Purpose: Virtual non-contrast images derived by Dual Energy CT (DECT) may potentially obviate the need for true non-contrast images. We evaluated the reliability and conspicuity of the abdominal organs on virtual non-contrast (VNC) images derived from single-source spectral DECT compared with true non-contrast (TNC) images.
Materials and Methods: Thirty patients who underwent triple-phase abdominal DECT (IQon, Philips Healthcare, Eindhoven, The Netherlands) between January and April 2017 were retrospectively reviewed. TNC images were performed using conventional single-energy mode at 120 keV. VNC images were reconstructed from the venous phase images of the conventional study. Hounsfield unit (HU) values of liver, spleen, right kidney upper pole and aorta were compared between TNC and VNC images. Qualitative assessments of the liver parenchyma, as well as the spleen, pancreas and the osseous of the celiac trunk were performed on the TNC and VNC images, and rated on a scale of 1-5 (5 being the highest). Paired t-test was used to assess the significance of the differences between the TNC and VNC images.
Results: The mean difference in HU values on VNC and TNC images was 1.8 HU. The difference ranged in various organs from -2.2HU to 3.8HU, and was not statistically significant in most organs. The mean score of the qualitative assessment based on VNC images was 4.45 compared to 3.53 on TNC images. This score was significantly higher (p<0.001) on the VNC images, in all anatomical locations.
Conclusion: Similar attenuation values were found between VNC and TNC. There is a significantly higher conspicuity of findings in the VNC images in all evaluated locations. This suggests that VNC images may replace TNV images, thus decreasing the radiation exposure to the patient and shortening the scan duration.
