DaTSCAN is not diagnostic. It cannot differentiate PD from other atypical parkinsonisms (PSP, MSA, etc.), so it has only been used as a supportive criterion along with a clinical exam, especially in younger patients.

DaTSCAN is sometime used to differentiate other forms of tremor from tremor-dominant PD, especially if they don’t respond to levodopa. In general, if a patient does not respond to levodopa (up to 600mg/day for at least 14 days), most likely the condition is NOT Parkinson’s and diagnosis might need to be reconsidered.

Hope this is helpful.

Debi