Ziel/Aim To develop a safe and simple small animal FDG PET/CT protocol with CT contrast for improved anatometabolic assessment of the abdomen.
Methodik/Methods 12 mice underwent sequential (1) non-contrast CT, (2) i.p. application of 50 µl iodinated CT contrast agent (Ultravist 300, Bayer AG) together with 5 MBq i.v. FDG, (2) after 60 minutes of uptake time CT with PET in a dedicated small animal X- and beta-cubes system (Molecubes, Ghent, Belgium), respectively. Immediately thereafter mice were sacrificed and organs were taken for ex vivo weight and gamma counter activity measurements as reference standard. Visual organ delineation was compared for non-contrast versus contrast CT by three blinded readers using 3-point Likert Scale. Mean PET %IA/g for manually delineated abdominal organ VOIs was compared with the ex vivo reference standard using paired Student’s t test.
Ergebnisse/Results Mean Likert Score (SD) (higher score for improved delineation) for contrast versus non-contrast CT was 2,2 vs 1,8, 2,2 vs 1,2, 1,9 vs 1,5, 2,3 vs 2,1 for Kidney, Liver, Spleen, and Stomach, respectively. Visual reproducibility was higher for contrast versus non-contrast CT for kidney (Kappa 0,4 vs 0,3), spleen (0,51 vs 0,32), stomach (0,45 vs 0,4) and lower for liver (0,3 vs 0,42). When compared to the reference standard contrast versus non-contrast CT had a lower error for 12 (100 %), 7 (58,3 %), 11 (91,7 %), 9 (75 %) of 12 Kidney, Liver, Spleen, and Stomach %IA/g assessments. PET reconstruction with contrast versus non-contrast CT µ-map showed no impact on %IA/g quantification. Mice demonstrated no adverse effects after i.p. contrast application up to day 7 follow-up. Improved tumor assessment was confirmed for murine spontaneous intraabdonimal neuroblastoma.
Schlussfolgerungen/Conclusions We report a safe and simple intraperitoneal contrast enhanced small animal FDG PET/CT protocol for improved abdominal delineation and quantification.
