| The human brain has the characteristics of impedance, including electrical and magnetic properties. When there are lesions in the brain, the tissue of lesion will have an impact on its impedance characteristics, so the study of the brain disease detection method can be set out from this point. Magnetic signal measurement technique is a noninvasive technique for measuring the biological impedance. Magnetic induction signal detection technology has two advantages. On the one hand, the magnetic field excitation mode is used in this technology,which can be very easy to "penetrate" the skull. On the other hand, this technology has a very strong central sensitivity of the measured structures. Therefore, magnetic induction signal detection technology has a significant advantage in the detection of brain diseases.This research was carried out from two aspects based on the characteristics of human brain impedance and the principle of magnetic induction detection of brain diseases. Firstly,the influence of the skull on the magnetic induction signal was studied during which a set of magnetic induction signal detection system was designed, and a hemispherical head model was designed using agar and electrical conductivity solution. The results show that the presence of skull changes the magnitude of magnetic induction signal but does not change the trend of the data, which shows the characteristics of "penetrating" skull of the magnetic induction signal system. The attenuation coefficient of the skull to the measured data is about0.5, which can play a good reference in the selection of the parameters in the image reconstruction. In the judgment of actual amount of bleeding, the closest state of the actual situation is to double the amount of bleeding.Then, the characterization methods of the impedance variation of intracranial hemorrhage were studied. In this process, a magnetic induction signal detection system for intracranial hemorrhage was designed, and a real head model was designed using agar and electrical conductivity solution, and a variety of intracranial hemorrhage were simulated. Because the skull only affects the size of magnetic induction signal but not the trend, so the state with skull is not considered in the study, and intracranial hemorrhage model without skull is used to do the experimental study directly. The results show that, when the lesions appear in the brain, thenearest receiving coil can be a good judge of the location of the lesion, and its adjacent two receiving coils can play an effective auxiliary role. The degree and location information of lesions are characterized through the interaction of receiving coil qualitatively. In addition, the data measured by the real intracranial hemorrhage model is obviously increased compared with the hemispheric cerebral hemorrhage model which indicates that the real intracranial hemorrhage model is more suitable for the experimental study of brain diseases. Therefore, it is very important for the application of the magnetic induction impedance measuring technique in the clinical diagnosis of brain diseases. |
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