Quantitative evaluation of the development of fetal conus medullaris and the diagnostic value of terminal caudal vertebral ossification center count in closed spina bifida by three-dimensional ultrasound
10.3969/j.issn.1009-0754.2025.01.008
- VernacularTitle:三维超声定量评估孕中晚期胎儿脊髓圆锥发育及其末端尾侧椎体骨化中心计数对闭合性脊柱裂的筛查价值
- Author:
Jinghua ZHEN
1
;
Xiangling WU
;
Weina ZHOU
;
Yan ZHAO
;
Chunqing LI
Author Information
1. 071000 河北保定,保定市第一中心医院影像 1 科
- Keywords:
Conus medullaris;
Three-dimensional ultrasound;
Second and third trimesters of pregnancy;
Ossification center count;
Closed spina bifida;
ROC curve;
Cut-off value
- From:
Journal of Navy Medicine
2025;46(1):32-37
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study the development of conus medullaris by quantitative three-dimensional ultrasound in the second and third trimesters of pregnancy,and to analyze the value of terminal caudal vertebral ossification center count in diagnosis of closed spina bifida.Methods A total of 108 normal fetuses in the second and third trimesters of pregnancy who were admitted to Baoding No.1 Central Hospital from January 2019 to March 2024 were selected and assigned to the normal group.The distance between the fetal conus medullaris and the first sacral vertebra,the distance between the end of the conus medullaris and the end of sacrum,and the number of corresponding vertebrae were measured by three-dimensional ultrasound at different gestational weeks.Meanwhile,54 fetuses who were confirmed to have closed spina bifida after delivery were enrolled into the abnormal group.The number of ossification centers on the median sagittal section of the caudal spine was counted and compared between the two groups.The receiver operating characteristic(ROC)curve was drawn to analyze the value of ossification center count of distal caudal vertebrae in diagnosis of closed spina bifida.Results With the increase of gestational weeks,the distance between the fetal conus medullaris and the first sacral vertebra and the distance between the end of the conus medullaris and the end of the sacral bone were gradually increased.The conus medullaris of normal fetuses was mainly located in L1.5,L2 and L2.5,accounting for 85.19%(92/108).The ossification center count of distal caudal vertebra was slightly increased with the increase of gestational weeks in the normal group.At 17-20 gestational weeks,85.71%(12/14)of the ossification center count of distal caudal vertebra was 5 to 7.At 21-28 gestational weeks,100.00%(45/45)of the ossification center count was 6 and more.At week 29 and above,100.00%(45/45)of the ossification center count was more than 7.In the abnormal group,96.30%(52/54)of the fetuses had the ossification center less than 6,and 85.71%(42/49)of the ossification center count was≤5 at 21-32 gestational weeks.There were significant differences in the ossification center count between the two groups at 17-20,21-24,25-28,29-32,and 33-36 gestational weeks(P<0.05).ROC curve showed that,at 17-20,21-24,25-28,29-32,and 33-36 gestational weeks,the area under the curve(AUC)in prediction of closed spina bifida was 0.804,0.744,0.776,0.819,and 0.722 when the ossification center count of distal caudal vertebra was 5.31,4.59,4.81,4.67,and 5.49 as the cut-off value,respectively.Conclusion The conus medullaris moves upward with the increase of gestational weeks in the second and third trimesters of pregnancy.The ossification center count of the distal caudal vertebra is less than 6 in most fetuses with closed spina bifida,which is conducive to screening for closed spina bifida.
