Ultrasonic tissue characterization of fetal lung, liver, and placenta for the purpose of assessing fetal maturity.

The purpose of this research effort was to establish a physical basis for the development of an accurate noninvasive technique to differentiate between mature and immature fetal tissues, particularly the lung and placenta. The research utilized RF waveform analysis via a microcomputer-based digital processing system interfaced directly to a standard real-time clinical diagnostic ultrasound instrument. Differences between the frequency spectra of the RF waveforms for mature and immature fetal tissues could be demonstrated in accordance with proposed tissue models.