Imler 2017.

Study characteristics
Patient Sampling	Type of study: randomised
Patient characteristics and setting	Sample size: 37 Females: 26 Mean age: 13.5 Inclusion criteria: Patients between 2 and 30 years old Exclusion criteria: Surgical review prior to recruitment Appendicitis not a differential diagnosis Contraindication to MRI or ultrasound Claustrophobia Imaging protocol not followed Setting: university teaching hospital, USA, 2014
Index tests	Index test: MRI Index test criteria for positive diagnosis: see Appendix 5
Target condition and reference standard(s)	Target condition: appendicitis Reference standard: histology or follow‐up
Flow and timing	Type and length of follow‐up: 7‐day telephone follow‐up Number of participants who were excluded from the analysis: unclear
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Avoids Inappropriate Exclusion	Yes
Could the selection of patients have introduced bias?		Low 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?	Yes
If a threshold was used, was it pre‐specified?	Unclear
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
Are the reference standards (histo or F/U) likely to correctly classify the target condition?	No
Were the reference standard (histo or F/U) results interpreted without knowledge of the results of the index test	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?			Low concern
DOMAIN 4: Flow and Timing
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Yes
>95% histo or F/U	Yes
all +ve MRI had surgery or F/U	Yes
all ‐ve MRI had surgery or F/U	Yes
choice of reference standard independent of MRI	No
Could the patient flow have introduced bias?		High risk