# US 7,466,132 B2 · Squid detected NMR and MRI at ultralow fields > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,466,132 B2 - Document ID: US7466132B2 - Status: Granted - Kind: B2 - Application number: 11/740,339 - Filed: 2007-04-26 - Published: 2008-03-27 - Granted: 2008-12-16 - Earliest claimed: 2002-02-06 - Assignees: The Regents of the University of California - Inventors: John Clarke; Alexander Pines; Robert F. McDermott; Andreas H. Trabesinger - Web page: https://patentgrep.com/patent/US7466132B2 ## CPC - G01R 33/326: {involving a SQUID} - G01R 33/0356: {with flux feedback} - G01R 33/445: {MR involving a non-standard magnetic field B0, e.g. of low magnitude as in the earth's magnetic field or in nanoTesla spectroscopy, comprising a polarizing magnetic field for pre-polarisation, B0 with a temporal variation of its magnitude or direction such as field cycling of B0 or rotation of the direction of B0, or spatially inhomogeneous B0 like in fringe-field MR or in stray-field imaging} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## 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. 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. ## Claims ### Claim 1 A computer controlled method for performing nuclear magnetic resonance (NMR) imaging of a sample, said method including a sequence of computer controlled steps comprising: the providing of computer instructions for effecting the prepolarizing of nuclear spins in the sample in a millitesla magnetic field; and, the processing by computer of the detected nuclear magnetic resonance (NMR) signals from the sample in a microtesla magnetic field with an untuned low critical temperature (Tc) superconducting quantum interference device (SQUID) magnetometer. ### Claim 2 (depends on 1) The computer controlled method of claim 1 wherein the detecting magnetic field is in the range of about 150 μT to about 1 μT. ### Claim 3 (depends on 2) The computer controlled method of claim 2 wherein the prepolarizing magnetic field is tens of mT. ### Claim 4 (depends on 1) The computer controlled method of claim 1 wherein the SQUID is maintained substantially at liquid helium temperature and the sample is at room temperature. ### Claim 5 (depends on 1) The computer controlled method of claim 1 wherein the prepolarization is performed by resonant spin manipulation and the prepolarization and detection fields are orthogonal. ### Claim 6 (depends on 1) The computer controlled method of claim 1 wherein the prepolarization is performed by nonresonant spin manipulation and the prepolarization and detection fields are parallel. ### Claim 7 (depends on 1) The computer controlled method of claim 1 wherein the detection magnetic field is substantially inhomogeneous. ### Claim 8 (depends on 1) The computer controlled method of claim 1 further comprising operating the SQUID in a flux locked mode. ### Claim 9 (depends on 8) The computer controlled method of claim 8 wherein the output of the SQUID is amplified, integrated, and then fed back to a flux modulating coil positioned near the input coil of the SQUID. ### Claim 10 (depends on 1) The computer controlled method of claim 1 further comprising performing magnetic resonance imaging (MRI) of the sample by forming an image from the detected NMR signals. ### Claim 11 (depends on 10) The computer controlled method of claim 10 further comprising applying encoding magnetic field gradients to the sample. ### Claim 12 (depends on 1) The computer controlled method of claim 1 further comprising simultaneously detecting multinuclear species. ### Claim 13 (depends on 1) The computer controlled method of claim 1 further comprising obtaining scalar (“J”) coupling information from the NMR signals. ### Claim 14 Apparatus for nuclear magnetic resonance (NMR) imaging of a sample, comprising: prepolarization coils for providing a millitesla magnetic field for prepolarizing nuclear spins in the sample; measurement coils for providing a microtesla magnetic field for detecting nuclear magnetic resonance (NMR) signals from the sample; an untuned low critical temperature (Tc) superconducting quantum interference device (SQUID) magnetometer for detecting nuclear magnetic resonance (NMR) signals from the sample; and, a computer having stored therein software that controls the prepolarization coils, and processes inputs received from the SQUID magnetometer, whereby NMR or MRI images of the sample may be constructed. ### Claim 15 (depends on 14) The apparatus of claim 14 further comprising a flux locked loop connected to the SQUID. ### Claim 16 (depends on 14) The apparatus of claim 14 wherein the detecting magnetic field is in the range of about 150 μT to about 1 μT and the prepolarizing magnetic field is tens of mT. ### Claim 17 (depends on 14) The apparatus of claim 14 further comprising a liquid helium Dewar in which the SQUID is mounted to maintain the SQUID at liquid helium temperature while the sample is at room temperature. ### Claim 18 (depends on 14) The apparatus of claim 14 further comprising means to perform magnetic resonance imaging (MRI) of the sample by forming an image from the detected NMR signals. ### Claim 19 (depends on 18) The apparatus of claim 18 wherein the means to perform MRI include gradient field coils. ### Claim 20 (depends on 18) The apparatus of claim 18 further comprising a SQUID array for performing magnetoencephalography. ### Claim 21 A method for detecting heteronuclear scalar couplings in a sample, comprising: prepolarizing nuclear spins in the sample in a millitesla magnetic field; detecting nuclear magnetic resonance (NMR) signals from the sample in a microtesla magnetic field with an untuned low critical temperature (Tc) superconducting quantum interference device (SQUID) magnetometer; and detecting heteronuclear scalar couplings from the NMR signals.