Table 1.

Features extracted from PET and MR images

Type of feature	Imaging modality	Feature
Macroscopic features	PET	Metabolic tumor volume (MTV) [cc]
		Partial volume corrected mean body-weighted standardized uptake value (SUVmean) [g/cc]
		Maximum body-weighted standardized uptake value (SUVmax) [g/cc]
		Total lesion glycolysis (TLG) [g]
	MR	Apparent diffusion coefficient functional volume (V ADC) [cc]
		Mean apparent diffusion coefficient (ADCmean) within V ADC [mm2/s]
		Minimum apparent diffusion coefficient (ADCmin) within V ADC [mm2/s]
		Total lesion diffusion (TLD) [cm5/s]
Intensity-based features (first-order statistics)	PET/MR	Energy [(g/cc)2]–[(mm2/s)2]
		Entropy
		Kurtosis
		Maximum [g/cc]–[mm2/s]
		Mean [g/cc]–[mm2/s]
		Mean absolute deviation [g/cc]–[mm2/s]
		Median [g/cc]–[mm2/s]
		Minimum [g/cc]–[mm2/s]
		Range [g/cc]–[mm2/s]
		Root mean square (RMS) [g/cc]–[mm2/s]
		Skewness
		Standard deviation [g/cc]–[mm2/s]
		Uniformity
		Variance[(g/cc)2]–[(mm2/s)2]
Shape- and size-based features	PET/MR	Surface area [cm2]
		Spherical disproportion
		Sphericity
		Surface to volume ratio [cm−1]