A brain scan is a non-invasive imaging test that captures detailed images of the brain’s condition, function, or structure. These procedures allow medical professionals to “see inside” the skull without surgery, providing valuable insights into neurological health. People seek brain scans for a variety of reasons, from investigating concerning symptoms to participating in scientific studies aimed at expanding our understanding of the brain.
Reasons for a Brain Scan
Brain scans are used for diagnosis when symptoms indicate a neurological issue. Persistent headaches, seizures, unexplained numbness, weakness, or changes in vision are common reasons for a scan. These imaging tests can help identify conditions such as stroke, brain injury, tumors, cysts, blood vessel abnormalities, or neurodegenerative diseases like Alzheimer’s and Parkinson’s.
Beyond diagnosis, scans also monitor known conditions. They track disease progression (e.g., multiple sclerosis) or assess treatment effectiveness for brain tumors or hydrocephalus. This allows healthcare providers to adjust treatment plans as needed. Individuals also participate in scientific research studies, contributing to a deeper understanding of brain function and the development of new treatments.
Types of Brain Scans
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) uses a powerful magnetic field and radio waves to create detailed images of brain structures. It works by aligning hydrogen atoms in water molecules, disrupting them with radiofrequency pulses. As atoms realign, they release energy detected by the scanner and converted into images. MRI is useful for visualizing soft tissues and detecting conditions such as tumors, strokes, multiple sclerosis, brain trauma, and structural abnormalities.
Computed Tomography (CT) Scan
A Computed Tomography (CT) scan uses X-rays to produce cross-sectional images of the brain, skull, and blood vessels. A donut-shaped scanner rotates around the head, capturing multiple X-ray views. These images are compiled by a computer to create 2D or 3D representations. CT scans are used in emergency situations due to their speed, for rapid detection of bleeding, swelling, or skull fractures.
Positron Emission Tomography (PET) Scan
Positron Emission Tomography (PET) scans provide insights into brain activity and metabolism using a radioactive tracer. This tracer, typically a glucose analog, is injected into a vein and travels to the brain. More active brain areas utilize more glucose and appear brighter, detecting early signs of diseases like Alzheimer’s, certain cancers, or epilepsy. The scan detects photons emitted as the tracer decays, creating an image map of tissue function.
Electroencephalography (EEG)
Electroencephalography (EEG) measures the electrical activity produced by brain neurons. Small metal discs called electrodes are placed on the scalp, detecting electrical impulses brain cells use to communicate. These signals are recorded by an EEG machine and displayed as wavy lines on a computer screen. While EEG has excellent temporal resolution, showing rapid changes in brain activity, its spatial resolution is more limited. This makes it useful for diagnosing conditions characterized by abnormal electrical patterns, such as epilepsy or certain sleep disorders.
The Process of Getting a Brain Scan
Obtaining a brain scan for medical reasons begins with a consultation with a primary care physician. Discuss all symptoms and medical history, as the doctor will evaluate the necessity of a scan and provide a referral as needed. For urgent concerns like suspected brain cancer or progressive neurological decline, an urgent referral, sometimes within 48 hours, may be issued.
After referral, an appointment is scheduled with an imaging center. Preparation varies by type; for an MRI, all metal objects must be removed, and patients with internal metal implants or pacemakers must inform staff due to the strong magnetic field. Some PET scans may require fasting, and for CT scans, a contrast dye might be administered to enhance image clarity.
During the scan, patients lie still on a table that slides into the imaging machine. MRI machines produce loud knocking sounds, so earplugs or headphones are provided, and communication with the technician is maintained via intercom. A CT scan lasts about 20 minutes, while an MRI can take between 30 to 60 minutes.
After the scan, the images are analyzed by a radiologist, a medical doctor specializing in imaging interpretation. The radiologist then sends a report to the referring physician, typically within one to two days for routine cases, or faster in emergencies. The patient will then discuss the results with their healthcare provider to understand findings and determine next steps.
The cost of a brain scan varies significantly, ranging from approximately $825 to $4,800 for a CT scan and $1,600 to $8,400 for an MRI without insurance. Most insurance plans cover medically necessary brain scans, but typically require a doctor’s referral and often prior authorization. Patients should contact their insurance provider to understand their specific coverage, deductibles, and potential out-of-pocket expenses.
For those interested in research, many universities and medical centers recruit healthy volunteers for brain imaging studies. These are generally free and may offer compensation. Eligibility criteria often include age limits and the absence of certain medical conditions or implanted devices.