A comparison of striatal-to-occipital ratio quantification approaches in F-FDOPA pet imaging

Background. Parkinson's disease (PD) can be challenging to diagnose in the clinical setting. 6-[18F] fluoro-L-3,4-dihydroxyphenylalanine (18F-FDOPA) PET imaging may assist in the diagnosis of Parkinson's disease by assessing pre-synaptic dopamine dysfunction. The striato-occipital ratio (SOR) is a measure of the uptake in the striatum (caudate and putamen) referenced against the activity in the occipital lobe (representing background activity). Manual quantification of these regions of interest (ROI) is commonly performed however this is time-consuming and may be susceptible to variances in inter-reader interpretation. Aims. The aim of this audit was to compare manual quantification of 18F-FDOPA PET SOR, performed as standard practice at our institution, to a commercially available automated SOR quantification program. Methods. The scans of 95 consecutive patients (40 female, 55 male, 59.77 ± 15.26 years) who underwent 18F-DOPA PET imaging for evaluation of Parkinsonism were retrospectively reviewed. Each PET scan was analysed using manual quantification by two Nuclear Medicine consultants, and the mean of these sets of quantitative values was compared against the automated quantification generated via Siemens SyngoVia software package MI-Neurology. This study has institutional approval as a Quality Initiative project. Results. 90 scans were evaluable by both manual and automated methods. Five patients who were unable to undergo automated quantitative analysis due to either inadequate image times or administrative errors were excluded from the comparative analysis. Statistical analysis comparing SOR obtained by manual and automated methods demonstrated high intraclass correlation (ICC), with minimal variance (Table 1). Conclusion. Automated quantification of SOR demonstrated statistically significant agreement with manual quantification methods highlighting its potential to be utilised to increase efficiency in 18F-FDOPA PET imaging interpretation.