Using Nuclear Medicine to Determine Brain Death

Nuclear Medicine Exam for Determining Brain Death

I learned something new at work the other day: how to determine if a person is brain dead.  No, there's no punchline.  This isn't a joke. I work in Radiology and a co-worker was doing a study on a young lady that partied a little too hard on her birthday.  So hard that she ended up in our ICU (Intensive Care Unit) and was completely unresponsive to external stimuli.

Turns out, there is a medical test to determine brain death.  I remember not too long ago they used to do EEGs (electroencephalograms) to examine brain wave activity.  You've seen the pictures on television most likely. A bunch of wires gets hooked up to electrodes on a person's head and the electric impulses are displayed on a machine that draws big wavy lines on paper.

Well, in this particular case, a Nuclear Medicine Brain Scan was ordered. For this test, a particular radioactive chemical is injected into the patient using an IV (intravenous catheter).  This particular chemical is taken up by the brain and carried around or perfused throughout the brain during normal brain activity. In a person with no brain activity, the chemical simply does not show up in the area of the brain.

For this particular type of test, the chemical shows up as a dark color, much like the outline of the body in the picture below does.  Therefore, in the following picture, the area of the brain showing no dark colors indicates that this patient has no brain activity, ie brain death.

This is a delayed image test meaning that images are taken every five minutes or so to "track" the flow of the radioactive chemical.  You can see the flow appearing darker throughout the body (shoulders, neck, and face) but none shows up within the brain cavity.

Here is an example of normal brain perfusion:

Notice how the brain becomes darker colored as does the rest of the body? That is a sign of normal brain perfusion. Here's a larger version:

The brain above is noted as "robust cerebral and cerebellar profusion".

I've been in healthcare for a long time and I had never seen one of these studies. I looked it up and in the four years my current hospital has been open, we've only done four of these. Coincidentally, three of the four were young females.

So, now you know one-way doctors can officially determine brain death.