Bicolor K-edge spectral photon-counting CT imaging for the diagnosis of thoracic endoleaks: A dynamic phantom study

Purpose: The purpose of this study was to investigate the feasibility of identifying and characterizing the three most common types of endoleaks within a thoracic aorta aneurysm model using bicolor K-edge imag-ing with a spectral photon-counting computing tomography (SPCCT) system in combination with a biphasic contrast agent injection.Materials and methods: Three types of thoracic endoleaks (type 1, 2 and 3) were created in a dynamic anthro-pomorphic thoracic aorta phantom. Protocol consisted in an injection of an iodinated contrast material fol-lowed 80 seconds after an injection of a gadolinium-based contrast agent (GBCA). The phantom was scanned using a clinical prototype SPCCT during bicolor phase imaging consisting in an early distribution of GBCA and a late distribution of iodine. Conventional and spectral images were reconstructed for differentiating between the contrast agents and measuring their respective attenuation values and concentrations inside and outside the stent graft.Results: Conventional images failed to provide specific dynamic imaging contrast agents in the aneurysmal sac and outside the stent graft while spectral images differentiated their specific distribution. In type 1 and 3 thoracic endoleaks, GBCA concentration was measured outside the stent graft at 6.1 +/- 3.7 (standard deviation [SD]) mg/ mL and 6.0 +/- 4.0 (SD) mg/mL, respectively, in favor of an early blood flow. In type 2 thoracic endoleak, iodine was measured outside the stent graft at 24.3 +/- 5.5 (SD) mg/mL in favor of a late blood flow in the aneurysmal sac.Conclusion: Bicolor K-edge imaging enabled SPCCT allows a bicolor characterization of thoracic aorta endo-leaks in a single acquisition in combination with a biphasic contrast agent injection.(c) 2023 The Authors. Published by Elsevier Masson SAS on behalf of Societe francaise de radiologie. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Automated summary

This study aimed to investigate the feasibility of identifying and characterizing the three most common types of endoleaks in a thoracic aorta aneurysm model using bicolor K-edge imaging and a biphasic contrast agent injection. The results showed that bicolor K-edge imaging allows for the bicolor characterization of thoracic aorta endoleaks in a single acquisition.