Could temporal window for the computed tomography hepatic venography (CTHV) be extended?: A comparative study between spectral and conventional CT using porcine models.

Objective: To investigate the feasibility of extending the acceptable temporal window for hepatic venography with dual-energy spectral CT imaging.

Methods: Five normal pigs anesthetized intramuscularly were scanned on a multislice CT (GE Discovery HD750 CT) after bolus contrast injection. Twelve CT scans with dual-energy spectral imaging mode were performed on each pig with a 10-second interval. Both conventional polychromatic and monochromatic image sets were reconstructed. The optimal energy level for hepatic vein imaging was selected from the monochromatic image sets based on the contrast-to-noise ratio (CNR) analysis. Subjective assessment of image quality was performed on volume-rendering images at 12 imaging points in time.

Results: The CNRs for hepatic veins in the polychromatic, default monochromatic 65 keV, and the optimal energy images were 2.24 ± 1.09, 3.48 ± 1.73, and 6.72 ± 2.56, respectively, with a significant difference among 3 groups (P < 0.001). There was no acceptable temporal window for imaging hepatic veins in the polychromatic group, but a peak plateau existed. The temporal window in the 65-keV group was 20 seconds, whereas it was 70 seconds in the optimal energy group.

Conclusions: Compared with conventional polychromatic CT images, monochromatic images provided superior CNR for hepatic veins and 3.5 times temporal window of hepatic venography in spectral CT.