researchers have used computer simulations to explore the potential effects but, because so far it is has been technically challenging to simultaneously track receptor binding and blood flow, reliable experimental data has proved elusive. Now, though, using the state-of-the-art simultaneous PET/MR scanner in the Center, Sander and colleagues have shown they can measure receptor binding (using PET) and blood flow (using arterial spin labeling [ASL]) at the same time. In doing this, they were able to determine the effects of changes in blood flow on receptor binding studies.

The impact of blood flow, as they reported in the JCBFMpaper, was so small that it was not even measurable. This will be welcome news to PET researchers as it puts to rest the debate as to whether flow affects the delivery and washout of PET radiotracers. In effect, investigators can now interpret findings from the studies with more confidence than ever before.

Other authors of the paper included the Center’s Joe Mandeville, Hsiao-Ying (Monica) Wey, Ciprian Catana, Jacob Hooker and Bruce Rosen.