99mTc-rhAnnexin V-128 in Diagnosis of Spondyloarthritis

Inclusion Criteria: For the first 5 patients enrolled in the POC part: 1\. Patients with clinical suspicion or confirmed diagnosis of SpA, based on the ASA criteria with active symptoms including back, hip or buttock pain prior to: * A change in NSAID therapy or * A change in non-biologic DMARD or * A start of non-biologic DMARD. For the next 15 patients enrolled in the Phase II part: 1. Patients with clinical suspicion or confirmed diagnosis of SpA, based on the ASAS criteria with active symptoms including back, hip or buttock pain prior to: * A change in NSAIDs therapy * A change in non-biologic DMARD * A start of non-biologic DMARD * A start of biologic DMARD For all patients: 2. Age over 18 years old. 3. Signed Informed Consent Form Exclusion Criteria: 1. Pregnancy or lactation 2. Liver impairment (ALT, AST or Bilirubin \> 2 ULN) at screening visit or baseline 3. Kidney impairment (serum creatinine \> 1.5 mg/dL) 4. History of any disease or relevant physical or psychiatric condition or abnormal physical finding which may interfere with the study objectives at the investigator judgment 5. Known hypersensitivity to the investigational drug or any of its components 6. Contraindication(s) to the MRI procedure (claustrophobia, prosthetic valve, pacemaker, inability to lie still in a supine position) 7. Participation to another clinical trial within 4 weeks before study inclusion except for patients who have participated or who are currently participating in an interventional study without any study drug administration.