Kim Annink

218 Chapter 10 ABSTRACT Background: Little is known about brain temperature of neonates during MRI. Brain temperature can be estimated non-invasively with proton Magnetic Resonance Spectroscopy ( 1 H-MRS), but the most accurate 1 H-MRS method has not yet been determined. The primary aim was to estimate brain temperature using 1 H-MRS in infants with neonatal encephalopathy following perinatal asphyxia (NE). The secondary aim was to compare brain temperature during MRI with rectal temperatures before and after MRI. Methods: In this retrospective study, brain temperature in 36 (near-)term infants with NE was estimated using short (36ms) and long (288ms) echo time (TE) 1 H-MRS. Brain temperature was calculated using two different formulas: formula of Wu et al. and a formula based on phantom calibration. The methods were compared. Rectal temperatures were collected <3hours before and after MRI. Results: Brain temperatures calculated with the formula of Wu et al. and the calibrated formula were similar as well as brain temperatures derived from short and long TE 1 H-MRS. Rectal temperature did not differ before and after MRI. Conclusion: Brain temperature can be measured using 1 H-MRS in daily clinical practice using the formula of Wu et al . with both short and long TE 1 H-MRS. Brain temperature remained within physiological range during MRI.