| CPC A61B 5/0515 (2013.01) [G01R 33/1276 (2013.01)] | 10 Claims |
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1. A three-dimensional (3D) magnetic particle imaging (MPI) method without rotating a field-free line (FFL), comprising:
generating, by an FFL generation module, an FFL at a center of an imaging field of view, wherein magnetic particles in a region far from the FFL enter a magnetic saturation state;
applying a non-uniform mixed-frequency excitation magnetic field parallel to the FFL, to excite magnetic particles at different positions on the FFL to generate intermodulation response signals;
wherein the non-uniform mixed-frequency excitation magnetic field comprises alternating magnetic fields of at least two frequencies: a high-frequency uniform magnetic field and a low-frequency gradient magnetic field; the high-frequency uniform magnetic field is configured to simultaneously excite the magnetic particles on the FFL to generate magnetization response signals with a high signal-to-noise ratio (SNR); and the low-frequency gradient magnetic field is configured to spatially encode the magnetic particles on the FFL, wherein the magnetic particles at different positions on the FFL generate different magnetization response signals;
the intermodulation response signals refer to different magnetization response signals of the magnetic particles at different positions on the FFL, and the magnetization response signals are mixed-frequency signals; and
the intermodulation response signals each comprise two excitation frequency components and a frequency component after intermodulation of two excitation frequencies; and the intermodulation response signals are time-domain or frequency-domain signals;
acquiring, by a receiving coil parallel to the FFL, the intermodulation response signals on the FFL; and amplifying and filtering the intermodulation response signals, and transmitting the intermodulation response signals to a digital signal processing unit and an image reconstruction unit;
constructing an encoding matrix, by the digital signal processing unit, based on the intermodulation response signals processed by the digital signal processing unit;
reconstructing, by the image reconstruction unit, a one-dimensional (1D) concentration distribution of the magnetic particles on the FFL based on the encoding matrix and an actually measured voltage signal; and
driving the FFL for line-by-line scanning along a vertical plane of the FFL by applying an orthogonal magnetic field perpendicular to the FFL, achieving 3D imaging,
wherein the actually measured voltage signal is measured by the imaging coil corresponding to the intermodulation response signals.
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