The role of ceus in the characterization of indeterminate focal liver lesions at second-level imaging methods (INFOLIL STUDY).

[BACKGROUND] Focal liver lesions cannot always be characterized with certainty by using CT, MRI, or PET. In these cases, the Radiologist or Nuclear Medicine specialist often recommends performing CEUS.

[PURPOSE] the main aim was to determine the accuracy of CEUS in characterizing (as benign or malignant) focal liver lesions for which CT, MRI, and/or PET have not provided conclusive results.

[MATERIAL AND METHODS] a retrospective study was conducted by enrolling patients referred to our ultrasound unit to undergo CEUS examination based on the recommendation of the radiologist to characterize a focal liver lesion identified by CT, MRI, or PET. The reference gold standard was the histological examination in cases where it was performed; otherwise, findings from radiological and clinical follow-up were considered.

[RESULTS] A total of 109 patients were enrolled in the study. Of these, 11 (10.1%) were not included in the analysis. The remaining 98 patients underwent ultrasound and CEUS examinations. Regarding the diagnostic accuracy of CEUS to characterize the nature of focal liver lesions in comparison with the reference standard, the method was characterized by an area under the curve (AUC) of 0.92 (95% CI: 0.83-1.00). The sensitivity of CEUS was 88.9% (95% CI: 65.3%-98.6%) and the specificity was 97.5% (95% CI: 91.2%-99.7%). For lesions smaller than 1 cm in diameter, all lesions in this category were characterized as benign on CEUS. For lesions between 1 and 2 cm in size, the AUC reached 1.00, with both sensitivity and specificity at 100%, suggesting an optimal performance of CEUS for this category of lesions. Regarding lesions larger than 2 cm, the AUC was 0.96 (95% CI: 0.85-1.00). Sensitivity was 90.9% (95% CI: 58.7%-99.8%), and specificity was 100% (95% CI: 78.2%-100%).

[CONCLUSIONS] CEUS proves to be a valuable diagnostic tool in the characterization of focal liver lesions, improving clinical management with a less invasive approach. CEUS may be an integral part of the diagnostic pathway for patients with indeterminate focal liver lesions. Key results CEUS demonstrated an overall AUC of 0.92 in characterizing indeterminate focal liver lesions. Sensitivity was 88.9%, with specificity of 97.5%. For lesions measuring 1-2 cm, CEUS achieved 100% sensitivity and specificity.