Extended MRI-based PET motion correction for cardiac PET/MRI

Abstract Purpose A 2D image navigator (iNAV) based 3D whole-heart sequence has been used to perform MRI and PET non-rigid respiratory motion correction for hybrid PET/MRI. However, only the PET data acquired during the acquisition of the 3D whole-heart MRI is corrected for respiratory motion. This study introduces and evaluates an MRI-based respiratory motion correction method of the complete PET data. Methods Twelve oncology patients scheduled for an additional cardiac 18 F-Fluorodeoxyglucose (18 F-FDG) PET/MRI and 15 patients with coronary artery disease (CAD) scheduled for cardiac 18 F-Choline (18 F-FCH) PET/MRI were included. A 2D iNAV recorded the respiratory motion of the myocardium during the 3D whole-heart coronary MR angiography (CMRA) acquisition (~ 10 min). A respiratory belt was used to record the respiratory motion throughout the entire PET/MRI examination (~ 30–90 min). The simultaneously acquired iNAV and respiratory belt signal were used to divide the acquired PET data into 4 bins. The binning was then extended for the complete respiratory belt signal. Data acquired at each bin was reconstructed and combined using iNAV-based motion fields to create a respiratory motion-corrected PET image. Motion-corrected (MC) and non-motion-corrected (NMC) datasets were compared. Gating was also performed to correct cardiac motion. The SUV max and TBR max values were calculated for the myocardial wall or a vulnerable coronary plaque for the 18 F-FDG and 18 F-FCH datasets, respectively. Results A pair-wise comparison showed that the SUV max and TBR max values of the motion corrected (MC) datasets were significantly higher than those for the non-motion-corrected (NMC) datasets (8. 2 ± 1. 0 vs 7. 5 ± 1. 0, p < 0. 01 and 1. 9 ± 0. 2 vs 1. 2 ± 0. 2, p < 0. 01, respectively). In addition, the SUV max and TBR max of the motion corrected and gated (MCG) reconstructions were also higher than that of the non-motion-corrected but gated (NMCG) datasets, although for the TBR max this difference was not statistically significant (9. 6 ± 1. 3 vs 9. 1 ± 1. 2, p = 0. 02 and 2. 6 ± 0. 3 vs 2. 4 ± 0. 3, p = 0. 16, respectively). The respiratory motion-correction did not lead to a change in the signal to noise ratio. Conclusion The proposed respiratory motion correction method for hybrid PET/MRI improved the image quality of cardiovascular PET scans by increased SUV max and TBR max values while maintaining the signal-to-noise ratio. Trial registration METC162043 registered 01/03/2017.