Intravascular magnetic resonance imaging using a loopless catheter antenna.

Recently, intravascular catheter probes have been developed to increase signal-to-noise ratio (SNR) for MR imaging of blood vessels. Miniaturization of these catheter probes without degrading their performances is very critical in imaging small vessels such as coronary arteries. Catheter coils have a loop incorporated in their structure and have limitations in physical dimensions and electromagnetic properties. The use of a loopless intravascular catheter antenna is proposed to overcome these problems. The catheter antenna is essentially a dipole, which makes a very thin diameter possible, and its electronic circuitry can be placed outside the blood vessels without performance degradation. The theoretical foundation for the design and operation of the catheter antenna is presented. Several catheter antennae, as small as 1.5 French, were constructed and tested on phantoms and rabbits with great success. The catheter antenna has a simple structure and is easy to design, implement, and operate.