Magnetic field distribution of birdcage coil for 4 T MRI system with no lumped circuit elements

Recently, Magnetic Resonance Imaging (MRI) system which operates up to under 3 T is being used in clinical practice in Japan. In order to achieve the requirement of obtaining more high-quality images and short imaging time, devices utilize high magnetic field (>3 T) and high power electromagnetic (EM) wave pulses has been developed. The rise of the static magnetic field is proportional to the increase of the EM wave frequency which brings down issues of variation in capacitance used in the radio frequency (RF) coil for MRI system. In addition, increasing power causes problems of withstanding voltage and these approach leads to generation of non-uniform magnetic field inside the RF coil. Hence, if we can develop the birdcage coil for MRI system with no lumped circuit elements, it is extremely useful. In this paper, birdcage coil without the use of lumped circuit elements for 4 T MRI system was proposed and its magnetic field distribution was investigated. As a result, it was confirmed that the proposed birdcage coil has equivalent performances of the conventional birdcage coil which includes several capacitors.