SQUID-based instrumentation for ultralow-field MRI
Abstract
Magnetic resonance imaging at ultralow fields (ULF MRI) is a promising new imaging method that uses SQUID sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at a microtesla-range measurement field. In this work, a seven-channel SQUID system designed for simultaneous 3D ULF MRI and magnetoencephalography (MEG) is described. The system includes seven second-order SQUID gradiometers characterized by magnetic field resolutions of 1.2-2.8 fT Hz-1/2. It is also equipped with five sets of coils for 3D Fourier imaging with pre-polarization. Essential technical details of the design are discussed. The system's ULF MRI performance is demonstrated by multi-channel 3D images of a preserved sheep brain acquired at 46 µT measurement field with pre-polarization at 40 mT. The imaging resolution is 2.5 mm × 2.5 mm × 5 mm. The ULF MRI images are compared to images of the same brain acquired using conventional high-field MRI. Different ways to improve imaging SNR are discussed.
- Publication:
-
Superconductor Science Technology
- Pub Date:
- November 2007
- DOI:
- arXiv:
- arXiv:0705.0661
- Bibcode:
- 2007SuScT..20S.367Z
- Keywords:
-
- Physics - Medical Physics;
- Physics - Instrumentation and Detectors
- E-Print:
- To appear in Proceedings of 11th International Superconductive Electronics Conference (ISEC 2007)