Room: Room 202
Purpose: One potential application of multi-energy CT (MECT) is to acquire multi-phase CT data using only one scan, but multiple injections of different contrast agents, aiming to reduce radiation dose. However, it remains unknown whether the radiation dose can truly be reduced compared with traditional multi-phase scans for the same target image quality. The purpose of this work is to evaluate the dose efficiency of MECT for multi-phase liver imaging using two contrast agents (iodine/gadolinium).
Methods: Both simulation and experimental studies were performed to compare the dose efficiency of a single-scan MECT (MECT_1s) protocol using two contrast agents (iodine/gadolinium) and a traditional two-phase protocol with two-scan single-energy CT (SECT_2s) using one contrast agent (iodine). For SECT_2s, an abdominal phantom containing two sets of iodine samples was designed to mimic the contrast enhancement at late-arterial and portal-venous phases. For MECT_1s, the same phantom containing a different set of iodine/gadolinium samples was used, with the iodine enhancement corresponding to the late-arterial phase and the gadolinium enhancement to the portal-venous phase. The total radiation dose in the two protocols was matched. A generic image-based material decomposition method was employed to solve the densities of iodine, gadolinium, and water, based on which CT images at the two phases were synthesized. The noise levels on the original images acquired with the SECT_2s protocol and the synthesized images generated with the MECT_1s protocol were compared.
Results: The average noise levels on MECT synthesized images were 400-700% higher than those acquired from SECT in the simulation study. Similar findings were observed in the phantom experiments, with 300-1600% higher noise with the MECT_1s protocol, dependent on the MECT tube energy selection, phantom size, and scanner platform.
Conclusion: Single-scan MECT for multi-phase CT imaging using two contrast agents (iodine/gadolinium) is intrinsically dose inefficient compared with traditional multi-phase SECT.
Funding Support, Disclosures, and Conflict of Interest: National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award Numbers EB024071 and EB016966. CHM receives research support from Siemens Healthcare.
Not Applicable / None Entered.