SQUID detected NMR and MRI at ultralow fields

US6885192B2 · kind B2 · utility

Assignee

• The Regents of the University of California · US

Inventors

• John M. Clarke · Dunlap, US
• Robert McDermott · Lompoc, US
• Alexander Pines · Berkeley, US
• Andreas Trabesinger · Zürich, CH

Key dates

• Filing date: Feb 6, 2003
• Grant date: Apr 26, 2005
• Expiry date: Feb 6, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/445
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned de superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.