MRI’s and CT scans examine the structure of the brain and can be used to detect fractures, hemorrhages, swelling and some types of tissue damage. PET and SPECT scans examine the functioning of the brain.
An MRI uses a large magnet and radio waves to generate images of the brain without exposing the patient to x-ray radiation. MRI’s have a higher resolution than CT scans and can show differences in brain tissues based on their fat and water content. Patients must remain motionless for up to 20 minutes for MRI scanning so MRI scans may not be possible during the early stages of a brain injury. The location of a brain injury can be assessed using an MRI scan after the patient is more stable.
CT scans can detect physical changes in the brain such as blood clots and swelling, which may require immediate treatment. A CT scan uses x-rays taken from numerous angles to create cross-sectional images at different levels throughout the brain. CT scans are often used in the early phases of treatment to assess for life threatening conditions.
A SPECT scan measures blood flow and activity levels in the brain. SPECT scans can examine areas of the brain deeper than what can be seen from CAT scans and MRI’s . A SPECT scan indicates when there is too much or too little activity in one area of the brain, or when there are asymmetrical areas of activity that should be symmetrical.
A PET scan offers greater clarity than a SPECT scan but is a more expensive diagnostic test. PET scans color code parts of the brain based on the absorption of radioactively tagged glucose. Parts of the brain that are healthy absorb a lot of glucose and appear bright orange or red. Blue or purple indicates parts of the brain that absorb little glucose because they are damaged, dying, or dead.
An fMRI creates images of the brain nearly every second. An fMRI scan identifies with greater precision activity within certain brain regions and how long those regions remain active. This scan also identifies the exact areas of the brain being activated.
An EEG is a test that detects abnormal electrical activity in the brain. Persons who have sustained a head injury are 12 times more likely to suffer seizures than the general population. An EEG is the most useful test for diagnosing epilepsy. Seizures can be detected by using the EEG to monitor changes in the normal pattern of brain activity.
Neuropsychological testing consists of a battery of psychological tests conducted over a period of several hours. Such tests are recognized as specifically sensitive to the presence of brain dysfunction. Neuropsychological testing can identify brain impairments and provide useful information toward the development of cognitive remediation and rehabilitation strategies to improve cognitive function. Often, neuropsychological testing is conducted as part of a comprehensive neuropsychological evaluation of pre- and post-injury records from schools, employers, and medical providers, as well as the consideration of information provided by friends, family members, and co-workers regarding cognitive, emotional and physical changes apparent after the brain injury.