Which imaging technique enhances tissue contrast and helps in differentiating between structures?

Harmonic imaging is a technique that improves tissue contrast by using higher-frequency echoes generated by the ultrasound system. It takes advantage of nonlinear propagation of sound waves in tissue, producing images that reduce noise and artifacts while enhancing the clarity of the structures being examined. This method allows for better differentiation between adjacent tissues by providing a clearer representation of their interfaces and boundaries. As a result, harmonic imaging is particularly useful for visualizing subtle details that might otherwise be difficult to discern in standard imaging techniques.

Other options may have their specific benefits, such as power Doppler being useful for visualizing blood flow, contrast ultrasound enhancing vascular structures with the use of contrast agents, or 3D ultrasound providing volumetric imaging of structures, but they do not focus primarily on enhancing tissue contrast in the same way harmonic imaging does.