Automatic Fetal Head Circumference Measurement in 2D Ultrasound Images Based On Optimized Fast Ellipse Fitting

Gestational age (GA) monitoring from fetal ultrasound imaging is one method to observe pre-birth risk factors and to prepare early treatment for neonatal problems. There are several parameters in an ultrasound image that can be used to estimate GA, one of which is the fetal head circumference (HC). However, fetal HC measurement is prone to error since it relies on manual annotation by sonographer or obstetrician. This research aims to design an algorithm to automatically calculate the fetal HC based on optimized ellipse fitting on a localized region of interest (RoI) previously defined as fetal head candidate area. Our optimization method consists of pre-processing steps to exclude noise within the RoI and to select the optimum representation of fetal head pixels to be processed by the ellipse fitting algorithm. We managed to perform ellipse fitting on 699 and 141 ultrasound images representing respectively the second and third trimester pregnancies; with the average dice similarity coefficient (DSC) of 95.27%±6.25%, hausdorff distance (HD) of 3.51 mm±5.54 mm, a difference in fetal HC (DF) of -3.42 mm±13.66 mm, and an absolute difference in fetal HC (ADF) of 6.53 mm±12.5 mm. The results demonstrated that the presented method performed comparably to other systems published in the literature. Moreover, our results represent an evaluation of a significantly larger number of data compared to most of the previous works.