Abstract
BackgroundRespiratory motion in PET/CT leads to well-known image degrading effects commonly compensated using elastic motion correction approaches. Gate-to-gate motion correction techniques are promising tools for improving clinical PET data but suffer from relatively long reconstruction times. In this study, the performance of a fast elastic motion compensation approach based on motion deblurring (DEB-MC) was evaluated on patient and phantom data and compared to an EM-based fully 3D gate-to-gate motion correction method (G2G-MC) which was considered the gold standard.MethodsTwenty-eight patients were included in this study with suspected or confirmed malignancies in the thorax or abdomen. All patients underwent whole-body [18F]FDG PET/CT examinations applying hardware-based respiratory gating. In addition, a dynamic anthropomorphic thorax phantom was studied with PET/CT simulating tumour motion under controlled but realistic conditions. PET signal recovery values were calculated from phantom scans by comparing lesion activities after motion correction to static ground truth data. Differences in standardized uptake values (SUV) and metabolic volume (MV) between both reconstruction methods as well as between motion-corrected (MC) and non motion-corrected (NOMC) results were statistically analyzed using a Wilcoxon signed-rank test.ResultsPhantom data analysis showed high lesion recovery values of 91% (2 cm motion) and 98% (1 cm) for G2G-MC and 83% (2 cm) and 90% (1 cm) for DEB-MC. The statistical analysis of patient data found significant differences between NOMC and MC reconstructions for SUV max, SUV mean, MV, and contrast-to-noise ratio (CNR) for both reconstruction algorithms. Furthermore, both methods showed similar increases of 11–12% in SUV max and SUV mean after MC. The statistical analysis of the MC/NOMC ratio found no significant differences between the methods.ConclusionBoth motion correction techniques deliver comparable improvements of SUV max, SUV mean, and CNR after MC on clinical and phantom data. The fast elastic motion compensation technique DEB-MC may thereby be a valuable alternative to state-of-the art motion correction techniques.
Highlights
Respiratory motion in Positron emission tomography (PET)/Computed tomography (CT) leads to well-known image degrading effects commonly compensated using elastic motion correction approaches
The fast elastic motion compensation technique Deblurring motion correction (DEB-MC) may thereby be a valuable alternative to state-of-the art motion correction techniques
While Gata-to-gate motion correction (G2G-MC) estimates the motion vector field (MVF) between each gate and a reference gate and has to pre-reconstruct all respiratory gated images, DEB-MC only needs to estimate the deblurring kernel between the optimal gating (OG) and the non motion-corrected (NOMC) reconstructions, Table 3 Mean ± Standard deviation (SD) for Standardized uptake value (SUVmax), Standardized uptake value (SUVmean), metabolic volume (MV), and contrast-to-noise ratio (CNR) of all lesions reconstructed with and without MC
Summary
Respiratory motion in PET/CT leads to well-known image degrading effects commonly compensated using elastic motion correction approaches. The performance of a fast elastic motion compensation approach based on motion deblurring (DEB-MC) was evaluated on patient and phantom data and compared to an EM-based fully 3D gate-to-gate motion correction method (G2G-MC) which was considered the gold standard. PET has continuously been improved from a low-sensitive 2D imaging technology with poor spatial resolution into a high-resolution 3D technique with excellent signal-to-noise (SNR) characteristics using time-of-flight (TOF) capabilities [1,2,3]. This enabled a significant reduction in acquisition time to few minutes per bed position. Different motion correction (MC) approaches have been proposed before which compared for example gated (amplitude-based or phase-based) to non-gated reconstructions or optimal respiratory-gating 4D PET/CT to 3D PET/CT [7,8,9,10,11]
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