Design and realization of data acquisition system for MAET-MI inside strong magnetic field of an MR scanner

Date

2025-2

Author

Tetik, Ahmet Önder

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Magneto-acousto-electrical tomography with magnetic field measurement (MAET-MI) is a hybrid imaging technique that leverages ultrasound imaging’s high spatial resolution to map soft tissue conductivity. In this method, an ultrasound transducer generates pressure waves inside the body, causing conductive tissues to vibrate in a static magnetic field, which induces currents detected by receiver coils. This study aims to obtain conductivity images of the lowest values reported in the literature and develop an experimental setup to achieve this. High-quality factor circular coils were designed to enhance the signal-to-noise ratio (SNR), and the effect of coil quality factor on imaging performance was analyzed. This research presents a practical method for estimating the coil’s transfer function. The point spread function (PSF) was characterized for MAET-MI for the first time in literature, and the lateral resolution of sector scan conductivity images was enhanced through two-dimensional (2D) deconvolution with the PSF. A figure-of-eight coil was recommended alongside a circular coil for broader imaging coverage. In numerical studies, the rotational image of the simplified breast model was obtained. Experiments were conducted at the METU Medical Imaging Research Lab and UMRAM using a magnetic field generator and an MR device. With the help of the MR device, a conductivity interface image was successfully reconstructed from a phantom consisting of a Delrin block and a saline solution with a conductivity of 7.95 S/m. A conductivity interface image was obtained from the phantom having the lowest conductivity value in the literature of MAET-MI imaging method.

Subject Keywords

Magneto-Acousto-Electrical Tomography, MAET, Circular coil, Wiener filter, Delay-and-sum method, Ultrasound imaging

URI

https://hdl.handle.net/11511/113771

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Graduate School of Natural and Applied Sciences, Thesis