Table 2.

Reporting guidelines on the computation of radiomics features (adapted from Refs.⁶⁵ and ¹⁴⁶).

GENERAL
Image acquisition	Acquisition protocols and scanner parameters: equipment vendor, reconstruction algorithms and filters, field of view and acquisition matrix dimensions, MRI sequence parameters, PET acquisition time and injected dose, CT x-ray energy (kVp) and exposure (mAs), etc.
Volumetric analysis	Imaging volumes are analyzed as separate images (2D) or as fully-connected volumes (3D).
Workflow structure	Sequence of processing steps leading to the extraction of features.
Software	Software type and version of code used for the computation of features.
IMAGE PRE-PROCESSING
Conversion	How data were converted from input images: e.g, conversion of PET activity counts to SUV, calculation of ADC maps from raw DW-MRI signal, etc.
Processing	Image processing steps taken after image acquisition: e.g., noise filtering, intensity non-uniformity correction in MRI, partial-volume effect corrections, etc.
ROI SEGMENTATION a;b	How regions of interests (ROIs) were delineated in the images: software and/or algorithms used, how many different persons and what expertise (specialty, experience), how a consensus was obtained if several persons carried out the segmentation, in automatic or semi-automatic mode, etc.
INTERPOLATION
Voxel dimensions	Original and interpolated voxel dimensions.
Image interpolation method	Method used to interpolate voxels values (e.g, linear, cubic, spline, etc.) as well as how original and interpolated grids were aligned.
Intensity rounding	Rounding procedures for non-integer interpolated gray levels (if applicable), e.g., rounding of Hounsfield units in CT imaging following interpolation.
ROI interpolation method	Method used to interpolate ROI masks. Definition of how original and interpolated grids were aligned.
ROI partial volume	Minimum partial volume fraction required to include an interpolated ROI mask voxel in the interpolated ROI (if applicable): e.g., a minimum partial volume fraction of 0.5 when using linear interpolation.
ROI RE-SEGMENTATION
Inclusion/exclusion criteria	Criteria for inclusion and/or exclusion of voxels from the ROI intensity mask (if applicable), e.g., the exclusion of voxels with Hounsfield units values outside a pre-defined range inside the ROI intensity mask in CT imaging.
IMAGE DISCRETIZATION
Discretization method	Method used for discretizing image intensities prior to feature extraction: e.g., fixed bin number, fixed bin width, histogram equalization, etc.
Discretization parameters	Parameters used for image discretization: the number of bins, the bin width and minimal value of discretization range, etc.
FEATURE CALCULATION
Features set	Description and formulas of all calculated features.
Features parameters	Settings used for the calculation of features: voxel connectivity, with or without merging by slice, with or without merging directional texture matrices, etc.
CALIBRATION
Image processing steps	Specifying which image processing steps match the benchmarks of the IBSI.
Features calculation	Specifying which feature calculations match the benchmarks of the IBSI.

^aIn order to reduce inter-observer variability, automatic and semi-automatic methods are favored.

^bIn multimodal applications (e.g., PET/CT, PET/MRI, etc.) ROI definition may involve the propagation of contours between modalities via co-registration. In that case, the technical details of the registration should also be provided.