Study Design and Population

This retrospective study included 170 patients who underwent preoperative contrast-enhanced CT between April 2017 and October 2021. Patients with bowel obstruction, inflammatory disease, or collateral venous pathways were excluded. The final cohort was divided into two groups:

• CO₂ insufflation group: n = 86.
• Non-insufflation group: n = 84.
  

  Fig 4: A total of 170 patients who underwent preoperative contrast-enhanced CT colonography were retrospectively analyzed and divided into CO₂ insufflation and non-insufflation groups.

CT Acquisition Protocol

Portal venous phase imaging was performed at fixed delays of 25, 30, or 35 seconds after initiation of arterial-phase scanning. Attenuation values (HU) of the IMV and SMV were measured at their venous roots using standardized region-of-interest placement.

Fig 5: Portal venous phase imaging was performed at fixed delays of 25, 30, or 35 seconds after arterial-phase triggering to evaluate delay-dependent changes in venous enhancement.

In the CO₂ insufflation group, colonic gas volume was quantified to reflect the degree of intraluminal CO₂ insufflation.

Statistical Analysis

The following analyses were performed:

• Comparison of venous attenuation across scan delays.
• Correlation analysis between enhancement and scan delay.
• Multivariate linear regression analysis restricted to the CO₂ insufflation group to identify predictors of mesenteric venous enhancement.
  

  Fig 6: CT attenuation values of the IMV and SMV were measured at the venous roots, followed by correlation analysis with scan delay and multivariate regression to identify predictors of venous enhancement.