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News Release

July 3, 1997

Team Develops Non-invasive Procedure for Examining Fetal Heart

- SQUID-based method of separating signals of fetus and mother will enable pre-birth diagnosis -

A team of scientists from the Institute of Clinical Medicine, University of Tsukuba and Hitachi, Ltd. has developed a procedure for non-invasively examining the heart of a fetus. By using superconducting quantum interference devices (SQUIDs) to measure the minute magnetic fields generated by the heart, the team, headed by Professor T. Mitsui, was able to distinguish between the magnetic signals generated by the fetal heart and the mother's heart. The new procedure will make it possible to diagnose fetal heart conditions by means of an examination that takes just a few minutes to complete.

The SQUIDs were developed by the Superconducting Sensor Laboratory, one of the founders of the Japan Key Technology Center.

At present, the most common way of diagnosing fetal heart ailments is through an ultrasound examination. While ultrasound can reveal the shape of the heart and provide some information about the working of the heart and blood flow, it is unable to provide the type of electrophysiological information directly related to cardiac activity that is furnished by an electrocardiogram or magnetocardiogram. Attempts have been made to obtain electrocardiograms from the fetal heart using electrodes placed on the mother's abdomen. However, the electrical fields emitted by the fetal heart are so minute that it is difficult to separate them from the electrical signals generated by the mother's heart.

Using a SQUID-based sensor enables the weak magnetic fields generated by the fetal heart to be measured by placing the sensor on the mother's abdomen. Measurements obtained with this method are virtually unaffected by the amniotic fluid or fetal fat, making it possible to obtain signals with a higher resolution than an electrocardiogram.

A new sensor was developed that reduces the influence of the mother's myocardial magnetic field on the measurements and makes it possible to accurately measure the cardiac magnetic field of the fetus. The fetus's heart is normally about 6 cm from the surface of the mother's abdomen, so the new sensor was developed with a high sensitivity that, compared to a conventional sensor, gives it more sensitivity at a deeper depth. The new procedure can also be used to perform separate measurements on twins.

Fetal electrocardiograms can be obtained as early as the twentieth week of pregnancy. Thus, the new procedure should make possible the early detection of fetal cardiac ailments, and thereby facilitate treatment of the condition, either before or immediately after birth.

Results obtained with the new technology will be announced at the 33rd meeting of the Japan Infant Circulatory System Society to be held starting July 10 in Kyoto.

- Notes -
SQUID (superconducting quantum interference device):
A magnetic sensor that utilizes superconductivity to produce a response to extremely weak magnetic fields. For this research, a high-reliability, high-sensitivity low-Tc SQUID was utilized that operates at liquid-helium temperatures.

Superconducting Sensor Laboratory:
Jointly set up by ten enterprises between 1990 and 1996 under the auspices of the Japan Key Technology Center to develop advanced systems for measuring biological magnetism.

WRITTEN BY Secretary's Office
All Rights Reserved, Copyright (C) 1997, Hitachi, Ltd.