Test-retest variability of adenosine A2A binding in the human brain with (11)C-TMSX and PET.

Background: The goal of the present study was to evaluate the reproducibility of cerebral adenosine A2A receptor (A2AR) quantification using (11)C-TMSX and PET in a test-retest study.
Methods: Five healthy volunteers were studied twice. The test-retest variability was assessed for distribution volume (V T) and binding potential relative to non-displaceable uptake (BPND) based on either metabolite-corrected arterial blood sampling or a reference region. The cerebral cortex and centrum semiovale were used as candidate reference regions.
Results: Test-retest variability of V T was good in all regions (6% to 13%). In the putamen, BPND using the centrum semiovale displayed a lower test-retest variability (3%) than that of BPND using the cerebral cortex as a reference region (5%). The noninvasive method showed a higher or similar level of test-retest reproducibility compared to the invasive method.
Conclusions: Binding reproducibility is sufficient to use (11)C-TMSX as a tool to measure the change in A2AR in the human brain.