Kim Annink

50 Chapter 3 ABSTRACT Background: Postmortem examinations frequently show cerebellar injury in infants with severe hypoxic-ischemic encephalopathy (HIE), while it is less well visible on magnetic resonance imaging (MRI). The primary aim was to investigate the correlation between cerebellar apparent diffusion coefficient (ADC) values and histopathology in infants with HIE. The secondary aim was to compare ADC values in the cerebellum of infants with HIE and infants without brain injury. Methods: ADC values in the cerebellar vermis, hemispheres and dentate nucleus (DN) of (near-)term infants with HIE (n=33) within the first week after birth were compared with neonates with congenital non-cardiac anomalies, normal postoperative MRIs and normal outcome (n=22). Microglia/macrophage activation was assessed using CD68 and/or HLA-DR staining and Purkinje cell (PC) injury using H&E stained slices. The correlation between ADC values and the histopathological measures was analyzed. Results: ADC values in the cerebellar hemispheres were comparable. ADC values in the vermis (p=0.021) and DN (p<0.001) were significantly lower in infants with HIE compared to controls. ADC values in the vermis were correlated with the number and percentage of normal PCs, otherwise ADC values and histology were not correlated. Conclusion: Infants with HIE had lower ADC values in the vermis and DN than controls. ADC values were only correlated with normal PCs in the vermis.