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.