Development of low-cost optically pumped magnetometer system for fetal applications

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Abstract Currently, we can record non-invasive fetal magnetocardiographic (FMCG) signals with a magnetic sensor- based system called SARA (SQUID Array for Reproductive Assessment) installed at University of Arkansas for Medical Sciences. The study of the fetal heart, and in particular, the developing cardiac conduction system, has been significantly aided in the last two decades by the introduction of FMCG. The American Heart Association recently acknowledged the academic and clinic usefulness of this new modality. Several studies have shown that FMCG can provide new relevant clinical parameters for assessment of fetal cardiac activity and also supplement the parameters that are currently available. Despite all these benefits, the major hurdles facing SQUID technology include system and maintenance cost, cryogenic helium cooling, a rigid one-size-fits-all array, and a single position option for the mother. We have shown the feasibility of using uncooled biomagnetometer for potential prenatal assessments based on microfabricated optically-pumped magnetometers (OPM). The OPMs have many features similar to cryogenic SQUID-based systems as they measure the same field components, and are compatible with standard magnetically-shielded rooms. This proposal is in response to NIBIB’s PAR-19-158 Bioengineering Research Grants, where we apply a multidisciplinary integrative team approach to we plan to design, test and validate a 24-channel OPM sensor system that fits over the maternal abdomen. Performance of the OPM in a three-layered shielded room will be evaluated with respect to the data quality of FMCG signals which will be compared to those obtained from a gold standard SQUID based system. The overall goal is to demonstrate that with OPM systems (a) we can design a stand-alone flexible array for maternal-fetal application (b) record the desired biomagnetic signals equivalent to SQUID sensors; (c) be able to separate the signal into their constituents to extract FMCG and (d) quantify fetal heart signals and the relevant metrics. We believe that with potential lower costs and maintenance requirements, the benefits of using fetal biomagnetometery could be translated from the research to possible widespread clinical applications. The specific aims are as follows: Aim 1: Design and configure a bed-based stand-alone array of OPMs that conforms to the shape of the maternal abdomen in order to obtain signals with sufficient signal-to-noise ratio for fetal applications. Aim 2: Extract and quantify the FMCG waveform components to compute a) PQRS and T wave detection rates and cardiac time intervals (CTI). Aim 3: Record and characterize FMCG of fetuses that have been referred with abnormal heart conditions detected through routine ultrasound examination.