| Part Ⅰ MRI Multimodal Imaging Study of Bone Marrow in Animal Models of Rheumatoid ArthritisObjective: To investigate the application of multimodal MRI quantitative technique in the animal model of rheumatoid arthritis.Methods: Chicken egg albumin as inducer is used to establish seven RA animal models of New Zealand white rabbit with three normal rabbits as the control group.Siemens 3.0T MR scanner was used to perform FS-TSE-T2 WI,T1mapping,T2 mapping and IVIM multi-sequence scanning of the knee joints of model animals and control-group animals at different stages after modeling,and the T1,T2,FP,D and DP values of the distal femoral epiphysis of each animal were measured.The differences of quantitative values between the control group and the model group were analyzed by combining the pathological sections of the animals.Results: In the distal femur of the 7 rabbit models,no MRI hyperintensity bone marrow edema foci were found at the 4th week after modeling while they were found at the 7th and 8th week after modeling.In the meantime,MRI bone marrow edema has not been observed in the distal femur of normal control group.The bone marrow section of the distal femur of the normal control group showed that the bone marrow adipocytes were the majority and the articular surface cartilage and bone trabecula were normal.After modeling,inflammatory cells in bone marrow increased gradually while articular cartilage and bone trabecula were destroyed gradually.The intra-group correlation coefficients of T1,T2,FP,D and DP measured by two observers were 0.912,0.925,0.789,0.853 and 0.702,respectively(P < 0.01).There were significant differences in T1 and D values between the control group,the RA model without MRI bone marrow edema group and the bone marrow edema group(P < 0.05),with the highest values in the bone marrow edema group and the lowest values in the normal control group.The T2 value of the control group was the highest and significantly higher than that of the model group(P < 0.05),but there was no significant difference between the model groups(P > 0.05).There were no significant differences in FP and DP values among the three groups(P > 0.05).Conclusion: T1 mapping,T2mapping and IVIM sequence can be used for bone marrow imaging in animal models.Quantitative values such as T1,T2 and D can effectively distinguish the differences between normal control group and RA model group in bone marrow,and indicate the pathological changes of bone marrow in RA animal model earlier than conventional MRI technology.Part Ⅱ Comparison of MRI Semi-quantitative Score and Quantitative Value of Bone Marrow Edema in RA PatientsObjective: To analyze the relationship between MRI multimodal quantitative value and semi-quantitative score of bone marrow edema in RA patients.Methods: FS-TSE-T2 WI,T1mapping,T2 mapping and IVIM sequence multimodal scanning were performed by Siemens 3.0T MR scanner in patients with clinically diagnosed RA,and the values of T1,T2,FP,D and DP of bone marrow edema were measured.A total of 71 patients(17 males,54 females)who met the study conditions were enrolled,with a median age of 49 years old,45 cases of right wrist and 26 cases of left wrist.Among them,63 patients completed all sequence scans,and 8 patients only completed FS-TSE-T2 WI,T1mapping,and T2 mapping sequence scans.According to the different measuring target range of bone,measurements can be divided into three groups,which respectively are target group with 15 pieces of bone(distal ulnar and radius,each wrist bone and each metacarpal base),target group with 8 pieces of bone(scaphoid,lunate,traquetral,capitate,hamate,distal radius and base of the 2nd and 3rd metacarpal bones)and target group with 3 pieces of bone most prone to bone marrow edema,and the control group is each patient without MRI measured values of bone marrow edema area in distal radius.Rheumatoid arthritis magnetic resonance image scoring(RAMRIS)system was used to evaluate the wrist bone marrow edema of each patient.The quantitative value of bone marrow edema in each patient and the quantitative value of bone marrow edema in the radius without MRI were analyzed,and the correlation between MRI semi-quantitative score and the quantitative value of target bone in different ranges of the three groups were compared respectively.Results: The correlation coefficients of T1,T2,FP,D and DP were 0.897,0.909,0.729,0.831 and 0.572,respectively(all P < 0.05).The lunate,traquetral and capitate bone were the three bones most prone to bone marrow edema,and the mean T1 and D values of bone marrow edema were significantly higher than the quantitative values of bone marrow edema in the radius without MRI(all P < 0.05),while there were no statistical differences in T2 values,FP and DP values between the bone marrow edema with and without MRI(all P > 0.05).The sum of T1 and D values of bone marrow edema in 15 bone target groups and 8 bone target groups was highly positively correlated with RAMRIS semi-quantitative score(all P < 0.05).The sum of T1 and D values in the bone marrow edema area of lunate,traquetral and capitate bone target groups were moderately positively correlated with RAMRIS semi-quantitative score(P < 0.05).Conclusion: The quantitative value of MRI can reflect the bone marrow edema in RA patients.The T1 and D value of wrist edema bone can be used as the quantitative index of bone marrow edema in RA patients,which bears a high correlation with conventional MRI semi-quantitative score.In addition,only the quantitative value of lunate,traquetral and capitate bone can achieve a good effect.Part Ⅲ Efficacy Evaluation of Multimodal MRI in RA Based on Bone Marrow EdemaObjective: To investigate the value of multimodal MR imaging based on bone marrow edema in evaluating the efficacy of RA.Methods: A Siemens 3.0T MR scanner was used to carry out the baseline and follow-up review of the wrist of patients with RA.The scanning sequence included FS-TSE-T2 WI,T1mapping,T2 mapping and IVIM.Forty-eight patients(10 males and 38 females)with a median age of 50(20-70 years old)were included in the follow-up review,with 30 cases of the right wrist and 18 of the left among which 38 cases were reviewed twice,27 cases three times,and 18 cases four times.Data were collected respectively with 8 bones(scaphoid,lunate,traquetral,capitate,hamate,distal radius and base of the 2nd and 3rd metacarpal bones)as target and 3 bones(lunate,traquetral and capitate bone)as target.DAS28-ESR scores were also collected from baseline to each review.The correlation between DAS28-ESR value,T1,T2,FP,D,DP value and RAMRIS in the follow-up process was analyzed,and the difference of MRI quantitative value change rate at the end of the first course of treatment in different efficacy was compared.Results: At baseline,42 patients were clinically highly active and 6 patients were moderately active.There was no significant difference in MRI quantitative values among patients with different clinical activity levels at baseline(P > 0.05).At the end of each course of treatment,there was a positive correlation between T1 and D values and DAS28-ESR values(P < 0.05),while there was no correlation between T2,FP and DP and DAS28-ESR values(P > 0.05).At the end of the first course of treatment,there was therapeutic effect in 31 patients while none in 17 patients.The rate of change of T1 value at the end of the first course of treatment was significantly different between patients with and without treatment(P < 0.05).The measured value with lunate bone,triangular bone and cephaloid bone as targets showed the highest reliability where the AUC of ROC curve was 0.763,the sensitivity of optimal bound value was 0.871,and the specificity was 0.588.RAMRIS score did not change significantly during follow-up and was not associated with changes in DAS28-ESR.Conclusion: T1 mapping and IVIM imaging can effectively and quantitatively evaluate the initial efficacy of RA patients.With the decline of clinical scores,T1 and D values also decreased.The significance of T2 mapping bone marrow imaging in RA efficacy monitoring is not obvious,and its clinical application remains to be explored.The change rate of T1 value of wrist bone marrow edema at the end of the first course of treatment can be helpful to judge the efficacy of RA.Lunate bone,triangular bone and cephalic bone can be used as new observation points to evaluate the clinical efficacy of RA. |
