Automatic fetal head measurements from sonographic images

Rationale and Objectives. We designed an image processing technique to automatically measure the biparietal diameter (BPD) and head circumference (HC) from prenatal sonograms, We evaluated the performance of the algorithm by comparing the resulting measurements with those made by experienced sonographers. Methods. Thirty-five digitized sonograms of the fetal head were obtained during routine imaging, The BPD and HC were automatically computed by detecting the inner and outer boundaries of the fetal skull using the computer vision technique known as the ''active contour model.'' Six experienced sonographers also measured the BPD and HC on these images. Results. The algorithm failed to locate the boundaries in two of the 35 cases. For the remaining cases, the mean absolute difference betnieen the automated measurements and the average of the six observers was 1.4% for BPD and 2.9% for HC. The correlations were .999 for the BPD and .994 for the HC. The computer's measurements were no different from the six observers' measurements than the observers' measurements were from one another. Conclusion. The tested algorithm effectively and accurately measures BPD and HC automatically. We are currently in the process of integrating this algorithm into an ultrasound machine.