Comparison of ultrasound-detected and undetected hepatocellular carcinomas: a post-hoc, subgroup analysis from the MAGNUS-HCC surveillance trial

Purpose: This study aimed to compare the clinical and imaging features of hepatocellular carcinomas (HCCs) detected versus undetected on surveillance ultrasound (US), based on a prospective cohort. Methods: This post-hoc subgroup study analyzed data from MAGNUS-HCC trial, a prospective multicenter study evaluating both biannual US and annual non-contrast abbreviated magnetic resonance imaging (NC-AMRI) for HCC surveillance in high-risk patients. Among 34 HCCs, 16 tumors were detected and 18 tumors were undetected on US. We compared clinical features such as sex, age, body mass index (BMI), liver disease etiology, α-fetoprotein (AFP) level, and Child-Pugh class between participants who were diagnosed on US and those who were not. Imaging features including size, hemiliver distribution, anatomical section, subcapsular location, blind spot location, the presence of hepatic steatosis, and the presence of poor sonic window were also compared. NC-AMRI features were also assessed. Results: No significant differences were observed between US-detected and US-undetected groups in terms of sex, age, liver disease etiology, AFP level, or Child-Pugh class. Patients with US-undetected HCCs had higher BMI (25.7 vs. 23.8 kg/m², P=0.049). Lesions in blind spots were significantly more common in the US-undetected group (55.6% vs. 18.8%, P=0.039), as were lesions in the left hemiliver (38.9% vs. 6.3%, P=0.043). No significant differences were found in tumor size, anatomical section, subcapsular location, presence of poor sonic window, presence of hepatic steatosis, or magnetic resonance imaging characteristics. Of the 16 US-detected tumors, 62.5% were hypoechoic and 37.5% were hyperechoic. Conclusion: US is less effective in detecting HCCs in patients with a higher BMI and tumors located in the blind spots or left hemiliver. These limitations should be considered in planning and interpreting surveillance strategies.