Contrast-enhanced ultrasound LI-RADS nonradiation treatment response assessment: applications, challenges, and future directions

Hepatocellular carcinoma (HCC) requires nuanced treatment response assessment to balance oncologic control with preservation of liver function. CT and MRI, cornerstones of response evaluation, are often limited by contraindications to their use or indeterminate findings. The recently introduced ACR LI-RADS Contrast-Enhanced Ultrasound (CEUS) Non-Radiation Treatment Response Assessment (TRA) algorithm offers a real-time, radiation-free alternative for evaluating treated HCC after ablation, transarterial therapies, or surgical resection. This review summarizes the CEUS TRA lexicon, criteria, and application across common clinical scenarios, emphasizing its value as a troubleshooting tool when conventional imaging is non-evaluable due to artifacts, contrast limitations, or heterogeneous post-treatment changes. We highlight pitfalls unique to CEUS interpretation, including poor lesion visibility, resection cavity complexity, and the inability to assess extrahepatic disease. Emerging areas include CEUS assessment after radiation-based therapies and the potential for integration of Kupffer-cell-specific contrast agents. Together, these developments position CEUS as an increasingly important modality for precise, timely, and individualized management of HCC following non-radiation locoregional therapy.