Table 3 Descriptions of used VOI methods and quantitative metrics
From: Quantitative implications of the updated EARL 2019 PET–CT performance standards
VOI methods | Description |
A50P | Region-growing-based VOI using 50% of SUVpeak with adaptation to local tumor-to-background contrast [32, 30] |
SUV4 | Region-growing-based VOI using a threshold of SUV equal to 4 |
MAX41 | Region-growing-based VOI using a threshold equal to 41% of SUVmax |
Quantitative metrics | Description |
MATV | Volume of a lesion segmented using A50P, SUV4 or MAX41 method in mL |
SUVmean | Ratio of image-derived average radioactivity concentration within a region of interest and the estimated whole body concentration of the injected radioactivity, normalised to bodyweight |
SUVmax | Ratio of image-derived maximum (single pixel) radioactivity concentration within a region of interest and the whole body concentration of the injected radioactivity, normalised to bodyweight |
SUVpeak | Ratio of image-derived average radioactivity concentration within a 12-mm-diameter spherical volume (taking into account fractional voxels) within the region of interest, positioned to yield the highest uptake across all tumor voxel locations, and the whole body concentration of the injected radioactivity, normalised to bodyweight [30, 31] |
TLG | Total lesion glycolysis equal to the MATV times SUVmean |