TY - JOUR T1 - Incorporation of respiratory motion estimation within a MAP super-resolution algorithm for image enhancement in 4D PET JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 593 LP - 593 VL - 50 IS - supplement 2 AU - Daphne Wallach AU - Frederic Lamare AU - Christian Roux AU - Dimtris Visvikis Y1 - 2009/05/01 UR - http://jnm.snmjournals.org/content/50/supplement_2/593.abstract N2 - 593 Objectives Super-resolution (SR) aims at generating a high-resolution image or image sequence from several slightly different low-resolution images. A maximum a posteriori (MAP) SR algorithm has been implemented and applied for simultaneous motion estimation and image quality enhancement of respiratory synchronized gated frames. Methods The algorithm was tested on GATE simulated images (8 frames of the NCAT phantom with 7-22 mm lung lesions) reconstructed using OPL-EM. SR was performed on the gated images with the proposed MAP algorithm using a Huber prior as regularization term. The function yielded by the MAP method was optimized with respect to both the high-resolution image and the motion parameters through a steepest descent algorithm. Two motion estimation models were compared. The first one based on a sinusoidal model of fixed phase with the motion amplitude optimized for each voxel, while the second model considers motion as a linear combination of cubic b-splines. Lesion positions were recovered using profiles and image enhancement was assessed by signal-to-noise ratio (SNR) and contrast measures. Results SR led to improved SNR and contrast while maintaining the motion compensation achieved by respiratory synchronization. The b-splines based motion estimation led to superior results in comparison to a sinusoidal model. SNR was 2.20 higher in the SR image than in the first gated frame, and 1.1 higher than in the sum of registered frames. Conclusions A MAP based super-resolution algorithm, incorporating simultaneous motion estimation has been implemented and applied to respiratory gated images, leading to accurate motion compensation and improved image SNR and contrast. ER -