Dual Energy on Dual Source CT in Abdominal Imaging: Comparison between Virtual-Non-Contrast and True-Non-Contrast images using quantitative and qualitative analysis and evaluation of dose report

Abstract

Establish whether virtual non-contrast images can replace real non-contrast images, avoiding the preliminary scan,
thus saving the patient dose.
Forty-one patients were studied on a second-generation dual-source scanner, triphasic were applied on all patients,
arterial and venous phase was acquired in dual-energy. HU values of TNC and VNC scans were compared through
ROI on liver, spleen, kidneys, aorta, muscle, and fat. Qualitative analysis of the data sets was performed by four readers and the values from 1 to 4 (1. poor, 2. fair, 3. good, 4. excellent.) were assigned to define the diagnostic quality of
the images. Then the absorbed dose ratios between the virtual images and the pre-contrast and portal phase images
were compared.
HU values were analyzed with the t-test and the difference was statistically significant P<0.0001. Image quality was
evaluated as excellent or good in 91,3% of TNC and 81,6% of VNC. At last, VNC showed a sensitive dose reduction
-46% compared to conventional triphasic protocol.
Overall VNC has shown a good image quality comparable to TNC. The dose reduction obtained from the extraction
of images without iodine, avoiding further scans, suggests the use of the dual-energy protocol in many exams.