Test-retest reproducibility of [C]-L-deprenyl-D binding to MAO-B in the human brain.

BACKGROUND

[C]-L-deprenyl-D is a positron emission tomography (PET) radioligand for measurement of the monoamine oxidase B (MAO-B) activity in vivo brain. The estimation of the test-retest reproducibility is important for accurate interpretation of PET studies.

RESULTS

We performed two [C]-L-deprenyl-D scans for six healthy subjects and evaluated the test-retest variability of this radioligand. MAO-B binding was quantified by two tissue compartment model (2TCM) with three rate constants (K , k , k ) using metabolite-corrected plasma radioactivity. The λk defined as (K /k ) × k was also calculated. The correlation between MAO-B binding and age, and the effect of partial volume effect correction (PVEc) for the reproducibility were also estimated. %difference of k was 2.6% (medial frontal cortex) to 10.3% (hippocampus), and that of λk was 5.0% (thalamus) to 9.2% (cerebellum). Mean %difference of all regions were 5.3 and 7.0% in k and λk , respectively. All regions showed below 10% variabilities except the hippocampus in k (10.3%). Intraclass correlation coefficient (ICC) of k was 0.78 (hippocampus) to 0.98 (medial frontal cortex), and that of λk was 0.78 (hippocampus) to 0.95 (thalamus). Mean ICC were 0.94 and 0.89 in k and λk , respectively. The highest positive correlation with age was observed in the hippocampus, as r = 0.75 in k and 0.76 in λk . After PVEc, mean %difference were 5.6 and 7.2% in k and λk , respectively. Mean ICC were 0.92 and 0.90 for k and λk , respectively. These values were almost the same as those before PVEc.

CONCLUSIONS

The present results indicate that k and λk of [C]-L-deprenyl-D are reliable parameters for test-retest reproducibility with healthy subjects both before and after PVEc. The studies with patients of larger sample size are required for further clinical applications.