Qualitative And Quantitative Study Of Skeletal Muscle MRI In Duchenne Muscular Dystrophy

Objective To evaluate the MRI involvement pattern of fat infiltration and inflammatory edema in lower extremity muscles of children with Duchenne muscular dystrophy(DMD)and its correlation with muscle strength score,creatine kinase(CK)and different gene mutation types.To explore the value of T2,FF and R2 water values of gluteus maximus and adductor maximus before and after glucocorticoid treatment in the evaluation of short-term non-invasive efficacy.Methods 1.Thirty five children with DMD diagnosed by gene were selected.29 muscles in thigh and calf and 15 muscles in thigh were assessed for fat infiltration and inflammatory edema respectively.T1 WI sequence was used for skeletal muscle fat infiltration score(0-4 points);t2dixon sequence water map was used for assessment of skeletal muscle inflammatory edema score(0-3points);10 point grading system was used for clinical muscle strength(0-5levels).2.For 13 children with DMD who had good compliance,T2 mapping,HISTO-MRS and QDixon were scanned prospectively at the baseline,the third month and the sixth month after the treatment.Gluteus maximus and adductor maximus were selected as the targets,and the changes of T2,FF and r2 water values before and after the treatment were analyzed.Result1.In 35 cases of DMD,the degree of fat infiltration in different muscle groups of the lower extremities was quite different.The degree of fat infiltration in the same muscle group was symmetrical on the left and right sides.The higher the frequency of fat infiltration was,the more obvious the degree of fat infiltration was,and the cumulative score of fat infiltration in the thigh muscle group was higher than that in the lower leg.The inflammatory edema of the same muscle group of thigh is asymmetric on the left and right sides.There was a strong negative correlation between muscle fat infiltration and muscle strength score(r=-0.623,P<0.01),but no correlation with CK.There was no correlation between inflammatory edema and muscle strength score,CK.There was no significant difference in cumulative score of muscle fat infiltration,muscle strength score and CK value among different gene mutation types.2.There was a significant correlation between HISTO-FF of gluteus maximus and adductor magnus at baseline and T1 WI fat infiltration score and QDixon-FF(r of gluteus maximus was 0.843,R of adductor magnus was 0.890,R of adductor magnus was 0.976,P < 0.01).3.Thirteen cases of DMD were followed up and reexamined,including 9cases in the third month after hormone therapy and 10 cases in the sixth month after hormone therapy.At the 3rd and 6th month after treatment,the score of fat infiltration in thigh muscle on T1 WI was the same as that at baseline.There was no significant difference between the mean value of muscle strength score at the3 rd and 6th month after treatment and the baseline(t value was 0.426,-0.200,P >0.05).There was no significant difference between the T 2 values of gluteus maximus and adductor major at the 3rd and 6th month after treatment and the baseline(T values of gluteus maximus and adductor major were 0.746,-0.443,2.120 and 1.745,respectively,P > 0.05).There was no significant difference in HISTO-FF between gluteus maximus and adductor maximus in the third month after treatment compared with the baseline(t value was 2.001,-2.056,P > 0.05).The difference was statistically significant in the sixth month compared with the baseline(t value was 4.739,3.429,P < 0.05).At the third month after treatment,the R2 water value of gluteus maximus and adductor maximus increased significantly compared with the baseline(t = 5.806,3.556,P < 0.01),and there was no significant difference compared with the baseline at the sixth month(t =0.450,-0.056,P > 0.05).Conclusion1.In DMD patients,the MRI features of the lower extremity muscles are characteristic,the fat infiltration of the affected muscle groups is symmetrical on the left and right sides,and different muscle groups have specific selective involvement mode,while the inflammatory edema is asymmetric on the left and right sides.2.In DMD patients,T1 WI fat infiltration score of thigh muscle is not related to gene type,but significantly related to clinical muscle strength and age.It can be used as a useful index to evaluate the severity of disease.Inflammatory edema of muscle can not reflect the state of motor function.3.HISTO-MRS can rapidly quantify the skeletal muscle fat content of DMD patients,and it can be used as an effective means of follow-up and reexamination,and its sensitivity is higher than that of T1 WI fat infiltration score.HISTO-R2 water has the potential to quantitatively evaluate the progress of inflammatory activity and the short-term effect of hormone in children with DMD.