Comparison of True and Virtual Non-Contrast Images of Liver Obtained with Single-Source Twin Beam and Dual-Source Dual-Energy CT

Purpose To assess the magnitude of differences between attenuation values of the true non -contrast image (TNC) and virtual non -contrast image (VNC) derived from twin -beam dual -energy CT (tbDECT) and dual-source DECT (dsDECT).<br /> Materials and Methods This retrospective study included 62 patients who underwent liver dynamic DECT with tbDECT ( n = 32) or dsDECT ( n = 30). Arterial VNC (AVNC), portal VNC (PVNC), and delayed VNC (DVNC) were reconstructed using multiphasic DECT. Attenuation values of multiple intra-abdominal organs ( n = 11) on TNCs were subsequently compared to those on multiphasic VNCs. Further, we investigated the percentage of cases with an absolute difference between TNC and VNC of <= 10 Hounsfield units (HU).<br /> Results For the mean attenuation values of TNC and VNC, 33 items for each DECT were compared according to the multiphasic VNCs and organs. More than half of the comparison items for each DECT showed significant differences (tbDECT 17/33; dsDECT 19/33; Bonferroni correction p < 0.0167). The percentage of cases with an absolute difference <= 10 HU was 56.7%, 69.2%, and 78.6% in AVNC, PVNC, and DVNC in tbDECT, respectively, and 70.5%, 78%, and 78% in dsDECT, respectively.<br /> Conclusion VNCs derived from the two DECTs were insufficient to replace TNCs because of the considerable difference in attenuation values.