Subsurface tissue lesions created using an Nd: YAG laser and a sapphire contact cooling probe

Background and Objectives: This study investigates deep laser coagulation of tissue in combination with contact cooling of the tissue surface for potential use in noninvasive procedures in urology. Study Design/Materials and Methods: A laser probe was designed and tested for simultaneous Nd:YAG laser irradiation and sapphire contact cooling of liver and skin tissue samples, ex vivo. Gross and histologic examination was used to quantify thermal lesion dimensions. Results: Liver lesions measured 5.5 ± 0.3 mm in diameter, while preserving the tissue surface to a depth of 2.1 ± 0.2 mm (n = 5). Skin lesions measured 4.3 ± 0.9 mm in diameter, while preserving the skin surface to a depth of 1.1 ± 0.2 mm (n = 6). There were no statistical differences in lesion diameter and layer of preserved tissue between contact (sapphire) cooling and prior non-contact (cryogen spray) cooling results for a given tissue type (P > 0.05). Conclusions: Noninvasive laser procedures targeting tissue structures for thermal coagulation within a few millimeters of the tissue surface are feasible and may expand the use of combined laser/cooling techniques for applications in urology and general surgery. In vivo animal studies are currently in development to optimize the laser and cooling parameters for potential clinical applications.