Kim Annink

230 Chapter 10 but this might be due to the small sample size. In addition, infants are placed in a relatively cool MRI scanner environment (temperature 18°C), which might decrease body temperature. This is supported by the fact that a larger head circumference was associated with a smaller difference between brain temperature and rectal temperature before MRI using short TE. As core temperatures may fluctuate when an infant is exposed to the cooler temperature of the MRI environment, monitoring body temperature during MRI might be recommended to prevent cooling down. An option to prevent body cooling might be the use of a temperature-controlled MRI incubator. A rise in brain temperature in neonates during MRI has never been found, but a decline has also not been described before in NE (4). More research is needed and the results should be interpreted with caution, because the decrease in temperature was not found for all TEs and rectal and brain temperatures were compared. The lack of information about (brain) temperature during MRI in neonates emphasizes the need for an easy and non-invasive method to measure temperature. This becomes even more important with the use of ultra-high field imaging. Ultra-high field imaging improves the quality of MRI (22), which might also be beneficial in neonates. However, higher field strengths might increase the SAR and thereby the risk of a rise in brain temperature (22). Then, monitoring brain temperature becomes even more important. Additionally, brain temperature measurements can possibly help to assess the severity of brain injury. In adults with stroke, the temperature in injured brain tissue was higher compared to non-injured tissue (23,24). Also in children with epilepsy, the brain temperature in the focal epileptogenic lesions was higher than in controls (25). Therefore, Wu et al. investigated brain temperature in infants with NE during and after therapeutic hypothermia. Both during and after therapeutic hypothermia brain temperatures were significantly higher in infants with severe NE compared to moderate NE (8). Subsequently, Owji et al. confirmed that infants with NE with brain injury have significantly higher brain temperatures compared to healthy controls. This increase in brain temperature of the injured brain might be explained by the combination of the inflammatory response to injury, chemical reaction in ischemic cells such as the production of oxygen radicals and excitatory amino acids and/or reduced cerebral blood flow leading to less release of heat (24). Furthermore, non-invasive brain temperature measurement during therapeutic hypothermia might provide more information about the actual effect on the brain temperature.