title: Impact of infrared laser light-induced ablation at different wavelengths on bovine intervertebral disc ex vivo: evaluation with magnetic resonance imaging and histology.
abstract: OBJECTIVE
  Percutaneous laser disc decompression is commonly used to lower high pressure in the nucleus pulposus in degenerative disc diseases. The aim of this study was to investigate the impact of diode laser disc decompression at different wavelengths (980-nm vs. 1,470-nm, i.e., different water absorption characteristics).
  
  
  METHODS
  To model decompression, a flexible laser quartz fiber inserted into the nucleus pulposus of ex vivo bovine spines using computer-assisted surgical navigation was utilized to vaporize tissue. The same energy (500 J) was delivered using both 980-nm and 1,470-nm wavelength lasers. To determine the different impact of the wavelengths before and after the procedure we evaluated the discs with MRI (T(1), T(2), diffusion maps) and with histopathology.
  
  
  RESULTS
  There were no visible changes on T(1) and T(2) maps after 1,470-nm wavelength laser irradiation; however, the 980-nm wavelength caused significant changes on T(1) (decrease) and T(2) (increase) in the vaporization zone at the site of the quartz fiber. Pathological findings showed carbonization and steam-bubble formation in addition to the T(1) and T(2) changes. No significant changes were detected in the value of apparent diffusion coefficient (ADC) measurements in intervertebral disc with the 980-nm wavelength, but significant ADC and T(1) signal increase was detected with the 1,470-nm wavelength when the whole nucleus pulposus was considered.
  
  
  CONCLUSIONS
  The 1,470-nm laser light had an effect in the whole nucleus pulposus and not only at the site of the quartz fiber, whereas with the 980-nm laser irradiation, significant changes were demonstrated only at the application site.
authors.affiliation: Health Center, Kaposvár University, Kaposvár, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Cselik
authors.forename: Mihály
authors.initials: M
authors.lastname: Aradi
authors.forename: Ronald A
authors.initials: RA
authors.lastname: von Jako
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Lelovics
authors.forename: Ivett
authors.initials: I
authors.lastname: Juhász
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Egyházi
authors.forename: Péter
authors.initials: P
authors.lastname: Bogner
authors.forename: Imre
authors.initials: I
authors.lastname: Repa
authors.forename: Attila
authors.initials: A
authors.lastname: Schwarcz
mesh_terms: D000818:Animals; D002417:Cattle; D066298:In Vitro Techniques; D007259:Infrared Rays; D007403:Intervertebral Disc / Q000473:pathology / Q000528:radiation effects*; D054023:Lasers, Semiconductor; D008279:Magnetic Resonance Imaging; D023421:Models, Animal