Motion detection in hybrid PET/SPECT imaging based on the spatial cross-correlation of temporal sinograms

摘要

Patient motion in gamma camera coincidence imaging results in severe reconstruction artifacts. A protocol is proposed to automatically detect and correct motion from SPECT coincidence studies. The method is based on fractionating the acquisition into three full temporal sets of coincidence data. For each set and camera position, partial sinograms are calculated by rebinning events acquired at the same rotation. Partial sinograms from successive angular positions as well as from successive sets are cross- correlated along their common range of projections. Decreases in the cross-correlation values indicate that data from two successive rotations or sets became inconsistent and permit localization of the motion that occurred during the study. Events acquired during motion are eliminated while pre and post motion events are recombined into sets of consistent rebinned data that are reconstructed independently and fused to provide a motion-artifact free reconstructed image. The methods were tested using a wide range of experimental motion data obtained from cylindrical phantoms containing spheres filled with Fluorine-18. Single arbitrary motions that occurred during the study could be detected and further corrected in all phantom studies when the total number of coincident events acquired was greater than 5 x 10~6 for lesion-to-background ratios greater than 5.