Provided are an ultra-low field nuclear magnetic resonance device and a method for measuring an ultra-low field nuclear resonance image. The ultra-low field nuclear magnetic resonance device includes an AC power supply configured to supply a current to a measurement target in such a manner the current flows to the measurement target, magnetic field measurement means disposed adjacent to the measurement target, and measurement bias magnetic field generation means configured to apply a measurement bias magnetic field corresponding to a proton magnetic resonance frequency of the measurement target. A vibration frequency of the AC power supply matches the proton magnetic resonance frequency of the measurement target, and the magnetic field measurement means measures a nuclear magnetic resonance signal generated from the measurement target.

One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

Techniques are described for determining cognitive impairment, an example of which includes accessing a set of epochs of magnetoencephalography (MEG) data of responses of a brain of a test patient to a plurality of auditory stimulus events; processing the set of epochs to identify parameter values one or more of which is based on information from the individual epochs without averaging or otherwise collapsing the epoch data. The parameter values are input into a model that is trained based on the parameters to determine whether the test patient is cognitively impaired.

One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

A method for hyperpolarizing spins includes the following steps: a) placing a sample containing spins (s) in a stationary magnetic field; b) magnetically coupling the sample to an electromagnetic resonator having a resonance frequency .sub.0 equal to the Larmor frequency of the spins in the stationary magnetic field, such that the coupling with the resonator dominates the relaxation dynamics of the spins; and c) reducing the effective temperature of the electromagnetic field inside the electromagnetic resonator below its physical temperature and that of the sample; whereby the polarization of the spins of the sample is established at a value higher than its thermal equilibrium value. An apparatus for implementing such a method is also provided.

A magnetic resonance force detection apparatus, comprising: a sample carrier for carrying a sample to be tested; a magnetic field source configured to provide a magnetic field to a sample when it is carried by the sample carrier; a support for supporting either the sample carrier or the magnetic field source; a support-driving-mechanism configured to drive the support such that the sample carrier moves relative to the magnetic field source, such that the magnetic field is configured to cause the spins of one or more nuclei or electrons in the sample to flip, and wherein the flipping of spins exerts a force on the support; and a support-displacement-measuring-sensor configured to measure displacement of the support and generate a signal representative of the displacement of the support.

One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

The present invention provides methods and apparatuses for detecting, measuring, or locating cells or substances present in even very low concentrations in vivo in subjects, using targeted magnetic nanoparticles and special magnetic systems. The magnetic systems can comprise magnetizing subsystems and sensors subsystems, including as examples SQUID sensors and atomic magnetometers. The magnetic systems can detect, measure, or location particles preferentially internalized by cells due to the action of antibodies, proteins, macromolecules, or nutrients required for cellular metabolism. Example magnetic systems are capable of detecting sub-nanogram amounts of these nanoparticles.

An ultrahigh resolution magnetic resonance imaging method and apparatus, the method comprises the following steps of: placing a test sample within an action range of a magnetic gradient source and a nano-scale superconducting quantum interference device, applying a static magnetic field on the test sample by a static magnetic source, and applying a nuclear magnetic resonance radio-frequency pulse on the test sample by a radio-frequency source to excite the test sample to cause nuclear magnetic resonance; directly coupling the nano-scale superconducting quantum interference device with the test sample to detect nuclear magnetic resonance spectrum signals generated by the test sample; establishing an image of the test sample according to the detected nuclear magnetic resonance spectrum signals and space distribution information of gradient magnetic fields generated by the magnetic gradient source.

A magnetic resonance system, comprising at least one SQUID, configured to receive a radio frequency electromagnetic signal, in a circuit configured to produce a pulsatile output having a minimum pulse frequency of at least 1 GHz which is analyzed in a processor with respect to a timebase, to generate a digital signal representing magnetic resonance information. The processor may comprise at least one rapid single flux quantum circuit. The magnetic resonance information may be image information. A plurality of SQUIDs may be provided, fed by a plurality of antennas in a spatial array, to provide parallel data acquisition. A broadband excitation may be provided to address a range of voxels per excitation cycle. The processor may digitally compensate for magnetic field inhomogeneities.