Acoustic Radiation Force Impulse (ARFI) Ultrasound at Leeds Hospital

What is ARFI ultrasound?

Acoustic Radiation Force Impulse (ARFI) ultrasound is a scan that measures how stiff or soft a part of your body is. It uses a short, focused pulse of sound to nudge the tissue very slightly, then tracks how quickly it settles back to work out how firm the tissue is.

Why might I need ARFI ultrasound?

Doctors can use ARFI ultrasound to check for fibrosis (scarring) in the liver, particularly if you have chronic (long-term) hepatitis B or C. Researchers have also studied ARFI as a way of looking more closely at tendon and ligament problems, since it can pick up information about tissue quality at exact points that a standard ultrasound picture cannot show as clearly.

What are the benefits of ARFI ultrasound?

• It's non-invasive, using sound waves rather than needles or cuts
• It can show tissue quality at exact points, rather than the more general picture from a standard ultrasound
• Research comparing ARFI with liver biopsy results found it reliable at identifying cirrhosis (severe liver scarring).

Are there different types of ARFI ultrasound?

ARFI ultrasound mainly produces a qualitative image, showing softer and stiffer areas of tissue as different shades on screen. Researchers are also working on more advanced versions that aim to give an exact stiffness measurement rather than just an image, though these are not yet standard.

What happens during ARFI ultrasound?

Here's what happens during the scan:

1. The probe sends a few gentle reference pulses of sound, giving the machine a starting point for your tissue's position.
2. The probe then sends one short, focused pulse, which nudges the tissue by a tiny amount, just 1 to 10 micrometres (a micrometre is a millionth of a metre).
3. The probe tracks the tissue as it settles back into place, usually within 4 to 6 milliseconds – stiffer tissue moves less and settles back quickly, while softer tissue moves more.
4. This is repeated at different points across the area being checked, so the machine can build up a picture of tissue stiffness.