Correlation between apparent diffusion coefficient of sacroiliac joint and SPARCC score in ankylosing spondylitis patients with different grade sacroiliac joint inflammation
Objective To observe the correlation between apparent diffusion coefficient(ADC)of sacroiliac joint and spondyloarthritis research consortium of Canada(SPARCC)score in ankylosing spondylitis(AS)patients with different grade sacroiliac joint inflammation.Methods MR examinations of sacroiliac joint were prospectively performed in 35 AS patients(AS group)and 30 healthy controls(HC group).The grade of sacroiliac joint inflammation and SPARCC score in AS group were evaluated according to MRI findings,and the patients were then further divided into bone marrow oedema(BMO)subgroup(n=19)and non-BMO subgroup(n=16)according to whether BMO presented under articular surface or not,and ADC of sacroiliac joint(ADCsacroiliac)were measured.Receiver operating characteristic curve was drawn,the area under the curve(AUC)was calculated to evaluate the efficacy of ADCsacroiliac for assessing AS sacroiliac joint inflammation grade.Pearson correlation analysis was performed to analyze the correlation between ADCsacroiliac and SPARCC score in AS patients with different grade sacroiliac joint inflammation.Results ADCsacroiliac in BMO subgroup and non-BMO subgroup was(4.85±1.44)×10-4 and(4.30±0.64)×10-4 mm2/s,respectively,being not significantly different(P>0.05)but both higher than that in HC group([3.32±1.36]×10-4 mm2/s,both P<0.05).The sensitivity of ADCsacroiliac for assessing grade of sacroiliac joint inflammation in AS patients was 49.44%,51.94%,73.06%and 60.50%,with specificity of 75.00%,78.92%,83.33%and 66.67%,respectively,and AUC of 0.613,0.712,0.837 and 0.645,respectively.ADCsacroiliac was moderately-highly positively correlated with SPARCC score of AS patients with Ⅱ and Ⅲgrade sacroiliac joint inflammation(r=0.580,0.933,both P<0.05),but no obvious correlation was detected between ADCsacroiliac and SPARCC score of AS patients with Ⅰ or Ⅳ grade sacroiliac joint inflammation(both P>0.05).Conclusion ADCsacroiliac was positively correlated with SPARCC scores of AS patients with Ⅱ and Ⅲ grade sacroiliac joint inflammation,which could be regarded as a reliable quantitative parameter for monitoring sacroiliac joint BMO.