Purpose: The aim of this paper was to report a heterogeneous late-phase hepatic enhancement pattern observed after administration of a sonographic contrast agent and to present an aetiological hypothesis for the phenomenon.
Materials and methods: A total of 1,729 (1,012 women and 717 men; age range 28-82; mean age 51) patients underwent contrast-enhanced sonography of the liver. The examination was performed with a low mechanical index (MI <0.09) after injection of sulphur-hexafluoride-filled microbubbles, using different sonographic equipment and different contrast-specific algorithms.
Results: Heterogeneous delayed liver enhancement was observed in six patients in the late phase (180 s), with the presence of multiple, partially confluent, hyperechoic areas peripheral to the portal vessels. The pattern appeared spontaneously between 1 and 4 h after the examination and was associated with the presence of an anomalous echogenicity in the superior mesenteric vein. No patient experienced adverse reactions.
Conclusions: The phenomenon of heterogeneous hepatic enhancement may be related to gas from the intestinal microcirculation being transported to via the enteroportal circulation and becoming trapped in the hepatic sinusoids.