A Novel Application of Focused Ultrasound for the Treatment of Port Wine Stain Birthmarks

Annually, 0.3-0.5 % of the population is born with a Port Wine Stain (PWS) birthmark. A PWS is a capillary malformation that results in a visible, localized vascular lesion. This lesion is characterized by an increased number of dilated capillaries that give the PWS its red discoloration. The gold standard of PWS treatment is photothermolysis with Pulsed Dye Laser (PDL) emitting at a wavelength of 595 nm. The PDL selectively damages the PWS by using the wavelength at which hemoglobin absorbs light to thermally destroy capillaries. Due to limitations of PDL penetration depth, the deepest capillaries are often left untreated. This can form seed locations where new capillaries can develop, causing the PWS to darken in color over time.

Focused ultrasound therapies are non-invasive alternatives to treating tissue at depth. We investigated a novel application of therapeutic ultrasound to treat PWS. We used a transducer operating at 1.47 and 4.42 MHz and FDA-approved microbubbles to induce cavitation as a non-thermal mechanism of damage to the PWS. An ultrasound phantom was created to mimic the vasculature of the PWS for determining the functional ultrasound parameters. We report on the ability of these parameters to selectively damage vasculature in phantoms and ex vivo animal tissues.