Design, evaluation and comparison of endorectal coils for hybrid MR-PET imaging of the prostate

Abstract

Prostate cancer is one of the most common cancers among men and its early detection is critical for its successful treatment. The use of multimodal imaging, such as MR-PET, is most advantageous as it is able to provide detailed information about the prostate. However, as the human prostate is flexible and can move into different positions under external conditions, it is important to localise the focused region-of-interest using both MRI and PET under identical circumstances. In this work, we designed five commonly used linear and quadrature radiofrequency surface coils suitable for hybrid MR-PET use in endorectal applications. Due to the endorectal design and the shielded PET insert, the outer face of the coils investigated was curved and the region to be imaged was outside the volume of the coil. The tilting angles of the coils were varied with respect to the main magnetic field direction. This was done to approximate the various positions from which the prostate could be imaged. The transmit efficiencies and safety excitation efficiencies from simulations, together with the signal-to-noise ratios from the MR images were calculated and analysed. Overall, it was found that the overlapped loops driven in quadrature were superior to the other types of coils we tested. In order to determine the effect of the different coil designs on PET, transmission scans were carried out, and it was observed that the differences between attenuation maps with and without the coils were negligible. The findings of this work can provide useful guidance for the integration of such coil designs into MR-PET hybrid systems in the future.

Project-Oriented RF Coil Comparison and Optimization for Preclinical, Single-Voxel MR Spectroscopy of the Rat Visual Cortex at 9.4 T

“…In general, a coil benchmarking may have to be carried out when a coil is newly developed [53], [54], [55] or when the performance of a double-tuned or MR-PET hybrid coil is compared against its counterpart single-tuned or singlemodality coil [56], [57]. In this study, we built three coils with different coil types and geometries, and each coil was built to focus on the coverage of a different target.…”

Magnetostatic Simulation and Design of Novel Radiofrequency Coils Based on Transverse Field Current Elements for Magnetic Resonance Applications

“…Differently shaped surface RF coils have been designed over the years for improving the MR SNR performance or the ROI localization, even exploiting the B 1 field parallel to the coil plane [3]. Although few works in the literature are focused on exploiting the transverse components of the B 1 field of loop RF coils [4,5], more are dedicated to different surface coil topologies, in particular the so-called Butterfly Coil (BC) and Figure-of-eight Coil (FC). Their design has two central straight current elements producing a B 1 field that, in the ROI Sensors 2024, 24, 237 2 of 16 located close to the RF coil axis, has a direction orthogonal to that axis and parallel to the coil plane [6].…”