First test results of a commercially available clinical PET scanner using the NEMA NU 4 - 2008 small animal PET standards

The recently published NEMA NU 4 - 2008 Standards has been specially designed for the performance evaluation of small animal PET scanners with appropriate scaling for the mice, rats or monkeys used in pre-clinical applications. In this paper, we report on the NU 4 performance of a commercially available clinical scanner (PEM Flex Solo II, Naviscan, Inc., San Diego) that was designed for human PET imaging of small organs such as the female breast. Due to the compact design of the PEM Flex, the NU 4 Standards is better suited for evaluating its performance over the clinical scanner standard of NU 2. The following results were obtained based on the NU 4 standard: Trans-axial spatial resolution 1.6 mm FWHM for high resolution reconstruction and 2.4 mm FWHM for standard resolution reconstruction with no significant variation within the field of view. The total system sensitivity was 0.16 cps/Bq. For the mouse and rat phantoms, the respective system sensitivities were 0.067 cps/Bq and 0.14 cps/Bq. In image quality testing, the uniformity was found to be 2.7% STD at the standard resolution mode and 6.1% at the high resolution mode. Although there is no specific NEMA testing protocol for planar geometry PET scanners, the NEMA NU 4 - 2008 Standards proved to be a useful tool to evaluate the performance of the PEM Flex scanner with minor modification to address the specifics of its detector configuration.