I-Corps: Acousto-optical RF Field Sensor for Magnetic Resonance Imaging

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is to improve the safety of magnetic resonance imaging (MRI) procedures by sensing the radio frequency (RF) signals during interventional and diagnostic procedures. During interventional procedures, especially critical for children who cannot be imaged using X-rays, this sensor provides the location and orientation of devices, such as catheters, inside the patient's body to guide the physicians. Since an acousto-optical sensor is used, this information transfer is achieved with no adverse effects, such as RF heating. During diagnostic procedures, the sensor can help quantify the RF field exposure of the patient in real-time, preventing excessive tissue heating. Furthermore, it may enable imaging of patients with medical implants who are not currently imaged by MRI due to safety concerns. As a commercial product, the sensor will potentially decrease the costs for all the stake-holders within the health industry (hospitals, insurance companies, governmental institutions, etc.) while decreasing the risk to the patients and improving health outcomes. This I-Corps project is based on a radio frequency (RF) safe acousto-optical sensor to locally measure the RF field in magnetic resonance imaging (MRI) which in turn provides the signals to track the interventional devices like catheters and needles during interventional procedures under MRI as well as to measure RF energy exposure of the patient. The main safety concern with MRI is RF heating due to metal cables required to carry the signal from an antenna to the outside system. The solution here is replacing all the metal cables with optical glass fiber, which eliminates the RF heating. To convert the RF signal into optical modulation, a compact acousto-optic sensor is used as an intermediate medium between the antenna and the optical fiber. This is achieved by exciting a piezoelectric transducer on an optical fiber with the RF signal generated by miniature MRI coils and antennas which in turn generates acoustic waves in the optical fiber. Since the signal is generated and transmitted over an optical fiber to the MRI system without any conductors, this eliminates the RF heating safety issue. The sensor prototype has been successfully bench tested and proof of principle for interventional procedures has been demonstrated. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.