Preliminary clinical study of sacroiliac activity in ankylosing spondylitis patients using quantitative dynamic contrast enhanced MRI

Abstract

Objective To investigate the diagnostic values of DCE-MRI quantitative evaluation of the activity of sacroiliac joints in ankylosing spondylitis. Methods Forty two patients (36 male and 6 female) with ankylosing spondylitis in our hospital were enrolled prospectively according to the standard of diagnostic criteria for ankylosing spondylitis revised in 1984. All of them were evaluated with the blood sedimentation, C-reactive protein and ankylosing spondylitis activity index (BASDAI). We divided the patients with ankylosing spondylitis into stationary phase group and active phase group. We analyzed each of the MRI images of the two patients groups using the extended Tofts model to determine the quantitative parameters of DCE-MRI, such as contrast transfer coefficient (Ktrans) , reflux constant (Kep) , extravascular extracellular volume fraction (Ve) , plasma volume fraction (Vp). And then the differences of quantitative data between the two groups were compared. Spearman correlation analysis was performed between the parameters with statistically significant difference and BASDAI scores. Results Among the 42 patients, 22 patients (18 male and 4 female) were in active phase group and the other 20 patients (18 male and 2 female) were in stationary phase group. Ktrans, Kep, Ve were (0.750±1.130) /min, (1.008±0.732) /min, 0.460±1.735; (0.163 ± 0.401) /min, (0.505 ± 0.902) /min, 0.345 ± 3.460 for active phase group and the stationary phase group, respectively. The results of the active phase group was significantly higher than the stationary phase group (Z=3.727, 2.317, 3.696, respectively;all P 0.05). Strong correlations existed between Ktrans, Kep, Ve and BASDAI score, the correlation coefficients were 0.714, 0.430, and 0.676 (P<0.05). Conclusions Quantitative DCE-MRI parameters can evaluate the activity of the ankylosing spondylitis. Strong correlations exist between Ktrans, Kep, Ve and BASDAI score. Key words: Spondylitis, ankylosing; Magnetic resonance imaging; Sacroiliitis