Purpose: To investigate the effect of arterial injection site and splenic volume on the hepatic zebra pattern seen at computed tomographic (CT) arterial portography.
Materials and methods: Images from CT arterial portographic examinations, performed via either the splenic artery (SA)(n = 47) or superior mesenteric artery (SMA)(n = 51) in 98 patients, were reviewed. The hepatic parenchymal enhancement pattern was assessed by three blinded reviewers. Splenic volume was determined.
Results: Twenty-two of 98 (22%) CT arterial portographic studies showed a zebra pattern: 10 of 47 (21%) with injection via the SA and 12 of 51 (24%) with injection via the SMA. The mean percentage of hepatic parenchyma with nontumorous perfusion defects was 55% with the zebra pattern versus 12% without (P < .001). For SA injections, the mean splenic volume was lower in patients with the zebra patterns (321 vs 409 cm3, P = .09). For SMA injections, it was higher in patients with zebra patterns (372 vs 291 cm3, P = .10).
Conclusion: The zebra pattern can cause difficulties in interpreting images. It is due to alternating, well-defined regions of portal venous hyper- and hypoperfusion; it likely has a multifactorial cause and is likely due to technical parameters such as the injection site, the volume of the spleen, and the hemodynamic effects of the tumor.