Characterization of Center-of-Mass and Rebinning in Positron Emission Tomography with Motion

Sammanfattning: Medical molecular imaging with positron emission tomography (PET) is sensitive to patient motion since PET scans last several minutes. Despite advancements in PET, such as improved photon-pair time-of-flight (TOF) difference resolution, motion deformations limit image resolution and quantification. Previous research of head motion tracking has produced the data-driven centroid-of-distribution (COD) algorithm. COD generates a 3D center-of-mass (COM) over time via raw list-mode PET data, which can guide motion correction such as gating and event rebinning in non-TOF PET. Knowledge gaps: COD could potentially benefit from sinogram corrections used in image reconstruction, while rebinning has not extended to TOF PET. Methods: This study develops COD with event mass (incorporating random correction and line-of-response (LOR) normalization) and a simplistic TOF rebinner. In scans of phantoms and moving heads with F11 flouro-deoxy-glucose (FDG) tracer, COD alternatives are evaluated with a signal-to-noise ratio (SNR) via linear fit to image COM, while rebinning is evaluated with mean squared error (MSE). Results: COD SNR did not benefit from a corrected event mass. The prototype TOF rebinning reduced MSE, although there were discretization errors and event loss at extreme bins for LOR and TOF due to the simplistic design, which introduced image artifacts. In conclusion, corrected event mass in COD is not promising, while TOF rebinning appears viable if techniques from state-of-the-art LOR rebinning are incorporated.