Sedation and monitoring of paediatric patients undergoing open low-field MRI

The purpose of this study was to determine the need, effectiveness and safety of sedation and monitoring in infants and children in a paediatric open low-field MRI system. Of 274 patients (median age 9 y) examined, only 74 children (median age 25 mo) needed sedation. Sedation was achieved by intravenous administration of midazolam (0.2 mg/kg) and etomidate (0.2 mg/kg). Mean total doses required were 0.28 and 0.27 mgl/kg, respectively. With the exception of eight primarily ventilated patients, all children breathed spontaneously. O2 saturation, arterial blood pressure and ECG were monitored. The low resonance frequency of the MRI system required a specially designed high frequency (HF) shielding of the monitor system to avoid HF artifacts. The overall sedation rate was markedly lower (74/274 = 27%) compared to a control group previously examined in a closed high-field MRI system (52/111 = 47%). This was due to a significant lower need for sedation in patients aged up to 10 y (p < or = 0.0001) in the open MRI unit. General anaesthesia could be avoided in all patients. No significant movement artifacts occurred in any of the MRI examinations and no serious side effects were observed.

MRI of children is easier in an open MRI system and with fewer sedations, as in closed high-field systems. Sedation by a combination of midazolam and etomidate is highly effective and safe. Monitoring devices for high-field systems may have to be modified for low-field systems. An in-house paediatric MRI unit with an open and special paediatric design is of major advantage for imaging paediatric patients.