MSE Seminar: Novel Hardware to Enable Safe and Efficient RF Parallel Transmission...
Speaker: Natalia Gudino, Ph.D., Staff Scientist, Neurological Disorders and Stroke at the National Institute of Health (NIH)
Title: Novel Hardware to Enable Safe and Efficient RF Parallel Transmission in Ultra-High Field MRI
Ultra-high field MRI of the brain yields increased contrast, sensitivity, and resolution. Unfortunately, wavelength effects at high fields compromise the homogeneity of the MRI excitation magnetic field (B1), decreasing image quality. It has been shown that a multiple-channel transmitter, or parallel transmission (pTx) system, can be successfully used to shim the B1 field. Today, the majority of pTx systems are built by replicating the conventional radiofrequency (RF) transmit chain built with remote amplifiers. This approach presents critical limitations, such as increased scanner time to perform subject-specific adjustments of the hardware for safe RF transmission. Dr. Gudino’s research demonstrates that by rethinking the RF power amplifier, one can drastically change the transmit chain and obtain a more efficient, compact and low-cost implementation of pTx systems. On-coil current-source RF amplification, allows replacing lossy coaxial cables by optical fibers, and removing matching and tuning networks from the transmit chain. Furthermore, the direct connection between the amplifier and the MRI coil allows real-time monitoring and feedback of the RF current (and B1) by additional electronics on the amplifier board. In a pTx setup, accurate amplitude and phase control of the current in the individual coils is necessary to ensure performance and safety. This new technology will facilitate the implementation of pTx systems enabling advances in ultra-high field clinical MRI.
Natalia Gudino received an electrical engineering degree from the National University of Rosario, Argentina, and a Ph.D. in biomedical engineering from Case Western Reserve University, Cleveland, Ohio. She is currently a Staff Scientist at the MRI Engineering Core of the Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH in Bethesda. Throughout her career Gudino has worked on designing and implementing digital and analog electronics to improve and reduce the cost of biomedical devices. Her current research focuses on the design and development of new technologies for radiofrequency transmission and reception to improve brain imaging at ultra-high field MRI (7T and above).