Feasibility and Accuracy of Dual-Source Dual-Energy CT for Noninvasive Determination of Hepatic Iron Accumulation

Abstract

To retrospectively assess feasibility of dual-source dual-energy (DSDE) computed tomography (CT) for evaluation of hepatic iron accumulation in a liver phantom and liver transplantation candidates and to compare its accuracy with that of 3-T magnetic resonance (MR) imaging. This study was approved by the institutional review board; informed consent was waived. A liver agar phantom containing six tubes of iron (concentrations, 100-5000 mg of iron per 100 mL of solution) was scanned at 80 and 140 kVp with both DSDE mode and single-source dual-energy (SSDE) CT with sequential scanning mode. Difference of averaged attenuation between 80 and 140 kVp at CT (ΔH) was measured and correlated with iron concentration. Thirty-two liver transplant recipients and 55 donors who underwent DSDE CT at 80 and 140 kVp were included. Twenty-three underwent 3-T liver MR with dual-echo in-phase and opposed-phase T1-weighted and spin-echo T2-weighted imaging. Hepatic ΔH was measured at CT. On T1- and T2-weighted MR images, iron indexes were calculated. Degree of iron accumulation and macrosteatosis were determined at histologic examination (reference). Diagnostic performance of ΔH at CT and iron indexes at MR for diagnosing clinically important iron accumulation was evaluated (receiver operating characteristic [ROC] analysis). For phantom study, ΔH obtained from both DSDE mode and SSDE CT with sequential scanning mode was correlated with iron concentration (correlation coefficient, 1.00 and 0.943, respectively; P = .173). ΔH (13.53) in 10 patients with clinically important (≥ 10%) iron accumulation was significantly higher than that (7.39) in 77 patients with normal or mild iron deposition (P < .001). ΔH was significantly correlated with degree of iron accumulation (correlation coefficient, 0.430; P < .001) but not with degree of hepatic macrosteatosis (P = .216). Area under the ROC curve for diagnosing clinically important iron accumulation was 0.881 and 0.897 with CT and MR, respectively (P = .851). DSDE CT is accurate for diagnosing clinically important hepatic iron accumulation without confounding influence of hepatic steatosis, with diagnostic performance on par with MR.