Program Information
Measuring Infant Body Composition Using An RF Resonant Cavity Perturbation Technique
L Kotowski1*, J Shepherd2 , B Fan, 2 , (1) ,,,(2) UC San Francisco, San Francisco, CA
Presentations
WE-RAM1-GePD-I-4 (Wednesday, August 2, 2017) 9:30 AM - 10:00 AM Room: Imaging ePoster Lounge
Purpose: Infant body composition is an important measure of immediate and lifelong health. This research proposes to use resonant cavity perturbation as a cost effective method for determining an infant’s body composition.
Methods: A screened enclosure of dimensions 1.5m×1.0m×0.4m acts as an RF resonant cavity designed to resonate at 173.5MHz, a frequency which the permittivity of tissues is correlated to their moisture content. The system was tested using a vector network analyzer to measure the transverse electric mode inside the cavity. A mathematical model was created which showed the relationship between the size, shape, and composition of a sample and the shifts in resonant properties. The shift in resonant properties correlates to the average composition of the phantoms, and characteristic curves for each composition can be used to determine the dielectric constant of the sample
Results: The resonant frequency of the cavity was found to be 173.73±0.48 MHz and was stable over the 6 month experimental period. Ambient humidity changes did not effect the resonant frequency over a ranges of X to Y. There was some dependence of temperature on resonance (r_temperature=0.4 over range of X to Y). Percent fat was estimated from measured shifts in resonant frequency to be (99.7±2.1)% for pure lard phantoms and (0.1±0.3)% for pure water phantoms. The relation between known and estimated fat mass was Pfat_known=0.9783Pfat_calculated+1.4764. The precision of calculated fat mass was found to have an RMSE of 1.37 g.
Conclusion: The resonant cavity perturbation technique was found to be a reliable and reproducible way to measure fat mass values in the range found for small infants. This cost-effective technology may be a novel and accessible method to accurately assess infant body composition, and is especially suitable for low-resource settings.
Funding Support, Disclosures, and Conflict of Interest: This research was funded using a Radiology seed grant from the University of California, San Francisco.
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