Title:  Acusto-optic Sensing for Safe MRI Procedures

Committee: 

Dr. Degertekin, Advisor

Dr. Adibi, Chair

Dr. Oshinski

Abstract:

The objective of the proposed research is to develop optical fiber based acousto-optic sensors for safe MRI procedures. RF induced heating is a concern for most MRI procedures: diagnostic imaging, implants and interventional procedures.  Naturally measuring the RF field with high SNR without image distortion and additional RF heating is key for evaluating MRI safety. Coil antennas have been used for measurement of RF fields. However, use of long conductor cables to carry the signal out of the MRI system causes RF induced heating. In this work, an acousto-optic sensor coupled with a coil antenna is developed to replace the conductor cables with optical fiber. In the proposed sensor, a piezoelectric transducer is electrically connected to a miniature coil and mechanically connected to a fiber Bragg grating (FBG). Local MR signal received by the coil is converted to elastic waves by the piezoelectric transducer. Elastic waves changes the grating geometry, thus the reflected light from FBG is modulated. So far, the FBG is modeled, characterized and a proof of concept prototype is built. RF signal detection and visibility of the sensor is demonstrated under a clinical MRI system. As part of the proposed work, an end-to-end model will be developed and used for the design of an optimized sensor. Different coil designs will be investigated for different applications. Lastly, MRI compatibility, visibility and safety of the sensor in phantom and animals will be performed.