Magnetic Resonance Imaging (MRI) is an imaging technique used to visualize internal body structures. For the skull, an MRI scanner uses powerful magnetic fields and radio waves to generate detailed images of the brain, surrounding soft tissues, and structures within the inner ear and facial bones. Unlike X-rays or CT scans, MRI does not use ionizing radiation. Instead, it works by detecting changes in hydrogen protons in the body’s water content, translating these signals into anatomical pictures.
Reasons for a Skull MRI
Doctors order a skull MRI to investigate neurological symptoms and conditions affecting the brain and surrounding structures. This imaging method helps determine the underlying cause of persistent headaches, especially with other concerning signs. Individuals experiencing unexplained dizziness, seizures, or sudden changes in vision or hearing may also undergo a skull MRI to diagnose the cause.
A skull MRI is also used for evaluating suspected conditions like brain tumors and assessing the impact of a stroke. It can help diagnose inflammatory conditions such as multiple sclerosis, which causes lesions on nerve fibers, or infections like encephalitis and meningitis. It also helps investigate hormonal imbalances linked to the hypothalamus or pituitary gland, and changes in thinking or behavior.
Preparing for a Skull MRI
Preparation for a skull MRI involves steps to ensure patient safety and image clarity. Patients must inform the medical team about any metal implants or devices, such as pacemakers, cochlear implants, heart valves, or aneurysm clips. The strong magnetic field can interfere with these devices or pose a risk. It is also important to disclose any history of working with sheet metal, which might leave tiny metallic fragments in the eyes.
Before the scan, all metal objects must be removed. This includes:
Jewelry
Watches
Hearing aids
Hairpins
Clothing with metal zippers or buttons
Certain cosmetics, nail polish, and hair products can contain metallic particles that may distort images, so it is advisable to avoid them. If a contrast dye, typically gadolinium, will be administered, patients might receive instructions to fast for a few hours before the scan. Patients with kidney disease should also inform their provider, as kidney function can affect the safe use of contrast material.
What Happens During a Skull MRI
Upon arrival, patients change into a hospital gown. They then lie on a table that slides into the tunnel-shaped MRI scanner. The head is positioned within a specialized coil designed to capture detailed images of the brain. Some individuals may experience claustrophobia, and sedatives or an “open” MRI machine can be an option for comfort.
During the scan, the MRI machine produces loud noises, such as tapping or banging, due to the rapid switching of magnetic gradients. Patients are provided with earplugs or headphones to reduce the noise, and sometimes music can be played. The procedure usually lasts 30 to 60 minutes. Maintaining stillness is crucial for clear images; movement can blur them. If a contrast agent is needed, it is injected into a vein, which may cause a cool sensation or a temporary metallic taste.
What a Skull MRI Can Reveal
A skull MRI provides a view of the soft tissues and structures within the head. It can detect and characterize brain tumors, distinguishing between benign and malignant growths, and offering information about their size and location. The scan is also adept at identifying the aftermath of a stroke, revealing areas of brain damage, bleeding (hemorrhage), or blood clots.
It can reveal signs of neurodegenerative conditions such as multiple sclerosis, by visualizing lesions that represent areas of inflammation or damage to nerve fibers. It helps diagnose infections of the brain or its coverings, like encephalitis or meningitis, by showing inflammation or fluid buildup. The detailed images also allow for the detection of aneurysms, hydrocephalus, and structural anomalies present from birth. It can provide insight into unexplained symptoms like vision problems or hearing loss, by visualizing structures in the inner ear, optic nerves, and other cranial nerves.