Frontotemporal dementia (FTD) is a dementia that occurs in the frontal and temporal lobes of the brain. The lobes will shrink over time, which causes problems in brain functioning, especially
with personality, behaviors and language.
Symptoms of FTD include:
1) Changes in personality: a person can become behaviorally impulsive or emotionally labile
2) Loss of ability to use and understand language
3) Movement: sometimes there can be rigidity, weakness, and muscle spasms
FTD is often misdiagnosed as a psychiatric problem, because there is no one specific test that can be done to identify it. So, to answer your question, PET scans cannot truly diagnose FTD, although they may see some of the atrophy that occurs in this disease. FTD is usually diagnosed clinically, which means health professionals attempt to identify the disease by finding characteristic features in their patients. All the testing that is done, like neuroimaging, are used to rule out other causes of neurological changes, like clots on the brain, bleeding or tumors.
One thing that can be helpful in diagnosis is neuropsychological testing, which is comprehensive memory testing that is usually done to help try to differentiate between the different types of dementia.