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Subsurface tissue lesions created using an Nd:YAG laser and a sapphire contact cooling probe
Rahayu Ramli1, Chia-Chun Chung, Nathaniel M Fried
1Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
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.
