Diagnostic value of diffusion weighted magnetic resonance image in early ankylosing spondylitis

Abstract

Background: Diffusion-weighted MRI (DW-MRI) shows the early changes in microscopical movement of water molecules, hence diagnosis of early sacroiliitis which is one of the diagnostic criteria of seronegative spondyloarthropathies. Objective: To determine the value of DW-MRI in detection of signal characteristics of the sacroiliac joints in patients with early ankylosing spondylitis (AS). Patients and methods: Fifteen patients with clinically suspected AS, 20 patients with mechanical low back pain and 20 healthy controls underwent conventional MRI and DWI. Apparent diffusion coefficient (ADC) was measured. In addition ten clinically confirmed AS patients underwent whole body-DWI. Results: Mean ADC values of both sacroiliac joints in AS patients were (0.523 ± 0.15) × 10−3 mm2/s in the ilium and (0.502 ± 0.15) × 10−3 mm2/s in the sacrum. There was no significant difference between mechanical LBP and healthy controls. But there was a significant difference between AS and LBP patients. Mean ADC value of focal lesions of clinically confirmed AS was 0.965 ± 0.25 × 10−3 mm2/s in the sacrum and 0.932 ± 0.31 × 10−3 mm2/s in the ilium. Conclusion: Subchondral bone marrow ADC values of sacroiliac joints allow differentiation between inflammatory and mechanical LBP. Furthermore, it may be helpful in evaluating the efficacy of the treatment and determine disease prognosis.

Keywords

• Ankylosing spondylitis
• Diffusion-weighted MRI
• AS
• Diffusion W
• MRI