AUTOMATED FETAL BREATHING MOVEMENT DETECTION FROM INTERNAL SMALL DISPLACEMENT MEASUREMENT

We have previously proposed a method to measure small displacements of internal tissue which is based on an ultrasonic pulsed Doppler techni que. The Doppler frequency shift of the ultrasonic waves due to the ti ssue movement is detected using a modified quadrature detector, and th e displacement of the internal tissue is estimated by using an arctang ent method. Based on the algorithm, we have constructed a quantitative monitoring system for fetal breathing movement. The fetal breathing m ovement is a rhythmic movement of the fetal diaphragm and it is record ed as a nearly sinusoidal displacement with a repetition frequency fro m 0.5 Hz to 2 Hz. In this pa per, an automated fetal breathing movemen t detection algorithm for the displacement data observed by using the small displacement measurement system is proposed. This method uses a modified autocorrelation technique for detecting the displacement due to the fetal breathing movement. The method is applied to five fetuses of late pregnancy and the result is compared with the manual detectio n.