| In general, in the course of many common neural diseases, such as stroke, braininjury, encephalitis and intracranial tumors, the serious brain edema and intracranialhypertension are occurred. If there is no prompt treatment, the death rate and disabilityrate are very high undoubtedly. Early, timely and accurate evaluation of, the location,nature and extent or severity, as well as the development and drug response of the tissuelesions, which are caused by various etiologies, is directly related to correct process ofcerebral edema and intracranial pressure.meanwhile, this is the key to the neurologicalemergency rescue.The traditional detection technology, e.g., head CT, Magnetic Resonance Imaging(MRI) and Diffusion Weighted Imaging and Diffusion Tensor MR Imaging (DWI), canaccurately determine the critical nature, range and degree of the disease, but these aren’tstill available to continuous imaging for monitoring. However in some critical cases,patients need to be moved repeatedly to monitor the dynamic changes of the lesions.Hence, these existing devices are limited to the timely judging disease and adjustingtreatment. Therefore, there is urgent demand for a kind of portable medical imagingequipment, which can continuously monitor the patient, especially for effectivecontinuous monitoring of brain edema and intracranial pressure.Magnetic Induction Tomography (MIT), which is one of the current advancedresearches in the nondestructive testing of biomedical engineering, is a novelnon-contacting technology for the tissue conductivity imaging; MIT has severaladvantages, for example, fast, portable, low-cost, and noninvasive. Because of thesefeatures, it has a good application prospect in the biomedical noninvasive imaging andcontinuous dynamic monitoring fields, especially in the continuous monitoring ofintracranial diseases.This main purpose of this dissertation is to study the real-time monitoring ofintracranial lesion tissue. The main work is to develop a rapid, real-time monitoring,and portable MIT functional imaging system and discuss the reconstruction algorithmand experiments. The main research contents and summarizes as follows:①This paper proposed the Helmholtz coil which can generate a set of uniformexcitation fields, and analyzed the uniformity of excitation field.②The forward problem of the magnetic induction tomography. The corresponding finite element equations were established by MATLAB software using the edge finiteelement. The distributions of eddy current with or without perturbation object werecalculated by the finite element equations. In addition, the measuring voltages in thedifferent rotation angles were also calculated to provide guidance and data sources forthe inverse problem.③Research on the reconstruction algorithm of magnetic induction tomographybased on the uniform magnetic excitation. The effect of reconstruction algorithm in thedifferent models and its noise immunity were tested.④Hardware research. The high precision phase detection circuit usingsynchronous detection, the constant current source circuit, and the high SNR coil sensorwas developed. The key performance of a single channel experiment platform wastested.⑤A rotating MIT system was designed. The system was tested for the imagingeffect in the several models, such as a single object, double object agar models. Thesephysical model experiments, which lay a solid foundation for intracranial monitoring,provide the guidance for clinical experiments in the future.⑥A set of16channels direct projection MIT clinical system was established.Using the MIT measurement system, seven preliminary clinical experiments, including2mumps with meningitis patients, and5brain normal patients were carried out inChildren Hospital. Comparing the results of the two kinds of cases, the values ofmeningitis patients are higher than these of normal patients, which is a very valuablereference for the future dynamic monitoring. |
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