Small‐animal, whole‐body imaging with metamaterial‐inspired RF coil

Abstract

Particular applications in preclinical magnetic resonance imaging require the entire body of an animal to be imaged with sufficient quality. This is usually performed by combining regions scanned with small coils with high sensitivity or long scans using large coils with low sensitivity. Here, a metamaterial-inspired design employing a parallel array of wires operating on the principle of eigenmode hybridization was used to produce a small-animal imaging coil. The coil field distribution responsible for the coil field of view and sensitivity was simulated in an electromagnetic simulation package and the coil geometrical parameters were optimized for whole-body imaging. A prototype coil was then manufactured and assembled using brass telescopic tubes with copper plates as distributed capacitance. Its field distribution was measured experimentally using the B mapping technique and was found to be in close correspondence with the simulated results. The coil field distribution was found to be suitable for large field of view small-animal imaging and the coil image quality was compared with a commercially available coil by whole-body scanning of living mice. Signal-to-noise measurements in living mice showed higher values than those of a commercially available coil with large receptive fields, and rivalled the performance of small receptive field and high-sensitivity coils. The coil was deemed to be suitable for some whole-body, small-animal preclinical applications.

Hardware Considerations for Preclinical Magnetic Resonance of the Kidney

“…State-of-the-art small-animal MRI systems are usually equipped with 4-16 Rx channels, to which custom-tailored RF coils may be connected. Less popular are metamaterial-inspired RF coils, which have been developed for superficial tissue imaging in order to provide the best compromise of high SNR over a large FOV, while using only one receive channel [34].…”

Adaptive Cylindrical Wireless Metasurfaces in Clinical Magnetic Resonance Imaging

“…The first involves planar metasurfaces, such as Swiss-roll arrays, [11] split-ring arrays with negative magnetic permeability, [12,13] and metallic wire arrays. [14][15][16][17][18][19][20] However, these configurations perform poorly in terms of the magnetic field uniformity, especially in the direction perpendicular to the metasurfaces. The inhomogeneous distribution of the radio frequency (RF) magnetic field changes the image contrast, reduces image uniformity, increases artifacts, and even results in incorrect diagnoses.…”

“…Some studies have investigated the application of metasurfaces in MRI systems. [11][12][13][14][15][16][17][18][19][20][21][22][23] They can be divided into two types in terms of their configurations. The first involves planar metasurfaces, such as Swiss-roll arrays, [11] split-ring arrays with negative magnetic permeability, [12,13] and metallic wire arrays.…”

Four-Mode Programmable Metamaterial Using Ternary Foldable Origami

“…Since the first experimental demonstration in 2000, metamaterials have become an attractive and important research area not only because they exhibit many extraordinary physical properties but also due to their broad applicability, particularly in physics and engineering fields. The requirements of modern scientific and technological developments have stretched metamaterial research from meghertz to visible ranges, − across many application fields including energy, − healthcare, − engineering, , environment, , and mechanics. − However, a common restriction in all these metamaterials is that each functionality requires a distinct structure, making each metamaterial suitable only for a specific task and limiting its applications. Currently, programmable metamaterials have long been a wide-ranging research topic of interest for scientists and engineers due to the controllability of their EM or mechanical behaviors and functionalities.…”