Clinical Relevance of Partial-Volume Effect: Dependence on Lesion size and Shape

This study sought to systematically assess the influence of partial-volume effect (PVE) and segmentation on PET quantitative measures, hinging on lesion geometry. How this affects, e.g., prevalent maximum standardised uptake values, SUV-{\max}, and potentially impact clinical applications, e.g., response evaluation has yet to be fully discerned. From PET simulations with open-source software of variable-sized ellipsoidal lesions inserted in an anthropomorphic phantom, images of two contrasts and resolutions were generated. SUV-{\max} and volumetric indices extracted with six different segmentations were compared for variability and test-retest repeatability. The study showed similar or larger shape dependent variability and lower repeatability in SUV-{\max} than SUV-{m\mathrm{e}an}. Alternative volumetric indices might provide more robust measures but require better contouring than common thresholding. Thus findings suggested significant impact of PVE and segmentation in clinically relevant lesion sizes that can bias interpretation of SUV changes.