Positron Emission Computed Tomography or PET

PET Scanning is the best imaging technique to assist in the diagnosis of subtle brain injury because it is a functional imaging test, very sensitive to the diffuse changes seen after concussion.

The advantage of functional imaging studies is that by measuring some aspect of brain function, it can show us something about the living brain that an evaluation of its structures alone cannot. Because they show how the brain is functioning, they can identify evidence of diffuse, yet microscopic, brain damage. When radio labeled compounds are injected in tracer amounts, their photon emissions can be detected much like x-rays in CT. The images made represent the accumulation of the labeled compound. The compound may reflect, for example, blood flow, oxygen or glucose metabolism, or dopamine transporter concentration. Often these images are shown with a color scale.

Functional tests include:

• PET
• SPECT
• FMRI
• MRI – Spectroscopy: New, but may be the breakthrough test.
• EEG and QEEG, i.e., Brain Mapping.
• Evoked response.

The way in which a functional test does this is by looking at how the brain is functioning, by examining a specific aspect of a brain’s function, such as glucose or oxygen consumption in the case of PET.

PET Scanning features:

• PET uses a radioactive isotope.
• PET is positive in a significant majority of subtle cases.
• PET is highly correlative to Neuropsych Testing.
• PET is the best way to determine the severity of brain damage in catastrophic brain injury.

NEXT: SPECT.

Understanding Subtle Brain Injury

The concussions that disable, are almost always more symptomatic at 24 hours, than at the 2-4 hour time frame when injured persons are evaluated in the emergency room. Brain injury symptoms escalate over the first 24 hours, because brain injury involves a cascade of events. It is critical that if you are still symptomatic the day after your injury, go back to the same Emergency Room, don’t wait for a doctors appointment. It is critical that the Emergency Room personnel see that the symptoms still persist or have gotten worse.

View Our Video Series on Concussions