Magnetic Induction Phase Shift Research Articles

Conductivity reactivity index for monitoring of cerebrovascular autoregulation in early cerebral ischemic rabbits

BackgroundCerebrovascular autoregulation (CVAR) is the mechanism that maintains constant cerebral blood flow by adjusting the caliber of the cerebral vessels. It is important to have an effective, contactless way to monitor and assess CVAR in patients with ischemia.MethodsThe adjustment of cerebral blood flow leads to changes in the conductivity of the whole brain. Here, whole-brain conductivity measured by the magnetic induction phase shift method is a valuable alternative to cerebral blood volume for non-contact assessment of CVAR. Therefore, we proposed the correlation coefficient between spontaneous slow oscillations in arterial blood pressure and the corresponding magnetic induction phase shift as a novel index called the conductivity reactivity index (CRx). In comparison with the intracranial pressure reactivity index (PRx), the feasibility of the conductivity reactivity index to assess CVAR in the early phase of cerebral ischemia has been preliminarily confirmed in animal experiments.ResultsThere was a significant difference in the CRx between the cerebral ischemia group and the control group (p = 0.002). At the same time, there was a significant negative correlation between the CRx and the PRx (r = − 0.642, p = 0.002) after 40 min after ischemia. The Bland–Altman consistency analysis showed that the two indices were linearly related, with a minimal difference and high consistency in the early ischemic period. The sensitivity and specificity of CRx for cerebral ischemia identification were 75% and 20%, respectively, and the area under the ROC curve of CRx was 0.835 (SE = 0.084).ConclusionThe animal experimental results preliminarily demonstrated that the CRx can be used to monitor CVAR and identify CVAR injury in early ischemic conditions. The CRx has the potential to be used for contactless, global, bedside, and real-time assessment of CVAR of patients with ischemic stroke.

Simulation of dynamic monitoring for intracerebral hemorrhage based on magnetic induction phase shift technology.

Intracerebral hemorrhage (ICH) is a common and severe brain disease associated with high mortality and morbidity. Accurate measurement of the ICH area is an essential indicator for doctors to determine whether a surgical operation is necessary. However, although currently used clinical detection methods, such as computed tomography (CT) and magnetic resonance imaging (MRI), provide high-quality images, they may have limitations such as high costs, large equipment size, and radiation exposure to the human body in the case of CT. It makes long-term bedside monitoring infeasible. This paper presents a dynamic monitoring method for ICH areas based on magnetic induction. This study investigates the influence of the bleeding area and the position of ICH on the phase difference at the detection point near the area to be measured. The study applies a neural network algorithm to predict the bleeding area using the phase difference data received by the detection coil as the network input and the bleeding area as the network output. The relative error between the predicted and actual values of the neural network is calculated, and the error of each group of data is less than 4%, which confirms the feasibility of this method for detecting and even trend monitoring of the ICH area.

A novel sensor system to detect cerebral hemorrhage in rabbits through MIPS.

Magnetic-induction phase shift (MIPS) was rarely used in vivo and clinically because of low sensitivity and nonquantitative detection. The conventional single excitation coil and single detection coil (single coil-coil) generates divergent excitation magnetic field, resulting in different sensitivity of different object positions. To improve the sensitivity and linearity of MIPS and object volume to realize quantitative detection, a novel sensor system was proposed. The novel sensor system adopted uniform rotating magnetic field replacing the divergent magnetic field for the first time integrated with primary field cancellation. The uniform rotating magnetic field was generated by a birdcage coil excited by two orthogonal current; the primary field cancellation was realized by a specially arranged solenoid receiver coil installed co-axially with the birdcage coil detecting the z, not x and y-component of the secondary magnetic field. The saltwater simulation experiment showed that MIPS changed high linearity with the injection volume of all four different conductivity solutions. The experimental results of rabbit cerebral hemorrhage (CH) revealed that with injected blood volume increased to 3ml, the MIPS linearly decreased to -1.916°, which was 5.5 times higher than that of the single coil-coil method. Compared with the single coil-coil method, this novel detection system was more sensitive and linearly correlated for the detection of bleeding volume. It provided the probability of quantitative detection of the CH volume and a series of brain-content diseases.

A noninvasive and comprehensive method for continuous assessment of cerebral blood flow pulsation based on magnetic induction phase shift.

Cerebral blood flow (CBF) monitoring is of great significance for treating and preventing strokes. However, there has not been a fully accepted method targeting continuous assessment in clinical practice. In this work, we built a noninvasive continuous assessment system for cerebral blood flow pulsation (CBFP) that is based on magnetic induction phase shift (MIPS) technology and designed a physical model of the middle cerebral artery (MCA). Physical experiments were carried out through different simulations of CBF states. Four healthy volunteers were enrolled to perform the MIPS and ECG synchronously monitoring trials. Then, the components of MIPS related to the blood supply level and CBFP were investigated by signal analysis in time and frequency domain, wavelet decomposition and band-pass filtering. The results show that the time-domain baseline of MIPS increases with blood supply level. A pulse signal was identified in the spectrum (0.2–2 Hz in 200–2,000 ml/h groups, respectively) of MIPS when the simulated blood flow rate was not zero. The pulsation frequency with different simulated blood flow rates is the same as the squeezing frequency of the feeding pump. Similar to pulse waves, the MIPS signals on four healthy volunteers all had periodic change trends with obvious peaks and valleys. Its frequency is close to that of the ECG signal and there is a certain time delay between them. These results indicate that the CBFP component can effectively be extracted from MIPS, through which different blood supply levels can be distinguished. This method has the potential to become a new solution for non-invasive and comprehensive monitoring of CBFP.

A High-Sensitivity and Shielding-Free Rabbit Brain MIPS Scanner

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Goal:</i> The purpose of this paper is to improve the detection sensitivity and quantitative assessment of different levels of cerebral hemorrhage (CH), a high-sensitivity and shielding-free rabbit brain magnetic induction phase shift (MIPS) scanner was developed and validated. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Methods:</i> First, a uniform rotating magnetic field generated by a birdcage coil was utilized instead of the divergent magnetic field for the first time, and the birdcage structure has inherent characteristics of shielding external interference. Furthermore, the primary field was cancelled, and the axial and tangential magnetic field components of the secondary magnetic field were synchronously detected and then synthesized for the first time using a magnetron sensor coil and a circular solenoid coil. Specifically, a field programmable gate array-based spectrometer was used to guarantee the two-channel signal of high-precision quadrature excitation for birdcage coil, signal acquisition, and data processing. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Results:</i> Experimental results indicated that the phase shift difference decreases linearly with the volume increase of blood injection, and the average MIPS caused by a 3-ml blood injection of rabbit inner capsule hemorrhage was 2.709°, which was 7.7 times higher than that of the traditional single excitation coil and single receiving coil (single coil–coil) method. The results have proven that this scanner has high sensitivity, strong anti-interference ability, and potential to realize the quantitative detection of hematoma volume.

Twenty-four-hour real-time continuous monitoring of acute focal cerebral ischemia in rabbits based on magnetic inductive phase shift

BackgroundAs a serious clinical disease, ischemic stroke is usually detected through magnetic resonance imaging and computed tomography. In this study, a noninvasive, non-contact, real-time continuous monitoring system was constructed on the basis of magnetic induction phase shift (MIPS) technology. The “thrombin induction method”, which conformed to the clinical pathological development process of ischemic stroke, was used to construct an acute focal cerebral ischemia model of rabbits. In the MIPS measurement, a “symmetric cancellation-type” magnetic induction sensor was used to improve the sensitivity and antijamming capability of phase detection.MethodsA 24-h MIPS monitoring experiment was carried out on 15 rabbits (10 in the experimental group and five in the control group). Brain tissues were taken from seven rabbits for the 2% triphenyl tetrazolium chloride staining and verification of the animal model.ResultsThe nonparametric independent-sample Wilcoxon rank sum test showed significant differences (p < 0.05) between the experimental group and the control group in MIPS. Results showed that the rabbit MIPS presented a declining trend at first and then an increasing trend in the experimental group, which may reflect the pathological development process of cerebral ischemic stroke. Moreover, TTC staining results showed that the focal cerebral infarction area increased with the development of timeConclusionsOur experimental study indicated that the MIPS technology has a potential ability of differentiating the development process of cytotoxic edema from that of vasogenic edema, both of which are caused by cerebral ischemia.

A noninvasive flexible conformal sensor for accurate real-time monitoring of local cerebral edema based on electromagnetic induction.

Cerebral edema (CE) is a non-specific pathological swelling of the brain secondary to any type of neurological injury. The real-time monitoring of focal CE mostly found in early stage is of great significance to reduce mortality and disability. Magnetic Induction Phase Shift (MIPS) is expected to achieve non-invasive continuous monitoring of CE. However, most existing MIPS sensors are made of hard materials which makes it difficult to accurately retrieve CE information. In this article, we designed a conformal two-coil structure and a single-coil structure, and studied their sensitivity map using finite element method (FEM). After that, the conformal MIPS sensor that is preferable for local CE monitoring was fabricated by flexible printed circuit (FPC). Next, physical experiments were conducted to investigate its performance on different levels of simulated CE solution volume, measurement distance, and bending. Subsequently, 14 rabbits were chosen to establish CE model and another three rabbits were selected as controls. The 24-hour MIPS real-time monitoring experiments was carried out to verify that the feasibility. Results showed a gentler attenuation trend of the conformal two-coil structure, compared with the single-coil structure. In addition, the novel flexible conformal MIPS sensor has a characteristic of being robust to bending according to the physical experiments. The results of animal experiments showed that the sensor can be used for CE monitoring. It can be concluded that this flexible conformal MIPS sensor is desirable for local focusing measurement of CE and subsequent multidimensional information extraction for predicting model. Also, it enables a much more comfortable environment for long-time bedside monitoring.

Noninvasive real-time detection of cerebral blood perfusion in hemorrhagic shock rabbits based on whole-brain magnetic induction phase shift: an experimental study

Objective: This study aimed to perform experiments to investigate the change trend in brain magnetic induction phase shift (MIPS) during hemorrhagic shock of different degrees of severity and to find the correlation between brain MIPS value and commonly used physiological indicators for detecting shock so as to explore a noninvasive method suitable for prehospital real-time detection of cerebral blood perfusion in hemorrhagic shock. Approach: The self-developed MIPS detection system was used to monitor the brain MIPS value in the whole process of hemorrhagic shock models of rabbits with different degrees of severity (control, mild, moderate, and severe) of shock in real time. Meanwhile, common physiological parameters, including arterial blood lactate (ABL), mean arterial pressure (MAP), heart rate (HR),core body temperature (CBT), regional cerebral blood flow (rCBF), and electroencephalogram (EEG), were also evaluated. Main results: The findings suggested that the brain MIPS value showed a downward trend in the shock process, and the decline degree of the MIPS value positively correlated with the severity of shock. Moreover, it showed a good detection and resolution ability in time/process and severity (P < 0.05). The MIPS values significantly correlated with ABL (P < 0.01), CBT (P < 0.01), and EEG (P < 0.05) at all four shock levels; with MAP (P < 0.05) and rCBF (P < 0.05) in the control, moderate, and severe groups; and with HR (P < 0.01) only in the severe group. Significance: The results demonstrated that the brain MIPS value has the capability of detecting hemorrhagic shock. The MIPS technique is a noninvasive method suitable for prehospital real-time detection of cerebral blood perfusion in hemorrhagic shock.

A cerebral edema monitoring system based on a new excitation source.

Real-time clinical monitoring of cerebral edema (CE) is of great importance and requires continuously improved and optimized measurement hardware. A new excitation source with higher frequency stability and wide output power range is presented in this work. The proposed excitation source is small in size and easy to integrate. The output power range of excitation signal used is 1.5 ∼ 33 dBm with a reference signal of 9 ∼ 11 dBm, and the phase shift stability of the excitation signal and reference signal reach 10-7 within 20 min. When normal saline (0.9%, 10 mL, 20 mL, 30 mL, 40 mL, and 50 mL) is injected into a human head phantom model, the magnetic induction phase shift (MIPS) changes from 252.78 ± 7.61 degrees to 252.40 ± 7.77 degrees. The MIPS signal shows a downward trend with increasing volume, indicating that MIPS can reflect the volume change of the measured object. Moreover, a more dramatic trend is visible when the solution volume increases from 0 to 10 mL and from 40 to 50 mL. This occurs where the volume increment is closer to the upper and lower sides of the over-ear sensor, where the magnetic field is strongest. The phantom simulation experiments illustrate that the proposed MIPS detection system based on a signal source can detect the real-time progress of CE. Advantages of low cost, high precision, and high sensitivity endow this system with excellent application prospects.

Experimental study on healthy volunteers based on magnetic induction brain edema monitoring system.

BACKGROUND:Cerebral edema is a common secondary disease after stroke. It is very important to realize real-time continuous monitoring of cerebral edema for stroke patients.OBJECTIVE:A non-contact magnetic induction phase shift (MIPS) detection system is used to monitor the change of global brain electrical conductivity during cerebral edema.METHODS:In order to verify the feasibility of this system monitoring, we carry out salt solution simulation experiments and healthy people breath holding experiments. As a comparison of later clinical experiments, 13 young healthy volunteers aged 22–35 are selected for this study to carry out a 10 minute/time monitoring experiment.RESULTS:It is found that the MIPS values measured by the salt solution of edema and the salt solution of bleeding are significantly different. The results show that the MIPS value of healthy young people is in a stable state with an MIPS mean value of 1.106 ( 0.736). Compare it with the monitoring results of a cerebral edema patient. The MIPS of patient fluctuates greatly, and the changes of MIPS and intracranial pressure show consistent trend at the peak of the edema period.CONCLUSIONS: We preliminarily verify that the system can be used for cerebral edema monitoring.

An experimental study on the early diagnosis of traumatic brain injury in rabbits based on a noncontact and portable system.

Closed cerebral hemorrhage (CCH) is a common symptom in traumatic brain injury (TBI) patients who suffer intracranial hemorrhage with the dura mater remaining intact. The diagnosis of CCH patients prior to hospitalization and in the early stage of the disease can help patients get earlier treatments that improve outcomes. In this study, a noncontact, portable system for early TBI-induced CCH detection was constructed that measures the magnetic induction phase shift (MIPS), which is associated with the mean brain conductivity caused by the ratio between the liquid (blood/CSF and the intracranial tissues) change. To evaluate the performance of this system, a rabbit CCH model with two severity levels was established based on the horizontal biological impactor BIM-II, whose feasibility was verified by computed tomography images of three sections and three serial slices. There were two groups involved in the experiments (group 1 with 10 TBI rabbits were simulated by hammer hit with air pressure of 600 kPa by BIM-II and group 2 with 10 TBI rabbits were simulated with 650 kPa). The MIPS values of the two groups were obtained within 30 min before and after injury. In group 1, the MIPS values showed a constant downward trend with a minimum value of −11.17 ± 2.91° at the 30th min after 600 kPa impact by BIM-II. After the 650 kPa impact, the MIPS values in group 2 showed a constant downward trend until the 25th min, with a minimum value of −16.81 ± 2.10°. Unlike group 1, the MIPS values showed an upward trend after that point. Before the injury, the MIPS values in both group 1 and group 2 did not obviously change within the 30 min measurement. Using a support vector machine at the same time point after injury, the classification accuracy of the two types of severity was shown to be beyond 90%. Combined with CCH pathological mechanisms, this system can not only achieve the detection of early functional changes in CCH but can also distinguish different severities of CCH.

An Experimental Study of Relationship Between Magnetic Induction Phase Shift and Brain Parenchyma Volume With Brain Edema in Traumatic Brain Injury

As a very common secondary disease after traumatic brain injury (TBI), brain edema can lead to increased intracranial water content and elevated intracranial pressure (ICP), which makes the patient suffer a less favorable prognosis outcome such as hemiplegia, aphasia, dysgnosia, and even death. Its realtime monitoring is of great significance for improving the therapeutic condition of TBI and reducing the mortality and disability rate. Magnetic induction phase shift (MIPS) has the advantages of non-invasive, non-contact, strong penetration, and real-time bedside monitoring. In this work, 34 rabbits divided into the experimental group (n = 26) and control group (n = 8) were used to carry out 24-h MIPS monitoring in brain edema. Meanwhile, ICP and brain water content (BWC) were chosen as references. The MIPS of rabbits in the experimental group decreased continuously in 24 h, while the ICP and BWC increased. Furthermore, MIPS detection sensitivity became lower and lower within the development of brain edema. The weights of ICP and BWC estimated by MIPS in three different stages were calculated to get the index of brain edema severity (BESI), which can evaluate the severity of brain edema. The BESI of rabbits in the experimental group increased over time, ranging from 0 to 1. The 0 represents normal, and the 1 represents severe brain edema. The first stage of BESI changed from 0 to 0.43, the second stage from 0.43 to 0.917, and the third stage from 0.917 to 1. The BESI of rabbits in the control group did not increase obviously within time. There were significant differences among them. Through the comparative experimental study of MIPS, ICP, and BWC on rabbits with brain edema, a more effective and direct parameter was found, which can promote the application value of MIPS in the real-time bedside monitoring of brain edema.

Multimodal Monitoring Technologies for Pathophysiology and Management of Traumatic Brain Injury

Despite decades of efforts, severe traumatic brain injury (TBI) is still the leading cause for mortality and immobility of children and young adults worldwide and is a great burden to the health-care system. After injury, the oxygen supply is conventionally considered the monitoring parameter in a neurosurgical Intensive Care Unit. However, the overall mortality rate has only slightly improved since the late twentieth century. Evolving evidence suggests that dysfunction of oxygen utilization might be the underlying pathophysiology of secondary brain injury, which should also be a key parameter for multimodal monitoring and management after severe TBI. In this review, we summarize the current and advanced understanding of multimodal monitoring for severe TBI along with novel noninvasive technologies in this field. By continuously monitoring patients with severe TBI, the use of multimodal monitoring technologies including (but not limited to) computed tomography, cerebral microdialysis, near-infrared spectroscopy, magnetic resonance spectroscopy, high-performance liquid chromatography, and magnetic induction phase shift method will be crucial for observing disease changes such as intracranial pressure and brain tissue oxygen partial pressure as well as developing potential therapeutic strategies after severe TBI.

An experimental study of pulse wave measurements with magnetic induction phase shift method.

BACKGROUND: Pulse wave monitoring is widely used to evaluate the physiological and pathological states of the cardiovascular system.OBJECTIVE:High-sensitivity ring sensors were designed, and a simultaneous acquisition platform based on National Instruments T-Clock technology (NI-TCLK) was used to achieve simultaneous pulse detection using both the traditional method and the magnetic induction phase shift (MIPS) method.METHODS:The excitation signal had a frequency of approximately 10.7 MHz and power of about 20 dBm. A total of 30 volunteers (adults, aged 20–30 y) were selected to corroborate the feasibility of our measurement system. The subjects wore the proposed sensor on their right-hand forefingers and for reference, the piezoelectric pulse sensor on the left-hand forefinger. The pulse waves of these 30 subjects were measured over 2 min each.RESULTS: The phase shift of the magnetic induction detection signal ranged from 0.6–0.8 degrees. Comparison of detection results for the same subject between the two methods showed that the pulse rate measured by magnetic induction exhibited fewer deviations and better stability than the traditional method. In addition, spectral analysis indicated that the pulse frequencies obtained using the 2 methods were concentrated between 1–3 Hz and were regular in the 1.5 Hz frequency region.CONCLUSIONS:These results prove that the magnetic induction pulse wave can be used to accurately measure pulse wave features.

A Non-Invasive Non-Contact Continuous Monitoring System of Brain Edema Based on Magnetic Induction Phase Shift and Computer Programming

A Non-Invasive Non-Contact Continuous Monitoring System of Brain Edema Based on Magnetic Induction Phase Shift and Computer Programming

Investigating the Relationship between Cerebrospinal Fluid and Magnetic Induction Phase Shift in Rabbit Intracerebral hematoma expansion Monitoring by MRI

In a prior study of intracerebral hemorrhage monitoring using magnetic induction phase shift (MIPS), we found that MIPS signal changes occurred prior to those seen with intracranial pressure. However, the characteristic MIPS alert is not yet fully explained. Combining the brain physiology and MIPS theory, we propose that cerebrospinal fluid (CSF) may be the primary factor that leads to hematoma expansion being alerted by MIPS earlier than with intracranial pressure monitoring. This paper investigates the relationship between CSF and MIPS in monitoring of rabbit intracerebral hemorrhage models, which is based on the MIPS measurements data, the quantified data on CSF from medical images and the amount of injected blood in the rabbit intracerebral hemorrhage model. In the investigated results, a R value of 0.792 with a significance of 0.019 is observed between the MIPS and CSF, which is closer than MIPS and injected blood. Before the reversal point of MIPS, CSF is the leading factor in MIPS signal changing in an early hematoma expansion stage. Under CSF compensation, CSF reduction compensates for hematoma expansion in the brain to keep intracranial pressure stable. MIPS decrease results from the reducing CSF volume. This enables MIPS to detect hematoma expansion earlier than intracranial pressure.

Twenty-Four-Hour Real-Time Continuous Monitoring of Cerebral Edema in Rabbits Based on a Noninvasive and Noncontact System of Magnetic Induction.

Cerebral edema is a common disease, secondary to craniocerebral injury, and real-time continuous monitoring of cerebral edema is crucial for treating patients after traumatic brain injury. This work established a noninvasive and noncontact system by monitoring the magnetic induction phase shift (MIPS) which is associated with brain tissue conductivity. Sixteen rabbits (experimental group n = 10, control group, n = 6) were used to perform a 24 h MIPS and intracranial pressure (ICP) simultaneously monitored experimental study. For the experimental group, after the establishment of epidural freeze-induced cerebral edema models, the MIPS presented a downward trend within 24 h, with a change magnitude of −13.1121 ± 2.3953°; the ICP presented an upward trend within 24 h, with a change magnitude of 12–41 mmHg. The ICP was negatively correlated with the MIPS. In the control group, the MIPS change amplitude was −0.87795 ± 1.5146 without obvious changes; the ICP fluctuated only slightly at the initial value of 12 mmHg. MIPS had a more sensitive performance than ICP in the early stage of cerebral edema. These results showed that this system is basically capable of monitoring gradual increases in the cerebral edema solution volume. To some extent, the MIPS has the potential to reflect the ICP changes.

Construction of a Cerebral Hemorrhage Test System Operated in Real-time

The real-time monitoring and evaluation of the severity and progression of cerebral hemorrhage is essential to its intensive care and its successful emergency treatment. Based on magnetic induction phase shift technology combined with a PCI data acquisition system and LabVIEW software, this study established a real-time monitoring system for cerebral hemorrhage. To test and evaluate the performance of the system, the authors performed resolution conductivity experiments, salted water simulation experiments and cerebral hemorrhage experiments in rabbits and found that when the conductivity difference was 0.73 S/m, the phase difference was 13.196°. The phase difference change value was positively proportional to the volume of saline water, and the conductivity value was positively related to the phase difference of liquid under the same volume conditions. After injecting 3 mL blood into six rabbits, the average change in the blood phase difference was −2.03783 ± 0.22505°, and it was positively proportional to the volume of blood, which was consistent with the theoretical results. The results show that the system can monitor the progressive development of cerebral hemorrhage in real-time and has the advantages of low cost, small size, high phase accuracy, and good clinical application potentiality.

Experimental study on the detection of rabbit intracranial hemorrhage using four coil structures based on magnetic induction phase shift.

Intracranial hemorrhage (ICH) is the bleeding induced by parenchyma vascular rupture. In this paper, four novel coils (a contralateral hemisphere cancellation coil, a coaxial coil, a double-end exciting coil, and a Helmholtz coil) were developed to detect the volume change of ICH with the magnetic induction phase shift (MIPS) technique. Both numerical studies on an ICH model and animal experiments on rabbits' hemorrhage model were performed with four coils. Twenty rabbits were measured for each coil. The animal results were consistent with the simulation and the theoretical analysis for each coil. The MIPS first declined and then increased with increasing injection volume, indicating the existence of a turning point. The MRI images showed that the average CSF decreased in the heads of five rabbits after blood injection was approximately equal to the average injection volume corresponding to the turning point of all animals. Thus, we concluded that when the MIPS turning point occurs, the CSF is already exhausted and the compensatory stage has ended. The results show that the MIPS technique has the potential to detect ICH growth and MIPS changes with increasing blood in a regular way. The turning point is expected to provide an early warning for ICH growth.

The Experimental Study of Increased ICP on Cerebral Hemorrhage Rabbits with Magnetic Induction Phase Shift Method

Introduction Measuring magnetic induction phase shift (MIPS) changes as a function of cerebral hemorrhage volume has the potential for being a simple method for primary and non-contact detection of the occurrence and progress of cerebral hemorrhage. Our previous MIPS study showed that the intracranial pressure (ICP) was used as a contrast index and found the primary correlation between MIPS and ICP. Materials and Methods In this study，we theoretically deduced the approximate relationship between MIPS and ICP and carried out a comparison study between MIPS and ICP on cerebral hemorrhage in rabbits in this study. Acute cerebral hemorrhage was induced by injecting autologous blood (3 to 6mL) into the brain of rabbits in the experimental group (n=7). Results The animal experiment results showed that the MIPS decreased significantly as a function of injection volume in the experimental group and the changes of ICP and MIPS of rabbits from experimental group presented a negative correlation. We also found that the MIPS slopes of all experimental samples had a change trend from fastness to slowness with a reverse of the change of ICP. Conclusion These observations suggested that the non-contact MIPS method might be valuable and potential for monitoring acute cerebral hemorrhage and obtaining the ICP information.