| Objective:To quantitatively analyze the T2 value and T2*value of hip joint cartilage in patients with ankylosing spondylitis(AS)by 3.0T MR T2mapping and T2*mapping,and to explore the correlation between them and clinical index.Materials and Methods:49 patients with AS diagnosed by rheumatologists from February 2019 to November 2019 in our hospital were collected in this study.At the same time,22 healthy volunteers matched with the patients' gender and age were recruited as the control group.The clinical indicators(CRP and ESR)of patients were collected within one week after MRI examination.The patients were assessed with Bath AS disease activity index(BASDAI)and AS disease activity score(ASDAS).According to the BASDAI score,AS patients were divided into active group and stable group.All subjects underwent sacroiliac joint routine scanning,right hip joint routine scanning and right hip joint T2mapping and T2*mapping scanning on Siemens Magnetom Prisma 3.0T MRI scanner.The sacroiliac joints of the patients were scored by the Spondyloarthritis Research Consortium of Cananda(SPARCC).The anterior superior and posterior superior areas of hip joints' cartilage were manually delineated on the pseudo-color images of T2mapping and T2*mapping by the post-processing software of MRI workstation,and the T2 values and T2*values were measured.The mean T2 and T2*values of the two subregions represent the T2 and T2*values of the hip cartilage.One way ANOVA was used to compare the T2 value and T2*value of hip joint cartilage between the active group,the stable group and the control group.The T2 value and T2*value of two subareas of hip joint cartilage in each group were compared by paired-samples t test.The diagnostic value of T2 value and T2*value in AS patients group and control group,active group and stable group,active group and control group,stable group and control group was assessed by ROC curve.The results are represented by area under curve(AUC).The AUCs of two parameters were compared by Z test.Pearson's correlation analysis was used to investigate the correlation between T2 and T2*values of hip cartilage and body mass index(BMI),onset age,clinical course,BASDAI,ASDAS and SPARCC in AS patients.Results:49 AS patients were included in this study,including 26 in the active group(18 males and 8 females,aged 22-37 years)and 23 in the stable group(14 males and 9 females,aged 24-37 years).There were 22 volunteers in the control group(12 males and 10 females,aged 20-38 years).There was no significant difference in gender,age,height,weight and BMI among the three groups.The T2 values of hip cartilage in the active group,the stable group and the control group were(35.39±3.21)ms,(33.06±3.41)ms and(32.47± 2.54)ms.The T2*values of hip cartilage in the active group,the stable group and the control group were(29.51±2.91)ms,(27.53±2.79)ms and(26.30±2.35)ms.There were significant differences in T2 and T2*values among the three groups(P<0.05).The values of T2 and T2*in the active group were higher than those in the stable group and the control group(P<0.05).The values of T2 and T2*in the stable group were higher than those in the control group(P>0.05).The T2 values of the anterior superior areas of the hip cartilage in the active group,the stable group and the control group were(38.43±3.3 1)ms,(35.81±3.38)ms and(35.20± 2.63)ms.The T2 values of the posterior superior areas were(32.34±3.13)ms,(30.30±3.46)ms(29.72 ± 2.47)ms.The T2*values of the anterior superior areas were(32.41 ± 2.83)ms,(30.41±3.19)ms and(29.34 ± 2.48)ms.The T2*values of the posterior superior area were(26.59 ± 3.00)ms,(24.65±2.42)ms and(23.26±2.24)ms.The statistical results of paired-samples t test showed that the T2 value and T2*value in the anterior superior areas were higher than those in the posterior superior areas(P<0.001).ROC curve analysis showed that T2 value and T2*value had diagnostic value in distinguishing AS patients group from control group,active group from stable group,active group from control group.The AUCs of T2 value were:0.660,0.686 and 0.755,respectively.The AUCs of T2*value were 0.719,0.684 and 0.802,respectively.There was no diagnostic value of the two parameters in differentiating the stable group from the control group.The statistical results of Z test showed that AUC of T2 and T2*were 0.660 and 0.719 respectively when distinguishing AS patients group and control group,the difference was statistically significant(P<0.05).Pearson correlation analysis showed that there was no correlation between the changes of T2/T2*values of hip cartilage and BMI in AS patients(P>0.05).T2 value was correlated with age,course,CRP,ESR,BASDAI,ASDAS-CRP,ASDAS-ESR and SPARCC(r=-0.598,0.339,0.500,0.451,0.534,0.556,0.542,0.572,respectively,P<0.05),T2*value was correlated with age,course,CRP,ESR,BASDAI,ASDAS-CRP,ASDAS-ESR and SPARCC(r=-0.555,0.315,0.570,0.553,0.530,0.616,0.611,0.653,respectively,P<0.05).Conclusion:MR T2mapping and T2*mapping can quantitatively analyze the early molecular changes of hip cartilage in AS patients,which is related to the onset age and disease activity. |
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