Dopamine transporter SPECT imaging in corticobasal syndrome: A peak into the underlying pathology?

Background: Multiple pathologies may underlie corticobasal syndrome (CBS), including Alzheimer's disease (AD). Dopamine transporter density imaging with Ioflupane 123 I SPECT (DaTscan) may be normal in CBS. No studies to date have examined the relationship between DaTscan status and underlying pathology in CBS. Objectives: The main objective of the study was to test whether a normal DaTscan in CBS patients is indicative of an underlying AD pathology, as determined by cerebrospinal fluid (CSF) biomarkers. Methods: Eighteen CBS patients were included. They were divided into patients with an AD and a non‐AD disease pathology, based on their cerebrospinal fluid biochemical profile. A typical AD CSF profile was defined as an increase in total and phosphorylated at threonine 181 tau protein in addition to a decrease in amyloid‐beta with 42 amino acids. DaTscan data were compared in these two groups. Results: Eight of the 18 CBS patients (44%) had a normal DaTscan. Seven of the 18 CBS patients (39%) had an AD cerebrospinal fluid biochemical profile. Two of seven CBS patients with AD biomarker profile had abnormal DaTscans. Three of 11 CBS patients with a non‐AD biomarker profile had normal DaTscans. A normal DaTscan was indicative of AD pathology with suboptimal (~70%) sensitivity and specificity. Semi‐quantitative DaTscan analysis did not differentiate between AD from non‐AD CSF biomarker profile in CBS. Conclusion: A normal DaTscan is indicative of AD in CBS, but the sensitivity and specificity of DaTscan as an in vivo marker of AD pathology is suboptimal. [ABSTRACT FROM AUTHOR]