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Title: Fetal skeletal imaging using 3D ultrasound and the impact of maternal vitamin D
Author: Ioannou, Christos
ISNI:       0000 0004 2745 7879
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2012
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Background: Previous research suggests that vitamin D deficiency during pregnancy may be associated with suboptimal fetal growth, but direct evidence is lacking. Our objectives were 1) to develop a method for measurement of the fetal sphenoidal fontanelle area (FA) and femur volume (FV) using 3D ultrasound; 2) to create normal charts for FA and FV; and 3) to correlate FA and FV with maternal vitamin D concentration. Methods: FA measurement in 3D was evaluated in vitro and in vivo. Different segmentation methods for FV measurement were explored. A novel FV method was described which consists of three linear measurements and a volume equation; this was validated in vitro and also by comparing FV measured sonographically to the true volume assessed by computed tomography (CT), in 6 cases following pregnancy termination. A cohort of 868 uncomplicated pregnancies was selected on the basis of strict inclusion criteria; participants underwent serial ultrasound scans for FV and multilevel modeling was used for the creation of a “prescriptive” FV chart. Finally, a different cohort of 357 healthy pregnant women had serum vitamin D levels and FV ultrasound at 34 weeks gestation and dual emission x-ray absorptiometry (DEXA) of their neonates in order to investigate the prenatal determinants of fetal bone mass. Results: FA measurement was accurate in vitro, but unreliable in vivo and was therefore abandoned. A novel FV method had excellent agreement with CT and superior repeatability compared with segmentation-based methods. A normal FV chart was created and the regression equations for the median and percentile values were presented. Vitamin D demonstrated a significant correlation with FV. Conclusions: FV is a reliable sonographic marker of skeletal growth. Maternal vitamin D deficiency is associated with reduced FV. This finding has public health implications as reduced bone mass may increase the lifetime risk of osteoporosis, through fetal programming.
Supervisor: Papageorghiou, Aris T.; Javaid, Kassim M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Medical Sciences ; Obstetrics ; Epidemiology ; Vitamin D ; ultrasound ; femur ; fetal growth ; fetal development