Brain scans are imaging tests taken of the head to identify possible injury or disease of the brain. A physician might recommend a brain scan for many reasons, such as diagnosing disease, monitoring disease progression or healing, and planning treatment.

Various neurological conditions can be diagnosed with a brain scan. These include brain tumors, cerebral aneurysm, stroke, cranial neuralgia, infection, cerebral palsy and some movement disorders (e.g., multiple sclerosis, amyotrophic lateral sclerosis).

Different types of imaging technology are available for brain imaging purposes. The most common technologies used for brain scans include magnetic resonance imaging (MRI), computed axial tomography (CAT) and positron emission tomography (PET).

Brain scans are typically painless and minimally invasive. In many cases, any potential risks are outweighed by the information obtained that is helpful in diagnosis and treatment. In certain cases, information obtained through brain scans can lead to life-saving treatments.

Preparation for a brain scan depends on the type of imaging test being used. Patients are generally asked to remove all metallic objects, and in some cases, they might be asked to restrict what they eat or drink for a certain length of time prior to the examination. Patients should also inform their physician about any medical conditions (including allergies), medications they are currently taking, and whether they are pregnant or breastfeeding.

Most brain imaging scans are performed by a technician in a hospital or outpatient clinic. The exact steps of the procedure differ, depending on the imaging technology used. In most cases, a patient is asked to lie still on a scanning table, surrounded by imaging equipment. Machinery noise is common in most procedures, although patients may be given earphones or headphones to help them relax. The length of the test varies, although brain scans on average take about an hour to complete. Patients can generally return to their regular daily routines immediately after the brain scan is completed.