ADRSupport Community - MRI report question

That is a good thing and normal. A link to the wikipedia MRI physics section is below. Here's the basic info for your question: When you are placed in the MRI unit, a certain number of the protons in hydrogen in water molecules in your body start to line up in the direction of the magnetic field. These protons are normally spinning in no orderly fashion, but in a strong magnetic field, a fraction of them will all start to spin in the same direction.

The MRI equipment then rapidly and repeatedly sends a radio pulse through the area being examined which changes how these protons spin. After each pulse, the equipment "listens" for the energy given up by the protons as they return to their direction of spin in the magnet. The computer then generates an image based on how long it takes for each proton to give up the energy and how much energy is given up. "Signal" in radiology reports usually means how bright something is on the picture.

Signal void means no signal was detected. That can be caused by tightly bound protons like in ligaments and tendons which are dark or by very few protons such as in air-containing structures.

In your question, signal void means that blood is flowing through the blood vessels. That happens because the protons that were changed by the radio pulse moved out of the area being imaged before they could give off their energy. No signal was received, so the area is shown as dark on the MRI picture.

If anyone is still with me, signal void in a blood vessel is good. It means that the blood is flowing. Using special techniques, MRI can give information about the direction and speed of the blood flow as well. However, you can't get that information from the imaging techniques used for routine spine MRI.

Well, I went much longer than I wanted. If your brave enough, check out the wiki link.

http://en.wikipedia.org/wiki/Magnetic_resonance_imaging