Validation of arterial input function measurements within an extracorporeal shunt driven by mouse blood pressure for preclinical dynamic PET-MRI

Ziel/Aim The dynamic arterial radiotracer concentration (arterial input function, AIF) is difficult to determine accurately in PET of mice. We already successfully performed AIF measurements using a pump-driven extracorporeal shunt [1]. We here investigate AIF measurements using the same setup without the pump, driven by mouse blood pressure alone, as the usage of a pump may not be possible in some cases, e.g. in preclinical PET-MRI.

Methodik/Methods The proposed setup involved extracorporeal shunting from the femoral artery to the tail vein for seven mice experiments using F-18-PSMA-1007, incorporating a blood radioactivity detector (Twilite, SwissTrace). Determination of the AIF was conducted in accordance to the previous study [1], with dispersion, introduced by the catheters in the setup, being characterized as a sum of two gamma variates [2]. Parametric deconvolution involved fitting AIF and the unknown dispersion kernel simultaneously. Mean and standard deviation (SD) of the peak height and the area-under-the-curve (AUC), normalized to the injected concentration, were calculated to compare the deconvolved AIF to an invasive intracorporeal AIF, determined using microprobes implanted into the aortic arch [3].

Ergebnisse/Results Deconvolution of the extracorporeal measurement was found to be numerically stable in all cases. Microprobe-based AIF measurements were successful with the exception of a single case. Mean and SD of peak height were 0.067±0.012 and 0.088±0.029 (p=0.12), and AUC after 5000 seconds were 8.8±1.2 s and 9.9±1.6 s for microprobe- and Twilite-derived AIFs (p=0.19), respectively.

Schlussfolgerungen/Conclusions The proposed extracorporeal measurement setup resulted in deconvolved AIFs which were similar to intracorporeally-measured AIFs. It might therefore be a valuable tool for kinetic modelling of preclinical PET-MRI data without the need of a pump.

Publication History

Article published online:
30 March 2023

• Literatur/References

• 1 Cufe J. et al. EJNMMI 2022; 49: S309
• 2 Cufe J. et al. Nuklearmedizin - NuclearMedicine 2022; 61: 167-168
• 3 Pain F. et al. J Nucl Med 2004; 45: 1577-1582