Ultrasound for the Anesthesiologists: Present and Future

Figure 1

Concept of ultrasonography: *tissues that allow the beam to pass easily (e.g., containing fluids or blood) create only little echo (hypoechoic) and appear black on the screen, while tissues that allows less beam to pass (e.g., fat and bone) create stronger echoes (hyperechoic) and thus appear white on the screen; **linear transducers have a higher frequency (10–15 MHz) and are usually used for superficial structures; curved transducers have a lower frequency (4–8 MHz) and are usually used for deeper structures.