Photon attenuation correction in misregistered cardiac PET/CT

Abstract

PET-CT misalignment has been reported as a source of artefacts in cardiac PET/CT due to a biased photon attenuation correction. Using the data from 28 cardiac PET/CT rest/stress examinations, PET-CT misalignment was corrected using three different methods: manual registration, automatic mutual information based image registration and an emission-driven correction algorithm. The clinical effects of the realignment were quantitatively assessed, and significant changes were observed in 6 out of 28 examinations (21.4%), in 5 of these studies resulting in the disappearance of large apparent perfusion defects. These results indicate that the excellent specificity of PET for the detection of perfusion defects could be compromised when CT-based attenuation correction is done without correction of PET-CT misalignment.