A clinical and histologic prospective controlled comparative study of the picosecond titanium:sapphire (795 nm) laser versus the Q-switched alexandrite (752 nm) laser for removing tattoo pigment☆,☆☆,★

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Abstract

Background: Theory predicts that picosecond lasers should be more effective than the currently available nanosecond lasers in removing tattoo ink. In addition to thermal confinement, such pulse widths cause optimal photomechanical disruption of the target. Objective: This study compared the efficacy of the picosecond titanium:sapphire (795 nm, 500 psec) laser and the Q-switched alexandrite (752 nm, 50 nsec) laser in the treatment of tattooed guinea pigs. Methods: Six albino guinea pigs, each with 6 uniformly 1 cm circular black tattoos, were treated. Three of the tattoos were divided into 2; one half was treated with the titanium:sapphire laser and the other half with the alexandrite laser. Fluences used for both lasers were 6.11, 4.24, and 2.39 J/cm2 with spot sizes of 1.25, 1.5, and 2 mm, respectively. The remaining spots served as control. Clinical evaluation and biopsies were performed at baseline and at 11 and 16 weeks after a single laser treatment. Results: Greater clearance of tattoo was observed in titanium:sapphire laser–treated areas in 2 of the 4 surviving guinea pigs. In some areas total clearing was observed after the single titanium:sapphire laser treatment. Clearing improved with higher fluences. No scarring was present. Histologic results showed similar findings. Conclusion: Our findings suggest that the picosecond titanium:sapphire laser is more effective than the Q-switched alexandrite laser in removing tattoo pigment and may be of significant clinical utility. (J Am Acad Dermatol 1999;40:603-6.)

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MATERIAL AND METHODS

This study was approved by the Institutional Review Board of the Beth Israel Deaconess Medical Center.

The experimental laser was a 795 nm titanium:sapphire (Ti:sapphire) laser, which produced 500 psec pulses. The laser was assembled on an optical bench. Initial calibration identified the 3 points on the bench at fixed distances from the laser where the guinea pigs were held in the path of the beam. These represented spot sizes of 1.25, 1.5, and 2 mm at fluences of 6.11, 4.24, and 2.39 J/cm2,

RESULTS

Two of the 6 guinea pigs died before completion of the study and were excluded from evaluation. Although 6 circular spots were uniformly tattooed, 5 months later some spots did not exhibit uniform pigmentation. Only the 4 most uniformly tattooed spots were evaluated.

Some clearance of the tattoos was observed in areas treated by both lasers. However, in 2 of the 4 guinea pigs a significantly greater response was noted in picosecond laser–treated areas (Figs 2 and 3).

. Significantly greater

DISCUSSION

By employing the principles of selective photothermolysis,1 several Q-switched lasers have effectively destroyed tattoo particles while sparing the surrounding dermis. The Q-switched ruby laser (694 nm) was the first Q-switched laser demonstrated to be effective in removing tattoo pigment.2 However, because this wavelength is so well absorbed by melanin,3 hypopigmentation is not uncommon after laser treatment. The Q-switched Nd:YAG4, 5 and Q-switched alexandrite6 lasers have also effectively

Acknowledgements

We thank Paul Morrison and Chris Jones for their technical assistance.

References (10)

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Supported by a National Institutes of Health–funded Small Business Innovative Research grant in collaboration with the Candela Laser Corporation, Wayland, Mass.

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Reprint requests: Jeffrey S. Dover, MD, FRCPC, 25 Boylston St, Suite 104, Chestnut Hill, MA 02167. E-mail address: [email protected].

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Copyright © 1999 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.