Norio Shinozuka

Formulas for fetal weight estimation by ultrasound measurements based on neonatal specific gravities and volumes

To improve the accuracy of fetal weight estimation by ultrasound measurement, especially in low birth weight infants, including those with intrauterine growth retardation, two new formulas were developed from a new point of view. The formulas were established by (1) actual measurements of the volumes of the neonatal head and trunk with limbs, (2) analysis of the relationship between the sizes of the parts of the fetal body measured by ultrasound examination before birth and the volumes of the parts of the neonatal body, and (3) calculation of the specific gravities of the parts of the neonatal body. The prospective study showed a high correlation between estimated weights and actual birth weights with a small range of error in infants weighing between 450 and 4800 gm.

A study on the development of sleep-wakefulness cycle in the human fetus

We observed fetal behavior by using three ultrasonic real-time scanners simultaneously in 30 normal pregnant women between 20 and 40 weeks of gestation and analyzed developmental changes in behavioral pattern focussing the attention on the characteristics of REM and non-REM sleep and wakeful state. The frequency of REM significantly increased with gestational age, and its occurrences formed a group in late pregnancy. REM and non-REM periods, which were defined as the phase with uninterrupted appearance of rapid eye movements and the phase without them over 3 min, respectively, became clearly distinguishable between 28 and 31 weeks of gestation. The correlation between the occurrence of rapid eye movements and breathing movements was high after 27 weeks. These results demonstrate the course of the development of sleep-wakefulness cycle in the human fetus.

Development of Artificial Placenta: Oxygen Metabolism of Isolated Goat Fetuses with Umbilical Arteriovenous Extracorporeal Membrane Oxygenation

To assess the oxygen utilization of extrauterine goat fetuses with arteriovenous extracorporeal membrane oxygenation via umbilical vessels, oxygen delivery (OD) and oxygen consumption (OC) were investigated in 19 long-term incubations (incubation periods 58-236 h). The OCs did not change (6.4 +/- 1.3 ml/min/kg, mean +/- SD, n = 227) when the ODs were more than 10 ml/min/kg, but were significantly suppressed when the ODs were less than 10 ml/min/kg. It was suggested that the oxygen metabolism of extrauterine goat fetuses is equivalent to that of fetuses in utero.

Automated Fetal Breathing Movement Detection from Infernal Small Displacement Measurement - Die automatische Ermittlung fötaler Atembewegungen durch die Messung kleiner interner Verschiebungen

We have previously proposed a method to measure small displacements of internal tissue which is based on an ultrasonic pulsed Doppler technique. The Doppler frequency shift of the ultrasonic waves due to the tissue movement is detected using a modified quadrature detector, and the displacement of the internal tissue is estimated by using an arctangent method. Based on the algorithm, we have constructed a quantitative monitoring system for fetal breathing movement. The fetal breathing movement is a rhythmic movement of the fetal diaphragm and it is recorded as a nearly sinusoidal displacement with a repetition frequency from 0.5 Hz to 2 Hz. In this paper, an automated fetal breathing movement 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 detection.

Internal tissue displacement measurement based on ultrasonic wave Doppler signal digital detection and its application to fetal movement monitoring

We have developed a fetal movement monitoring system based on small displacement measurement of internal tissues. When ultrasonic pulses are transmitted to the fetus, the reflected ultrasonic waves which have a Doppler frequency shift due to the fetal movements are detected by using an ultrasonic pulsed Doppler technique. In this paper, we propose a displacement measurement method for internal tissues which is based on the Doppler signal digital detection technique. In the method, the received ultrasonic RF signals are sampled with a sampling frequency of four times higher than the centre frequency of the ultrasonic waves; the Doppler frequency shift signals are derived using digital signal processing. From the detected signals, the internal displacements are estimated using the arc-tangent method. The basic algorithm of the detection method has already been used in the area of blood flow sensing, however, we apply the algorithm to the displacement measurement of internal tissues. The comparison between the proposed method and the conventional method is presented. The fetal movement quantitative monitoring system based on the method which has been constructed is shown.

Computer-assisted analysis of fetal behavior in fetal abnormalities.

Fetal behavior was studied in 17 cases of fetal abnormalities including nonimmune hydrops fetalis and in 11 cases of intrauterine growth retardation (IUGR) in comparison to 30 healthy fetuses. Breathing movements, rapid eye movements and trunk movements were observed ultrasonically and analyzed using a computer-assisted system. The cases with central nervous system anomalies showed a markedly different behavioral pattern. In the fetal abnormalities without chromosomal anomalies, the cases without major behavioral disorders were cured by neonatal treatment. IUGR cases with decreased trunk, breathing and REM period were finally diagnosed as having fetal distress by fetal heart rate monitoring. The findings on fetal behavior hint at the possibility of diagnosing abnormalities in neural development as well as in well-being.