MRI Under General Anesthesia

When imaging methods such as X-ray, computed tomography (CT), and ultrasonography are insufficient for diagnosis, magnetic resonance (MR) imaging may be required. However, compared to other imaging methods, this examination has certain limitations: it takes longer, requires the patient to remain still during the procedure, and involves entering the tube-shaped magnetic field. MR imaging under anesthesia can solve the imaging challenges for this restricted group of patients.

In Which Cases is MR Imaging under Anesthesia Needed?

MR imaging under anesthesia may be required in patients who:

• Cannot remain still or are expected to be unable to (e.g., altered consciousness or dementia)
• Are children of an age or condition unable to follow instructions (e.g., breath-holding commands)
• Experience significant pain when lying on their back (MR scans are usually performed in the supine position)
• Require ventilator support
• Suffer from claustrophobia (fear of enclosed spaces, e.g., entering the MR tube)

Because MR operates using a strong magnetic field, patients must be screened for certain conditions before entering the MR room, including:

• Presence of a pacemaker
• Metallic implants of unknown composition
• Removable metallic dental devices
• Metal fragments in the eye that could moveAneurysm clips in brain vessels

The presence of any of these can prevent MR imaging. Additionally, a history of allergies that could interfere with anesthetic drugs will also be evaluated before the procedure.

How is MR Imaging under Anesthesia Performed?

During the procedure, having an empty stomach helps prevent stomach contents from entering the airways in case of vomiting. Therefore, depending on the patient’s age, a fasting period of approximately 4–6 hours is usually required.

Before the scan, anesthesia is administered by a specialized anesthesiologist, typically either through inhalation of a gas or intravenous medication. The primary goal is to ensure the patient remains still during the MR scan.

The anesthesiologist monitors the patient’s blood pressure, heart rate, body temperature, and respiration-oxygen saturation throughout the procedure. This monitoring is performed using MR-compatible equipment designed to function safely within the magnetic environment.

The anesthetized MR examination may last approximately 30–90 minutes, depending on the area being scanned and whether intravenous contrast is used. After the procedure, patients may require 1–2 hours of observation to ensure the effects of anesthesia have worn off.

Patients may experience mild drowsiness, fatigue, or decreased attention for the rest of the day due to anesthesia. Considering these effects, it is recommended that adult patients also attend anesthetized MR scans with a companion.