Reijo Luukkainen¹, Kimmo O.J. Virtanen² and Pekka Luukkainen³

¹Department of Rheumatology, Satakunta Central Hospital, Rauma, Finland. ²Department of Radiology, Satakunta Central Hospital, Pori, Finland. ³Tapiola Insurance Company, Espoo, Finland.

Abstract

Objective: To compare the radiological (X-ray) and magnetic resonance imaging (MRI) findings in the sacroiliac (SI) joints in patients with early spondylarthropathy (SpA).

Methods: Forty consecutive HLA B27 antigen positive patients with early SpA and inflammatory low back pain (LBP) were studied. Their SI joints were investigated by posterior anterior plain X-ray and MRI.

Results:  The X-ray and MRI examinations gave similar results in the SI joints in 24 patients, whereas they differed in 16, this difference being significant (p =  0.007). In those 16 patients, in whom the findings differed, the X-ray findings were normal but MRI showed sacroiliitis which was bilateral in 13 and unilateral in 3 patients. The kappa coefficient between these investigations was 0.346, showing poor agreement.

Conclusion:  These results indicate that MRI may considerably improve the diagnosis of sacroiliitis in HLA B27 antigen positive patients with early SpA and inflammatory LBP.