A magnetoacoustic imaging method and system based on active detection

Abstract

The invention discloses an active detection-based magnetic-acoustic imaging method and system. The active detection-based magnetic-acoustic imaging method comprises the following steps: applying a low-frequency narrow-band excitation signal to an exciting coil based on the active detection-based magnetic-acoustic imaging method, and generating a dynamic magnetic field; generating a Lorentz force by a target object located in a static magnetic field under the action of the dynamic magnetic field and the static magnetic field, and generating a vibration displacement signal under the action of the Lorentz force; then carrying active detection on the vibration displacement signal by virtue of a multi-channel data acquisition module, and analyzing vibration displacement and vibration velocity information of each particle of the target object according to an echo signal fed back by the target object; and then reconstructing an electrical conductivity distribution image of the target body according to the vibration displacement and the vibration velocity information. The active detection-based magnetic-acoustic imaging method and system which are disclosed by the invention have the advantages that the low-frequency narrow-band excitation signal is adopted, so that design requirements of an excitation source are greatly lowered, and the cost of an imaging device is saved; and active detection and analysis are carried out on the displacement signal of the target object, so that limitation of low signal to noise ratio of a passive detection sound signal is effectively avoided, and the acquisition efficiency and image reconstruction effect are improved.

Description

technical field [0001] The invention relates to the field of medical technology, in particular to a magnetoacoustic imaging method and system based on active detection. Background technique [0002] Cancer has become the primary killer threatening human health. Tumor mechanistic studies have shown that during tumor development, angiogenesis leads to changes in tissue electrical conductivity. Therefore, measuring tissue conductivity has important application value for early non-invasive diagnosis of diseases. [0003] Magnetoacoustic coupling imaging is a new type of non-invasive functional imaging technology of electrical characteristics of biological tissues. According to different excitation methods, it can be divided into injection current magnetoacoustic coupling imaging and inductive magnetoacoustic coupling imaging. The schematic diagram of inductive magnetoacoustic coupling imaging is as follows: figure 1 As shown, the main principle is to place the target body in ...

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Problems solved by technology

[0004] First of all, inductive magnetoacoustic coupling imaging usually uses μs-level narrow pulses for excitation. Due to the limitation of the working frequency range of the transducer, the energy of the acoustic signal that the transducer can receive is limited, resulting in a low pulse energy conversion rate; secondly, the transducer The electrical signal energy generated by the device comes from the weak vibration excited by the Lorentz force and propagates the sound wave of tens of millimeters, so the passively received magnetoacoustic signal is weak

In order to improve the sensitivity to weakly conductive human tissue, the published implementation methods usually use kV-level high-voltage excitation to increase the intensity of the induced current density J. In addition, weak magneto-acoustic signals are also susceptible to high-frequency spatial electromagnetic field coupling interference, limiting The image quality is improved; and the acoustic signal received by the acoustic sensor is the integral sum of the acoustic signals of all paths, and the external noise is also mixed into it, resulting in a low signal-to-noise ratio (so amplification and filtering is required), and the difficulty of reconstruction increases; The element transducer and the single-channel system receive the magnetoacoustic signal, so that the magnetoacoustic signal of a single spatial point can only be collected after each pulse excitation of the coil. In order to form a two-dimensional image, a mechanical scanning device is required to drive the single vibration element. The transducer collects data at each pixel, coupled with the above-mentioned sensitivity problem, the signal-to-noise ratio is improved by repeating the excitation acquisition signal many times, resulting in a long acquisition time, and the target needs to be exposed to the pulsed magnetic field area for a long time to acquire enough The data is used for imaging, and there are certain security issues

[0005] Moreover, since the ultrasonic frequency to be detected by the ultrasonic probe is the same as the frequency of the excitation magnetic field B(t), the ultrasonic probe will be subject to inevitable direct electromagnetic interference from the excitation coil, and this interference signal is consistent with the sample due to the Lorentz force mechanism The resulting signal is independent, in order to partially reduce electromagnetic interference, the probe can be placed at a greater distance from the induction coil and the sample, but this practice also reduces the sensitivity and signal-to-noise ratio

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