Partial Volume Averaging - Video Lesson

This CT artifact lesson is about something we call partial volume averaging. Partial volume averaging is just the result of different tissues being averaged together into one slice. Obviously, this happens all of the time in CT, but sometimes it can become a problem. So this artifact is a result of multiple tissues being averaged together into one slice, but this can sometimes result in the misrepresentation of tissues or pathologies, and it is more likely with thicker slices. In the image to the left, you can see in the pulmonary artery, it really looks like there's pulmonary embolism. Here's an example of that same image. The red arrow is pointing at the filling defect in the left pulmonary artery and really does look like a pulmonary embolism. That's a five millimeter slice. When you compare that five millimeter slice to a thinner one millimeter slice, that filling defect is suddenly gone. So what's going on? What happened in the five millimeter slice is the contrast in