Assessment Of Hypothalamic Ischemic Damage With Shear Wave Elastography And Doppuler Ultrasound In Newborn Rabbit

Objective:To explore the correlation among Young’s modulus、hemodynamic and pathological changes of thalamus applying shear wave elastography（SWE）and Color Doppler ultrasound in newborn hypoxicischemic brain damage（HIBD）rabbit models.Methods:1.To build the New Zealand rabbits in utero hypoxic-ischemic model,nineteen pregnant New Zealand rabbits were randomly divided into four groups.Group G25 consists 6 rabbits on the 25^thh of gestation,Group 21 consists of 9 rabbits on the 21^th of gestation.For rabbits of both groups,40%⁵0%uteroplacental vessel are ligatured.Control group C21 and C25 consist of 2 rabbits respectively.On the21^th and 25^thh of gestation respectively,abdominal cavity of rabbits of each group were opened,uteroplacental vessel weren’t ligatured.Fetuses were taken out on the29±1^th of gestation by cesarean section.Two newborn rabbits were selected randomly from each pregnant rabbit for analysis.2.10 newborn rabbits were collected randomly and examined by 2 operators through SWE.Minimum value,maximum value and mean value of Young’s modulus are recorded to analyzed the repeatability/consistency.3.For 12 pregnant New Zealand rabbits which lived to the 29±1^thh of the gestation,2 new born rabbits were selected from each pregnant rabbits to apply SWE and DUS examination,the average of Young’s modulus（Emean）,the systoli velocity（Vs）,the diastolic velocity（Vd）and resistance index（RI）of middle cerebral artery（MCA）were recorded.4.After the examination,thalamus were obtained for HE stain and quantitative pathological scoring;thalamus microglial cells were marked using IB4 to calculate integral optical density;thalamus apoptotic cells were marked using TUNEL,and positive cells were counted to calculate its percentage.5.Analyze the correlation between the above values.Results:1.General conditions of models:Mortality of G21 group and G25 group was81.9%（4/30）and 47.2%,respectively.For G21 group and G25 group,the birth weight,placental weight and brain weight decreased,compared to control group（P<0.05）.The crown-rump length of G21 group decreased compared to control group（P<0.05）.The brain/body weight ratio of G21 and G25 group increased compared to control group.（P<0.05）.In addition,For G21 group,the body weight,placental weight and brain weight were lower compared to G25 group（P<0.05）,while the brain/body weight ratio increased compared to G25 group,respectively（P<0.05）.2.The Vd,Vs and RI of MCA:For G25 group,the Vs,Vd and RI were not significantly different compared to control group（P>0.05,respectively）.For G21group,the Vs,Vd and RI decreased compared to control group（P<0.05,respectively）.In addition,for G21 group,the Vs and RI decreased compared to G25group（P<0.05,respectively）.3.Repeatability/consistency:the correlation/repeatability reliability of the Emean by the same/two different operator were better than Emin and Emax.4.Emean and pathology analysis of thalamus:Emean of G25 and G21decreased compared to control group,Emean of G21 group decreased compared to G25 group（P<0.05）;For G25 group and G21 group,the pathological scores of thalamic injury,the percentage of apoptotic cells and the integral optical density of microglia increased compared to control group（P<0.05）;integral optical density of microglial cells of G25 and G21 group improved compared to control group（P<0.05）.5.Correlation analysis:The Vs and RI of MCA were negatively correlated with thalamic pathological score,the integral optical density of microglial cell and the percentage of apoptotic cells in newborn rabbits.The Vs and Vd of MCA were positively correlated with Emean of thalamic in newborn rabbits.Emean of thalamic of new born rabbits were negatively correlated with pathological score,the integral optical density of microglial cell and the percentage of apoptotic cells in the total number of cells in newborn rabbits.Conclusion:1.The model of 40%to 50%ligature of uteroplacental vessels in the pregnant rabbit in different gestational ages can be applied to research on hypoxic ischemic brain damage of different degree.2.The Vs and RI of MCA significantly decreased over the hypoxic time in intrauterine,indicating the cerebral hemodynamics of newborn rabbits is affected by intrauterine hypoxia.3.The Vs and Vd of middle cerebral artery are positively correlated with Emean of the thalamic in newborn rabbits.4.SWE can be used for quantitative examination of hypoxic-ischemic encephalopathy in newborn rabbits,the more histological brain hypoxic changes,the lower value of Emean.