To explore the effect of different contrast agent concentrations in CT portal venography and improve the success rate of examination.

A total of 103 patients who underwent abdominal contrast-enhanced CT scan in Zhongda Hospital Southeast University from February to June 2019 were retrospectively analyzed. These patients were divided into two groups based on different contrast agent concentrations. Among them, 51 received high-concentration contrast agent (400 mg/ml) and 52 received low-concentration contrast agent (320 mg/ml). The data of portal vein phase were employed for portal venograpy reformation, and the CT values of the main portal vein, superior mesenteric vein, splenic vein, and portal vein enhanced were measured. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated to evaluate image quality objectively. Subjective assessment of image quality of CT images was performed by two experienced radiologists. Combining objective and subjective evaluations gave the overall evaluation of the image quality, implying whether different contrast agent concentrations would produce inconsistent image quality in portal venoraphy. Mann-Whitney U test and t test were used.

The image scores of the high and low concentration groups were 4.00 (3.97, 4.22) and 4.00 (3.40, 4.02), respectively. The difference was statistically significant (Z=-2.329, P=0.020). The CT values of the portal vein, superior mesenteric vein, and portal vein enhanced in the high concentration group were higher than those in the low concentration group (P< 0.05). However, no significant difference in CT value of spine vein, SNR nor CNR of the portal vein was detected between the two groups (P>0.05).

Using the same scanning technique and contrast injection protocol, portal venography examination with high contrast agent concentration can effectively improve the success rate and image quality.

Tomography, X-ray computed; Contrast media; Portal vein; Comparative study