Fetal craniofacial abnormalities are challenging to detect and diagnose on prenatal ultrasound (US). Image segmentation and computer analysis of three-dimensional US volumes of the fetal face may provide an objective measure to quantify fetal facial features and identify abnormalities. We have developed and tested an atlas-based partially automated facial segmentation algorithm; however, the volumes require additional manual segmentation (MS), which is time and labour intensive and may preclude this method from clinical adoption. These manually refined segmentations can then be used as a reference (atlas) by the partially automated segmentation algorithm to improve algorithmic performance with the aim of eliminating the need for manual refinement and developing a fully automated system. This study assesses the inter- and intra-operator variability of MS and tests an optimized version of our automatic segmentation (AS) algorithm. The manual refinements of 15 fetal faces performed by three operators and repeated by one operator were assessed by Dice score, average symmetrical surface distance and volume difference. The performance of the partially automatic algorithm with difference size atlases was evaluated by Dice score and computational time. Assessment of the manual refinements showed low inter- and intra-operator variability demonstrating its suitability for optimizing the AS algorithm. The algorithm showed improved performance following an increase in the atlas size in turn reducing the need for manual refinement.

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Objective To investigate and compare the effect of simulator training on quantitative scores for ultrasound‐related skills for trainees with novice level ultrasound experience and expert ultrasound operators. Methods Three novice (comprising of 11, 32, 23 participants) and one expert (10 participants) subgroups undertook an ultrasound simulation training session. Pre‐ and post‐training test scores were collected for each subgroup. Outcome measures were as follows: mean accuracy score for obtaining the correct anatomical plane, percentage of correctly acquired target planes, mean number of movements, time to achieve image, distance travelled by probe and accumulated angling of the probe. Results The novices showed improvement in image acquisition after completion of the simulation training session with an improvement in the rate of correctly acquired target planes from 28–57% to 39–83%. This was not replicated in the experts. The novice’s individual ratios based on pre‐ vs. post‐training metrics improved between 1.7‐ and 4.3‐fold for number of movements, 1.9‐ and 6.7‐fold for distance, 2.0‐ and 5.2‐fold for time taken and 1.8‐ and 7.3‐fold for accumulated angling. Among the experts, there was no relationship between pre‐training simulator metrics and years of ultrasound experience. Conclusions The individual simulation metrics suggest the sessions were delivered at an appropriate level for basic training as novice trainees were able to show demonstrable improvements in both efficiency and accuracy on the simulator. Experts did not improve after the simulation modules, and the novice scores post‐training were similar to those of experts, suggesting the exercises were valid in testing ultrasound skills at novice but not expert level.

Electronic poster abstractsMethods: 63 singleton low-risk pregnancies without any known pathologic states were prospectively evaluated in 20-24, 25-29, 30-34 and > 35 weeks of gestation. Siemens Acuson S2000 premium system with the 1.5 -6.0 MHz 6C1 probe was used by 3 skilled sonographers, after a set of 10 pilot measurements each and their evaluation. The sample volume was placed over the organ of interest (lungs, liver, placenta) in a place of homogenous echogenicity. Regions with acoustic shadowing or artifacts of adjacent structures were avoided, especially fetal ribs or content of the maternal intestine. 6 consecutive measurements in each organ were provided. The insonation angle and probe placement were different for each measurement. The SWV was measured in the left and right lung and both lobes of the liver in each participant. All measurements were recorded and used for calculations. The study was approved by the hospital ethics committee. Results: The SWV in placental and liver parenchyma were all statistically significantly higher in the third trimester than in the second trimester, while the velocities in lungs did not differ between the second and the third trimester (figure 1). Inter-and intraobserver agreement of the SWV measurements was good. Conclusions: Shear wave elastography provides numerical values of fetal lung and liver stiffness and reflects gestational age-related changes in these organs. SWV in the liver and placenta might reflect not only changes in different gestational weeks in physiologic pregnancies, but further studies might be necessary to show if there are different SWV in fetuses with intrauterine restriction or other fetal pathologies.