MRI Features Of Congenital Muscular Torticollis And Its Comparison With Pathology

Objective: To explore MRI features of congenital muscular torticollis and its comparison with pathology,to find a method to evaluate the patient’s condition by MRI scan,and to predict the degree of fibrosis and abnormal fat infiltration in the sternocleidomastoid muscle through the analysis of magnetic resonance images.The final purpose of this study is to provide a non-invasive method for early evaluation of the severity of the disease,judging the prognosis and guiding the treatment.Method : A total of 38 patients with congenital muscular torticollis underwent MRI examination before surgery,which were divided into group 1(Group I,18 cases)and group 2(Group II,20 cases).Preoperative T1 WI and T2 WI scanning was performed in both groups.In addition,Group II was scanned by T1 mapping sequence to measure the degree of fibrosis and Q-dixon sequence to measure fat content before surgery.After operation,Masson staining was performed on pathological sections to calculate the proportion of fibrosis in the two groups.HE staining was performed to grade fat infiltration in the Group II.At the level of the maximum cross-sectional area of the affected SCM,paired T-test was used to compare the differences in the value of the cross-sectional area、T1、T2、T1 mapping and Q-Dixon between the affected SCM and the healthy SCM of the children in the two groups.Pearson correlation was used to evaluate the correlation between the degree of fibrosis measured by T1 mapping sequence and the proportion of pathological fibrosis calculated by Masson staining.Rank correlation was used to evaluate the correlation between the fat content measured by Q-Dixon sequence and the grading of fat infiltration by HE staining in Group II.Results: At the level of the maximum cross-sectional area of the affected SCM,the cross-sectional area of the affected SCM was larger than the healthy side in 38 patients of two groups,and the difference was statistically significant(p=0.001).The mean values of the affected SCM measured by T1 WI and T2 WI were lower than those of the healthy SCM,the differences were statistically significant(p=0.001;p=0.001).The standard deviation of T1 and T2 of the affected side were greater than that of the healthy side,and the difference was statistically significant(P=0.001;P=0.001).On T1 WI and T2 WI images of the neck,20(53%)showed one or more hypointensities in the affected SCM on T1-weighted and T2-weighted images,and the hypointensities were all within the SCM.In Group II,the mean values of the affected SCM measured by T1 mapping sequence was lower than those of the healthy SCM,and the difference was statistically significant(p=0.001),but there was no significant difference in the mean value between the affected SCM and the healthy SCM measured by Q-dixon sequence(p=0.478).There was no significant correlation between the degree of fibrosis measured by T1 mapping sequence and the proportion of fibrosis calculated by Masson staining in Group II(r=-0.265;p=0.260).There was a correlation between fat content measured by Q-dixon and grading of fat infiltration calculated by HE staining in Group II(r=0.651;p=0.002).Conclusion: MRI scanning with different parameters can detect the abnormal signal on cross-sectional area of the affected SCM and the special scanning sequence can find the degree of fibrosis of the affected SCM that support the initially or the most severely fibrotic site may be located inside the SCM.It also suggests that when the surgeon needs to complete SCM release,it is necessary to completely amputate the SCM,rather than only the part or the surface of the SCM.In clinical,preoperative MRI examination can choose T1 mapping sequence to measure the degree of fibrosis of the affected SCM,and the Q-dixon sequence is more comprehensive and sensitive to quantitate the fat content of SCM.