A noninvasive non-ionizing technique for three-dimensional quantitative measurement of intra-abdominal and peripheral body fat is proposed. The technique utilizes the sharp contrast of dielectric permittivity between fat and other tissues. It employs 1-2 GHz microwaves as probing radiation and employs a Fourier transform algorithm to reconstruct three-dimensional profile of dielectric permittivity of a target from near-field or Fraunhoffer scattering data measured by an array of small antennas. Three- dimensional imaging is achieved by scanning any pair or some combination of the three parameters, viz., incident direction, scattering angle, and microwave frequency. The target and the antenna array are buffered in a layer of dielectric fluid to improve impedance matching, reduce scattering strength, and contract the microwave wavelength. For a water buffered system with 2 GHz microwave frequency, the image can differentiate dielectric permittivity up to +0.01, and yield a resolution up to 2 mm in all three dimensions. While there exist many noninvasive interrogation devices, direct three-dimensional imaging of dielectric permittivity is currently unavailable. The research is expected to lead to development of a low-cost and transportable dielectric imaging system for non-invasive quantitative measurement of body fat and other diagnostic applications.
