Feasibility of Gd Contrast Agent in Spectral Computed Tomography

Abstract: X-ray computed tomography (CT) is currently a vital diagnostic tool in hospitals the world over. To be able to image a patient's interior quickly can facilitate a diagnosis so that proper treatment can be administered. In some cases a contrast agent is administered intravenously prior to the CT-scan, in order to enhance image quality. Most contrast agents are heavy-element based and have a sudden increase in attenuation at the k-edge due to photoelectric absorption of the photons. New technology utilizing multi-bin spectral CT is under development. This tech- nology opens up for the possibility to isolate the image contribution of this sudden increase in attenuation at the the k-edge. This report investigates the feasibility of using gadolinium-based contrast agents (GBCA) in multi-bin spectral CT. With a high k-edge, gadolinium is well suited for k-edge imaging. However, GBCA are currently only endorsed for magnetic res- onance imaging (MRI), raising the question if currently used concentrations are su-cient for CT practice. We model two cross-sections containing targets of various areas and determine the detectability of said targets for concentrations currently endorsed in MRI. Higher concentrations are considered when motivated. We conclude that detection of lesions and haemorrhaging in soft tissue, as well as cerebral haemorrhaging, is possible with the concentrations currently exercised in MRI. Additionally, we conclude that to detect residual blood 　ow in the case of ischemia caused by thrombosis, higher concentrations must be considered. These results clearly indicate that currently endorsed concentrations of GBCA, in combination with k-edge imaging, could provide su-cient contrast in CT-practice.