Performance Evaluation of a Next-generation Human Brain PET Imager: the NeuroEXPLORER

The NeuroEXPLORER (NX) is a dedicated human brain PET/CT imager with fine spatial resolution, high sensitivity, and continuous head motion correction capability. The performance of the scanner was evaluated based on the NEMA NU 2-2012 standard. With FBP reconstruction, the average radial/tangential spatial resolutions were 1.89 and 2.27 mm, and the axial spatial resolutions were 3.03 and 3.34 mm in FWHM, corresponding to radial offsets of 1-, and 10-cm from the center, respectively. The measured system TOF resolution was 236 ps and the energy resolution was 10.5%. The sensitivities were 46.0 and 47.6 kcps/MBq at the center and 10 cm radial offset, respectively. The peak noise-equivalent count (NEC) rate was 1,300 kcps at an activity concentration of 57.5 kBq/mL, and the average scatter fraction was 35%. The maximum count rate error at peak NEC rate was < 5.0%. The contrast recovery coefficients from the NEMA IQ phantom varied from 75.7% (10-mm sphere) to 92.1% (37-mm sphere), and the background variability (BV) varied from 3.3% to 1.4% with a hot sphere-to-background concentration ratio of 4:1. With TOF and DOI-rebinning OSEM reconstruction (5 iterations, 10 subsets) the transverse and axial spatial resolutions at 1-cm from the center were further improved to 1.22 and 1.77 mm, respectively. OSEM reconstruction resolved 1.6 mm hot rods of a mini-Derenzo phantom using ≥ 8 iterations and 10 subsets with 0.6 mm voxels.