Vietti Violi 2020.

Study characteristics
Patient Sampling	Retrospective single‐centre study in which authors searched the institutional electronic imaging database in 2017 for consecutive patients who underwent in‐house MRI for HCC screening/surveillance. Included: adult aged ≥ 18 years with cirrhosis of any aetiology and patients with chronic hepatitis B without cirrhosis who underwent a complete gadoxetate‐enhanced MRI for HCC screening at authors' institution. According to the AASLD criteria for HCC screening, patients with Child‐Pugh class C were included if listed for transplantation. Among 415 initial patients, 178 were excluded. The final group included 237 participants. Excluded: patients who underwent MRI with extracellular contrast.
Patient characteristics and setting	People at risk for HCC were screened with MRI.
Index tests	Positivity criteria: LI‐RADS 5 – features include a 10–19 mm nodule with non‐rim arterial phase hyperenhancement and non‐peripheral washout appearance, regardless of capsule appearance, or a ≥ 20 mm nodule with non‐rim arterial phase enhancement with either enhancing capsule appearance or non‐peripheral washout appearance or both. Aim: to compare the performance of 3 different MRI protocol sets extracted from a complete gadoxetate‐enhanced MRI obtained for HCC screening.
Target condition and reference standard(s)	Reference standards: liver explant pathology, biopsy, MRI criteria, clinical data, and follow‐up. Classification based on the review of all available participant data including imaging examinations, pathology, any subsequent treatment, and decision from the multidisciplinary tumour board.
Flow and timing	Time between index test and reference standard not reported.
Comparative
Notes	Authors disclosed potential COI and private and public funding.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	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 (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
Were positivity criteria clearly defined?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear 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?	No
Were the reference standard results interpreted without knowledge of the results of the index tests?	No
Could the reference standard, its conduct, or its interpretation have introduced bias?		High risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		High risk