NMR and MRI apparatus and method

US7187169B2 · kind B2 · utility

Assignee

• The Regents of the University of California · US

Inventors

• John M. Clarke · Dunlap, US
• Nathan Kelso · Albany, US
• SeungKyun Lee · Berkeley, US
• Michael Moessle · Berkeley, US
• Whittier Myers · Berkeley, US
• Robert McDermott · Lompoc, US
• Bernard ten Haken · Delden, NL
• Alexander Pines · Berkeley, US
• Andreas Trabesinger · Zürich, CH

Key dates

• Filing date: Nov 3, 2004
• Grant date: Mar 6, 2007
• Expiry date: Feb 13, 2025

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/326
• 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 dc 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. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. 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.