| Internal hemorrhage is a common disease with the sudden occurrence,serious development and high mortality,which mainly occurs in the cranium or the abdominal organs.Early detection is the key to the treatment of internal hemorrhage.However,the medical diagnosis technology is unable for early detection as the continuous monitoring of the disease process is now unavailable.Therefore,a clinical diagnosis technology with the function of monitoring and early warning is badly necessary.Magnetic Induction Tomography(MIT)is a kind of contactless electrical impedance tomography method which is based on the changes of the eddy current induction that produced by the object in the alternating magnetic field generated by the non-contacting drive coils.MIT is nonradiative,noninvasive,non-contacting and real-time,which will be suitable for detecting human internal hemorrhage.Presently,the MIT researches mainly focus on the aspects of the reconstruction algorithm,the data acquisition system,the physical model experiment and so on,while few researches about the imaging experiments on biological tissues are reported especially the in vivo imaging experiments,which is a main barriers of MIT development.In order to fill the blank of in vivo imaging of MIT research,we have established an original MIT research system using two kinds of rabbit internal hemorrhage models(agglomerate hemorrhage models and dispersive hemorrhage models)and following the data analysis.Part Ⅰ:In vivo MIT research system and preliminary experimentsThe MIT research system is composed of 16-channel MIT detector,sliding operating platform of experimental animals and a holder.The measurement accuracy of the experimental system is less than 0.3%,which is better than the 1.0% required by medical MIT imaging.The average time of the system data acquisition is 4s per frame in the case of continuous measurement and imaging.For the first time,a rabbit hemorrhage model was established for MIT research.To test the stability of the system and the feasibility of in vivo detection,the dying rabbits(low vital activity with heart beats and weak breath)were subcutaneously injected with the saline on the abdomen and following with the continuously in vivo monitoring experiments.The result of preliminary experiments indicated that he experimental platform has good environment and stability which meet the requirements of animal experiment and continuous detection.Part Ⅱ: The MIT research in the agglomerative hemorrhage model.The aggregation hemorrhage model was established by subcutaneously injecting fluid into the abdomen of adult rabbits.The rabbits were divided into two groups which were saline group and blood group.3mL was injected respectively in each rabbit for 8 doses with a interval of 1-2min.Data was collected after more than 10 stable frames.After each injection,an image was analyzed.When the upper and lower limits of image reconstruction were unified,it can be observed that the conductivity of images were apparently increased,and the area increased as well as the color deepened with the increase of the dose regardless of injection of saline or rabbit blood.The results showed that the reconstruction value of both two groups linearly increased with the dose increasing and the linearly dependent coefficients were 0.914 and 0.909.That the slope of saline group being higher than the slope of blood group in the dose-response curve indicated the difference of the conductivity between the saline and the blood.Part Ⅲ: The MIT research in the dispersive hemorrhage modelThe dispersive hemorrhage model was established by blood celiac injection of adult rabbits.10 mL was injected respectively in each rabbit for 8 doses with an interval of 1-2min.Data was collected after more than 10 stable frames like Part II.The result showed that the reconstruction value of the images increased with the dose increasing.Compared with the agglomerative hemorrhage models,the area was larger,which indicated the changes of the dispersive conductivity.When the upper and lower limits of image reconstruction were unified,the area increased as well as the color deepened with the dose increasing.To linear regression analysis showed that the approximate linear relationship between reconstruction value and injection dosage,the linear correlation coefficient is 0.846 lower than the clustering model,reflecting the conductivity distribution in diffuse model change degree of weak controllability.To sum up,we set up the in vivo MIT experimental platform and verified the stability of the system.Two living animal models were established for two kinds of hemorrhage and the feasibility of MIT in real-time dynamic continuous monitoring was verified as well as the relation between dose and conductivity.Our research lays a foundation of further study of animal experiments and even clinical trials of MIT technology.There are two innovations of this study: 1)the first use of in vivo MIT technology living animal models and the detection of the changes of internal conductivity distribution;2)the minimum detectable dose of the aggregation hemorrhage model is 3mL and the minimum detectable dose of the dispersive hemorrhage model is 10 mL.The the reconstruction value was linearly related with dose and the dose-response curve slope of two kind of models was different. |
