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Purpose: This postmortem magnetic resonance imaging (MRI) study of the fetal spine aimed to describe the timing of appearance, shape, volume, and relative positions of the S1-S3 costal element ossification centers (CEOCs)., Methods: We obtained sagittal 3D dual-echo steady-state with water excitation T2 images of the entire spine in 71 fetuses (gestational ages (GAs), 17-42 weeks). Computed tomography and histological examinations were performed on two fetal specimens (GAs, 21 and 30 weeks) to validate the MR images. The presence/absence of each sacral CEOC was recorded according to the GA. CEOC volume was measured. We analyzed the CEOC position relative to the vertebral column and ilium., Results: The S1, S2, and S3 CEOCs first appeared at 23, 22, and 29 weeks, respectively. The S1 and S2 CEOCs could be detected in all fetuses with GAs of ≥ 30 weeks and ≥ 35 weeks, respectively, while the S3 CEOCs were variably present until term. The percentages of detection of the S1 and S2 CEOCs were significantly greater than that of the S3 CEOCs at each GA. At S1 and S2, the CEOC volume increased exponentially with GA. The relative positions of the S1 and S2 CEOCs, but not the S3 CEOCs, significantly correlated with GA (P < 0.001)., Conclusion: We have described the timeline of appearance as well as the volume and position of the S1-S3 CEOCs in the fetal spine on postmortem MRI according to GA.

Purpose: To describe the temporal pattern of the appearance of the S1-Co1 centrum ossification centers (COCs) and provide reference data for the S1-S5 COCs and sacral length at various gestational ages (GAs)., Methods: Postmortem magnetic resonance imaging (MRI) was performed on 71 fetuses (GA, 17-42 weeks) using the 3D dual-echo steady-state with water excitation T2 sequence in the sagittal plane. To confirm the reliability of this sequence, the MRI data were compared with the CT and histologic data obtained from two fetuses (GAs, 21 and 30 weeks). The presence or absence of each sacrococcygeal COC was recorded. Sacral length and S1-S5 COC height, sagittal diameter, transverse diameter, cross-sectional area, and volume were measured., Results: All fetuses showed S1-S3 COCs by 17 weeks, S4 COCs by 19 weeks, and S5 COCs by 28 weeks. The S4, S5, and Co-1 COCs were visualized in 70 (98.59%), 51 (71.83%), and 21 (29.58%) fetuses, respectively. Sacral length, height, sagittal, and transverse diameters increased linearly, while cross-sectional area and volume increased exponentially with advancing GA. Mean growth rates of the sagittal and transverse diameters, cross-sectional area, and volume, but not of height, significantly differed among the S1-S5 vertebrae., Conclusion: We have presented the timing of appearance of individual sacrococcygeal COCs and the age-specific, normative MRI reference values for sacral length and the morphometric parameters of the sacral COCs, which are of clinical importance in the diagnosis of congenital sacral abnormalities and skeletal dysplasia.

Objective: To obtain the three dimensional visualization model with normal measurements of fetal brain in the second trimester and analyze the developmental changes with gestational age (GA), sexual dimorphisms and cerebral asymmetries., Methods: The brains of 69 fetal specimens of 12 - 22 weeks GA were scanned by 7.0T magnetic resonance imaging (MRI). The developing structures were analyzed and a three dimensional visualization model was rebuilt with Amira 4.1 software., Results: Most sulci, except for postcentral and intraparietal sulcus, were present until 22 weeks GA. And none developed secondary branches. Laminar organization, described as early as 12 weeks GA, was delineated as layers with different signal intensities and became typical after 16 weeks GA. Basal nuclei was distinctly visible. Brains had different growth rates linearly increasing with GA. But neither sexual dimorphisms nor cerebral asymmetries was detected., Conclusions: The initial developmental stage of fetal brain occurs at 12 - 22 weeks GA. The developing structures may be distinctly visualized on 7.0T post-mortem MRI. And the three dimensional visualization model aids greatly in the precise cognition of immature brain.

Objective: To provide sectional anatomic data for the precise localization of developmental malformation of fetal brain in sagittal magnetic resonance imaging (MRI)., Method: After abdominal and pelvic MRI scanning, the gravid specimen was cut into serial sagittal slices in correspondence with MRI in a low temperature laboratory to demonstrate the structures of fetal brain., Result: (1) Directional determination of the sloping and rotating fetal head. From the serial sagittal sections of pregnant cadaver at term, we concluded that, the longitudinal lying and cephalic presentation fetal had run into maternal pelvis, and rotated and sloped to right. Anteroposterior position and median sagittal plane of the fetal was in correspondence with his mother's. (2) Seven serial sagittal sections of the fetal brain were obtained through lateral surface of the right cerebral hemisphere, lateral sulcus, internal capsule, median sagittal plane, middle cerebellar peduncle, brainstem, and lateral surface of the left cerebral hemisphere., Conclusion: Through the comparison study between sagittal sections and corresponding MRI of fetal brain at term, we could obtain morphological anatomic structures and MRI of fetal brain, providing morphological demonstration of the intrauterine development of fetal brain and auxiliary diagnosis of ultrasound and MRI in pregnant woman., (Copyright © 2011. Published by Elsevier B.V.)