SPARTAN-SSR: New quantitative criteria: BME in ≥3 consecutive slices OR any two of (BME, Erosion, Fat lesion each in ≥3 SIJ quadrants) or ankylosis in ≥3 halves achieves 88-96% sensitivity and 90-98% specificity across 3 cohorts. Precision #axSpA imaging. Abstr OP0100