High Temperature Superconducting RF Coil on 3T MRI System: Animal Platform Development and Applications
Date Issued
2007
Date
2007
Author(s)
Chen, Kai-Yuan
DOI
en-US
Abstract
Signal-to-noise ratio (SNR) is a critical factor to image quality of Magnetic Resonance Imaging (MRI). To boost SNR, cryogenic radio-frequency (RF) coils using high-temperature superconducting (HTS) material can be used to reduce the noise from coil resistance. In our previous studies, using human HTS RF coil system with diameter of 7 cm at critical temperature can achieve 2.6 times SNR gain compared with conventional copper coil at room temperature. For animal HTS RF coil system with diameter of 4 cm, SNR can be achieved 3.8 times higher. However, owing to the limitation of cryostat design and thermal insulation, in-vivo animal studies have not been completely established. Therefore, the goal of this study was to build a HTS RF coil platform for in-vivo rat experiments and verification study of the capability was performed.
In this study, cooling the coils was accomplished with liquid nitrogen immersion. The cryostat was fabricated using glass material with vacuum layer for thermal insulation, which was approximately 20-mm thick. An animal holder was used for rat experiments, including anesthesia transportation system and warming bed to preserve the physiological condition of rats. To verify the capability, the experiments of phantom and rat brain were performed. Compared with HTS coil, a comparable copper coil was used with the same configuration. To implement on in-vivo experiment, dynamic contrast-enhanced (DCE) MRI on mice kidney was studied.
In results, the SNR gain of saline phantom was 3 folds higher using HTS coil and in anatomical image comparison of rat brain, 3.5-fold SNR gain was achieved. Consistent with previous studies, SNR gain in the same level was accomplished. Furthermore, improved SNR can be translated to increase the spatial resolution of MR images, which was verified in the high-resolution imaging study with 65x 84 μm2 in-plane resolution. The feasibility of the HTS coil platform was verified in DCE experiments, which was used to observe the metabolism of mice kidney by Gd-DTPA injection. Coronal sections of mice kidney were acquired to evaluate the SNR gain over the kidney and temporal change of signal intensity. For anatomical images of kidney, SNR gain was 3.2 folds higher of using HTS coil, and similarly, for DCE images, the average SNR gain was 3 folds.
In this study, we successfully developed a HTS RF coil platform for in-vivo rat experiment and demonstrated its capability of improving SNR and sensitivity to DCE change. With higher SNR, better temporal and spatial resolutions can be achieved to gain more insights to pathophysiological changes of tissues. The future works of our study are to optimize the HTS coil platform and implementation on various applications, including high-resolution imaging, fiber tracking of diffusion imaging and molecular imaging.
Subjects
磁振造影
射頻線圈
DCE MR Imaging
MRI
RF coil
High Temperature Superconductor
Type
thesis
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