Automatic Alignment of Myocardial Perfusion Images With Contrast-Enhanced Cardiac Computed Tomography

Abstract

Explicit fusion of perfusion data from Positron Emission Tomography (PET) or Single Photon Emission Computed Tomography (SPECT) with coronary artery anatomy from Computed Tomographic Coronary Angiography (CTA) has been shown to improve the diagnostic yield for coronary artery disease (CAD) compared to either modality alone. However, most clinically available methods were developed for multimodal scanners or require interactive alignment prior to display and analysis. A new approach was developed to register the two distributions obtained either from a single multimodal imager or from separate scanners, and a preliminary validation was undertaken to compare the automatic alignment to interactive alignment by two experts.

Automatic detection of left and right ventricles from CTA enables efficient alignment of anatomy with myocardial perfusion data

“…and their usage for the automated alignment of CT myocardial images with PET myocardial perfusion by way of our previously developed algorithms for multimodality image registration (11). The reliability of the automatic segmentation was determined by comparing the radial boundary differences between the automatically extracted myocardial surfaces to those hand-traced by an expert, while the accuracy of the registration of the automatic segmentation was assessed in terms of rotation and translation between these CT surfaces after alignment with PET studies.…”

“…Our automatic technique for CT and MPI fusion has been previously described and tested (11). Briefly, once the LV/RV endo/epi structure was segmented on CTA acquisitions, a binary mask was created, the left and right ventricles separated and the short axis identified on the CTA acquisition based on the LV chamber symmetry axis.…”

“…Since the manual segmentation is considered the reference standard, the PET/CT alignment performed with the hand-traced mask was considered as the reference as well (11). Differences in alignment due to the use of the automatically segmented CTA myocardium instead of the manual ones were evaluated in terms of rotations around x, y and z axes and translations in the x, y and z directions between the two aligned CTs.…”

“…In a previous work published by our group (11), an algorithm for the automated alignment of MPI and CTA images obtained from different scanners was presented. Both left (LV) and right (RV) ventricles were manually identified on the two datasets, binary images were created and successively aligned using mutual information principles (12).…”

“…Secondly, perfusion images were aligned to the CTA acquisitions by means of our published second-generation biventricular fusion technique (11) using both the automatically segmented and the manually traced myocardial contours. Differences in translations and rotations between the two resulting alignments were estimated, with the registration of the manual tracings taken as the reference standard.…”