Mass-preserving motion correction of dual gated cardiac PET

Image degradation due to motion is a known problem in Positron Emission Tomography (PET). To reduce motion artifacts in PET, gating based techniques were found applicable. In pure respiratory gated PET, each gate still contains cardiac motion. Analogously, pure cardiac gated PET images still contain respiratory motion. Hence, we make use of dual (joint respiratory and cardiac) gating to further reduce the amount of motion contained in the images. The inclusion of non-rigid cardiac motion leads to intensity modulations caused by the Partial Volume Effect (PVE). To overcome the intensity modulations we identified and considered the mass-preserving property of PET images in the Variational Algorithm for Mass-Preserving Image REgistration (VAMPIRE). The aim of this paper is the elimination of both cardiac and respiratory motion in thoracic dual gated PET without a loss of statistic. The strategy of our proposed motion correction approach is: 1) Dual gating, 2) Mass-preserving motion estimation (VAMPIRE), and 3) Averaging of the aligned images. In a patient study we showed that the proposed mass-preserving motion correction strategy significantly removes motion artifacts in cardiac PET. VAMPIRE achieved accurate results that resemble cardiac and respiratory motion across all patients.