Abdominal vessel depiction on virtual triphasic spectral detector CT: initial clinical experience

Purpose: To evaluate vessel assessment in virtual monoenergetic images (VMI_40keV) and virtual-non-contrast images (VNC) derived from venous phase spectral detector computed tomography (SDCT) acquisitions in comparison to arterial phase and true non-contrast (TNC) images.

Methods: Triphasic abdominal SDCT was performed in 25 patients including TNC, arterial and venous phase. VMI_40keV and VNC were reconstructed from the venous phase and compared to conventional arterial-phase images (CI_art), TNC and conventional venous-phase images (CI_ven). Vessel contrast and virtual contrast removal were analyzed with region-of-interest-based measurements and in a qualitative assessment.

Results: Quantitative analysis revealed no significant attenuation differences between TNC and VNC in arterial vessels (p-range 0.07-0.47) except for the renal artery (p = 0.011). For venous vessels, significant differences between TNC and VNC were found for all veins (p < 0.001) except the inferior vena cava (p = 0.26), yet these differences remained within a 10 HU range in most patients. No significant attenuation differences were found between CI_art/VMI_40keV in arterial vessels (p-range 0.06-0.86). Contrast-to-noise ratio provided by VMI_40keV and CI_art was equivalent for all arterial vessels assessed (p-range 0.14-0.91). Qualitatively, VMI_40keV showed similar enhancement of abdominal and pelvic arteries as CI_art and VNC were rated comparable to TNC.

Conclusion: Our study suggests that VNC and VMI_40keV derived from single venous-phase SDCT offer comparable assessment of major abdominal vessels as provided by routine triphasic examinations, if no dynamic contrast information is required.