BACKGROUND & AIMS: This study aimed to compare ultrasonography (US) and noncontrast magnetic resonance imaging (MRI) in the surveillance of hepatic malignancy. METHODS: We conducted a randomized, nonblinded, single-center trial at a single center in South Korea. Eligible individuals were aged 20 to 70 years with liver cirrhosis, Child-Pugh class A, and no history of liver cancer or other recent malignancy. Participants were randomized 1:1 to receive up to 10 semiannual surveillance using US or noncontrast MRI with serum alpha-fetoprotein testing. The primary endpoints were the detection rates of Barcelona Clinic Liver Cancer (BCLC) stage 0 or A tumors, stage distribution at initial diagnosis, and false-positive referral rates. RESULTS: From June 2015 to November 2017, 416 patients were screened, and 414 were enrolled and assigned to the US (n = 207) or MRI (n = 207) group. In total, 23 participants in the US group and 25 in the MRI group were diagnosed with liver cancer by November 2022. The detection rates of BCLC stage 0 or A tumors were not different between the US and MRI groups (8%
[95% confidence interval (CI), 5%-13%] vs 12% [8%-17%]). BCLC stage 0 tumors were more prevalent in the MRI group than in the US group (8% vs 3%). The MRI group had earlier BCLC stage (P = .014) and lower false-positive referral rate (0.7% [95% CI, 0.4%-1.2%] vs 3.1% [2.3%-4.1%], P <
.001) compared with the US group. CONCLUSIONS: Noncontrast MRI is a better alternative to US for the surveillance of cirrhotic patients offering earlier stage at initial diagnosis and lower false-positive referral rate. (ClincalTrials.gov, Number: NCT02514434.).