In rodent studies the PET tracer is usually injected manually via tail-vein catheter. However, intraperitoneal injection is more convenient and can be reliable in small rodents, although it can fail, too, for example because of injection into the bowel (Steward et al., 1968; Miner et al., 1969; Arioli & Rossi, 1970; Gaines Das & North, 2007). Extravasation is common with intraperitoneal injections, too (Vines et al., 2011).
Intraperitoneal injection can be applied in sequential and multi-tracer studies (Wong et al., 2011), with proved reproducibility in [18F]FDG rat studies (Marsteller et al., 2006). Further, for mouse [18F]FDG studies, peritoneal injection has been shown to provide biodistribution that is comparable to tail vein injection results (Fueger et al., 2006; Schiffer et al., 2007) and SUV and Patlak results (Wong et al., 2011) within 60 min after administration.
Initial distribution of intra-peritoneally injected tracers in animals is slower because the tracer has to diffuse across the peritoneal membrane and the absorption is via the portal system (Lukas et al., 1971; Wong et al., 2011). The slower kinetics may require prolonged scan times, and may affect the SUV compared to intravenous injection (Schiffer et al., 2007). The passage through portal system may prevent the use of tracers which are quickly metabolized in the liver.
Arterial plasma input function measurement is easier and possibly more reliable after peritoneal injection than after intravenous injection because the slower distribution of the tracers requires less frequent plasma sampling, and dispersion and delay correction may not be needed (Wong et al., 2011). On the other hand, image-derived input function estimation methods may not perform as well, because it is more difficult to kinetically separate input function from tissue concentration curves. Also metabolite fractions may be higher and more variable after intraperitoneal injection.
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Created at: 2011-05-04
Updated at: 2018-11-30
Written by: Vesa Oikonen, Anne Roivainen