Evaluation with heterogeneous experimental phantoms of the impact of the intrinsic PET/CT system resolution on the robustness of radiomics-features: digital versus analog PET

Ziel/Aim The use of image features in Radiomics (radiomics-features, RF) requires an additional level of robustness beyond what is required for diagnostic imaging. The spatial resolution and signal to noise ratio conveyed by each modality have been proved to have an impact on RF variability. In the context of PET/CT systems development, recent efforts have been focused on the use of digital (d-) detectors instead of the conventional analog (a-) design. Although recent publications have reported the improvement in lesion detectability conveyed by d-PET/CT systems, their impact on RF robustness has not been previously investigated. The aim of our work was to evaluate if d-PET/CT imaging could improve RF robustness.

Methodik/Methods Twenty-seven heterogeneous phantoms, based on a mixture of fluorine-18 Fluorodeoxyglucose and alginate, have been placed in the NEMA-Phantom fulfilled with a background concentration (Bg). Each lesion presented three activity concentrations: high (HC), medium (MC=HC/2) and lower (LC = 10Bg). The measurements consisted on: (i) 18 lesions with the same size (22 ml) but different contrast (HC/LC: 10, 8 and 4) and (ii) 9 lesions with HC/LC = 6, but different sizes (0.7 to 12 ml). Scans from two PET/CT systems were analyzed: a-GEMINI-TF16-BigBore (BB) and d-Vereos (V). Three hours acquisition with V was stablished as a reference and the robustness of 135 RF was evaluated with respect to 10 min scans with both systems (BB-10min and V-10min). Analysis was based on Wilcoxon-Signed-Rank-Test (WSRT) and Spearman’s correlation (SC).

Ergebnisse/Results Enlarged number of RF showed a strong correlation (r > 0.8 and p < 0.05/135, Bonferroni correction), i. e. equivalent classification, for V-10min than for BB-10min: 134 vs 113 in (i) and 127 vs 109 in (ii). WSRT showed that more RF were comparable for V-10 min than for BB-10 min: 52 vs 25 in (i) and 51 vs 23 in (ii).

Schlussfolgerungen/Conclusions We could therefore conclude that the improved detectability of lesions observed by the d-V translated in an improvement of RF robustness.