Speaker
Description
PET human brain imaging has evolved dramatically, using specific radiotracers and imaging paradigms to measure numerous brain targets and to assess neurotransmitter and receptor dynamics. Until recently, dedicated brain PET has not progressed since the HRRT, so there is a compelling need to build next generation human brain PET systems. This is the goal of the NeuroEXPLORER (NX) project. Based on experience with >5000 human brain HRRT studies at Yale and with the total-body uEXPLORER system at UC Davis, the NX is being constructed to meet the following design goals: 1) Ultra-high sensitivity, to be achieved with a long axial field-of-view (aFOV) plus excellent time-of-flight (TOF); 2) Exceptional image resolution through small detectors, depth of interaction (DOI) readout, and corrections for inter-crystal scatter; 3) Continuous head motion tracking and correction. The NX design is a cylinder with diameter of 51.6 cm and aFOV of 48.1 cm. The system consists of 5 complete detector rings, with an additional incomplete 6th ring to accommodate shoulders to place the brain in the aFOV center. LYSO crystals (20-mm deep) have an in-plane dimension of 1.5 mm, leading to a resolution of 1.6-1.8 mm. To reduce parallax error, a novel single-end DOI design was developed with < 4 mm FWHM. The projected TOF resolution is < 270 ps. Combined with the long aFOV, we project that the NX will have > 10-fold higher effective sensitivity than the HRRT. Head motion tracking is performed with a real-time stereovision system. Optimization of reconstruction and quantification is performed with high-resolution brain simulations and novel phantom configurations. Ultimately, human paradigms will demonstrate the effectiveness of the NX: 1) showing the dramatic sensitivity increase compared to the HRRT, 2) leveraging high sensitivity to reliably measure uptake in small nuclei, and 3) opening new frontiers of imaging neurotransmitter dynamics.
