A six-year longitudinal PET study of (+)-[¹¹C]DTBZ binding to the VMAT2 in monkey brain

The longitudinal reproducibility of in vivo binding potential measures for [¹¹C]dihydrotetrabenazine ([¹¹C]DTBZ) binding to the vesicular monoamine transporter 2 (VMAT2) site in primate brain was examined using a unique dataset of repeated control PET imaging studies.

Forty-one dynamic [¹¹C]DTBZ PET studies were completed in a single rhesus monkey. Imaging equipment (microPET P4), personnel, radiotracer characteristics (injected mass amounts, molar activity) and image data analysis (BP_ND-Logan) were consistent throughout the entire sequence of PET studies.

Same day reproducibility of BP_ND-Logan estimates of specific binding was very good (-3% and -7% changes) for two control-control sessions. Over the full 74 months, the average BP_ND-Logan value for [¹¹C]DTBZ-PET studies was 4.19±0.52, for a variance of 12%. No age-dependent change in binding potentials was observed over the six-year period.

If the technical variables associated with PET scanner are consistently maintained, including PET scanner, imaging procedures and radiotracer preparation, in vivo biochemistry can be reproducibly measured in the primate brain over a multi-year period of time.