title: Internally cooled power laser for MR-guided interstitial laser-induced thermotherapy of liver lesions: initial clinical results.
abstract: OBJECTIVE
  To evaluate experimentally and clinically an internally cooled power laser system for percutaneous treatment of liver metastases, with magnetic resonance (MR) imaging guidance, to increase the volume of coagulative necrosis with single laser beam applications.
  
  
  METHODS
  The power laser system consisted of standard cannulation paraphernalia and a specially designed 7-F protective catheter for cooling the laser tip during treatment to avoid carbonization. A microdome laser beam applicator with a laser tip diameter of 0.95 mm kept the entire device as small as possible. After the unit was tested in 40 porcine livers, 532 laser beam applications (mean power, 27.5 W [range, 22.1-30.0 W]; mean application time, 19.8 minutes [range, 14-30 minutes]) were performed with MR guidance in 127 patients with 318 liver metastases. The safety of the procedure and the volume of induced necrosis were evaluated.
  
  
  RESULTS
  In vitro, cuboid areas of coagulative necrosis with a mean greatest diameter of 4.3 cm +/- 0.5 (SD) were demonstrated after single applications. In vivo, MR thermometry allowed accurate demarcation of changes induced by heat, with a mean diameter of necrosis of 3.3 cm +/- 1.4. No carbonization or vaporization of tissue or damage of equipment occurred during treatment.
  
  
  CONCLUSIONS
  This power laser system can increase the volume of laser-induced necrosis in liver metastases with a single application, thereby simplifying and accelerating the treatment of larger lesions.
authors.affiliation: Department of Radiology, Virchow-Klinikum, Humboldt-University of Berlin, Germany.
authors.forename: T J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: M G
authors.initials: MG
authors.lastname: Mack
authors.forename: A
authors.initials: A
authors.lastname: Roggan
authors.forename: R
authors.initials: R
authors.lastname: Straub
authors.forename: K C
authors.initials: KC
authors.lastname: Eichler
authors.forename: P K
authors.initials: PK
authors.lastname: Müller
authors.forename: V
authors.initials: V
authors.lastname: Knappe
authors.forename: R
authors.initials: R
authors.lastname: Felix
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D015179:Colorectal Neoplasms / Q000473:pathology; D004867:Equipment Design; D005260:Female; D006801:Humans; D017075:Laser Coagulation / Q000295:instrumentation* / Q000379:methods; D008099:Liver / Q000601:surgery; D008113:Liver Neoplasms / Q000556:secondary* / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013552:Swine