Comparing demographic, clinical, biochemical and imaging features between participants with and without identifiable ADC lesions
| With identifiable ADC lesions | Without identifiable ADC lesions | P value | |
| Age (N=301) (years) | 45.7±13.1 | 42.7±13.1 | 0.09 |
| Male gender (N=301) | 55 (67.1%) | 115 (52.5%) | 0.02 |
| Duration of back pain (N=299) (years) | 13.4±10.7 | 11.2±11.2 | 0.13 |
| HLA-B27 positivity (N=290) | 69 (85.2%) | 164 (78.5%) | 0.20 |
| History of inflammatory bowel disease (N=298) | 3 (3.8%) | 5 (2.3%) | 0.49 |
| History of psoriasis (N=298) | 8 (10.0%) | 36 (16.5%) | 0.16 |
| Family history of SpA (N=286) | 15 (19.5%) | 48 (23.0%) | 0.53 |
| Radiographical axial SpA (N=294) | 5 (71.4%) | 21 (52.5%) | 0.35 |
| Fulfilled ASAS axial SpA criteria (N=300) | 79 (97.5%) | 200 (91.3%) | 0.06 |
| Back pain NRS (N=294) | 5.8±2.4 | 5.6±2.4 | 0.50 |
| Ever peripheral arthritis (N=298) | 36 (45.0%) | 132 (60.6%) | 0.02 |
| Tender joint count (N=292) | 0.8±1.5 | 1.6±3.1 | 0.02 |
| Swollen joint count (N=293) | 0.3±0.9 | 0.7±1.6 | 0.02 |
| Ever enthesitis (N=297) | 35 (43.8%) | 97 (44.7%) | 0.88 |
| CRP (N=300) (mg/dL) | 1.2±1.4 | 1.0±1.9 | 0.48 |
| ESR (N=299) (mm/hour) | 37.1±23.3 | 30.1±24.9 | 0.03 |
| ASDAS-CRP (N=292) | 2.1±0.8 | 2.0±0.9 | 0.44 |
| ASDAS-ESR (N=291) | 3.3±1.0 | 3.1±1.1 | 0.11 |
| ADC background (N=82) (mm2/s) | – | – | |
| ADCmax (N=82) (mm2/s) | 1.45±0.31×10−3 | – | – |
| ADCmean (N=82) (mm2/s) | 0.77±0.19×10−3 | – | – |
| nADCmax (N=82) | 6.5±2.1 | – | – |
| nADCmean (N=82) | 3.4±1.0 | – | – |
| SPARCC SI MRI score (N=297) | 3.4±5.9 | 3.1±6.1 | 0.68 |
| SPARCC spine MRI score (N=294) | 13.7±10.2 | 3.5±6.0 | <0.001 |
ADC, apparent diffusion coefficient; ADCmax, maximum apparent diffusion coefficient; ADCmean, mean apparent diffusion coefficient; ASAS, Assessment of Spondyloarthritis International Society; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; N, number; nADCmax, normalised maximum apparent diffusion coefficient; nADCmean, normalised mean apparent diffusion coefficient; NRS, Numerical Rating Score; SPARCC, Spondyloarthritis Research Consortium of Canada; SpA, spondyloarthritis.