Pediatric MRI of the brain under anesthesia

An MRI of the brain requires cooperation from the patient, who mustn’t move for the duration of the exam (30 to 40 minutes). This constraint can lead to opportunity loss for many anxious, agitated or uncooperative children and young adults, depriving them of an exam that is essential to their diagnosis, treatment or follow-up care. The American Hospital of Paris is the only hospital to offer this procedure under short-term anesthesia for patients with autism, epilepsy, delayed development and neurodevelopmental disorders. 

Magnetic resonance imaging (MRI) uses a magnetic field (magnet) and radio waves to capture images of the human body thanks to the body’s hydrogen atoms. Placed within a magnetic field, all the hydrogen atoms turn to face the same direction. When stimulated by a radiofrequency pulse, they become “resonant” with the waves. When the pulse stops, the atoms release their stored energy by producing a signal, which is recorded and processed into images by a computer. No ionizing radiation is emitted.  
The MRI room is equipped with a machine comprising a tunnel-shaped magnet into which the scanning bed slides, and an antenna adapted to the various regions of the body to be explored.

MRI is the most precise imaging technique available for studying the brain. It can detect congenital morphological defects, enabling patients with epilepsy to seek neurosurgical treatment. It can highlight developmental disorders in the brain; assess vascularization and insufficient blood flow to the brain; and depict cerebrospinal fluid circulation in the brain’s ventricles.

In patients with autism, an MRI of the brain can detect possible inflammation, a developmental problem or insufficient blood supply to certain areas of the brain. In many developmental disorders, an MRI of the brain is the first step before conducting more in-depth, particularly genetic, investigations.

An MRI is a totally painless exam, but it is long and unpleasant due to the noise produced inside the machine. When under anesthesia, the patient doesn’t hear the noise.

The few contraindications and risks arise mainly from the use of a magnetic field. Any ferromagnetic materials implanted in the body which could be dislodged during the exam and any electromagnetically adjustable materials may present a risk for the patient or cease to function properly after an MRI.

Absolute contraindications for MRI include:

• Patients with a pacemaker (note that MRI-safe pacemakers have been available for several years; however, a consultation with a cardiologist before and after the MRI is necessary).
• Patients with metallic heart valves
• Patients with a brain or spinal cord neurostimulation device or a cochlear implant

Patients with a metallic foreign body must be assured of the absence of risk before undergoing an MRI. They include:    

• Patients that may have metal fragments in their eyes: a CT scan will determine the exact position of these foreign bodies in the eye socket.
• The same precautions must be taken for patients with a metallic foreign body near the vascular structures, particularly the arteries: an imaging exam must be done to verify the position of the foreign body in relation to the nearest organ.

As a precaution, best practice dictates that patients who have undergone a surgical implant of ferromagnetic material (artificial joints in particular) or vascular stents should wait at least three weeks after the surgery before undergoing an MRI. It is also important to know the exact nature of the material, in order to determine whether it is MRI-safe.

Allergies to the contrast medium (gadolinium) used for MRI occur far less frequently than allergies to iodine. The observed frequency of allergic reactions to gadolinium in children is from 1 to 4 /10,000; these reactions are almost always benign.

Contraindications and risks associated with anesthesia

At the American Hospital of Paris, the anesthesia protocol for children with autism includes the administration of clonidine, propofol and/or sevoflurane. The side effects and risks of these drugs are mainly respiratory, including hypoventilation, blocked breathing, regurgitation and inhalation of gastric contents (aspiration pneumonia).

Patients must refrain from eating solids for six hours and from drinking clear liquids for one hour before the MRI.

To ensure your child’s safety during the exam, we use airway management devices (laryngeal mask airway or endotracheal tube) and assisted ventilation. The new MRI room at the American Hospital of Paris is equipped with a non-magnetic ventilator. Patients are monitored by the anesthesiologist, who is present in the MRI room for the duration of the exam.

The effects of the anesthesia wear off after 20 to 30 minutes. However, full recovery of the upper body functions may take several hours. After being in the recovery room, your child will continue to be monitored in a resting lounge where he can have something to eat or drink and gradually resume normal activity before going home.

If you plan to return home with your own vehicle, an adult escort must be present in addition to the driver. Once home, your child may feel tired and need to sleep for a few hours, or she might have a temporary burst of energy. Whatever the case may be, there is no need to worry: simply let her resume normal activity at her own pace.

However, if he develops a fever above 38.5° C (101.3° F) or is unable to stay hydrated due to repeated vomiting, you must contact us.

The day of the procedure:

Go to the MRI department on Level -1. Your child must not eat any solids for six hours and must not drink clear liquids for one hour before the procedure. He must not be carrying or wearing any metallic objects such as a watch, ring, earrings or belt. Medications containing methylphenidate such as Ritaline®, Quasym® or Concerta® must be discontinued the day before the MRI.

You must bring:

• Carte Vitale insurance card
• MRI prescription
• Reports from any previous MRIs
• Consent form signed by both parents
• Tablet or favorite toy

Anesthesia consultation (around one week before the MRI):

Go to the Pediatric Department on the ground floor of the hospital.

You must bring:

• Health record (carnet de  santé)
• Letter from the child’s care facility detailing current care and medications
• Any hospitalization or surgery reports

At this time you may also finalize remaining any paperwork.

42 percent of the time, an MRI of the brain detects defects that are non-specific but manifest in young persons with autism.
For patients with epilepsy, an MRI raises the detection level of surgically curable focal brain lesions from 20 percent to 80 percent. 
Today, hundreds of children and young adults do not undergo MRI exams because the appropriate sedation/anesthesia is unavailable. This is an obvious loss of opportunity for them. 
The American Hospital of Paris is the only hospital to offer MRI under anesthesia for patients with autism, epilepsy, delayed development and neurodevelopmental disorders.