Whole spine three-dimensional MRI of adolescent idiopathic scoliosis versus healthy controls and its correlation with Cobb angle

Abstract

Objective To determine the longitudinal and cross-sectional morphology of the spinal column and cord in adolescent idiopathic scoliosis(AIS)versus healthy controls and their correlation with Cobb angle.Methods A prospective study of three-dimensional reconstruction MR examination of the whole spine and column and hindbrain was performed in 90 adolescents including 49 patients with AIS and41 healthy adolescents.The ratio of anteroposterior(AP)and transverse(TS)diameter of the cord,the con-cave and convex lateral cord space(LCS)were measured at each cervical and thoracic level.The data col-lected from three-dimensional MRI also included the cerebellar tonsillar level related to the basion-opsithion(BO)line,odontoid process level related to the BO line,location of conus medullaris,the angle between axis of cervical cord and medulla oblongata(α),the angle between axis of BO line and medulla oblongata(β),the cord length,the vertebral length,the cord/vertebral length ratio,the cord area,the vertebral canal area,the cord/vertebral canal area ratio.Results AP,TS,AP/TS and LCS ratio increased in patients with AIS.The position of cerebellar tonsillar had descended; while the conus medullaris had ascended obivously.β angle decreased and cord/vertebral area ratio increased when compared with normal controls(P＜0.01).AP,AP/TS and LCS ratio were correlated significantly with Cobb angle(r＞0.19,P＜0.05).Conclusion Our study re-vealed significantly abnormal cross-sectional morphology of spinal cord.Some changes are significantly rele-vant with Cobb angle.As for the longitudinal axis of spinal cord,there is tethering of the spine cord suggest-ing the presence of disproportional growth between the neural and skeletal system,which may explain patho-genesis of AIS. Key words: Scoliosis; Magnetic resonance imaging; Spine; Spinal cord