Initial results of in vivo CT imaging of contrast agents using MPPC-based photon-counting CT

X-ray computed tomography (CT) is an essential technology in modern medicine, as it enables three-dimensional non-destructive observation of the inside of the body. Contrast-enhanced CT scanning is widely performed for lesion-enhanced imaging. However, conventional X-ray CT systems integrate all incident X-ray signals, leading to the acquisition of monochromatic energy information and the prevention of material identification and quantitative evaluation of the concentration of contrast agents. Recently, photon counting CT (PC-CT) has been attracting attention as a new system for solving these problems. PC-CT utilizes the energy information of individual X-ray photons, enabling the identification of target materials. We have performed demonstrations combining the PC-CT system that we developed with fast scintillators and multi-pixel photon counters. In this study, we report on the initial results of in-vivo X-ray CT imaging with our established PC-CT system. We injected an iodine contrast agent into a mouse and visualized the spatial distribution of the contrast agent. Subsequently, we performed K-edge imaging and concentration mapping with the obtained CT images in multiple energy bands. The obtained images displayed successful three-dimensional contrast enhancement and a concentration map of the kidney and bladder in the mouse, indicating significant potential for the clinical application of this silicon photomultiplier-based PC-CT system.