Motion-corrected imaging of the aortic valve with18F-NaF PET/CT and PET/MRI: A feasibility study

Abstract

We investigated whether motion correction of gated 18F-fluoride PET/CT and PET/MRI of the aortic valve could improve PET quan-titation and image quality. Methods: A diffeomorphic, mass-preserving, anatomy-guided registration algorithm was used to align the PET images from 4 cardiac gates, preserving all counts, and apply them to the PET/MRI and PET/CT data of 6 patients with aortic stenosis. Measured signal-to-noise ratios (SNRs) and target-to-background ratios (TBRs) were compared with the standard method of using only the diastolic gate. Results: High-intensity aortic valve 18F-fluoride uptake was observed in all patients. After motion correction, SNR and TBR increased compared with the median diastolic gate (SNR, 51.61 vs. 21.0; TBR, 2.85 vs. 2.22) and the median summed data (SNR, 51.61 vs. 34.10; TBR, 2.85 vs. 1.95) (P 5 0.028 for all). Furthermore, noise decreased from 0.105 (median, diastolic) to 0.042 (median, motion-corrected) (P 5 0.028). Conclusion: Motion correction of hybrid 18F-fluoride PET markedly improves SNR, resulting in improved image quality.