Diagnostic Accuracy of Dual-energy CT

Exclusion Criteria

• •1. Known inflammatory rheumatic diseases (e.g. rheumatoid arthritis, gout, psoriatic arthritis, psoriasis, inflammatory bowel disease), or other joint diseases (haemochromatosis)
• •2. Positive anti-cyclic citrullinated peptide (\>10 kU/L)
• •3. Known cutaneous deposition diseases (e.g. amyloidosis or porphyria).
• •4. Foreign material/metallic implants at the area of interest will be excluded to avoid artefacts on CBCT \[68\].
• •5. Other diseases in the area - e.g. skin disease, known previous fracture in the joint of interest.
• •6. Participation in experimental device or experimental drug study 3 months prior to enrolment.
• •7. Pregnancy or breast-feeding.
• •8. Previous septic arthritis at the target joint.
• •9. Previous surgical procedures at the target joint.
• •10. Injection into the target joint within 3 months prior to enrolment.
• •11. Inability to speak and read Danish fluently.
• •12. Treatment with Colchicine within the last 30 days.
• •13. Treatment with systemic steroids ≥7.5 mg prednisolone within the last 30 days.
• •14. Lack of sample obtained for reference standard, i.e. unable to obtain either synovial fluid, joint lavage fluid, joint biopsy or excite joint.
• •15. Any other condition that in the opinion of the investigator may interfere with study participation.
• •There will be no restriction on sex or Kellgren-Lawrence (KL) grading.