Brain scans, such as MRI and CT, are used to get a picture of what the brain looks like. They are often normal in Lesch-Nyhan disease. In some cases, portions of the brain may appear smaller than normal. Because the brain scans are usually normal, they are not used for diagnosis of the disorder.
On the other hand, brain scans, such as PET, are used to get a picture of how the brain is working. PET scans have shown a problem with a region of the brain called the basal ganglia. Exactly what is going on in this region is not yet understood. These scans have been valuable for telling us what area of the brain we must look into more carefully, but the scans can't give us all the answers. In some cases, researchers need to look into the brain directly, as described in the next section.