Towards reliable automatic characterization of neonatal hip dysplasia from 3D ultrasound images

Abstract

Ultrasound (US) imaging is recommended for early detection of developmental dysplasia of the hip (DDH),which includes a spectrum of hip joint abnormalities in infants. However,the currently standard 2-dimensional (2D) US-based approach to measuring the dysplasia metric (DM),namely the α angle,suffers from high within-hip variability with standard deviations typically ranging between 3° − 7°. Such high variability leads to elevated over- and under-treatment rates in hip classification. To reduce this high variability inherent to the 2D α angle,α2D,we propose a 3D US-based DM in the form of a 3D α angle,α3D,that more accurately characterizes the morphology of an infant’s hip joint. Our method leverages phase symmetry features that automatically identify the 3D bone/cartilage structures to compute α3D. Validating on 30 clinical patient hip examinations,we demonstrate the within-hip variability of α3D to be significantly smaller than α2D (28.9% reduction,p < 0.01). Our findings indicate that α3D may be significantly more reproducible than the conventional 2D measure,which will likely reduce misclassification rates.