Early changes of the portal tract on microcomputed tomography images in a newly-developed rat model for Budd-Chiari syndrome

Background and Aim: The effect of increased sinusoidal pressure on the portal tract in Budd-Chiari syndrome (BCS) is as yet not elucidated. Our aim was to investigate portal changes in a newly-developed rat model for BCS. Methods: We created an outflow obstruction in Sprague-Dawley rats (n = 6) by diameter reduction of the inferior vena cava. Left and right liver lobes with portal vein contrast were scanned using microcomputed tomography, and volumes of the portal tree and liver parenchyma were computed by the ANALYZE software program. Results: Portal branching density was significantly lower in BCS than the shams, and decreased over time (P < 0.01). There was a significant drop in volume of both parenchyma and the portal tree in the left but not right lobes. At 6 weeks post-surgery, the perfusion index (i.e. ratio between both volumes) became equal to (left) or even higher than (right) the shams, suggesting a new equilibrium with preserved portal perfusion. Histological findings were consistent with those observed in humans. Conclusion: As early as day 2, a significant loss of peripheral portal branches was seen, which progressed over time. Inter-lobar differences in vascular abnormalities suggest compensatory mechanisms. Despite a decrease in both liver and portal vein volume, relative portal perfusion appeared spared.