| Hypoxic-ischemic encephalopathy (HIE) is a hypoxic brain lesion caused by perinatal asphyxia and clinically manifest with a series of encephalopathies, imaging examination can directly reflect intracranial lesions in type ^ extent and evolutionary process , provide objective reference for early clinical diagnosis, early therapy and evaluation of prognosis.MRI may reflect neuronal necrosis due to hypoxic ischemia (HI) , hemor-rahage, stasis of circulation, status marmoratus of basal ganglia etc. Recently MR molecular imaging technology (i. e. Diffusion weighted imaging, DWI and Perfusion weighted imaging, PWI etc. ) is developed based on fast MR scan techniques, which may evaluate motion of intracellular water ( hydrone) and mi-crocirculatory hemodynamics, clarify molecular mechanism of lesions on cellular level by apparent diffusion constant ( ADC) value changes which can reflect hydrone motion and analyze metabolism varieties of brain tissue using magnetic resonance spectroscopy ( H-MRS).We used molecular imaging means ( DWI etc. ) to examine piglet HIE models in order to determine the generation and development courses of lesion, compared histological changes with images at deferent time point to study the relationship between pathological variations and MR molecular imaging in hyper-acute HIE.In this study, we established animal model with HIE for dynamic diagnosis and therapy, researched and explained pathophysiological process of HIE on mo-lecular level, examined neonates with clinical asphyxia at hyperacute stage by molecular imaging technique to find lesions early, established diagnosis standard of early HIE to improve imaging diagnosis of HIE to molecular level and provide objective reference for early diagnosis and therapy of HIE.Methods Basal section1) 25 term piglets at an age of 3 to 7 days after birth were subjected and divided into one control group and two model experiment groups, model 1:11 piglets were subjected to unilateral common carotid artery ligation and exposure to 8% oxygen. Model 2; 9 piglets were subjected to bilateral common carotid artery transient block and giving 6% oxygen mechanically2) MR imaging: MR imaging was performed before hypoxia and 0 ~ 6h ,20 ~24h,44 ~48h,68 ~72h after hypoxia respectively using coronal T1,WI,T2WI,FLAIR,DWI with the thickness of 3 ~5mm. Multivoxel 1H-MRS was performed to measure 'H spectrum in basal ganglia and hippocampus region.3)ROI setting: select the section through basal ganglia and hippocampus, measure ADC values and spectral peak area of bilateral frontoparietal regions, basal ganglia and hippocampus.4) Pathological examination of brain tissue: On pathological big slices, observe extent of edema,the state of neurocyte and gliacyte ( HE stain) , pathological changes of gliacyte (immunohistochemical stain for labelling GFAP by SP method) , cell apoptosis (TUNEL stain) and the morphological changes of cellular ultrastructure ( transmission electron microscope).Clinical sectionMR imaging was prospectively performed in 36 neonates with HIE ( average age,8.44days) , 12 neonates with mild HIE, 4 neonates with severe HIE, others between mild and moderate.Conventional T1WI and T2WI were performed with conventional transverse scan (field of view, 17cm 17cm ~ 22cm 22cm; matrix, 182 256; thickness, 4mm).DWI was performed with motion probing gradient ( MPG) along the three orthogonal axes ( b value, 700 s/mm2; matrix, 128 x72; thickness, 4mm).Observe cortex and subcortical white matter, deep white matter, basal ganglia, brain stem ,thalamus,cerebella, cerebral ventricle and extra-cerebral interspace etc.Results Basal section1) Conventional MR imaging (i. e. T,WI ,T2WI) was normal in this stud-2 ) ADC values decreased after HI, and the severity was consistent with the extent of lesions. Baseline ADC value was 822.25 +54.32mmVs, ADC values decreased to 767. 35 + 55. 09 mm2/s,746. 47 + 54. 88 mm2/s,699. 22 + 73. 91mm2/s,741.91 +56.35 mm2/s , in 0 ~6h,20 ~24h,44 ~48h,58 ~72h respectively after HI...
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