Performance of a miniature high‐temperature superconducting (HTS) surface coil for in vivo microimaging of the mouse in a standard 1.5T clinical whole‐body scanner

Abstract

The performance of a 12-mm high-temperature superconducting (HTS) surface coil for in vivo microimaging of mice in a standard 1.5T clinical whole-body scanner was investigated. Systematic evaluation of MR image quality was conducted on saline phantoms with various conductivities to derive the sensitivity improvement brought by the HTS coil compared with a similar room-temperature copper coil. The observed signal-tonoise ratio (SNR) was correlated to the loaded quality factor of the radio frequency (RF) coils and is theoretically validated with respect to the noise contribution of the MR acquisition channel. The expected in vivo SNR gain was then extrapolated for different anatomical sites by monitoring the quality factor in situ during animal imaging experiments. Typical SNR gains of 9.8, 9.8, 5.4, and 11.6 were found for brain, knee, back, and subcutaneous implanted tumors, respectively, over a series of mice.

A Novel Receive-Only Liquid Nitrogen ($\hbox{LN}_{2}$ )-Cooled RF Coil for High-Resolution In Vivo Imaging on a 3-Tesla Whole-Body Scanner

“…The construction used here is simple and effective and merely serves as proof of principle. In future cryostats with better thermal performance and with a reasonable material strength can be constructed by using ceramic material [1]. Such designs would allow greater proximity of the coil to the tissue, important for very small coils.…”

“…With the development of high field MRI, there is an increasing interest in and demand for investigating physiological and pathological models of small rodents on high field whole body MR scanners widely available in clinics [1].…”

“…A 1.2 cm high temperature superconducting (HTS) coil has been utilised in mouse image on a 1.5 T whole body scanner [1].…”

“…This design creates difficulties of constructing suitable platforms for in-vivo samples, plus positioning and handling these samples with flexibility, and monitoring their physiological condition with ease. Thirdly, since most cryogenic probe-heads are designed as small surface coils with radii ≤ 2 cm [10], it is desirable to employ another transmitter to provide a homogenous B 1 field and achieve the designed flip angle while utilizing the cryogenic coil as a highly sensitive receiver [1], [7]. Finally, up-to now, cryogenic probes have been only accessible to a few research groups due to the complexity of instrumentation.…”

Realization of Flexible NMR Microcoils

“…In order to increase SNR in NMR application, there are essentially three methods: either by increasing the intensity of the static magnetic field, or by cooling the micro-coils [3] or also by reducing the size of the NMR sensors [4].…”