Contrast-Enhanced Ultrasound for Biliary Ischemia: A Possible New Clinical Indication.

ABSTRACT

OBJECTIVES: Biliary perfusion is considered to contribute to biliary diseases, but routine imaging methods are insufficient to show it. This research investigated the ability of contrast-enhanced ultrasound (CEUS) for biliary perfusion in a biliary ischemia model. METHODS: This research consisted of 2 parts. First, to determine whether CEUS enhancement of the tiny biliary wall represents biliary perfusion, a vascular tracer was used as a reference to evaluate the consistency with the enhancement of the biliary wall on CEUS and the staining by the vascular tracer under the conditions of occluded and recovered biliary perfusion. In the second part, the ability of CEUS for biliary ischemia was further evaluated with microvascular density measurement as a reference. The enhancement patterns were assigned CEUS scores, in which higher scores meant more decreased enhancement, and the diagnostic ability of CEUS was assessed by a receiver operating characteristic curve analysis. RESULTS: The biliary wall was unstained by the vascular tracer and nonenhanced on CEUS when biliary perfusion was interrupted and was stained blue and enhanced after recovery. The biliary wall in the ischemia surgery group showed lower microvascular density measurements (P < .001), decreased enhancement levels (P < .001), and higher CEUS scores (P < .001). When a CEUS score of 3 or higher (obvious decrease of the biliary wall to hypoenhancement or nonenhancement in the arterial phase or rapid wash-out to nonenhancement in the portal venous phase) was applied, CEUS had sensitivity of 87.8%, specificity of 98.3%, accuracy of 93.8%, and an area under the receiver operating characteristic curve of 0.98. CONCLUSIONS: Contrast enhancement of the biliary wall on CEUS represents biliary perfusion and has reasonably good diagnostic performance for biliary ischemia in an experimental animal setting.