ZEBRA PATTERN - A DIAGNOSTICALLY CHALLENGING HEPATIC PARENCHYMAL ENHANCEMENT PATTERN AT CT ARTERIAL PORTOGRAPHY

PURPOSE: To investigate the effect of arterial injection site and sple nic volume on the hepatic zebra pattern seen at computed tomographic ( CT) arterial portography. MATERIALS AND METHODS: Images from CT arteri al portographic examinations, performed via either the splenic artery (SA) (n = 47) or superior mesenteric artery (SMA) (n = 51) in 98 patie nts, were reviewed. The hepatic parenchymal enhancement pattern was as sessed by three blinded reviewers. Splenic volume was determined. RESU LTS: 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 parenc hyma with nontumorous perfusion defects was 55% with the zebra pattern versus 12% without (P < .001). For SA injections, the mean splenic vo lume was lower in patients with the zebra patterns (321 vs 409 cm(3) P = .09). For SMA injections, it was higher in patients with zebra patt erns (372 vs 291 cm(3), P = .10). CONCLUSION: The zebra pattern can ca use difficulties in interpreting images. It is due to alternating, wel l-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 hemodyna mic effects of the tumor.