Scan duration for dopamine transporter neuroimaging with[¹²³I]FP-CIT and a high-sensitivity multiple-pinhole SPECT/CT

Dopamine transporter (DAT) imaging with [¹²³I]FP-CIT (Ioflupane, DaTscan™) is an established diagnostic tool for diagnosing parkinsonism and usually requires 40 min. of scanning. The three-headed high-sensitivity multiple-pinhole SPECT/CT scanner with dedicated brain multi-pinhole collimators (MPH) has in many respects superior performance and potentially enables a reduced scan duration, which can be a major advantage for patients and increases the number of patient studies that can be performed in one day. The aim of this study is to determine the minimal required scan duration that still returns good image quality and diagnostic accuracy in parkinsonism.

Fifty patients suspected of parkinsonism (age range 52-87 years) and 9 healthy controls (age range 57-66 years) underwent imaging with Mediso AnyScan Trio SPECT/CT and MPH collimators for 40 min. three hours after injection of 185 MBq [¹²³I]FP-CIT. The images were reconstructed using four different acquisition lengths: 10, 20, 30, and 40 min., and subsequently quantified with an automatic image-based analysis. Outcomes of the different acquisition lengths were compared by statistical analysis of the SBR-values and by visual assessment by experienced physicians.

Compared to 40 min. acquisitions and both in patients and healthy controls, 10 min acquisitions resulted in a significantly higher specific binding ratio (SBR) (≥ 0.5) in the striatum, putamen and caudate (p ≤ 0.001). SBR did not differ statistically significant between 30- and 40-min. acquisitions. Mean SBR difference between 20- and 40-min. scans with the 40-min. scan as a reference was 0.07 with 95% CI [-0.45, 0.59] for the striatum. Visual inspection of images showed that 20 min. acquisitions resulted in acceptable image quality (≥84% rated as sufficient).

We find that the scan time with DAT SPECT imaging on SPECT/CT and MPH collimators can be reduced to 20 min. without compromising image quality and diagnostic outcome. A scan duration of 20 min is beneficial for both patient comfort and the clinical workflow.