Improved segmentation of ultrasound images for fetal biometry, using morphological operators

Currently, radiologists indicate the femur endpoints with an interactive marker device; however, these measurements are subjective and have proved to be inconsistent. The main objective of this work is to obtain a time-efficient morphology-based algorithm to recognize femur contour in fetal ultrasound images, refine its shape for automatic length measurement, and thus, attaining accuracy and reproducibility of measurement. To achieve these objectives a cross-sectional study with subjects belonging to different family units of different communities was carried out. The images obtained from the subjects were initially processed using morphological operators to remove the background from the image. Thereafter, to refine the shape of the femur, the images were metamorphosed, using the morphological operators, till a single pixel - wide skeleton of the femur was available in the most time-effective manner. The skeleton-end-points are assumed to be the femur-end-points, and the femur length is calculated as the distance between the end-points to estimate gestational age. The mean execution time of the proposed algorithm was around 4 seconds. Measurements, performed using the automation algorithm, were found to be closely correlated to those obtained manually. The proposed algorithm was found to be time-efficient, and the results obtained were comparable to those derived through the existing methods for estimation of gestational age.