| Objective: To evaluate the value of intravoxel incoherent motion diffusion-weighted imaging?IVIM-DWI?in diagnosing active sacroiliitis of Ankylosing Spondylitis?AS?.Methods: Forty-nine patients with AS?from the Department and Outpatient Department of Rheumatology in the Affiliated Hospital of North Sichuan Medical College from May 2016 to February 2017?and twenty-eight healthy volunteers were randomly enrolled in this study.The selected patients were assigned to active stage group?21 patients?and stable stage group?28patients?according to Erythrocyte sedimentation rate?ESR?,C-reactive protein?CRP?,Bath Ankylosing Spondylitis disease activity index?BASDAI?scores.The diffusion coefficient?D?,the pseudo-diffusion coefficient?D*?and the perfusion fraction?f?were measured using a region of interest approach in the diffusion-weighted imaging?FS-T2 WI and b=800s/mm2?,and data were analyzed by ANOVA.The ability of diagnosis was determined by using receiver operator characteristic analysis.Age,ESR,CRP and BASDAI scores were analyzed by Mann-Whitney U.Results:1.There was no significant difference in the age difference between the stable group and the active group?p >0.05?,activity group BASDAI scores,ESR and CRP were higher than the stable group,the difference was statistically significant?p <0.05?.2.IVIM parameters: activity group D,D *,f values were?0.72 ± 0.29?×10-3mm2/s,?5.79 ± 3.58?×10-3mm2/s,?13.56 ± 5.46?%,respectively.Stablegroup D,D *,f values were?0.35±0.16?×10-3mm2/s ??4.38±2.48?×10-3mm2/s??9.68±3.18?%,respectively.The control group D,D *,f values were?0.29 ± 0.08?×10-3mm2/s,?3.94 ± 2.88?×10-3mm2/s,?10.38 ± 4.23?%,respectively.The results showed that the difference of D value among the three groups was statistically significant?p <0.05?.There was no significant difference between the stable group and the control group?p >0.05?.Activity group D* value was higher than the stable group,the control group,and the difference was statistically significant?p <0.05?,there was no significant difference of D* value between stable group and control group?p >0.05?.Activity group f value was higher than the stable group,the control group,and the difference was statistically significant?p <0.05?,there was no significant difference of f value between stable group and control group?p >0.05?.3.Compared the area under the ROC curve of the three parameters,the area under curve?AUC?of D value was the largest,and the sensitivity and specificity was the highest.The optimal cut-off values?with respective AUC,sensitivity,specificity?between active group and stable group were D = 0.42× 10-3mm2/s?0.870,83.80%,74.80%?;The optimal cut-off values?with respective AUC,sensitivity,specificity?between active group and control group were D=0.38 ×10-3mm2/s?0.923,89.20%,85.30%?.Conclusion:IVDI-DWI can effectively and noninvasively reflect the proliferation and microcirculation perfusion of active sacroiliitis in AS,and D value,D * value and f value are conducive to the diagnosis of the activity of AS,and the D value has the best diagnostic efficiency. |
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