An Experimental Study Of The Potential Biological Effects Associated With 2D-Shear Wave Elastography On Neonatal Brain

Objective:With 2D-Shear Wave Elastography (2D-SWE) imaging technique being widely used in the clinical practice, some researchers have applied this technique in the evaluation of neonatal brains. However, the immediate and long-term impacts of dynamic radiation force exposure on the neonatal central nervous system remain unknown.1. The purpose of our study is to apply the 2D-shear Wave Elastography (2D-SWE) technique in mice and explore the immediate impacts of dynamic radiation force exposure on the neonatal central nervous system;2. The remaining mice were group-housed for three months, the Morris water maze (MWM) test, histological staining and western blotting were conducted to explore the long-term impacts of dynamic radiation force exposure on the neonatal central nervous system.Materials and methodsPart one:Two hundred and twenty-five postnatal 24-hour-old mice were divided into 5 groups: 0-min group (control group),5-min group,10-min group,20-min group and 30-min group. The neonatal mice from different test groups were exposed to 2D-SWE scanning for 5 minutes,10 minutes,20 minutes and 30 minutes, respectively. For the control group, the neonatal mice were sham-irradiated for 30 minutes with the machine powered off. Twenty-four hours after scanning, fifty mice from the five groups (10 per group) were euthanized by cervical vertebra dislocation. Their brains were then quickly removed and used for histological staining and western blot analysis.Part two:The remaining 175 mice were group-housed in standard laboratory conditions until they were 3 months old. After three months, seventy-five male mice (]5 per group) were randomly selected for the Morris water maze (MWM) test. Twenty-four hours after the MWM test was finished, the mice were deeply anesthetized. The brains were quickly removed and used for histological staining and western blot analysis.Results:Part one:Twenty-four hours after 2D-SWE scanning, no thermal or mechanical changes were found in the brain tissues subjected to 2D-SWE scanning for 5-30 minutes. But the Western blot analysis showed that the levels of p-PKCa in 10-min group,20-min group and 30-min group were lower than those in control group, and a decrease in the levels of p-mTOR and p-AKT in 30-min group was observed.Part two:Three months after scanning, no statistical difference was detected in the escape latency, platform crossing times and target quadrant searching time of MWM test between the 5 groups. And no changes was found in the histological staining and the western blotting of neither the cortex nor hippocampus tissues.Conclusion:Using 2D-SWE in evaluating brains of neonatal mice does not cause detectable histological changes, and does not have long term effects on their learning and memory abilities, either. However, the expression of p-PKCa was affected when the scanning lasted for over 10 minutes, and the P13K/AKT/mTOR pathway was disturbed when the scanning lasted for more than 30 minutes. Although these injuries may be self-repaired as the mice grew, more attention should be paid to the scanning duration when we apply 2D-SWE elastography in the assessment of neonatal brains.