Objective:To explore the MRI features of fetal coronal cleft vertebrae, and to compare the efficacy of MRI and ultrasound in the diagnosis of fetal coronal cleft vertebrae, and to analyze the outcome of fetal coronal cleft vertebrae.Methods:From September 2019 to June 2021, 40 fetuses suspected of fetal vertebral deformities by ultrasound were retrospectively collected in Shandong Provincial Hospital Affiliated to Shandong University, who were diagnosed as coronal cleft vertebrae after MRI examination. Five cases of induced labor and 14 cases lost to follow-up were excluded, and 21 fetuses who underwent MRI after delivery were finally included. The gestational weeks were 25-34 (29.1±2.6) weeks, and there were 19 males and 2 females. Fetal spine MRI includes susceptibility weighted imaging (SWI) and T 2-true fast imaging with steady-state (True-FISP). The MRI features and outcome of fetal coronal cleft vertebrae were explored. The image quality scores of SWI, T 2-True-FISP and ultrasound were compared with Friedman test and Wilcoxon signed-rank test. The diagnostic accuracy of fetal coronal cleft vertebrae of SWI, T 2-True-FISP and ultrasound was calculated. Cochran test was used to compare the efficiency of 3 kinds of images, and the modified McNemar test was used for pairwise comparison between groups. Results:There were 10 cases of single and 11 cases of multiple fetal coronal cleft vertebrae, 16 cases of simple lumbar vertebrae, 2 cases of simple thoracic vertebrae, and 3 cases of thoracolumbar vertebrae. The common SWI features of 21 cases show longitudinal strip or dot high signal on the sagittal plane, and transverse fissure like high signal on axial plane. Anterior part of vertebral body was larger than posterior part in 19 cases of them. The image quality scores of SWI, T 2-True-FISP and ultrasound were 4 (3, 4), 2 (2, 2), 2 (2, 2), and the difference was statistically significant in general (χ2=34.24, P<0.001). Pairwise comparison showed that the image quality of SWI was better than those of T 2-True-FISP and ultrasound ( Z=-4.04, P<0.001; Z=-4.11, P<0.001), and there was no statistically significant difference between T 2-True-FISP and ultrasound ( Z=-0.58, P=0.388). The diagnostic accuracy of SWI, T 2-True-FISP and ultrasound was 100% (21/21), 66.7% (14/21), 47.6% (10/21). The diagnostic accuracy of SWI was better than those of T 2-True-FISP and ultrasound (χ2=5.14, P=0.008; χ2=9.09, P<0.001), and there was no statistically significant difference between T 2-True-FISP and ultrasound (χ2=0.75, P=0.194). MRI showed that coronal cleft vertebrae disappeared in all 21 fetuses after birth, including 1 case of syringomyelia and 1 case of fatty filum terminal. Conclusions:MRI, especially SWI, plays an important role in the diagnosis of fetal coronal cleft vertebrae. Fetal coronal cleft vertebrae disappeared in the follow-up after birth, which proved to be a normal physiological variation from the radiographic perspective.

Objective:To measure the morphological parameters of the fetal vertebral centrum ossification centers (COC) in the second-third trimester using MRI susceptibility weighted imaging (SWI), and to explore the growth and development trajectory of the vertebrae.Methods:Fetus in the second-third trimester with normal vertebrae development were prospectively and continuously included in Shandong Provincial Hospital Affiliated to Shandong First Medical University from December 2015 to December 2021, and the SWI scanning of fetal spine was performed. The following morphometric parameters of the C4, T6, L3, S1 vertebrae COC were measured, including sagittal diameter, transverse diameter, height, cross-sectional area and volume. The linear and nonlinear regression analysis was used to derive the best-fit curve for each parameters and gestational age.Results:A total of 112 fetuses were recruited with gestatonal age 21-39 (29.4±3.9) weeks, including 30 cases of C4, 58 cases of T6, 92 cases of L3, 62 cases of S1. Fetal spine in utero with global curvature was kyphosis, presenting two primary curves (thoracic and sacral kyphosis). The morphological parameters sagittal diameter, transverse diameter, height, cross-sectional area and volume of C4 followed the quadratic polynomial rule during 25 to 38 weeks (R 2=0.938, 0.943, 0.952, 0.957, 0.982). During 21 to 38 weeks, the sagittal diameter, transverse diameter and height of the T6 followed the exponential growth pattern (R 2=0.915, 0.923, 0.849) and the growth of the area and volume followed the quadratic polynomial growth pattern (R 2=0.943, 0.961). The L3 followed the quadratic polynomial rule during 21 to 39 weeks (R 2=0.910, 0.916, 0.914, 0.942, 0.948) The sagittal diameter, transverse diameter and height of the S1 followed the linear growth pattern (R 2=0.905, 0.911, 0.922) and the area and volume followed the quadratic polynomial growth pattern (R 2=0.930, 0.964) during 23 to 39 weeks. Conclusions:The growth and development of C4, T6, L3 and S1 COC of fetus in the second-third trimester has a good correlation with gestational age. The growth of fetal vertebral COC in the early stage is slow, but with the growth of gestational age, the growth rate of vertebral bodies accelerates.