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

Abstract

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.

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

“…Our previous finding showed a 24 h downward trend of the MIPS with largest change of −13.1121 ± 2.3953 • at the 24th hour in CE group and no obvious trend in the control group (−0.87795 ± 1.5146 • at 24th hour). This conformal MIPS sensor is consistent with previous studies in monitoring and distinguishing CE (Li et al, 2017a;Li et al, 2017b;Li et al, 2017c;Zhao et al, 2019;Li et al, 2019), whereas the change trend of MIPS in the experimental group was opposite. Then, the differences between the experimental group and the control group were statistically analyzed (Table 2).…”

“…Sun et al (2016) deduced the relationship between MIPS and ICP. In 2017, Li et al built a real-time continuous CE monitoring system and the system is capable of monitoring the process of CE and reveal its severity (Li et al, 2017a;Li et al, 2017c). We also built a cerebral hemorrhage test system and proved that it can monitor the progressive development of cerebral hemorrhage in real-time (Li et al, 2017b).…”

“…MIPS data were obtained from the phase of S21 at its characteristic frequency (53.7 MHz), where the transmission coefficient reach its maximum. The selection method of characteristic frequency comes from previous researches (Pan et al, 2015;Li et al, 2017a;Li et al, 2017b;Li et al, 2017c;Oziel et al, 2016). Physical and subsequent animal experiments were both carried out under those parameter settings.…”

“…Thus, this experiment conduct animal models under controlled pathological conditions to better simulate the pathological progression of CE in a repeatable manner. Our previous researches had proved the validity of the CE model established by epidural freezing method (Kawai et al, 2003;Li et al, 2017a;Li et al, 2017b;Li et al, 2017c;Li et al, 2019). Rabbits were first anesthetized with pentobarbital (3%, 1 ml/kg) via ear vein.…”

A Portable Phase-Domain Magnetic Induction Tomography Transceiver with Phase-Band Auto-Tracking and Frequency-Sweep Capabilities

“…While the primary magnetic field from a transmitter coil is propagated through target objects, the secondary magnetic field at a receiver coil is phase-shifted by eddy currents which are dependent on their conductivities. Target objects can thereby be characterized by analyzing their phase-shifted amounts [ 1 ]. Applications include non-invasive medical imaging, such as brain activity monitoring and non-destructive testing (NDT) for material characterization.…”