Abstract

Motion correction in PET has become more important as system resolution has improved. Our previous simulation study based on measured subject motions showed that event-by-event motion correction has the best accuracy in static acquisitions. The purpose of this study was to evaluate the accuracy of both event-by-event and frame-based motion correction methods in simulated dynamic studies. Image reconstructions with various motion correction methods were carried out on simulated HRRT list-mode data that contained a wide range of motion based on actual motion data. The time-activity curves (TAC) of all regions of interest were fitted to a one-tissue compartment model to estimate the distribution volume (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) and the binding potential (BP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ND</sub> ). In addition, we explored the figure-of-merit sum of squared difference (SSD) between the raw TAC and the fitted curve as a potential tool to assess the success of motion compensation in dynamic PET studies. This study showed that event-by-event motion correction method works reliably for a wide range of human head motion, generating V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and BP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ND</sub> estimates that are comparable to the motion-free case. Frame-based methods introduce 5-10% bias in these parameters, as intra-frame motion gets larger than 5mm. For event-by-event motion correction, the SSD between the raw TAC and the fitted curve is consistent with the static motion-free reference for a wide range of motions. For the frame-based methods, the ratio of the SSD to the motion-free reference rises to 2-4 when the intra-frame motion exceeds 5mm, suggesting that this may be a useful measure of quality of motion correction.

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