Parameters Influencing PET Imaging Features: A Phantom Study with Irregular and Heterogeneous Synthetic Lesions

Abstract

Aim To evaluate reproducibility and stability of radiomic features as effects of the use of different volume segmentation methods and reconstruction settings. The potential of radiomics in really capturing the presence of heterogeneous tumor uptake and irregular shape was also investigated. Materials and Methods An anthropomorphic phantom miming real clinical situations including synthetic lesions with irregular shape and nonuniform radiotracer uptake was used. 18F-FDG PET/CT measurements of the phantom were performed including 38 lesions of different shape, size, lesion-to-background ratio, and radiotracer uptake distribution. Different reconstruction parameters and segmentation methods were considered. COVs were calculated to quantify feature variations over the different reconstruction settings. Friedman test was applied to the values of the radiomic features obtained for the considered segmentation approaches. Two sets of test-retest measurement were acquired and the pairwise intraclass correlation coefficient was calculated. Fifty-eight morphological and statistical features were extracted from the segmented lesion volumes. A Mann–Whitney test was used to evaluate significant differences among each feature when calculated from heterogeneous versus homogeneous uptake. The significance of each radiomic feature in terms of capturing heterogeneity was evaluated also by testing correlation with gold standard indexes of heterogeneity and sphericity. Results The choice of the segmentation method has a strong impact on the stability of radiomic features (less than 20% can be considered stable features). Reconstruction affects the estimate of radiomic features (only 26% are stable). Thirty-one radiomic features (53%) resulted to be reproducible, 11 of them are able to discriminate heterogeneity. Among these, we found a subset of 3 radiomic features strongly correlated with GS heterogeneity index that can be suggested as good features for retrospective evaluations.

Impact of contouring variability on oncological PET radiomics features in the lung

“…Concerns of reproducibility and reliability have been investigated by several studies with emphasis being put, respectively, on the impact onto PET radiomics features due to factors including PET scanner manufactures, acquisition and reconstruction algorithms, intensity discretization scheme, etc. [11][12][13][14] . As for the variability of contouring volume of interest (VOI) for inclusion to radiomics analysis, only a few existing studies investigated its impact on PET radiomics parameters 15,16 , even though contouring variability is commonly recognized as the largest source of error in the RT planning process 17 .…”

The Applications of Radiomics in Precision Diagnosis and Treatment of Oncology: Opportunities and Challenges

“…Recent results from Yan et al 26 and Veld et al 27 further confirmed this finding. Recently, Gallivanone et al 28 found that reconstruction settings largely affects the stability of radiomic features, and only 26% were stable when different parameters were considered in this anthropomorphic phantom study. Respiratory motion is another factor that should be concerned.…”

Physical imaging phantoms for simulation of tumor heterogeneity in PET, CT, and MRI: An overview of existing designs

“…In a recent study, lesions from oncological patients were segmented and 3D printed as shell compartments, which were filled with [18F]FDG radioactive gels . Plastic filaments of 3 mm diameter (Renkforce PLA300 Plastic PLA 3 mm) were used to imprint the compartments.…”

“…(b) Positron emission tomography images of three simulated heterogeneous lesions. Copyright © 2018 Francesca Gallivanone et al [Color figure can be viewed at wileyonlinelibrary.com]…”