A Novel Matching Strategy to Increase Power Efficiency of the Travelling Wave MR Imaging

Anna Andreychenko¹, Hugo Kroeze², Dennis W. Klomp², Jan J. Lagendijk¹, Peter Luijten², Cornelius A.T. van den Berg¹

Travelling wave MR imaging exploits the RF shield of the scanner as a waveguide. When a patient is placed in the bore a strong impedance mismatch occurs between the hollow (where antenna is located) and loaded parts of the bore. It causes wave reflection and inefficient power is transferred to the target region. To avoid this impedance mismatch we propose to insert a quarter-wavelength coaxial waveguide between the antenna and load which gradually transforms impedance of the antenna to the load impedance. The effectiveness of this inset has been demonstrated both in the simulations and in-vivo experiments.