Prolonged heterogeneous liver enhancement (CEUS)

Last revised by Arlene Campos on 30 May 2024

Prolonged heterogeneous liver enhancement (PHLE), also informally termed as the "disappearing liver" phenomenon, is a very rare, benign complication of ultrasound contrast media, of unknown etiology 1. PHLE manifests itself as confluent, rapidly appearing hyperechoic foci in the liver, that may even completely prevent the assessment of its structure using ultrasound. 

PHLE typically occurs in the portal venous phase of the CEUS exam. The typical manifestation is the appearance of hyperechoic foci along portal branches, that can rapidly grow and become confluent, even resulting in complete distal acoustic shadowing. In sharp contrast with the worrisome imaging appearance the patients nearly always remain asymptomatic 2. PHLE can make US evaluation of the liver structure impossible for several hours but is a self-limited condition that slowly subsides on its own in a few days. 

The exact cause of the phenomenon is unknown. Existing theories suggest premature destruction of the contrast agent microbubbles, microbubble pooling and fusion as the main culprits behind PHLE 1

Although PHLE is an extremely rare and benign condition, due to the striking, worrisome imaging appearance all CEUS examiners should be aware of its existence. No specific therapy is available or required, although follow-up US control of the patient is recommended until the condition subsides. 

PHLE should not be confused with the northern lights phenomenon, which is a migrating echogenic band within the field of view, and can be encountered during any CEUS exam where high mechanical index scanning is used after microbubble injection. 

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