Compare Rates of Agreement Between Clinical Diagnosis and Visual Assessment of DaTscan™ Images in Non-Caucasian and Caucasian Subjects With Parkinson's Disease (PD) or Essential Tremor (ET)

A Retrospective Clinical Study to Compare the Rates of Agreement Between Clinical Diagnosis and Visual Assessment of DaTscan™ Images in Non-Caucasian and Caucasian Subjects With Parkinson's Disease (PD) or Essential Tremor (ET)

The primary objective of this study is to determine if the diagnostic performance of DaTscan™ single photon emission computed tomography (SPECT) imaging is different in non-Caucasian subjects compared with Caucasian subjects with movement disorders.

Inclusion Criteria:

For Non-Caucasians:

• Non-Caucasian male and female adult participants (greater than or equal to 18 years of age) with an initial diagnosis of suspected PD or ET who underwent DaTscan SPECT imaging to assist with the participant's final clinical diagnosis of PD or ET.
• The participant had existing diagnostic-quality and interpretable DaTscan SPECT images of the brain.

For Caucasians:

• Caucasian male and female adult participants (greater than or equal to 18 years of age) with an initial diagnosis of suspected PD or ET who underwent DaTscan SPECT imaging to assist with the participant's final clinical diagnosis of PD or ET.
• The participant had existing diagnostic-quality and interpretable DaTscan SPECT images of the brain.
• The participant was matched by final clinical diagnosis, sex and age (±5 years) with a non-Caucasian participant.

Exclusion Criteria:

• Known/suspected structural abnormalities of the brain (e.g., hydrocephalus; brain tumor; stroke; etc.) that could grossly distort the DaTscan images.
• Participants whose race and ethnic information could not be determined from source document review.