ABSTRACT
Objective To compare the value of assessment with DWI and contrast-enhanced MRI (CE-MRI) in activity of sacroiliitis of patients with ankylosing spondylitis(AS).Methods Ninety-six patients conforming to modified New York criteria were prospectively collectedas the AS group, and twenty-one healthy volunteers were enrolled into the control group. According to the Bath AS disease activity index (BASDAI), erythrocyte sedimentation rate and C-reaction protein, AS patients were divided into the active AS group (n=60) and the chronic AS group (n=36) . All subjects were performed with conventional MRI, DWI and CE-MRI of bilateral sacroiliac joints. The MRI manifestations were reviewed and the ADC values and signal intensity enhancement rate (ΔSI) were measured.ANOVA was performed for the comparison ofΔSI and ADC values among active AS group, chronic AS group and control group with BASDAI and lab test results as the gold standards. ROC was analyzed with ΔSI and ADC values for activity of AS and paired samples t test was obtained to comparethe areas under the ROC ofΔSI and ADC values.Results Among 96 cases of AS patients, MRI of sacroiliac jointsshowed that 62 cases had subchondral bone edema (57 cases of active group, 5 cases of chronic group), that 11 cases had bone surface erosion(4 cases of active group, 7 cases of chronic group), that 15 cases had bone sclerosis(6 cases of active group, 9 cases of chronic group) and that 58 cases had fat deposition on the sacroiliac joints (27 cases of active group, 31 cases of chronic group). The ΔSI values of the active group, the chronic group and control group were respectively (2.51 ± 1.69)%,(1.19 ± 0.67)%and(0.75 ± 0.21)%, and the ADCvalues were(1.33 ± 0.33)× 10-3,(1.00 ± 0.43)× 10-3 and(0.38±0.13)×10-3mm2/s. There were significant differences forΔSI and ADC values among three groups (F=18.375, 16.366. P<0.01), and statistical significance ofΔSI and ADC values were found between every two groups of three(P< 0.05).The area under the ROC between ΔSI and ADC to determine activity of AS patients were respectively 0.814 and 0.730, which had nostatistical significance(t=1.632, P=0.103). The sensitivity and specificity to determine activity of AS patients byΔSI=1.44%were 81.67%and 80.00%.The sensitivity and specificity to determine activity of AS patients by ADC=1.15 × 10-3/mm2 were 76.67% and 71.43%.Conclusion DWI and CE-MRI performed equally in detecting activity of AS patients.