Purpose: Spondyloarthropathies are characterized by inflammatory involvement of the sacroiliac joints [SIJ] and sacroiliitis is a diagnostic criterion for the disease. Magnetic resonance imaging (MRI) is considered the preferred imaging modality for detection and diagnosis of sacroiliitis in its early stages. We reviewed MRI examinations of the SIJ performed in our institution, evaluated the findings and the change in study prevalence along the years.
Methods: All SIJ MRI studies performed in our institution between 2005-2009 were evaluated in consensus by an intern and a muscutoskeletal staff radiologist. The following findings were registered: Chronic changes: erosions, bony bridges, subchondral sclerosis. Acute findings: bone marrow edema, contrast enhancement. Sacroitiitis was diagnoses based on these findings. The prevalence of SIJ MRI studies was calculated and compared with all musculoskeletal MRI studies performed in these years.
Results: A total of 93 SIJ MRI studies were performed between 2005-2009. A gradual increase in the number of studies was detected in these years. The number of SIJ MRI studies performed during 2009, was 8.2 times higher than in 2005, while the increase in musculoskeletal MRI studies was only 2.5 fold (p < 0.001). 53 subjects (57%) were diagnosed with sacroiliitis (male/female: 25/28, average age: 30 years), alternative diagnosis was given in 4 cases and in the rest no abnormality was detected.
Conclusions: SIJ MRI is highly sensitive for inflammatory changes of the sacroiliac joints. Awareness of the important role of this study for early diagnosis and treatment of spondyloarthropathies as expressed in a substantial rise in referrals that has dramatically increased in the last years.