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

Background: The goal of the present study was to evaluate the reproducibility of cerebral adenosine A(2A) receptor (A(2A)R) quantification using C-11-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 C-11-TMSX as a tool to measure the change in A(2A)R in the human brain.