Benign Focal Liver Lesions on Contrast-Enhanced Ultrasound—Part 1: Common Entities and Pseudolesions—A Practical Guide for the Hepatologist

The incidental discovery of focal liver lesions (FLLs) has reached unprecedented levels due to the widespread use of high-resolution imaging, yet unenhanced ultrasound often lacks the specificity required for definitive characterization. This review identifies Contrast-Enhanced Ultrasound (CEUS) as a transformative diagnostic pillar for common benign focal liver lesions (BFLLs). By utilizing strictly intravascular second-generation microbubble agents, CEUS enables continuous, real-time visualization of microvascular hemodynamics. This high temporal resolution allows clinicians to identify pathognomonic vascular signatures, such as the “iris-diaphragm” centripetal fill-in of hemangiomas and the rapid centrifugal “spoke-wheel” hyperperfusion characteristic of focal nodular hyperplasia (FNH). Critically, this review highlights the unparalleled safety profile of CEUS. Because microbubbles are not excreted by the kidneys and carry no risk of nephrotoxicity, CEUS is an essential diagnostic option for patients with renal failure. Furthermore, the lack of ionizing radiation and the ability to perform examinations bedside provide a safe and versatile solution for pregnant patients and those with contraindications to traditional cross-sectional imaging. This review serves as a comprehensive informational framework, equipping clinicians with detailed pathological, clinical, and radiological insights into common entities like hemangiomas, FNH, and hepatocellular adenomas (HCA). It correlates fundamental histological features—such as the “map-like” glutamine synthetase staining in FNH—with essential clinical management strategies. While multiparametric MRI remains the premier tool for complex subtyping and molecular mapping—particularly for differentiating hepatocellular adenoma variants—CEUS is established as a cost-effective and radiation-free initial diagnostic solution. This review equips clinicians with a comprehensive framework of pathological, clinical, and radiological insights to optimize the management of common benign hepatic incidentalomas