A Novel open-ended intravascular MRI loop probe

Recently, intravascular catheter probes have been developed to increase SNR for MR imaging of coronary arteries. Miniaturization of these catheter probes without degrading their performances is very essential in imaging small arteries. Since both signal and noise received by intravascular loop probes are of low level, the noise generated by the cable connecting the probe to the matching circuit may reduce SNR significantly. Therefore, the tuning and matching circuit must be placed very close to the loop probe, which restricts its miniaturization and flexibility. We propose a novel open-ended loop probe for 64 MHz with an input impedance of 20 Ohm and a length of only 4 cm in the bare case. This has two advantages. Firstly, the matching and tuning circuits of the proposed probe can be located outside the vessel. Secondly, its signal level and uniformity is superior to that of the conventional loop antennas.