Thanks Megaspaz!) Like the left turn this is another hand signal that you should know if you have your license. Unlike the left hand turn this one is a little more tricky to figure out if you aren't familiar with it so don't expect your average car driver to know what this means.
A Single Photon Emission Computed Tomography (SPECT) scan is a type of nuclear imaging test that shows how blood flows to tissues and organs. A SPECT scan integrates two technologies to view your body: computed tomography (CT) and a radioactive material (tracer). The tracer is what allows doctors to see how blood flows to tissues and organs.
SPECT imaging uses an injected radioisotope to measure blood flow in different areas of the brain. Amen is exposing patients to radiation and charging them big bucks because his personal experience has convinced him SPECT is useful. So far, he has failed to convince the rest of the scientific medical community.