Establishing On-Site Reference Values for (123)I-FP-CIT SPECT (DaTSCAN®) Using a Cohort of Individuals with...

To overcome the issue of reference values for DaTSCAN® requiring healthy controls, we propose an original approach using scans from individuals with non-degenerative conditions performed at one single center following the same acquisition protocol.

From a cohort of 970 consecutive patients, we identified 182 patients with a clinical diagnosis of non-degenerative parkinsonism or tremor and a visually normal DATSCAN®. Caudate nucleus (C), putamen (P), and striatum (S) uptake values, C/P ratios, and asymmetry indexes (AI) were calculated using semi-quantitative methods. Outcomes were assessed according to age and gender, and reference limits were established using the percentile approach.

A significant negative linear effect of age was found upon striatal nuclei uptake of 0.21-0.22 per decade (6.8%/decade for striatum), whereas a potential gender influence proved unclear. Inferior reference limits were established at the 5th percentile. C/P ratios and AIs were not influenced by age or gender, and superior reference limits were set at the 95th percentile.

We here propose a convenient approach to calculate site-specific reference limits for DaTSCAN® outcomes not requiring scanning healthy controls. The method appears to yield robust values that range within nearly identical limits as those obtained in healthy subjects.