Clinical Review

Tattoo Removal by Q-Switched Laser

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When “tattoo regret” prompts patients to consider professional removal of a decorative tattoo, the clinician who understands the benefits and shortcomings of Q-switched laser systems can help them form realistic expectations and avoid complications.


 

References

Between seven and 20 million people in the United States, including adolescents as young as 12, are estimated to have at least one tattoo.1-3 Perhaps half later regret the decision to acquire a tattoo—for reasons ranging from an acute inflammatory reaction to the perception that having a tattoo might interfere with opportunities for professional advancement.4 The ­rising incidence of tattooing may be accompanied by increasing numbers of persons seeking to have decorative tattoos removed. Health care providers need to be aware of the modalities available, along with the risks and benefits of laser tattoo removal.

Tattoo types vary according to etiology, pigment, depth, and purpose. Cosmetic tattoos (“permanent makeup”) often serve to enhance physical features or mask scars; traumatic tattoos result from an injury in which foreign material is embedded in the skin. This article will focus on decorative tattoos and the clinical options for tattooed patients who regret these permanent markings and desire their removal.5

Decorative tattoos can be applied professionally or by amateurs, with pigment initially remaining in the superficial dermis; after several years, the pigment may migrate into deeper layers of the skin.6 Amateur tattoos are composed of ink or carbon; these pigments are usually less dense than those used by professionals, often making amateur tattoos easier to remove (ie, about five sessions of laser therapy for 90% clearance vs six to 10; see figures below).1,7

Professional tattoos are composed of organic pigments that vary in particle size but are applied at a uniform depth of needle penetration.5 The deposited pigment particles reside mainly in dermal fibroblasts and macrophages, although smaller collections of particles can be found within the interstitial space.

Tattoo Removal Techniques
Older techniques of tattoo removal, including surgical excision, salabrasion, dermabrasion, cryosurgery, and chemical peels, have largely been relinquished. Not only did these methods fail to yield desirable results, but they were associated with adverse effects, including hypopigmentation and scarring.5

Although continuous-wave lasers can also cause scarring, quality-switched (Q-switched) lasers have produced more favorable outcomes. The specific color and absorptive characteristics of each tattoo ink will help determine the ideal laser type to be used. In rare cases, patients may be able to contact the responsible artist and inquire about the inks used; information about the absorption spectrum of each pigment could facilitate the treatment plan. Even with this information, however, removal of intricate, colorful tattoos can be a challenge, since several different lasers, used in stages, may be needed.1,8

The patient’s skin type, too, may affect the response to treatment. Q-switched lasers are effective for all skin types, but complete pigment removal may be more difficult in lighter-skinned patients1 (ie, Fitzgerald skin types I and II). Similarly, in older tattoos, complete removal may not be possible, since some dermal pigment may have penetrated too deeply to be reached.5

Selective Photothermolysis
Laser removal of tattoos is accomplished by selective photothermolysis, a process that was first described by Anderson and Parrish in 1983.9,10 Photothermolysis targets specific microscopic sites on the skin, with effectiveness depending on the absorption spectrum of each pigment.4 The epidermis, dermis, and skin appendages are only minimally damaged in the process.6

Laser therapy modifies the optic properties of the tattoo pigments to be removed. The pigments absorb short laser pulses, which produce a high-intensity light in the pigments that is converted into heat.9 Shock waves shatter the pigment particles, achieving the selective death of the pigment-containing cells. The chemical composition of the pigment is also altered.

Lastly, the cell debris is phagocytized and transported to regional lymph nodes. Although they are hardly visible, some residual, scattered particles remain in the dermis. Only superficial pigment fragments are entirely eliminated during epidermal desquamation as repair is occurring, a development called transepidermal elimination.9

To produce the most effective treatment results, the laser wavelength must be absorbed by the ink, the heat should be confined to the target, and adequate energy must be delivered.1

Clinician–Patient Communication
Since the cosmetic outcome of laser therapy depends on both the laser wavelength and the absorption spectrum of each pigment, it is important for health care providers to understand the optimal wavelengths for each pigment type. They should be prepared to address with their patients the issues of incompatible lasers and resistance of certain pigments to treatment.11

Additionally, although Q-switched lasers are considered the gold standard for tattoo removal, realistic expectations should be established. Patients interested in treatment must be informed at the outset that complete clearance is not guaranteed and that the number of treatments and end result depend on factors that vary from patient to patient.4 Ten to 15 sessions, spaced six to eight weeks apart, may be required to achieve a desirable or even acceptable result,9 and the entire process could take a year or longer. The total cost can reach thousands of dollars.12

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