Can Dixon technique replace conventional magnetic resonance imaging for precise assessment of sacroiliitis in ankylosing spondylitis patients?

Abstract Background Ankylosing spondylitis (AS) is a subtype of arthritis from the axial spondylarthritis spectrum. Involvement of the sacroiliac joints is regarded as an early indicator of ankylosing spondylitis (AS), enabling early detection, and effective treatment of the condition. Ankylosing spondylitis disease activity score (ASDAS) is used for follow-up of diagnosed patient to detected disease activity during treatment. Dixon imaging can add more suppression of fat than conventional MRI. It has four images including in-phase (IP) and out-of-phase (OP), water only (WO), and fat only (FO), all can be acquired in just one acquisition. DIXON can detect chronic and active sacroiliitis. Objectives The objective of this study was to compare value of Dixon technique versus conventional MRI in assessment of sacroiliitis in ankylosing spondylitis patients. Methods The study was done on 32 patients with ankylosing spondylitis (AS) aged more than 18 years old in a period of 6 months (July 2024 to January 2025). Complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), urea, and serum creatinine were done. Disease activity was evaluated using Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and Bath Ankylosing Spondylitis Functional Index (BASFI). Imaging evaluation of both sacroiliac joints was done using T2 Dixon technique (4 phases) and conventional MRI including T1W1, T2W1, and fat suppression sequences, in axial and coronal planes. Results Thirty-two patients were enrolled in this study. Most of patients were males (62.5%). T2 DIXON had higher sensitivity than conventional MRI for detecting erosion, edema, backfill, and SPARCC score estimation (90%, 100%, 83%, and 89%, respectively). The SPARCC score was higher in Dixon technique with significant relation with T2 DIXON and conventional MRI. Conclusions Our results concluded that MRI T2 Dixon can serve as a reliable alternative to conventional MRI protocols for assessing active and chronic sacroiliitis. It can be utilized to detect disease activity at an early stage, guide clinical decision making, assess treatment effectiveness, and monitor disease progression. This promotes its integration in clinical practice.