Computer-aided diagnosis for contrast-enhanced ultrasound in the liver

Table 3 Image feature values used for CAD input data

Image feature values
Temporal features
Replenishment time (s)
Peak pixel value
Slope factor (β)
Morphologic features
Effective diameter of focal liver lesion
Average size of vessel-like patterns
Area ratio of vessel-like patterns
Gray-level features
Average pixel value with vessel-like patterns
Average pixel value without vessel-like patterns
Standard deviation of pixel value with vessel-like patterns
Standard deviation of pixel value without vessel-like patterns
Average pixel value ratio (focal liver lesion/adjacent liver parenchyma)
Average pixel value ratio (central/peripheral)
Features for hypoechoic region
Average pixel value
No. of hypoechoic regions
Area ratio of hypoechoic region
Difference in pixel value (delay-early)
Change in pixel value (delay-early)/s

Reproduced, with modification, from Shiraishi et al[32], Med Phys 2008; 35: 1734-1746.