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DECIDING on the best treatment for a burn is crucial: get it wrong and the
wound may fail to heal. Current techniques rely heavily on subjective
judgements, but now there鈥檚 a way to make the diagnosis less uncertain.

If a burn is shallow, it will heal by itself. Deeper burns destroy the skin鈥檚
underlying blood supply, which means that skin grafts are needed for them to
heal. Burns are traditionally assessed by looking for characteristic colours and
textures that can indicate how deep they run. But doctors get it wrong in up to
40 per cent of cases. 鈥淭he great majority of burns are in this grey area and
what you鈥檝e got to decide is whether to graft or not,鈥� says Ken Dunn, a plastic
surgeon at the Withington Hospital in Manchester.

So Joie Jones, a radiographer at the University of California at Irvine, set
out to develop an ultrasonic probe that measures just how bad a burn is.
Ultrasound is severely weakened when it passes from a solid probe into the air.
To prevent this, the probe of conventional imagers has to be placed in contact
with the skin, which makes them unsuitable for use on burns.

Jones overcame this problem by coating the tip of a conventional ultrasound
probe with layers of soft silicone, each studded with different quantities of
glass beads. There were most beads in the layer closest to the probe, and fewest
on the outermost layer. By using a coating in which stiffness gradually reduced
in this way, Jones found he could transmit ultrasound efficiently through air
and into skin.

鈥淵ou don鈥檛 have to touch the patient,鈥� he says. In shallow wounds, he got
strong reflections from the underlying bed of blood-carrying capillaries. Jones
says he鈥檚 now able to classify more than 90 per cent of burns correctly.