A photoacoustic probe for port wine stain (PWS), burn and melanin depth
measurements is comprised of optical fibers for laser light delivery and
a piezoelectric element for acoustic detection. The probe induced and
measured photoacoustic waves in acryl amide tissue phantoms and PWS skin
in vivo. Acoustic waves were denoised using spline wavelet transforms,
then deconvolved with the impulse response of the probe to yield initial
subsurface pressure distributions in phantoms and skin. The waves were
then analyzed for epidermal melanin concentration, using a photoacoustic
melanin index (PAMI) related to the amount of laser energy absorbed by
melanin. Propagation time of the photoacoustic wave was used to determine
the depth of blood perfusion underlying necrotic, burned tissue. Thus,
the photoacoustic probe can be used for determining PWS, burn and melanin
depth for most patients receiving laser therapy.