23Na MRI on 0,5T clinical scanner

Abstract

Object. The purpose of this work is to reveal the possibilities of low-field 23Na MRI. It was supposed to obtain images of various human organs using the 3D-scanning method, and to do this with minimal hardware modifications of a typical clinical 0,5T scanner. Materials and methods. The proprietary receiving coils, originally intended for registering proton signals (21,1 MHz), were transformed to transceiver ones and tuned to the sodium Larmor frequency of 5,6 MHz. The scanning was carried out by the 3D-gradient echo method with the parameters: TR/TE=44,7/12 ms, FA=45° and isotropic resolution of 6 mm. To increase SNR, apodization in k-space was applied during data processing. Results. 23Na MRI (including volumetric reconstructions) of several human organs – head, breast, heart, joints were obtained with SNR up to 15. Discussion. When developing low-field 23Na MRI, it is advisable to focus on recording only the T2long component (>15 ms). In this case, it is possible to narrow the receiver bandwidth as much as possible and thereby minimize noise. In addition, the requirements for the transmission path are reduced. As a result, for debugging MRI methods, the equipment of a typical clinical scanner, which is supplemented by coils tuned to the sodium NMR frequency only, can be used.