A hysteresis effect-based Field Free Point-Magnetic Particle Imaging (FFP-MPI) method includes the following steps: acquiring a hysteresis loop model of Superparamagnetic Iron Oxide Nanoparticles (SPIOs); calculating to obtain a Point Spread Function (PSF) of the SPIOs on the basis of a sinusoidal excitation magnetic field and the hysteresis loop model of the SPIOs; acquiring an original reconstructed image of FFP-MPI on the basis an FFP moving track and a voltage signal; performing deconvolution on the original image with respect to the PSF considering an hysteresis effect, so as to obtain a final reconstructed image; the artifacts and phase errors of image reconstruction caused by the hysteresis effect of the SPIOs with large particle sizes are reduced, the deficiency in reconstruction by the traditional reconstruction method that ignores the hysteresis effect is overcome, the reconstruction speed and the resolution are greatly improved, and the application range of the SPIOs is expanded.

A hysteresis effect-based Field Free Point-Magnetic Particle Imaging (FFP-MPI) method includes the following steps: acquiring a hysteresis loop model of Superparamagnetic Iron Oxide Nanoparticles (SPIOs); calculating to obtain a Point Spread Function (PSF) of the SPIOs on the basis of a sinusoidal excitation magnetic field and the hysteresis loop model of the SPIOs; acquiring an original reconstructed image of FFP-MPI on the basis an FFP moving track and a voltage signal; performing deconvolution on the original image with respect to the PSF considering an hysteresis effect, so as to obtain a final reconstructed image; the artifacts and phase errors of image reconstruction caused by the hysteresis effect of the SPIOs with large particle sizes are reduced, the deficiency in reconstruction by the traditional reconstruction method that ignores the hysteresis effect is overcome, the reconstruction speed and the resolution are greatly improved, and the application range of the SPIOs is expanded.

The vectorial magnetometer and associated methods can allow to distinguish the relative superposed amplitudes associated to different spin populations based on the known proportions of the Rabi attenuation in the different characteristic orientations of the spin populations due to application of different pulse parameters which can be specifically selected to create a contrast between the attenuation proportions stemming from the different spin populations.

A method and device for radio-frequency field inhomogeneity correction in magnetic resonance imaging. The method includes: obtaining a first MR image by scanning a target tissue using a first pulse sequence; obtaining a B.sub.1.sup.+ field map of the target tissue; obtaining a B.sub.1.sup.−: field map of the target tissue based on the first MR image and the B.sub.1.sup.+ field map; and performing B1 field inhomogeneity correction on a second MR image of the target tissue based on the B.sub.1.sup.+ field map and the B.sub.1.sup.− field map, where the second MR image is an MR image obtained after scanning of the target tissue using any imaging protocol and any pulse sequence.

The invention relates to a method for carrying out post-processing on a first set of samples measuring the magnitude of a WASAB1 signal delivered by a magnetic-resonance medical-imaging apparatus. Such a method comprises a step of detecting the samples of a first set Z, for which samples the respective polarities of the values of the measured signal are known, and of constructing a second set Y of “polarised” samples. Such a method further comprises a step of fitting a determined model to said second set Y, the two parameters of the determined model describing the static magnetic field B0 and excitation magnetic field B1 of the magnetic-resonance medical-imaging apparatus, respectively, and of producing an estimation of the parameters B0 and B1 of the model. Such a method relates to any magnetic-resonance-imaging application in which a correction for inhomogeneities in the fields B0 and B1 is required.

Ferrimagnetic oscillator magnetometers do not use lasers to stimulate fluorescence emission from defect centers in solid-state hosts (e.g., nitrogen vacancies in diamonds). Instead, in a ferrimagnetic oscillator magnetometer, the applied magnetic field shifts the resonance of entangled electronic spins in a ferrimagnetic crystal. These spins are entangled and can have an ensemble resonance linewidth of approximately 370 kHz to 10 MHz. The resonance shift produces microwave sidebands with amplitudes proportional to the magnetic field strength at frequencies proportional to the magnetic field oscillation frequency. These sidebands can be coherently averaged, digitized, and coherently processed, yielding magnetic field measurements with sensitivities possibly approaching the spin projection limit of 1 attotesla/√{square root over (Hz)}. The encoding of magnetic signals in frequency rather than amplitude relaxes or removes otherwise stringent requires on the digitizer.

A method can include obtaining a scaling factor for a location proximate a metallic object by optimizing a function of an acquired dataset and a simulated dataset. The simulated dataset can include a first signal from a first pulse having a first excitation flip angle and a first refocusing flip angle. The simulated dataset can include a second signal from a second pulse having a second excitation flip angle and a second refocusing flip angle.

A method of setting an RF operating frequency of an MRI system (1) uses a first reference frequency signal, obtained from a geo-satellite positioning system, as a stable long term frequency reference. A second frequency source (24) is calibrated using the first frequency reference signal and the second frequency reference source (24) is then used as the master clock for the MRI system (1), for setting the RF operating frequency.

A method for measuring a gradient field of a nuclear magnetic resonance (NMR) system based on a diffusion effect uses a non-uniform field magnet, an NMR spectrometer, a radio frequency (RF) power amplifier, an RF coil, and a standard quantitative phantom with known apparent diffusion coefficient (ADC) and time constant for decay of transverse magnetization after RF-pulse (T2). A plurality of sets of signals are acquired by an NMR sequence with different diffusion-sensitive gradient durations or different echo spacings and the magnitude of the gradient field is calculated by fitting based on the plurality of sets of signals. The method does not require an additional dedicated magnetic field detection device, has a short measurement time, is easy to use with the NMR system, and is convenient to complete gradient field measurement at the installation site, thereby improving the installation and service efficiency of the NMR system.

Apparatus for imaging during surgical procedures includes an operating room for the surgical procedure and an MRI for obtaining images periodically through the surgical procedure by moving the magnet up to the table. The magnet wire is formed of a superconducting material such as magnesium di-boride or Niobium-Titanium which is cooled by a vacuum cryocooling system to superconductivity without use of liquid helium. The magnet weighs less than 1 to 2 tonne and has a floor area in the range 15 to 35 sq feet so that it can be carried on the floor by a support system having an air cushion covering the base area of the magnet having side skirts so as to spread the weight over the entire base area. The magnet remains in the room during surgery and is powered off to turn off the magnetic field when in the second position remote from the table.