A New Intravascular Loopless Monopole Antenna (ILMA) for MR Imaging

In recent years, intravascular MR coil, which utilizes a special coil placed neighboring to the target artery, has been proposed to improve the local signal-to-noise ratio (SNR) and spatial resolution of vessel wall images. Especially the intravascular coil has identified its advantage in detecting atherosclerotic plaques [1]. At present, there are two types of intravascular MRI receivers: loop coil and loopless antennae [2]. The intravascular MR detectors mentioned in previous report are usually rigid and bulky, therefore are difficult to be inserted into small diseased vessels. Also the corresponding signal sensitivity of those small-loop coils falls off very rapidly. In this study, a novel long intravascular loopless monopole antenna (ILMA) design with a thin, non-shielded flexible guide-wire is presented. The guide-wire of ILMA, which was made of a flexible copper wire instead of conventional coaxial-cable, allowed a thinner volume to be applied into small vessels and enabled an enhanced longitudinal coverage. In vitro and in vivo test were carried out to assess the feasibility of the ILMA, including SNR, spatial resolution, and longitudinal coverage.