Experimental Research Of Relationship Between Volume Of Cerebrospinal Fluid And MIPS In ICH Detection

Stroke is one of the most common etiology affect human health.Stroke include hemorrhagic stroke and ischemic stroke which hemorrhagic stroke commonly known as cerebral hemorrhage.According to Chinese stroke prevention report in 2015,the cardiovascular and cerebrovascular diseases present a tendency of increasing incidence in recent years,and gradually become a serious social problem that threaten Chinese residents' health.The fatality rate of acute case of hypertensioncerebral hemorrhage reaches 50%-75%.The basic and clinical research and the improvement of diagnosis and treatment methods of cerebral hemorrhage has become the focus of hot spots.Pathological process of cerebral hemorrhage,especially the spontaneous hypertension cerebral hemorrhage,is a progressive process.About a third of the patients have sudden onset,and the rest of the patients will reach the peak after several hours of degradation and development.At present,the diagnosis and monitoring technology of cerebral hemorrhage is mainly the imaging examination method,such as X-ray computed tomography imaging(X-rayCT)and Magnetic Resonance Imaging(MRI)technology.For late-onset cerebral hemorrhage which has no physical changes but functional changerequires functional magnetic resonance imaging(f MRI)and Positron Emission Tomography imaging(PET).But advanced imaging technology is impossiblefor real-time monitoring and assessment,the temporal resolution is low and cannotrepeat many times to check in short time.Electromagnetic characteristic is one of the basic properties of organisms,Electromagneticcharacteristics of various biological tissues or organs in different physiological and pathological conditions are so different.Magnetic Induction Phase Shift(MIPS)is a new method detecting the characteristics of biological tissue.The principle of MIPS is to add anexcitation magnetic field with certain frequency on the organism or the organization being measured,organisms or biological tissues being measured produce induced current under electromagnetic induction,then the induced current generate inductive magnetic field.As we all know that induced magnetic field generated by various organism with different electrical conductivity is different,the intensity of the induced magnetic field is connected with resistance characteristics especially the electrical conductivity.Therefore,we can reflect the electrical conductivity of biological tissue by detecting induced magnetic field.MIPS technology is noninvasive,real-time,high sensitivity,low cost,and has become a research hotspot in the field of real-time monitoring system at present.MIPS detection technology is still in its infancy and has many problems:For the complicated brain,MIPS detection simplified the brain into homogeneous conductor and ignored the influence of the volume and geometric shape of various intracranial materials(cerebrospinal fluid,brain parenchyma and cerebral blood)on MIPS.Thus,researchers lost the high value information contained in the intracranial materials of MIPS signal inevitably.Average conductivity change can explain the change of whole intracranial,but the change of various intracranial materials cannot be deduced according to the average conductivity model.According to the MIPS research of animal cerebral hemorrhage model for many years,we can detect the early sensitive features of MIPS signals tothe conductivity of biological tissue,and has early forewarning function for detection of the occurrence of cerebral hemorrhage than traditional intracranial pressure detection method.But there was no scientific explanation of early sensitive characteristics based on the experimental research,and also failed to reflect the respectively change of various intracranial materials by early warning signals.Aimed at the shortcomings of existing research about the relationship of organization compositions' changeof intracranial materialsand MIPS,this thesis carried out some meaningful experiment based on cerebral hemorrhage models of small animals and large animals,to analysis the correlation and influence of different organization compositions of intracranial materials with MIPS.Part one: Established a measuring system of MIPS monitoring based on animal cerebral hemorrhage model.The system was based on signal sourceand NI PXI measurement platform.Signal source can output signalsof any frequency in the bandwidth,we wrote the Lab View phase shift measurement procedure combined with high speed data acquisition card,the system can achieve phase shift measurement with arbitrary frequencies below 50 MHz.We tested the performance of this system based on signal source and PXI instrument,the phase driftof system was defined as the difference between maximum and minimum of 4 hours.Based on the purpose of our experimental demand,we designed two sets of experiment scheme and two sets of test coil,respectively for cerebral hemorrhage MIPS monitoring of small animals(rabbit)and large animals(Bama minipig).The parallel experiment of intracerebral hemorrhage MIPS monitoring and cerebral hemorrhage MRI imaging(cerebrospinal fluid volume,CSF volume)was designed for rabbit,multi-physiologicalparameter measurement(intracranial pressure,arterial pressure and ECG)and cerebral hemorrhage MIPS monitoring was conducted for Bama minipig.Part two:Based on our previous study,we can realize the detection of overall change of cerebral hemorrhage by MIPS technology,and the systemwas sensitivefor early detection.But the mechanisms of the MIPS signal producing in intracerebral hemorrhage monitoring are not known.The alert ahead characteristic of MIPS has not to be explained and we cannot extract the physiology information in the brain from MIPS signal of monitoring intracerebral hemorrhage.This paper investigates the mechanisms of intracerebral hemorrhage monitored by MIPS on rabbit intracerebral hemorrhage model.It uses the medical imaging and advanced image processing techniques to observe and quantify the changes of cerebrospinal fluid(CSF)in ICH.Based on quantified data of CSF from medical images and the amount of injected blood in the rabbit intracerebral hemorrhage model,it investigates the mechanisms of MIPS monitoring ICH by analyzing the impact of the main changed volumetric tissues in brain(CSF and the bleeding)on MIPS signal and establishing the dependence relation among them statistically.In the investigated results,R value of 0.792 with the significance 0.019 between MIPS and CSF is retrieved,which is more relevant than MIPS and blood with R value of 0.748 with the significance 0.033.Meanwhile before a reversal point of MIPS,CSF is the leading factor on MIPS signal while the blood becomes leading factor on MIPS signal after the reversal point.Under CSF compensation,the MIPS decreases produced by CSF reducing while CSF reducing compensates the bleeding in brain to keep ICP stable.That makes the MIPS detect ICH earlier than ICP.This study will help using the MIPS techniques to demonstrate the changes of the main volumetric tissues in brain in ICH and accelerate the application of MIPS techniques in ICH monitoring.Part three:Established a multivariate relationship model of cerebrospinal fluid volume changes,the volume of cerebral hemorrhage and MIPS signal by rabbit cerebral hemorrhageexperiments,clarified the mechanism of MIPS and cerebral hemorrhage volume change for early monitoring.To conducthuman clinical experiment the next step,we set up a multiple physiological parameters monitoring system for Bama minipig cerebral hemorrhage MIPS measurement.The results demonstratedthat MIPS reduced gradually with increase of bleeding,the influence of cerebrospinal fluid on MIPS was the same as rabbit experimental results.We found that MIPS amplitude variation range has a significant correlation with the peak-peak value of corresponding MIPS signal of each Bama minipig,the correlation coefficient was 0.965.Then,we completedexponential fit of every MIPS curve and obtained the fitting equation,so that we can achieve the quantitative analysis between MIPS and the amount of bleeding.Finally,the results showed that there was a turning point of MIPS curve when conducted a difference analysis ofrabbit MIPS signal,we considered this phenomenon as the termination period of cerebrospinal fluid metabolism.However,the turning point of Bama minipig MIPS curve didn't appear which wethought there was a certain relationship with the injection volume.This result also illustratedthat the compensatory of cerebrospinal fluid played a key role on MIPS change in the early cerebral hemorrhage.