title: Subsurface tissue lesions created using an Nd:YAG laser and a sapphire contact cooling probe.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Rahayu
authors.initials: R
authors.lastname: Ramli
authors.forename: Chia-Chun
authors.initials: CC
authors.lastname: Chung
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Fried
authors.forename: Nicholas
authors.initials: N
authors.lastname: Franco
authors.forename: Michael H
authors.initials: MH
authors.lastname: Hayman
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D007036:Hypothermia, Induced / Q000295:instrumentation*; D017075:Laser Coagulation / Q000295:instrumentation*; D008099:Liver / Q000528:radiation effects*; D012867:Skin / Q000528:radiation effects*; D013552:Swine