Magnetic resonance imaging (MRI) is becoming increasingly important in the diagnosis and follow-up of pediatric diseases. However, successful MRI requires complete and prolonged immobility, which can be challenging for young children and infants. To overcome this challenge, various anesthesia techniques are employed by anesthesiologists. The ideal anesthesia method for children during MRI should be both safe and enable rapid recovery, allowing the child to remain still during the procedure while minimizing risks during the recovery period.

**Sevoflurane has become a popular choice for this purpose due to its rapid onset, limited respiratory side effects at low concentrations, reduced airway irritation, and hemodynamic stability. However, propofol and ketamine, used as an alternative sedation method, are also being increasingly utilized during these procedures. The major side effects of propofol include respiratory depression, apnea, loss of protective reflexes, and hemodynamic instability. To minimize these side effects, some experts recommend the combined use of propofol and ketamine. This combination provides effective sedation while also contributing to a reduction in side effects.

In this context, the aim of our study is to compare the efficacy of intravenous propofol and ketamine with sevoflurane administered via a face mask during pediatric MRI.

Participants were randomized in a 1:1 ratio using a computer program, stratified based on MRI durations, and divided into two groups: Group S and Group P.

All participants received intravenous midazolam at a dose of 0.05 mg/kg (max 2 mg). During MRI, all patients were monitored with pulse oximetry and end-tidal CO2, and procedural oxygen masks (POM) were applied to deliver oxygen at a flow rate of 5 L/min. For Group S, 8% sevoflurane was administered for induction via the procedural oxygen mask for 2 minutes through the external output of the anesthesia machine. The concentration was then reduced to 2%. If any undesired movements occurred, they were recorded, and the sevoflurane concentration was increased by 0.5%.

In Group P, 1 mg/kg ketamine was administered intravenously, followed by 1.0 mg/kg propofol as a bolus. In the event of undesired movements, an additional 0.5 mg/kg of propofol was administered, and all additional doses were recorded. The target sedation level was set at a Ramsay Sedation Scale (RSS) score of 4, which was maintained throughout the procedure. At the end of the procedure, patients were awakened with verbal and tactile stimulation. Once an RSS score of 2 was achieved, they were transferred to the Post-Anesthetic Care Unit (PACU).

Vital signs, procedure durations, and drug doses were recorded for each patient during the procedure. All clinical decisions regarding the patients were made by the attending anesthesiologist. In the PACU, patients with a modified Aldrete score of 10 were deemed eligible for discharge. After discharge approval, all patients were observed in the outpatient unit for 1 hour. The study concluded at this point.

Inclusion Criteria:

• Ages 3 months to 10 years.
• Classified as ASA I-II according to the American Society of Anesthesiologists (ASA) classification.
• Patients scheduled for MRI at Kocaeli City Hospital MRI unit.

Exclusion Criteria:

• Families or children who do not consent to participate in the study.
• Patients with allergies to ketamine, propofol, midazolam, or sevoflurane.
• Patients with known pulmonary or cardiac diseases.
• Patients with known congenital craniofacial or neck anomalies.
• Patients dependent on oxygen therapy.
• Patients with a recent respiratory tract infection within the past 2 weeks.
• Patients requiring tracheal intubation, laryngeal mask, or ventilator support.
• Patients at risk of upper airway obstruction.
• Patients with behavioral problems.
• Patients with gastroesophageal reflux disease.
• Patients with lethargy, stupor, or unresponsiveness to stimuli due to any cause
• Patients with active use of antiepileptic or antipsychotic medications

Personal data and study data will not be shared.

Only the participants will be blinded, making this a single-blind study design. The second anesthesiologist measuring the values in the PACU will also remain blinded to the group assignments.