Fig. 5

Contrast-to-noise ratio (CNR) for increasing acquisition times on the PET/MRI (1–10 min, OSEM with PSF, 3 iterations, and 2 mm voxel size) and the PET/CT (1–5 min, OSEM with PSF and TOF, 3 iterations, 2 mm voxel size) for the 4-mm and 5-mm spheres in the 8:1 activity concentration. Spheres detected in the human observer study are presented in green, while non-detected spheres are presented in red