Dynamic PET examinations of individual 1 (left panels) and individual 2 (right panels). The examinations reveal rapid high accumulation in the pancreas of both [11C]DHTP and [11C]HTP followed by washout which is completed after approximately 60 min (top panels). Selective inhibition of MAO-A reduces washout of both analogues to a minimum. [11C]DHTP and [11C]HTP are selective for neuroendocrine tissues, and consequently, no accumulation (under baseline conditions) or effects from inhibiting MAO-A are seen in tissues such as the liver (bottom panels). The [11C]HTP examinations have been published previously at group level .