Park 2020.

Study characteristics
Patient Sampling	This study was a retrospective analysis of prospectively collected data All included patients: i) were aged > 20 years; ii) were diagnosed histologically or radiologically with cirrhosis, with an estimated annual HCC risk > 5%; iii) had an Eastern Cooperative Oncology Group performance status of 0 or 1; and iv) had no previous history or current suspicion of HCC Age range: 29‐77. Males 57%
Patient characteristics and setting
Index tests	US examinations in the original study were performed by 4 board‐certified abdominal radiologists specializing in liver imaging (So Yeon Kim, So Jung Lee, Hyung Jin Won, and Jae Ho Byun) using a convex probe (SC6‐1, Supersonic Imagine SA; Aixplorer, France). The patient stay duration in the US room ranged from 15 to 20 min.
Target condition and reference standard(s)	Patients were evaluated by 1 to 3 rounds of surveillance tests, consisting of paired US and gadoxetic acid‐enhanced MRI performed within 7 days at 6 month intervals.
Flow and timing	The reference standard was performed within seven days after the index test.
Comparative
Notes	"The authors declare no conflicts of interest that pertain to this work."
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (AFP)
DOMAIN 2: Index Test (US+AFP)
DOMAIN 2: Index Test (US)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	No
Could the patient flow have introduced bias?		High risk