Liver Imaging Reporting and Data System Contrast-Enhanced US Nonradiation Treatment Response Assessment Version 2024

Abstract

The American College of Radiology Liver Imaging Reporting and Data System (LI-RADS) standardizes the imaging technique, reporting lexicon, disease categorization, and management for patients with or at risk for hepatocellular carcinoma (HCC). LI-RADS encompasses HCC surveillance with US; HCC diagnosis with CT, MRI, or contrast-enhanced US (CEUS); and treatment response assessment (TRA) with CT or MRI. LI-RADS was recently expanded to include CEUS TRA after nonradiation locoregional therapy or surgical resection. This report provides an overview of LI-RADS CEUS Nonradiation TRA v2024, including a lexicon of imaging findings, techniques, and imaging criteria for posttreatment tumor viability assessment. LI-RADS CEUS Nonradiation TRA v2024 takes into consideration differences in the CEUS appearance of viable tumor and posttreatment changes within and in close proximity to a treated lesion. Due to the high sensitivity of CEUS to vascular flow, posttreatment reactive changes commonly manifest as areas of abnormal perilesional enhancement without washout, especially in the first 3 months after treatment. To improve the accuracy of CEUS for nonradiation TRA, different diagnostic criteria are used to evaluate tumor viability within and outside of the treated lesion margin. Broader criteria for intralesional enhancement increase sensitivity for tumor viability detection. Stricter criteria for perilesional enhancement limit miscategorization of posttreatment reactive changes as viable tumor. Finally, the TRA algorithm reconciles intralesional and perilesional tumor viability assessment and assigns a single LI-RADS treatment response (LR-TR) category: LR-TR nonviable, LR-TR equivocal, or LR-TR viable.

Graphical abstract

Figure 1:

Liver Imaging Reporting and Data System (LI-RADS) Contrast-Enhanced US (CEUS) Nonradiation Treatment Response Assessment (TRA) Version 2024. LR-TR = LI-RADS treatment response, MWA = microwave ablation, PEA = percutaneous ethanol ablation, RFA = radiofrequency ablation, TACE = transarterial chemoembolization, TAE = transarterial embolization.

Figure 2:

US images of a treated lesion with intralesional and perilesional tumor viability category absent at 1 month after transarterial chemoembolization. (A) The B-mode image is used as an anatomic reference to define the margin of the treated lesion (dotted line), allowing separate evaluation of contrast enhancement inside and outside of the treated lesion margin. (B) The contrast-enhanced US image demonstrates no enhancement within the margin of the treated lesion (dotted line) and enhancement identical to surrounding liver along the treated lesion margin. A schematic summarizing intralesional and perilesional findings is shown in the lower left corner of each panel.

Figure 3:

US images of a treated lesion with intralesional tumor viability category uncertain at 1 month after microwave ablation. (A) The B-mode image is used as an anatomic reference to define the margin of the treated lesion (dotted line). (B) Arterial phase contrast-enhanced US image demonstrates irregular hypoenhancement within the margin of the treated lesion (dotted line). (C) Late phase contrast-enhanced US image demonstrates some degree of washout within the margin of the treated lesion (dotted line). A schematic summarizing intralesional findings is shown in the lower left corner of each panel.

Figure 4:

US images of a treated lesion with intralesional tumor viability category present at 1 week after transarterial chemoembolization. (A) The B-mode image is used as an anatomic reference to define the margin of the treated lesion (dotted line). (B) Arterial phase contrast-enhanced US image demonstrates nodular area of contrast isoenhancement within the margin of the treated lesion (dotted line). (C) Late phase contrast-enhanced US image demonstrates some degree of washout within the margin of the treated lesion (dotted line). A schematic summarizing intralesional findings is shown in the lower left corner of each panel.

Figure 5:

US images of a treated lesion with perilesional tumor viability category uncertain immediately after radiofrequency ablation. (A) The B-mode image is used as an anatomic reference to define the margin of the treated lesion (dotted line). (B) Arterial phase contrast-enhanced US image demonstrates nodular rim of hyperenhancement (arrow) adjacent to the margin of the treated lesion (dotted line). (C) Late phase contrast-enhanced US image demonstrates no detectable washout in previously hyperenhanced area (arrow) along the margin of the treated lesion. A pseudoenhancement artifact (*) from hyperechoic postablation changes is visible in the center of the treated lesion. A schematic summarizing perilesional findings is shown in the lower left corner of each panel.

Figure 6:

US images of a treated lesion with perilesional tumor viability category present at 1 month after microwave ablation. (A) The B-mode image is used as an anatomic reference to define the margin of the treated lesion (dotted line). (B) Arterial phase contrast-enhanced US image demonstrates nodular area of hyperenhancement (arrows) adjacent to the margin of the treated lesion (dotted line). (C) Late phase contrast-enhanced US image demonstrates mild washout in previously hyperenhanced area (arrows) along the margin of the treated lesion (dotted line). A schematic summarizing perilesional findings is shown in the lower left corner of each panel.