EP07.25: Standardisation and validation of two methods of measurement of the fetal cerebral lateral ventricles

Abstract

1. to generate the estimates of the difference in the measurements between the ambient cistern/parieto-occipital sulcus (ACPOS) method and the transventricular suprathalamic/glomus (STG) method; 2. to establish the technical feasibility of the ACPOS method of measurement of the dependent atrium. This is a single site prospective study that included 30 normal singleton pregnancies from 19-32 weeks. The dependent atrium was measured 3 times on a symmetric axial slice using each method on a GE Voluson E10 using a C1-5 or C4-8 mHz transducer. The following data was collected: gestational age, atrial measurements (mm), BMI, and beam depth (cm). Two independent evaluators assessed image quality based on each method's criteria. An average measurement was calculated within each subject after excluding those with no data or poor image quality. The average measurements were then compared between methods using a Bland-Altman comparative analysis to determine whether one method consistently over or under measures compared to the other. The Bland-Altman analysis reveals an estimated bias = 0.45 (95%CI = 0.14 to 0.76). This suggests that on average, the STG method is estimating a 0.45mm longer measurement compared to the ACPOS method. The ACPOS method is optimal after 21 weeks gestation when the landmark of the parieto-occiptal sulcus (POS) is more developed and better visualised. 1. assuming a normal cut-off of 10mm as defined by ISUOG, 0.45mm can mean the difference between a normal and an abnormal result. This difference is clinically important and warrants further study with regard to the diagnosis of ventriculomegaly; 2. Image quality is associated with technical feasibility therefore the possibility of identifying the slight depression of the less developed POS in fetuses less than 21 weeks decreases at greater depths. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.