Comparison of Contrast-Enhanced Ultrasound versus Contrast-Enhanced Magnetic Resonance Imaging for the Diagnosis of Focal Liver Lesions Using the Liver Imaging Reporting and Data System.

The aim of this retrospective study was to evaluate the Liver Imaging Reporting and Data System (LI-RADS) categorization of focal liver lesions (FLLs) on contrast-enhanced ultrasound (CEUS) in comparison with contrast-enhanced magnetic resonance imaging (CE-MRI). A total of 63 patients with 84 FLLs were included in the final study population, after review of the electronic medical records and clinical data. Two trained radiologists evaluated all CEUS and CE-MRI images independently. They assigned a LI-RADS category to each FLL and assessed major features based on CEUS LI-RADS Version 2017 and computed tomography/MRI LI-RADS Version 2018. The generalized estimating equation method was used to compare the diagnostic performance of the LI-RADS algorithm between CEUS and CE-MRI. The sensitivity of LR-5/LR-TIV (tumor in vein) categories for diagnosing hepatocellular carcinoma (HCC) differed significantly between CEUS and CE-MRI (88.9% [40/45], 95% confidence interval [CI]: 76.5%-95.2%), versus 64.4% (29/45; 95% CI: 49.8%-76.8%), p = 0.006; 82.2% (37/45; 95% CI: 68.7%-90.7%), versus 62.2% (28/45; 95% CI: 47.6%-74.9%), p = 0.034. Inter-observer agreement was substantial for assigning LR-5 on both CEUS and CE-MRI. For both reviewers, there was a higher frequency of LR-5 (44.0% vs. 25.0%, p = 0.009; 42.9% vs. 26.2%, p = 0.023) in CEUS compared with CE-MRI. Arterial phase hyper-enhancement (APHE) was less frequently observed on CEUS than on CE-MRI (46.4% vs. 61.9%, p = 0.044). However, the washout appearance was observed more frequently on CEUS than on CE-MRI (50.0% vs. 28.6%, p = 0.004). Inter-observer agreement between the two reviewers on APHE and washout appearance was excellent for both CEUS and CE-MRI. These findings suggest that CEUS had a much higher sensitivity than CE-MRI in the diagnosis of HCC using LI-RADS, and although the frequencies of major features differed, inter-observer agreement between the two reviewers on major features of HCC was excellent for both CEUS and CE-MRI.