Ultrasound scans are used to detect problems in the liver, heart, kidney or the abdomen. They may also be useful in helping the surgeon when carrying out some types of biopsies. Ultrasound frequency is between 2 and 18 MHz.
A Doppler ultrasound test uses reflected sound waves to evaluate blood as it flows through a blood vessel. It helps doctors evaluate blood flow through the major arteries and veins of the arms, legs, and neck.