Abstract 13442: Phase-Contrast Computed Tomography for the Characterization of Coronary Artery Disease - An Ex-vivo Feasibility Study

Abstract

Purpose: X-ray based phase-contrast imaging (PCI) is a novel imaging technique relying on photon phase-shift rather on pure absorption spectra.

Results from synchrotron sources indicate improved soft tissue resolution compared to conventional computed tomography (CT). The aim of this study was to examine the potential of PCI for the assessment of coronary atherosclerotic plaque in an ex-vivo validation setting.

Methods: Five ex-vivo human coronary arteries were imaged at a laboratory set-up using a grating interferometer. Effective pixel size was 100 µm. Subsequently, OCT and histopathology were performed, serving as the current in-vivo and ex-vivo goldstandard. Images were co-registered every 1.0 mm. Sensitivity, specificity and accuracy for the detection of different plaque types were calculated in comparison with histology. Lumen-, plaque- and vessel-area were measured in PCI, OCT and histology by independent observers. Results: In total, 585 cross-sections were assessed containing fibrous (F), lipid-rich (LR), and calcified (Ca) plaque in 339 (58%), 94 (16%), 54 (9%) cross sections by histopathology, respectively. Sensitivity, specificity and accuracy were 0.83, 0.95 and 0.96 for F, 0.85, 0.93 and 0.94 for LR and 0.92, 0.96 and 0.95 for Ca, respectively. Lumen, plaque and vessel area by PCI showed a good to excellent correlation with OCT (r=0.85, r=0.83 and 0.81; respectively, all p<0.05) and histopathology (r=0.95, r=0.91 and r=0.88; respectively all p<0.05). The observed absolute measurements were not significantly different between PCI and OCT (p=0.26) but significantly lower in histopathology (p<0.05).

Conclusion: In this experimental ex-vivo study, PCI allowed accurate measurements of vessel and plaque parameters and provided a high soft-tissue contrast in coronary atherosclerotic plaque compartments, indicating its high potential for improved assessment of coronary artery disease.