Differences in [¹²³I]Ioflupane Striatal Binding Between African American and White Patients

Abstract

Ethnic differences exist among patients with Parkinson disease (PD). PD is more common in the White than the African American population. This study aimed to explore whether differences exist in [¹²³I]ioflupane binding, which reflects dopamine transporter binding, between African American and White individuals. Methods: Medical charts were reviewed for patients who underwent [¹²³I]ioflupane SPECT imaging as part of routine practice in a single academic medical center. All images were visually graded as showing normal or abnormal presynaptic dopaminergic function (normal or abnormal scan status). Quantitative [¹²³I]ioflupane uptake as measured by the specific binding ratios in the right and left striata and their subregions (caudate nucleus and anterior and posterior putamen) and by bilateral putamen-to-caudate ratios were compared between African American and White patients using multiple linear regression adjusted for age, sex, and abnormal scan status. Additional models included an ethnicity–by–abnormal-scan-status interaction term to determine whether abnormal scan status was modulated by ethnicity effect. Results: The percentage of patients with abnormal scan status was comparable between African American and White patients. Compared with White patients (n = 173), African American patients (n = 82) had statistically significantly higher uptake as measured by specific binding ratios in the right and left striata and some of their subregions (right and left caudate nuclei and right posterior putamen). Ethnicity–by–abnormal-scan-status interactions were not statistically supported for any models. Conclusion: We observed differences in [¹²³I]ioflupane binding between African American and White patients independent of presynaptic dopaminergic dysfunction status. Future studies are needed to examine whether and how ethnicity affects dopamine transporter binding activities and its clinical relevance.