Background Magnetic resonance imaging (MRI) is able to detect “chronic” structural changes visible on conventional X-rays. Reliability of MRI in detection of such structural changes in SIJ remains unclear.
Objectives To evaluate the performance of MRI in detection of structural changes of the SIJ in comparison to conventional X-rays in patients with axial SpA.
Methods 112 patients with definite axial SpA and available imaging sets consisting of an X-rays and an MRI of the SIJ were included. X-rays of the SIJ were scored according to the modified New York criteria (grade 0 to grade IV) and according to the scoring system , which contains scores for subchondral sclerosis (score 0-2), erosions (score 0-3), and joint space changes (score 0-5) in each SIJ. MRIs of the SIJ (T1) were scored in the similar way. X-rays and MRIs were scored by two trained readers, which were blinded for all clinical data.
Results 224 SIJ from 112 patients were available. There was a rather low agreement between MRI and X-rays concerning definite erosions of SIJ (k=0.11, 95% confidence interval (CI) -0.02 to 0.23), a moderate agreement regarding definite subchondral sclerosis (k=0.46, 95% CI 0.34 to 0.57) and definite joint space abnormalities (k=0.41, 95% CI 0.28 to 0.53) and perfect agreement regarding joint ankylosis (k=0.85, 95% CI 0.74 to 0.96). MRI demonstrated good overall performance for the detection of definite “chronic” SI - figure. The sensitivity of MRI for the detection of “chronic” SI as compared to X-rays was 84% and the specificity was 61%. On the patients’ level, in 83 cases (74%), X-rays and MRI provided a unanimous conclusion regarding the presence or absence of SI fulfilling the modified New York criteria (K 0.451 (95% CI 0.280 to 0.622). The sensitivity of MRI in detection of SI fulfilling the modified New York criteria was 81%, the specificity 64%.
Conclusions MRI demonstrated good overall performance for the detection of chronic structural changes in the SIJ as compared to X-rays.
Poddubnyy D, et al. Ann Rheum Dis 2012;71(Suppl3):409.
Disclosure of Interest None Declared