Human Biodistribution and Radiation Dosimetry of the Tachykinin NK1 Antagonist Radioligand 18FSPA-RQ: Comparison of Thin-Slice Bisected and 2-Dimensional Planar Image Analysis

摘要

¹⁸F-Labeled substance P antagonist–receptor quantifier ([¹⁸F]SPA-RQ) [2-fluoromethoxy-5-(5-trifluoromethyl-tetrazol-1-yl)-benzyl]-[(2S,3S)-2-phenyl-piperidin-3-yl)amine] is a selective radioligand for in vivo quantification of tachykinin NK1 receptors with PET. The aims of this study were to estimate the radiation safety profile and relative risks of [¹⁸F]SPA-RQ with 3 different methods of image analysis.MethodsWhole-body PET images were acquired in 7 healthy subjects after injection of 192 ± 7 MBq (5.2 ± 0.2 mCi) [¹⁸F]SPA-RQ. Emission images were serially acquired at multiple time-points from 0 to 120 min and approximately 180–240 min after injection. Urine samples were collected after each imaging session and for 24 h after the last scan to measure excreted radioactivity. Horizontal tomographic images were compressed to varying degrees in the anteroposterior direction to create 3 datasets: thin-slice, bisected, and 2-dimensional (2D) planar images. Regions of interest were drawn around visually identifiable source organs to generate time–activity curves for each dataset. Residence times were determined from these curves, and doses to individual organs and the body as a whole were calculated using OLINDA/EXM 1.0.