Physically meaningful virtual unenhanced image reconstruction from dual-energy CT

Virtual unenhanced (VUE) image reconstruction techniques have the potential to eliminate the need for the acquisition of a non-contrast exam in imaging protocols that currently require both contrast and non-contrast computed tomographic (CT) scans. Here, we propose a new physically meaningful approach for the generation of VUE images as an application of a recently introduced technique for multi-material decomposition (MMD) from dual-energy CT. Rather than subtracting an estimate of the contribution to the image intensity in Hounsfield units due to contrast agent from the original image, the new algorithm replaces the estimated volume of contrast in each voxel by the same volume of the material that the contrast has displaced, namely, blood. Our results on both phantom and patient data demonstrate that VUE images can replace true unenhanced images effectively, thereby reducing radiation exposure and scan time of CT exams.