Table 4.
Radiomic features extracted from DCE sequence and their descriptions.
| Category | Feature name (unit) | Feature description |
|---|---|---|
| Geometry19 | Volume () | Volume of lesion |
| Effective diameter (mm) | Greatest dimension of a sphere with the same volume as the lesion | |
| Surface area () | Lesion surface area | |
| Maximum diameter (mm) | Maximum distance between any two voxels in the lesion | |
| Sphericity | Similarity of the lesion shape to a sphere | |
| Irregularity | Deviation of the lesion surface from the surface of a sphere | |
| Surface area/volume (1/mm) | Ratio of surface area to volume | |
| Morphology19 | Margin sharpness | Mean of the image gradient at the lesion margin |
| Variance of margin sharpness | Variance of the image gradient at the lesion margin | |
| Variance of radial gradient histogram | Degree to which the enhancement structure extends in a radial pattern originating from the center of the lesion | |
| Texture22 | Contrast | Location image variations |
| Correlation | Image linearity | |
| Difference entropy | Randomness of the difference of neighboring voxels’ gray levels | |
| Difference variance | Variations of difference of gray level between voxel pairs | |
| Angular second moment (energy) | Image homogeneity | |
| Entropy | Randomness of the gray levels | |
| Inverse difference moment (homogeneity) | Image homogeneity | |
| Information measure of correlation 1 | Nonlinear gray-level dependence | |
| Information measure of correlation 2 | Nonlinear gray-level dependence | |
| Maximum correlation coefficient | Nonlinear gray-level dependence | |
| Sum average | Overall brightness | |
| Sum entropy | Randomness of the sum of gray-level dependence | |
| Sum variance | Spread in the sum of the gray levels of neighboring voxels | |
| Sum of squares (variance) | Spread in the gray-level distribution | |
| Kinetics21 | Maximum enhancement | Maximum contrast enhancement |
| Time to peak (s) | Time at which the maximum enhancement occurs | |
| Uptake rate (1/s) | Uptake speed of the contrast enhancement | |
| Washout rate (1/s) | Washout speed of the contrast enhancement | |
| Curve shape index | Difference between late and early enhancement | |
| Enhancement at first postcontrast time point | Enhancement at first postcontrast time point | |
| Signal enhancement ratio | Ratio of initial enhancement to overall enhancement | |
| Volume of most enhancing voxels () | Volume of the most enhancing voxels | |
| Total rate variation () | How rapidly the contrast will enter and exit from the lesion | |
| Normalized total rate variation () | How rapidly the contrast will enter and exit from the lesion | |
| Enhancement-variance kinetics20 | Maximum enhancement-variance | Maximum spatial variance of contrast enhancement over time |
| Enhancement-variance time to peak (s) | Time at which the maximum variance occurs | |
| Enhancement-variance increasing rate (1/s) | Rate of increase of the enhancement-variance during uptake | |
| Enhancement-variance decreasing rate (1/s) | Rate of decrease of the enhancement-variance during washout | |
| Gray-level statistics24 | Mean voxel value precontrast | Average gray-level intensity within the lesion prior to contrast injection |
| Mean voxel value postcontrast injection | Average gray-level intensity within the lesion at first postcontrast injection time point | |
| Standard deviation of voxel value distribution precontrast | Variation in gray-level intensity within the lesion prior to contrast injection | |
| Standard deviation of voxel value distribution postcontrast | Variation in gray-level intensity within the lesion at first postcontrast injection time point | |
| Maximum voxel value precontrast | Maximum gray-level intensity within the lesion prior to contrast injection | |
| Maximum voxel value postcontrast | Maximum gray-level intensity within the lesion at first postcontrast injection time point | |
| Minimum voxel value precontrast | Minimum gray-level intensity within the lesion prior to contrast injection | |
| Minimum voxel value postcontrast | Minimum gray-level intensity within the lesion at first postcontrast injection time point | |
| Kurtosis of voxel value distribution precontrast | Tailedness of gray-level intensity distribution within the lesion prior to contrast injection | |
| Kurtosis of voxel value distribution postcontrast | Tailedness of gray-level intensity distribution within the lesion at first postcontrast injection time point | |
| Skewness of voxel value distribution precontrast | Asymmetry of gray-level intensity distribution about the mean within the lesion prior to contrast injection | |
| Skewness of voxel value distribution postcontrast | Asymmetry of gray-level intensity distribution about the mean within the lesion at first postcontrast injection time point |