Functional Magnetic Resonance Imaging In Sacroiliac Joint For Evaluating The Disease Activity Of Ankylosing Spondylitis

Part Ⅰ:Diffusion Kurtosis Imaging in Sacroiliitis to Evaluate the Activity of Ankylosing SpondylitisObjective:To explore the application of DKI in Sacroiliac joint evaluating the disease activity states of AS.Methods:Continuously and prospectively,forty four patients diagnosed with ankylosing spondylitis according to the Modified New York criteria were included,and laboratory examination and 3.0T Sacroiliac joint magnetic resonance examination(including DKI)were acquired.AS disease activity was evaluated according to the Ankylosing Spondylitis Disease Activity Score(ASDAS),and four disease activity states were chosen by consensus:inactive and low,high,and very high disease activity.The three cutoffs selected to separate these states were:1.3,2.1,and 3.5 units,respectively.Two-independent-samples t-test and one-way analysis of variance(ANOVA)were used to compare the DKI parameters among different groups,and post-hoc Scheffe’s method was adopted.Receiver operating characteristic(ROC)analysis and Spearman’s rank correlation were performed to test the diagnostic performance of DKI parameters in distinguishing different activity grades and the correlation between them,respectively.Results:The D and apparent diffusion coefficient(ADC)values of sacroiliac joints in the active group were significantly higher,while the the kurtosis of diffusion(K value)value was significantly lower than those of the inactive group(all P<0.001).The D value performed best in distinguishing different activity grades(all P<0.001).The D and ADC values correlated positively,while the K value correlated negatively with disease activity states significantly(r=0.918,0.798,and-0.765,respectively;all P<0.001).Conclusion:DKI of sacroiliac joints might be useful to evaluate the disease activity states of AS.Part Ⅱ:Comparing Whole-Lesion ADC Histogram Analysis and the Spondyloarthritis Research Consortium of Canada(SPARCC)MRI Index in Evaluating the Disease Activity of Ankylosing SpondylitisObjective:To compare the effectiveness in evaluating the disease activity states of AS between the whole-lesion ADC histogram analysis and the SPARCC MRI index.Methods:Continuously and prospectively,fifty seven patients diagnosed with ankylosing spondylitis according to the Modified New York criteria were included,and twenty seven volunteers were recruited as control group simultaneously,all patients received laboratory examination and 3.0T Sacroiliac joint magnetic resonance examination(including DWI),and volunteers were only received 3.0T Sacroiliac joint magnetic resonance examination(including DWI).AS disease activity was evaluated according to the Ankylosing Spondylitis Disease Activity Score(ASDAS),and four disease activity states were chosen by consensus:inactive and low,high,and very high disease activity.The three cutoffs selected to separate these states were:1.3,2.1,and 3.5 units,respectively.One-way analysis of variance(ANOVA)and Scheffe’s post-hoc was used to compare the parameters among different groups.A receiver operating characteristic(ROC)analysis and the Spearman rank correlation were performed to test the diagnostic performance of all parameters in distinguishing different disease activity states and determining the correlations between them.Results:The ADCmean,ADC percentiles,and SPARCC MRI index of the active group were significantly higher than those of the inactive and control groups(all P<0.001).The 90th percentile could differentiate the inactive from the control group and the low disease activity group from the inactive group(P=0.011 and 0.006,respectively).The 50th percentile of the high disease activity group was significantly higher than those of the low disease activity group(P=0.004),while the SPARCC MRI index of the very high disease activity group was significant higher than those of the high disease activity group(P<0.001).Conclusion:The whole-volume ADC histogram analysis was superior to the SPARCC MRI index in assessing AS disease activity states.Part Ⅲ:Intravoxel Incoherent Motion Diffusion-Weighted and MDIXON Quant MR Imaging for Evaluating the Disease Activity States of Ankylosing SpondylitisObjectives:To explore the application of IVIM and MDIXON Quant MR Imaging to evaluate the disease activity and activity states of AS and the efficiency of all parameters.Methods:Fifty AS patients according to Modified New York criteria underwent 3.0 T MR imaging.According to ASDAS classification,four different disease activity states were classified;furthermore,patients were classified in active and inactive group with the cut off ASDAS value of 1.3.Seventeen volunteers were recruited as the control group.ANOVA,Scheffe’s post-hoc test and ROC analysis were used to compare parameters among different groups.Results:The D and ADC values in the active group were significantly higher than those of the inactive and control group(all P<0.001);the FF value of the inactive group was significantly higher than that of the control group(P=0.006);the D and ADC values of the high disease activity group were significantly higher than those of the inactive group(P=0.002 and 0.001,respectively);the D and ADC values of very high disease activity group were significantly higher than those of the inactive group(all P<0.001).Conclusion:The IVIM parameters performed excellent in differentiating the active from the inactive and control group;MDIXON Quant parameter compensates the deficiency of IVIM parameters in differentiating the inactive group and control group.