A multiscanner evaluation of PET image quality using phantom studies

We present preliminary results from an investigation of the impact of phantom diameter on sinogram and image quality for two PET scanners, the Allegro and ECAT HR⁺, both operated in fully-3D acquisition mode. Here, we evaluate the global sinogram NEC measurement and in subsequent studies will be looking at a local image signal-to-noise ratio (SNR) estimate derived from a nonprewhitening matched filter observer (SNR_NPW). We evaluate two different metrics, the global sinogram NEC measurement and a local image signal-to-noise (SNR) estimate derived from nonprewhitening matched filter observer (SNR_NPW). There is a significant decrease in the NEC rates when going from small to large diameter phantoms. As the diameter of the tissue-equivalent attenuating cylinder increases from 20 cm to 35 cm, the peak NEC rate drops by a factor of six for the Allegro scanner. If √NEC is an accurate measure of image quality, we expect to see a corresponding degradation in detection specific tasks, such as the SNR_NPW for a nonprewhitening matched filter.