Quantitative determination of gadolinium and iodine contrast agents in dual-energy computed tomography via a dual-energy iterative reconstruction algorithm: a simulation study on multi-contrast imaging

Simultaneous quantification of two contrast agents in dual-energy CT (DECT) is promising for clinical diagnostics. This simulation study demonstrates that accurate estimation of iodine and gadolinium concentrations in unmixed aqueous solutions can be achieved using two-material decomposition and beam-hardening suppression with the dual-energy iterative reconstruction algorithm (DIRA). A simulated DECT imaging chain was used for evaluation. The phantom comprised a lipid cylinder containing five inserts filled with water, iodine (25 and 50 mg/mL), and gadolinium (25 and 50 mg/mL) solutions. X-ray projections at 80 and Sn140 kV were generated using Siemens' DRASIM code. DIRA was configured for two-material decomposition with water-bone, water-iodine, and water-gadolinium bases, and cylinder positions were manually defined during reconstruction. After approximately six iterations, accurate estimates of contrast agent mass fractions were obtained. These results confirm the feasibility of simultaneous iodine and gadolinium quantification in DECT and support further development toward a clinical application.