UBC Theses and Dissertations
Automatic characterization of developmental dysplasia of the hip in infants using ultrasound imaging Quader, Niamul
Developmental dysplasia of the hip (DDH) is the most common pediatric hip condition, representing a spectrum of hip abnormalities ranging from mild dysplasia to irreducible hip dislocation. Thirty-three years ago, the introduction of the Graf method revolutionized the use of ultrasound (US) and replaced radiography for DDH diagnoses. However, it has been shown that current US-based assessments suffer from large inter-rater and intra-rater variabilities which can lead to misdiagnosis and inappropriate treatment for DDH. In this thesis, we propose an automatic dysplasia metric estimator based on US and hypothesize that it significantly reduces the subjective variability inherent in the manual measurement of dysplasia metrics. To this end, we have developed an intensity invariant feature to accurately extract bone boundaries in US images, and have further developed an image processing pipeline to automatically discard US images which are inadequate for measuring dysplasia metrics, as defined by expert radiologists. If found adequate, our method automatically measures clinical dysplasia metrics from the US image. We validated our method on US images of 165 hips acquired through clinical examinations, and found that automatic extraction of dysplasia metrics improved the repeatability of diagnoses by 20%. We extended our automatic metric extraction method to three-dimensional (3D) US to increase robustness against operator dependent transducer placement and to better capture the 3D morphology of an infant hip. We present a new random forests-based method for segmenting the femoral head from a 3D US volume, and a method for automatically estimating a 3D femoral head coverage measurement from the segmented head. We propose an additional 3D hip morphology-derived dysplasia metric for identifying an unstable acetabulum. On 40 clinical hip examinations, we found our methods significantly improved the reproducibility of diagnosing femoral head coverage by 65% and acetabular abnormalities by 75% when compared to current standard methods.
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