No gadolinium K-edge detected on the first clinical photon-counting computed tomography scanner.

Abstract

This study aimed to elucidate whether gadolinium contrast in clinically relevant doses can be used with photon-counting computed tomography (PCCT) as an alternative contrast agent in clinical applications. A CTDI phantom with 3D printed rods filled with different concentrations of gadolinium and iodine contrast was scanned in a PCCT and an energy-integrated computed tomography (EICT). Attenuation values at different monoenergetic steps were extracted for each contrast concentration. For PCCT, gadolinium reached an attenuation>100 HU (103 HU) at 40keV with a concentration 5mmol/L whereas the same level was reached at 50keV (118 HU) for 10mmol/L and 90keV (114 HU) for 25mmol/L. For iodine, the same level of attenuation was reached at 100keV (106 HU) with a concentration 8.75mgI/mL. For EICT the lowest gadolinium contrast concentration needed to reach>100 HU (108 HU) was 10mmol/L at 50keV. For 25mmol/L 100 HU was reached at 100keV. For iodine contrast 108 HU was reached at 110keV for 8.75mg I/mL. No K-edge potential or difference in attenuation curves between iodine and gadolinium contrast is detected on the first clinical available PCCT. Clinically relevant attenuation levels were barely achieved in this setting with gadolinium concentrations approved for human use. The results of this study suggest that, given current scanning technology, gadolinium is not a clinically useful contrast agent for computed tomography because no K-edge was detected.