Magnetic resonance imaging of the sacroiliac joints in SpA: with or without intravenous contrast media? A preliminary report.

Active sacroiliitis based on magnetic resonance imaging (MRI) without intravenous (I.V.) contrast material injection is considered sufficient for the diagnosis of spondyloarthritis (SpA), according to the Assessment of SpondyloArthritis International Society (ASAS) criteria. This work shows the added value of administering I.V. contrast material when evaluating the response to tumor necrosis factor (TNF) antagonists therapy, on the extension of bone marrow oedema (BMO) and pathological enhancement (osteitis/synovitis) in the sacroiliac joints (SIJs) on MRI. Forty-three patients (25 females and 18 males, mean age of 54 ± 16.60 years, range 22-75 years) with a clinical diagnosis of SpA and active sacroiliitis at MRI with I.V. contrast material, were considered for a follow-up MRI after 6 months of TNF antagonists therapy. Disease activity was monitored by a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questionnaire. Descriptive statistics, Student's t test and Cohen's kappa were used. P < 0.05 was considered statistically significant. Thirty-eight patients were finally included in the study; 36 of them showed an improvement on clinical assessment after therapy. Score's difference (improvement) after treatment was calculated in the MRI sequences both with and without contrast agent (respectively, mean value and range 3.18, 0-12 with contrast and 1.63, 0-7 without contrast). This improvement was statistically significant in each group (P value of 7.097e-08 with contrast and 6.741e-06 without contrast), and there was a significant difference between the two group too (P-value of 8.598e-07). Cohen's kappa for dichotomous variables showed a better agreement between the post-contrast MRI findings and BASDAI (K = 0.53, agreement = 92.11%, P = 0.0001) than MRI without contrast and BASDAI (K = 0.11, agreement = 57.89%, P = 0.06). The evaluation of enhancement is a reliable tool for the assessment of the response to therapy in SIJs involvement in SpA, better than BMO; hence, it should be advised in the MRI of these patients.