Automated long axial field of view PET image processing and kinetic modelling with the TurBO toolbox

Long axial field of view (LAFOV) PET imaging requires extensive automation due to the large number of target tissues. Therefore, we introduce an open-source analysis pipeline (TurBO, Turku total-BOdy) for automated preprocessing and kinetic modelling of LAFOV [¹⁵O]H₂O and [¹⁸F]FDG PET data. TurBO enables efficient, reproducible quantification of tissue perfusion and metabolism at regional- and voxel-levels through automated co-registration, motion correction, CT-based region of interest (ROI) segmentation, image-derived input function (IDIF) extraction, and region-specific kinetic modelling.

The pipeline was validated with Biograph Vision Quadra (Siemens Healthineers) LAFOV PET/CT data from 21 subjects scanned with [¹⁵O]H₂O and 16 subjects scanned with [¹⁸F]FDG. Six CT-segmented ROIs (cortical brain gray matter, left iliopsoas muscle, right kidney cortex and medulla, pancreas, spleen and liver) were used to assess different levels of tissue perfusion and glucose metabolism.

Model fits showed high quality with consistent estimates at regional and voxel-levels (R² > 0.83 for [¹⁵O]H₂O, R² > 0.99 for [¹⁸F]FDG). Manual and automated IDIFs were in concordance (R² > 0.74 for [¹⁵O]H₂O, and R² > 0.78 for [¹⁸F]FDG) with minimal bias (< 4% and < 10%, respectively). Manual and CT-segmented ROIs showed strong agreement (R² > 0.82 for [¹⁵O]H₂O and R² > 0.83 for [¹⁸F]FDG). Motion correction had little impact on estimates (R² > 0.71 for [¹⁵O]H₂O and R² > 0.78 for [¹⁸F]FDG) compared with uncorrected data.

The TurBO pipeline provides fully automated and reliable quantification for LAFOV PET data. It substantially reduces manual workload and enables standardized, reproducible assessment of inter-organ perfusion and metabolism.