High-Resolution Implantable Microcoil Antennas for Blood-Vessel Imaging in High-Field MRIs

Abstract

This article presents rectangular and circular intravascular receive-only (Rx) open interior microcoils (MCs) for blood-vessel and brain-aneurysm imaging with two different magnetic resonance imaging (MRI) frequencies (128 and 298 MHz for field strengths 3 and 7 T, respectively). The proposed Rx MCs have a miniature volume of 4.92 mm(3). They offer a wider bandwidth, homogenous radio frequency (RF) receptivity, a high signal-to-noise ratio, and better vessel imaging than that offered by state-of-the-art MCs. In addition, they have open interiors that enable uninterrupted blood flow during MRI scanning and reduce motion artifacts. The proposed MCs were used to mimic different blood vessels of the brain, heart, neck, and kidneys in a realistic human voxel-based Duke model. We compared the reception efficiency (R-x,R-eff) and the sum of B-1(-) strengths (i.e., Sigma B-1(-)) in the region of interest (ROI) for the combined approach involving the birdcage (BC)/surface coil and the MC for various coil arrangements. The proposed MCs were fabricated and integrated with the 3-D-printed blood-vessel model. The simulation results indicate that the proposed MCs achieved the improvements of 72% and 75% in Sigma B-1(-) and R-x,R-eff, respectively, in the selected ROI (the blood vessel). Moreover, the MR images obtained by the proposed MCs exhibited high sensitivity of the blood signal and offered selective imaging of the arterial walls. According to the results, the proposed Rx MCs can be applied to perform intravascular imaging of smaller blood vessels.