title: Safety and effectiveness of black tattoo clearance in a pig model after a single treatment with a novel 758 nm 500 picosecond laser: a pilot study.
abstract: BACKGROUND
  Optimal selective photothermolysis of a pigment particle requires pulse durations equal to or less than the particle's thermal relaxation time (t(1/2)). Since tattoo particles in skin range in diameter from 40 to 300 nm, picosecond pulses would approximate t(1/2) more closely and, therefore, might be more effective at tattoo particle fragmentation.
  
  
  METHODS
  India Ink (carbon) or iron oxide tattoos were placed on the back of a Yorkshire pig. Six weeks later, each tattoo was treated with either a 758 nm 500 picosecond laser (Cynosure), a 755 nm 30-50 nanoseconds laser, or left untreated. After 4 weeks, clinical responses were evaluated by three dermatologists based on pre- and post-treatment photographs; histopathologic findings were evaluated by a dermatopathologist; and electron microscopic findings were analyzed for treated and non-treated carbon tattoos.
  
  
  RESULTS
  After a single treatment, picosecond-domain pulses at 758 nm produced a significantly greater degree of carbon tattoo clearance compared to nanosecond-domain pulses at 755 nm. For iron oxide tattoos, both modalities produced minimal-to-poor clearance that was generally comparable. Neither modality resulted in scarring, textural changes, or hypopigmentation, and there was no histopathologic evidence of scarring. Electron micrographs revealed the presence of amorphous material (treated pigment) in picosecond and nanosecond laser-treated tattoos, consistent with effective targeting of India Ink pigment.
  
  
  CONCLUSIONS
  The 758 nm 500 picosecond laser is more effective at carbon tattoo clearance after one session in a porcine model than the 30-50 nanosecond laser emitting at a similar wavelength. Both lasers cleared carbon tattoos more effectively than iron oxide tattoos. Both lasers have a comparable safety profile, and neither produced clinical or histopathologic scarring. Further studies in humans are necessary to evaluate whether repeated treatments with picosecond versus nanosecond domain modalities might yield superior tattoo pigment clearance with a comparable safety profile.
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, BHX 630, Bartlett Hall, Boston, Massachusetts 02114, USA. lizikson@partners.org
authors.forename: Leonid
authors.initials: L
authors.lastname: Izikson
authors.forename: William
authors.initials: W
authors.lastname: Farinelli
authors.forename: Fernanda
authors.initials: F
authors.lastname: Sakamoto
authors.forename: Zeina
authors.initials: Z
authors.lastname: Tannous
authors.forename: R Rox
authors.initials: RR
authors.lastname: Anderson
mesh_terms: D000818:Animals; D002244:Carbon / Q000032:analysis; D062109:Dermatologic Surgical Procedures; D005260:Female; D005290:Ferric Compounds / Q000032:analysis; D005547:Foreign Bodies / Q000628:therapy*; D053685:Laser Therapy / Q000295:instrumentation* / Q000379:methods; D007834:Lasers / Q000145:classification*; D010865:Pilot Projects; D012867:Skin / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D013552:Swine; D013653:Tattooing / Q000145:classification*; D016896:Treatment Outcome
chemical_list: D005290:Ferric Compounds; C028433:chinese ink; C000499:ferric oxide; D002244:Carbon