The left image is a regular grayscale ultrasound image. Contrast here depends on tissue density and interfaces between densities, which causes sound to bounce back to the transmitter/receiver at varying levels.

The middle image is the same ultrasound machine, but they turned on power doppler mode as well. Power doppler basically highlights all the areas where the reflected sound has a frequency shift from the original transmitted sound. Moving blood causes a frequency shift in the reflected sound wave (like how a passing truck sounds different coming towards vs away from you), thus power doppler basically highlights blood vessels, and in this case, the nice radial arrangement of vessels in these tumors.

The right image is an MRI of the liver, after they gave contrast. Again, nicely highlights the “spokewheel” arrangement of this tumor. Most tumors don’t have such a nice arrangement, and the malignant tumors generally look very disorganized and ugly.