Can radiologists rely on US LI-RADS for diagnosing HCC?

A recent study validating the 2017 version of the ultrasound Liver Imaging Reporting and Data System (US LI-RADS) for detecting hepatocellular carcinoma (HCC) identified a few limitations in its scoring.

According to Jung Hee Son, from the University of Ulsan College of Medicine in Seoul, South Korea and colleagues, the US-3 category—indicating a “positive” likelihood of HCC—resulted in high specificity but low sensitivity for diagnosing HCC. And visualization score C—an exam with “severe limitations” in quality—produced high false-negative rates compared to other visualization scores.

“Although the American Association for Study of Liver Disease practice guideline recommends US as the method for HCC surveillance, when these low-sensitivity values are considered, the value of US could be subject to substantial limitations in the screening or surveillance of early HCC,” Son, with Ulsan’s Department of Radiology and Research Institute of Radiology and colleagues wrote.

As mentioned, US is widely used for monitoring HCC, mainly due to its wide availability, cost-effectiveness and lack of radiation, but there are concerns about its ability to produce clear images of the liver in certain patients.

The LI-RADS group introduced an algorithm in 2017 that includes US visualization scoring (A, B and C) for determining scan quality and a US LI-RADS category for detecting HCC (US-1, US-2 and US-3). Until now, it’s diagnostic performance had not been validated, the researchers pointed out.

Son and colleagues prospectively recruited 407 patients with cirrhosis at high risk for HCC who also underwent US surveillance from November 2011 to August 2012. Two radiologists retrospectively reviewed the US images, assigning each a LI-RADS category and visualization score. Pathologic results and a CT or MRI were used as reference standards.

Of the 429 lesions, there were 32 cases of HCC in 28 participants. On per-lesion analysis, US-3 (positive) scored a specificity of 92% (366 of 397 lesions), but sensitivity was 34% (11 of 32). In per-patient analysis, specificity for US-3 was 93% and sensitivity was 39%.

Additionally, cases of US visualization score C (severe limitations) had an 86% false-negative rate for diagnosing HCC. This was related to high body weight (65 kilograms or more), Child-Pugh classification B and moderate to severe fatty liver.

“The clinical factors associated with a poor US visualization score could be used to identify those high-risk patients who present a severe limitation for US surveillance,” the group wrote. “Further studies are necessary to determine the clinically appropriate and sustainable surveillance strategies for such high-risk patients.”

In an accompanying editorial, Laurent Milot, from the body and VIR radiology department, Hôpital Edouard Herriot in France, wrote that the study highlights a few important findings for radiologists.

“First, the radiologist should spend a substantial amount of time determining whether the study was of sufficient quality, covering the entire liver without too many artifacts and/or regions of marked attenuation,” Milot explained. “Second, radiologists and other clinicians treating these patients must be aware of the limitations of the technique itself and should not shy away from using cross-sectional imaging if they feel it is appropriate.”