Adolescent Idiopathic Scoliosis MRI Changes And Correlation With Severity Of Scoliosis

Study Design. A retrospective and prospective study to evaluate the morphology and relative position of the spinal column and cord in adolescent idiopathic scoliosis (AIS) and healthy controls by using magnetic resonance imaging (MRI).Objective. Establish MRI data in healthy Chinese adolescents. To determine the longitudinal and cross-sectional morphology of the spinal column and cord in AIS subjects versus healthy controls and their correlation with Cobb’s Angle.Summary of Background Data. MRI is widely applied in AIS. Documented data is rarely found in normal adolescents. Literature is also rare in MRI study on AIS. No whole-spine column and cord measurements and theirs correlation with Cobb’s angle were studied.Methods. Part Ⅰ:A retrospective study of149AIS(mean age15yrs,19M,130F) with MRI examination of the spine and hindbrain. Measurements of the ratio of anteroposterior (AP) and transverse (TS) diameter of the cord, the concave and convex lateral cord space (LCS) were obtained at the apical level in AIS subjects. Measurements of cerebellar tonsillar level related to the basion-opsithion (BO) line, odontoid process level related to the BO line,location of conus medullaris, angle between axis of cervical cord and medulla oblongata(a), angle between axis of basion-opsithion (BO) line and medulla oblongata(β),cord area,vertebral canal area,ratio of cord area to vertebral canal area. Shape and position of subarachnoid signal were also observed. All of the same parameters were also measured in normal controls at matched vertebral levels. Their correlations with Cobb’s angle were made. Part Ⅱ:Measurements of cord length,vertebral length, cord/vertebral length ratio as well as all the parameters in Part Ⅰ.PartⅢ:A prospective study of3D-reconstruction MRI of AIS with measurements of all the parameters in Part Ⅱ. Results. AP, TS, AP/TS and LCS ratio were increased in AIS subjects with lowing positiong of cerebellar tonsillar level, upper-lifting of medullary conus, decreased β angle and cord/vertebral length ratio and increased cord/vertebral area ratio when compared with normal controls (P<0.01). AP, AP/TS and LCS ratio were correlated significantly with Cobb’s angle (Pearson Correlation Coefficient>0.19, P<0.05). The subarachnoid space seems to be more asymmetric, and the subarachnoid plaque shows a little bit high signal intensity in AIS compared with the normal controls (P<0.01).Conclusion. Our study revealed significantly abnormal cross-sectional morphology of spinal cord and some changes are significantly relevant with Cobb’s angle.Besides,there is abnormal subarachnoid signal in AIS. Along the longitudinal axis of spinal cord,there is tethering of the spine cord suggesting the presence of disproportional growth between the neural and skeletal system, which may indicate pathogenesis of AIS.