High-Resolution Ultrasound Imaging to Demonstrate and Predict Efficacy of Carbon Dioxide Fractional Resurfacing Laser Treatment

Abstract

Fractional resurfacing is a new laser treatment used mainly for treating photoaging and acne scars. To demonstrate the efficacy of carbon dioxide (CO(2) ) fractional resurfacing laser treatment using high-resolution ultrasound imaging and to evaluate factors predictive of response to the treatment. A prospective observational study was undertaken from January 2007 to August 2009. Laser treatment was performed using a CO(2) fractional resurfacing device. Patients were offered high-resolution ultrasound imaging to follow up their treatment. Dermal and subepidermal nonechogenic band (SENEB) thicknesses were measured. Twenty-four consecutive patients were included, allowing follow-up of 107 areas. Statistical analysis showed a significant increase in dermal thickness (mean variation +25.1%, (95% confidence interval=19.0-31.2). SENEB thickness was not changed. Older age and greater initial thickness were associated with a smaller increase in dermal thickness according to multivariate analysis. The region treated was also found to be a significant predictive factor. Smoking, topical anesthesia, severity of local side effects induced by the laser treatment, and phototype were not associated with significant modification of dermal thickness after laser treatment. This is the first report on the use of high-resolution ultrasound imaging to assess the efficacy of fractional laser operating with standard parameters. Increase in dermal thickness was evidenced, possibly explained by collagen neosynthesis or conformational changes in the extracellular matrix component, increasing dermal hydration, although there was no modification of SENEB thickness, suggesting that the skin retains the sequelae of ageing. The treatment appeared to be more effective in younger patients, probably because their fibroblasts are more prone to synthesizing collagen. Thinner skins were more effectively treated than thicker skins because they could be stimulated throughout their thickness with the treatment parameters used.