Assessment of different based regions of interest methods for [99mTc]Tc DAT-SPECT quantification using an anthropomorphic striatal phantom.

Abstract Background and Aims: Molecular imaging of the dopamine transporters (DAT) provides usefull information about neurodegenerative diseases, such as Parkinson’s. This study assessed the accuracy and precision of DAT-SPECT quantification methods. Methods: Twenty-three DAT-SPECT images of a striatal phantom. The specific chambers (caudate and putamen) and the nonspecific background activity chamber were filled with 99m Tc in different specific to nonspecific ratios of activity (10, 8, 6, 4 and 2 to 1). Then, the specific binding ratio (SBR) was determined. Five methods using ROIs were assessed: (a) Manual ROIs on SPECT images; (b) TwoBox and (c) ThreeBox Methods and VOIs using structural images; (d) MRI and (e) CT. Accuracy was evaluated by the concordance correlation coefficient (CCC) and precision by the Pearson’s coefficient and linear regression. Results: The SBR quantified in the specific and striatal chambers resulted in a CCC increase with a decrease of the nominal values used. For lower SBR, MRI and CT showed higher CCCs when caudate (CCC MRI-CA = 0.89 e CCC CT-CA = 0.84) and putamen (CCC MRI-PU = 0.86 e CCC CT-PU = 0.82) were evaluated. For striatal assessments, the TwoBox method was the most accurate (CCC TWOBOX-ST = 0.95). High Pearson’s coefficients were found in the correlations between all methods. Conclusions: All five methods showed high precision even when applied in images with different activity. For the individual assessment of the caudate or putamen, MRI and CT were the most accurate. To assess the striatal chamber and in the absence of structural information, the TwoBox method is advisable.