Typically, a mild traumatic brain injury is diagnosed by a qualified medical professional as the result of a detailed neurological examination. Such medical professionals most often include emergency room doctors, neurologists, and neuropsychologists. It is also possible that imaging of the brain by a CAT scan, MRI, SPECT or PET will assist in the diagnosis. But it is well-accepted that brain injuries are notoriously difficult to diagnose and that they may not present themselves for extended periods of time following an accident. Physical, occupational and speech therapists may also play a role in evaluation of a patient’s brain function deficits. In addition to scans of the brain, various screening tools measure a person’s speech, movement, memory and thought. A cognitive evaluation by a neuropsychologist who has experience and training in formal neuropsychological testing is often used to diagnose a traumatic brain injury.