Performance evaluation of Cerenkov luminescence imaging: a comparison of (68)Ga with (18)F

BACKGROUND: Cerenkov Luminescence Imaging (CLI) is an emerging technology for intraoperative margin assessment. Previous research only evaluated radionuclide 18-Fluorine ((18)F); however, for future applications in prostate cancer, 68-Gallium ((68)Ga) seems more suitable, given its higher positron energy. Theoretical calculations predict that (68)Ga should offer a higher signal-to-noise ratio than (18)F; this is the first experimental confirmation. The aim of this study is to investigate the technical performance of CLI by comparing (68)Ga to (18)F. RESULTS: The linearity of the system, detection limit, spatial resolution, and uniformity were determined with the LightPath imaging system. All experiments were conducted with clinically relevant activity levels in vitro, using dedicated phantoms. For both radionuclides, a linear relationship between the activity concentration and detected light yield was observed (R(2) = 0.99). (68)Ga showed approximately 22 times more detectable Cerenkov signal compared to (18)F. The detectable activity concentration after a 120 s exposure time and 2 × 2 binning of (18)F was 23.7 kBq/mL and 1.2 kBq/mL for (68)Ga. The spatial resolution was 1.31 mm for (18)F and 1.40 mm for (68)Ga. The coefficient of variance of the uniformity phantom was 0.07 for the central field of view. CONCLUSION: (68)Ga was superior over (18)F in terms of light yield and minimal detection limit. However, as could be expected, the resolution was 0.1 mm less for (68)Ga. Given the clinical constraints of an acquisition time less than 120 s and a spatial resolution < 2 mm, CLI for intraoperative margin assessment using (68)Ga could be feasible.