Synthesis and Imaging of [11C]Harmine

[¹¹C]harmine (7-[¹¹C]methoxy-1-methyl-9H-[3,4-b]indole) synthesis and quality control was performed according to procedures described by Philippe et al.^{23 (link)} All PET data was acquired using a GE Advance full-ring scanner at the PET Center at the Medical University of Vienna and in accordance with the center’s standard protocols. For tissue attenuation correction, a transmission scan of 5 min was carried out with ⁶⁸GE rod sources. An intravenous bolus of [¹¹C]harmine (4.6 MBq/kg body weight) was administered simultaneously with the start of PET. Dynamic PET was performed in 3D mode and reconstructed in 35 transaxial section volumes (128 × 128 matrix) with an iterative filtered backprojection algorithm (FORE-ITER) with a spatial resolution of 4.36 mm full-width at half maximum next to the center of the field of view. Fifty one successive time frames (12 frames of 5 s, 6 frames of 10 s, 3 frames of 20 s, 6 frames of 30 s, 9 frames of 1 min and 15 frames of 5 min) were collected, resulting in a total acquisition time of 90 min, optimized for modeling of [¹¹C]harmine. Arterial blood samples for [¹¹C]harmine quantification were drawn automatically for the first 10 min and manually at standardized intervals after [¹¹C]harmine injection^{15 (link)}.