基于CT影像儿童枢椎正常发育与变异的解剖特征

Anatomical characteristics of normal development and variation of axis in children based on CT images

背景:枢椎发育演变过程复杂,研究报道较少。CT成像可以显示枢椎的正常发育过程、解剖结构、发育变异与畸形,明确枢椎骨化中心出现与骺板闭合时间及其演变过程和规律具有重要的临床价值。目的:基于CT影像展示儿童枢椎正常发育与变异的解剖结构。方法:回顾性分析2016年6月至2019年11月行颈部扫描的732例0-15岁儿童CT图像。观察指标包括枢椎齿状突、双侧椎弓、椎体骨化中心,齿突尖部二次骨化中心,椎弓、齿突基底部及后正中骺板,以及枢椎发育变异或畸形。分析与比较各项指标在不同年龄下的变化情况,并利用SPSS 17.0统计学软件包进行数据分类处理及统计学分析。结果与结论:(1)732例研究对象包括枢椎正常发育718例(98.1%),畸形或发育异常14例(1.9%);(2)枢椎5个骨化中心,其中双侧椎弓及齿突、椎体骨化中心在出生时已出现;齿突尖部二次骨化中心出现的中位年龄是5.7岁,年龄四分位差(IQR)是4.1-7岁,最早出现的为8个月22 d,最迟未出现的为12岁10个月;(3)齿突尖骺板融合的中位年龄是6岁,IQR是5-8岁,未融合最大年龄是8岁9个月,融合的最小年龄是4岁3个月;(4)双侧椎弓骺板闭合的中位年龄约3.8岁,IQR约2.9-4.6岁,闭合的最小年龄是2岁3个月,未闭合的最大年龄是6岁;(5)齿突基底部骺板闭合的中位数5.2岁,IQR为3.5-6.8岁,闭合最小年龄是2岁6个月,最晚未闭合年龄是9岁6个月;(6)后正中骺板闭合年龄中位数为1.5岁,IQR为1.0-2.1岁,最晚未闭合2例分别为2岁5个月、14岁,最早闭合为6个月20 d;(7)枢椎畸形或发育异常,包括出现副骨化中心及副骺板7例、枢椎游离骨化小骨3例、后正中骺板不闭合2例、无齿突尖部二次骨化中心2例及枢椎齿突骨化中心未出现1例;(8)提示多层螺旋CT扫描、结合多平面重组技术可以完整显示枢椎的解剖结构,评估其正常发育变异及畸形。

BACKGROUND:The development and evolution of atlas are complex,and there are a few research reports.CT imaging can show the normal development process,anatomical structure,developmental variation and deformity of the axis.It has important clinical value to clarify the time of occurrence of ossification center of axis and closure of epiphyseal plate and its evolution process and law.OBJECTIVE:To present the anatomical structure of the normal development and variation of children’s axis based on CT images.METHODS:CT images obtained from 732 children aged 0 to 15 years who underwent neck scans between June 2016 and November 2019 were retrospectively analyzed.The observation indicators encompassed the axis odontoid,bilateral pedicle,vertebral ossification center,secondary ossification center at the tip of odontoid,pedicle,base of odontoid,and posterior median epiphyseal plate,as well as any variations or deformities in axis development.The changes in these indicators were analyzed and compared across different age groups.SPSS 17.0 statistical software package was utilized for data classification and statistical analysis.RESULTS AND CONCLUSION:(1)A total of 732 subjects were examined,comprising 718 cases(98.1%)with normal development of the axis and 14 cases(1.9%)exhibiting deformity or dysplasia.(2)The axis demonstrated the presence of five ossification centers,including those of the bilateral pedicles,odontoid process,and vertebral body,which were observed at birth.The median age for the secondary ossification center located at the tip of the odontoid process was determined to be 5.7 years,with an interquartile range of 4.1 to 7 years.The earliest recorded occurrence was observed at 8 months and 22 days,while the latest occurrence was noted at 12 years and 10 months.(3)The median age at which fusion took place was 6 years,with an interquartile range of 5-8 years.The maximum age at which non-fusion was observed was 8 years and 9 months,while the minimum age at which fusion occurred was 4 years and 3 months.(4)The median age at which bilateral epiphyseal plate closure occurred was approximately 3.8 years,with an interquartile range of about 2.9-4.6 years.The earliest observed closure was at 2 years and 3 months,while the latest observed unclosure was at 6 years old.(5)The median age at which odontoid base epiphyseal plate closure occurred was 5.2 years,with an interquartile range of 3.5-6.8 years.The minimum age for closure was 2 years and 6 months,and the latest age for non-closure was 9 years and 6 months.(6)The posterior median epiphyseal plate typically closed at a median age of 1.5 years,with an interquartile range of 1.0-2.1 years.However,two cases exhibited delayed closure,occurring at ages 2 years and 5 months,and 14 years,respectively.The earliest closure observed was at 6 months and 20 days.(7)Axis malformation or developmental abnormalities,including 7 cases of accessory ossification center and accessory epiphyseal plate,3 cases of free ossified small bones in the axis,2 cases of posterior median epiphyseal plate failure,2 cases of secondary ossification centers in the absence of the apex of odontosis,and 1 case of absence at ossification center in the odontoid of the armature vertebrae.(8)It is concluded that the utilization of multi-slice spiral CT scanning in conjunction with the multi-plane reconstruction technique enables comprehensive visualization of the anatomical structure of the axis,facilitating precise assessment of both its typical developmental variations and deformities.