Ultrasound imaging is excellent for diagnosing cysts and other fluids in soft tissue. For ultrasound imaging or ultrasonography, different modes are used to examine the arterial/venous system, heart, pancreas, urinary system, ovaries, spinal cord, joints and more.
Power levels, frequencies used, amplification, and beamforming determine the clarity of the image. These things are controlled by the sonographer, interacting with the properties of the ultrasound machine.

Various imaging modes:

Zero offset is the measurement recorded by an ultrasound machine under conditions of zero input, caused e.g. by occlusion of the vessel. A two point calibration can be performed by the combination of zero offset determination with timed collection.