Advancement in PET quantification using 3D-OP-OSEM point spread function reconstruction with the HRRT

Purpose Image reconstruction including the modelling of the point spread function (PSF) is an approach improving the resolution of the PET images. This study assessed the quantitative improvements provided by the implementation of the PSF modelling in the reconstruction of the PET data using the High Resolution Research Tomograph (HRRT). Methods Measurements were performed on the NEMA-IEC/ 2001 (Image Quality) phantom for image quality and on an anthropomorphic brain phantom (STEPBRAIN). PSF reconstruction was also applied to PET measurements in two cynomolgus monkeys examined with [(18)F]FE-PE2I (dopamine transporter) and with [(11)C]MNPA (D(2) receptor), and in one human subject examined with [(11)C]raclopride (D(2) receptor). Results PSF reconstruction increased the recovery coefficient (RC) in the NEMA phantom by 11-40% and the grey to white matter ratio in the STEPBRAIN phantom by 17%. PSF reconstruction increased binding potential (BP(ND)) in the striatum and midbrain by 14 and 18% in the [(18)F]FE-PE2I study, and striatal BP(ND) by 6 and 10% in the [(11)C]MNPA and [(11)C]raclopride studies. Conclusion PSF reconstruction improved quantification by increasing the RC and thus reducing the partial volume effect. This method provides improved conditions for PET quantification in clinical studies with the HRRT system, particularly when targeting receptor populations in small brain structures.