Table 2

Recommendation 1: summary of studies on the use of MRI in diagnosing axial spondyloarthritis

Studies	No.	Study population	Gold standard	SIJ/spine	MRI lesion	SE	SP	+LR	−LR
Longitudinal/RCT
Bennett et al19	50	SpA	X-ray	SIJ	Grade 3 SI+HLAB27 27B27	0.62	0.92	7.7	0.41
Marzo-Ortega et al20	76	IBP (NSBP, HC)	Clinical diagnosis	SIJ	Grade 1 SI	0.82	0.43	1.4	0.41
Marzo-Ortega et al20	76	IBP (NSBP, HC)	Clinical diagnosis	SIJ	Grade 2 SI	0.73	1.0	∞	0.73
Oostveen et al21	25	IBP	X-ray	SIJ	Grade ≥2 SI	0.85	0.47	1.6	0.31
Cross-sectional/case-control
Weber et al22 23	187	AS, IBP (NSBP, HC)	Clinical diagnosis	SIJ	BME (AS)	0.9	0.97	44.6	0.92
					BME (IBP)	0.51	0.97	26	0.50
					BME+ERO	0.81	0.97	27	0.19
Weber et al24 25	157	AS, IBP (NSBP, HC)	Clinical diagnosis	SIJ	BME	0.73	0.9	7.3	0.3
					BME and/or ERO	0.82	0.9	8.2	0.2
					FI	0.21	0.97	8.3	0.81
					FI with BME or ERO	0.24	0.97	9.2	0.78
Heuft-Dorenbosch et al27	68	IBP	X-ray	SIJ	chronic changes	0.49	0.97	16.3	0.52
Weber et al30	95	AS, IBP, (HC)	Clinical diagnosis	Spine	>2 CIL (AS)	0.69	0.94	12	0.32
					>2 CIL (IBP)	0.32	0.96	8	0.70
					LIL	0.97	0.31	1.4	0.09
Kim et al31	104	AS (HC)	Clinical diagnosis	Spine	MRI corner sign	0.44	0.96	11	0.58
Retrospective
Wick et al26	179	AS (various)	Clinical diagnosis	SIJ	ERO	0.11	0.93	1.57	0.95
Wick et al26	179	AS (various)	Clinical diagnosis	SIJ	BME	0.35	0.78	1.59	0.83
Bennett et al28 29	185	SpA (DA, IBP, HC)	Clinical diagnosis	SIJ and spine	>3 RLs	0.33	0.97	12.4	0.69
					Posterior BME lesion	0.13	0.99	14.5	0.87
					≥5 FRLs	0.22	0.98	12.6	0.79

The terms of the individual original publications have been used in the table.
AS, ankylosing spondylitis; BME, bone marrow oedema; CIL, corner inflammatory lesion; DA, degenerative arthropathy; ERO, erosion; FI, fatty infiltration; FRL, ‘fatty Romanus’ lesion; HC, healthy control; HLA27, human leucocyte antigen B27; IBP, inflammatory back pain; LIL, lateral segment inflammatory lesion; +LR, positive likelihood ratio; –LR, negative likelihood ratio; No., number of individuals included in the study; NSBP, non-specific back pain; RCT, randomised controlled trial; RL, ‘Romanus’ lesion; SE, sensitivity; SP, specificity; SI, sacroiliitis, SIJ, sacroiliac joints; SpA, spondyloarthritis.