Oral or Poster Presentation
Concurrent Session 3D - Neo Neurosciences & Neuro Critical Care
Introduction: The intracranial translucency (ICT) has gained widespread recognition as an effective screening tool for early detection of open spina bifida (OSB), particularly when combined with other fetal cranial posterior fossa markers (brain stem (BS), cisterna magna (CM) and BS to occipital bone (BSOB)). Accurate identification and measurement of these structures, which appear as three parallel echogenic lines of apparent decreasing size, is critical to early detection of OSB, yet the measurement technique has not been previously well-defined. The purpose of this study is to describe and validate a novel technique for measurement of the posterior brain markers for early detection of OSB, and to assess their relative sizes.
Methods: Prospective cohort study, consented singleton pregnant women undergoing first trimester anatomic scan. Mid-sagittal images of the fetal profile showing the posterior cranial fossa anatomy were collected and stored. Posterior fossa measurements were performed using our unique step-wise technique with specific landmarks for caliper positioning. The fetuses included in the study were all unaffected by OSB.
Results: 215 singleton pregnant women were recruited. The posterior fossa structures were successfully measured in 96.3% (207/215) of the participants confirming the feasibility of the technique in most cases. Measurement results: mean BS 2.9 mm (range 2.0 – 3.6 mm), mean ICT 2.1 mm (1.6 – 2.8 mm), mean CM 1.7 mm (0.8 – 1.6 mm), mean BSOB 4.5 mm (3.2 – 5.9mm) and mean BS/BSOB ratio 0.64 (range 0.5 – 0.9). The mean BS-ICT-CM measurements showed decreasing size.
Conclusion: Using this technique, we were able to accurately measure the structures of fetal cranial posterior fossa in almost all participants and demonstrate a pattern of decreasing size. This technique provides a standardized approach which can be complemented by pattern recognition to improve accuracy and consistency of the screening for OSB in the first trimester.