Treatment of cutaneous vascular lesions using multiple-intermittent cryogen spurts and two-wavelength laser pulses: numerical and animal studies.
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BACKGROUND AND OBJECTIVES: Presently, cutaneous vascular lesions are treated using a single cryogen spurt and single laser pulse (SCS-SLP), which do not necessarily produce complete lesion removal in the majority of patients. In this study, the feasibility of applying multiple cryogen spurts intermittently with multiple two-wavelength laser pulses (MCS-MTWLP) was studied using numerical and animal models. STUDY DESIGN/MATERIALS AND METHODS: Two treatment procedures were simulated: (1) SCS+532 nm SLP; and (2) MCS+532/1064 nm MTWLP. Light transport and heat diffusion in human skin were simulated with the Monte Carlo method and finite element model, respectively. Possible epidermal damage and blood vessel photocoagulation were evaluated with an Arrhenius-type kinetic model. Blood vessels in the rodent window chamber model (RWCM) were irradiated with either SLP or MTWLP. Laser-induced structural and functional changes in the vessels were documented by digital photography and laser speckle imaging (LSI). RESULTS: The numerical results show that the MCS-MTWLP approach can provide sufficient epidermal protection while simultaneously achieving photocoagulation of larger blood vessels as compared to SCS-SLP. Animal studies show that MTWLP has significant advantages over SLP by inducing irreversible damage to larger blood vessels without adverse effects. CONCLUSIONS: MCS-MTWLP may be a promising approach to improve therapeutic outcome for patients with cutaneous vascular lesions featuring large blood vessels.