Validation of Simple Quantification Methods for $^{18}F$-FP-CIT PET Using Automatic Delineation of Volumes of Interest Based on Statistical Probabilistic Anatomical Mapping and Isocontour Margin Setting

다국어 초록 (Multilingual Abstract)

Purpose $^{18}F$-FP-CIT positron emission tomography (PET) is an effective imaging for dopamine transporters. In usual clinical practice, $^{18}F$-FP-CIT PET is analyzed visually or quantified using manual delineation of a volume of interest (VOI) for the striatum. In this study, we suggested and validated two simple quantitative methods based on automatic VOI delineation using statistical probabilistic anatomical mapping (SPAM) and isocontour margin setting. Methods Seventy-five $^{18}F$-FP-CIT PET images acquired in routine clinical practice were used for this study. A study-specific image template was made and the subject images were normalized to the template. Afterwards, uptakes in the striatal regions and cerebellum were quantified using probabilistic VOI based on SPAM. A quantitative parameter, $Q_{SPAM}$, was calculated to simulate binding potential. Additionally, the functional volume of each striatal region and its uptake were measured in automatically delineated VOI using isocontour margin setting. Uptake-volume product ($Q_{UVP}$) was calculated for each striatal region. $Q_{SPAM}$ and $Q_{UVP}$ were compared with visual grading and the influence of cerebral atrophy on the measurements was tested. Results Image analyses were successful in all the cases. Both the $Q_{SPAM}$ and $Q_{UVP}$ were significantly different according to visual grading (P<0.001). The agreements of $Q_{UVP}$ or $Q_{SPAM}$ with visual grading were slight to fair for the caudate nucleus (${\kappa}$=0.421 and 0.291, respectively) and good to perfect to the putamen (${\kappa}$=0.663 and 0.607, respectively). Also, $Q_{SPAM}$ and $Q_{UVP}$ had a significant correlation with each other (P<0.001). Cerebral atrophy made a significant difference in $Q_{SPAM}$ and $Q_{UVP}$ of the caudate nuclei regions with decreased $^{18}F$-FP-CIT uptake. Conclusion Simple quantitative measurements of $Q_{SPAM}$ and $Q_{UVP}$ showed acceptable agreement with visual grading. Although $Q_{SPAM}$ in some group may be influenced by cerebral atrophy, these simple methods are expected to be effective in the quantitative analysis of $^{18}F$-FP-CIT PET in usual clinical practice.