H uman beings have been experimenting with tattoos since ancient times. And, it’s likely, that as long as tattoos have been around so has the need for tattoo removal. Through the years, many methods of removal have been attempted. As we discussed last month, some of the first attempts at removal were done through techniques such as dermabrasion, salabrasion, liquid nitrogen, and surgical excision, among others. The advent of the laser brought new options for removal — beginning with the argon laser and CO2 laser, which we also discussed last month. But these options have been replaced by newer options.

Here, we’ll discuss the three lasers most commonly used in tattoo removal — the quality switched (Q-switched) ruby, Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG), and
Q-switched alexandrite — and offer tips on choosing the best treatment for your patients.

The Q-Switched Lasers
Q-switching of a laser is a mechanism often used to control the light output by concentrating all the energy into intense bursts or series of pulses. To put it simply: The Q-switched lasers deliver a fast, powerful pulse. Due to their high energy and short pulse duration these lasers induce selective photothermolysis. The Q-switched lasers have uniformly replaced both the carbon dioxide and argon laser for the treatment of tattoo pigment.

Q-switched ruby laser: The Q-switched ruby laser is a laser containing a ruby crystal of aluminum trioxide doped with chromium ions. Doping is a process in which the crystal is grown in the presence of an impurity so that the crystal lattice purposely forms with an impurity within it. A ruby rod is placed within the laser cavity where flashlamps excite the chromium ions to produce photons at a wavelength of 694 nm with 20 ns to 40 ns pulse durations. Q-switched ruby laser light penetrates about 1 mm into the skin and is well absorbed by black tattoo ink. This level of penetration is clinically advantageous for reaching tattoo pigment located within the dermis. At a wavelength of 694 nm, the Q-switched ruby laser light is minimally absorbed by hemoglobin but is well absorbed by melanin.1

In 1965, Goldman documented the earliest report of tattoo pigment interaction with Q-switched lasers.2 Less than satisfactory results including necrosis and retention of tattoo ink were noted; however, Goldman continued to follow these patients and noted continued fading of the treated area with time.

In 1983, Reid et al. published a report on the removal of black pigment in professional and amateur tattoos with the Q-switched ruby laser. They reported good results, particularly with amateur tattoos but noted several disadvantages, such as the need for multiple treatments. They found that amateur tattoos cleared after about four to six treatments while professional tattoos required one to three additional treatment sessions for complete pigment removal.3,4
In a later study by Taylor et al., 35 amateur and 22 professional blue-black tattoos showed fading or total clearing in 78% of amateur and 23% of professional tattoos. Although these statistics were less than ideal, the authors were optimistic that the Q-switched ruby laser would become the favored treatment for tattoos.5

Lowe et al. demonstrated that after five treatment sessions, 22 of 28 professional tattoos showed excellent results (>75% improvement).6,7 Green pigmented tattoos responded variably but did fade with continued treatment. Kilmer and Anderson reported black and green ink to be the most responsive with other colors requiring significantly more treatments.8 They also noted that professional, distally located, recently acquired, or deeply placed tattoos may be more difficult to remove.

Overall, the Q-switched ruby laser was found highly effective for amateur tattoos, moderately effective for black professional tattoos, and less effective for brightly colored professional tattoos.9-11

Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG): The Q-switched Nd:YAG laser is a solid-state laser containing a crystal of yttrium-aluminum-garnet (YAG) doped with neodymium (Nd) ions. An Nd:YAG rod is placed within the laser cavity where xenon lamps excite the neodymium ions to provide an emission of 1064 nm with 5 ns to 20 ns pulse durations. The longer wavelength of the Q-switched Nd:YAG laser allows deeper penetration. Also, the 1064 nm light interacts less with absorption spectra of melanin, thus decreasing the incidence of hypopigmentation.

A benefit of the YAG laser is that it may be modified with “frequency doubling” or “harmonic generation.” Light is passed through a KTP crystal producing green light at a wavelength of 532 nm. This achieves good results in removing red tattoo pigment, a color resistant to treatment with the Q-switched ruby laser.12

DeCoste and Anderson showed the Q-switched Nd:YAG laser (1064 nm) to be equally as effective as the Q-switched ruby laser in removing black tattoo ink but with less blistering and pain, fewer textural changes, and no hypopigmentation.13 Subsequently, Jones et al. and Grevelink et al. demonstrated effective tattoo removal with minimal hypopigmentation or hyperpigmentation.14,15 This Q-switched Nd:YAG provides a benefit over the Q-switched ruby laser for darker-skinned patients in whom melanin absorption is a concern.

Studies showed that green, yellow, white and red inks were more resistant to Q-switched Nd:YAG laser treatment than black ink and cleared less than 25% of the time, even after four treatments. However, the frequency-doubled Q-switched Nd:YAG at 532 nm was the treatment of choice for red tattoo pigment, which faded completely in 75% of patients after three treatments.

The Q-switched Nd:YAG laser offers a great advantage for treating tattoos in darker-skinned patients. The 1064 nm wavelength effectively treats black ink and the 532 nm setting treats red, orange and purple ink colors. The primary disadvantage of this laser is the high cost.
Q-switched alexandrite: This laser contains a chrysoberyl crystal doped with chromium ions, which is placed within the laser cavity where flashlamps excite the chromium ions to produce photons with 100 ns pulse durations at a wavelength between the Q-switched ruby and Nd:YAG lasers of 755 nm. Studies show that the effect of the Q-switched alexandrite laser is similar to that of the Q-switched ruby laser.16

Fitzpatrick et al. evaluated the ability of the Q-switched alexandrite laser to remove tattoos in 15 patients with professional tattoos and eight patients with amateur black and blue-black tattoos. Twenty patients (80%) cleared greater than 95% of their ink with an average of 8.9 treatment sessions.17,18

Alster reported similar results in amateur and professional tattoos containing black, blue-black and green pigment. The number of treatments required for significant clearing varied from 2 to 13 with amateur tattoos averaging fewer treatments. Transient hypopigmentation and textural changes occurred in 50% to 80% and 12% of patients, respectively.19,20 Stafford et al. reported excellent fading of green, red and purple pigments after Q-switched alexandrite laser treatment.21,22

Mechanism of Action
Phagocytosis of pigment by macro-phages is the primary method of elimination; however, the precise mechanism of action for removing tattoo ink treated with Q-switched lasers is not completely known. Some ink is eliminated when post-treatment crust is sloughed.

The reason that amateur tattoo ink is eliminated faster than professional ink is most likely due to the less uniform, more shallow distribution in the dermis as well as larger size of the individual ink particles. Because post-laser treated tattoo pigment can be found in regional lymph nodes, it is believed that ink is removed, at least partially, through lymphatic drainage. As a result, tattoos located on distal extremities may require more treatments due to decreased lymphatic drainage while those located centrally may be eliminated quicker.

Anesthesia During Tattoo Removal
Pain is very personal and while some patients may forgo anesthesia altogether most patients will require some form of local anesthesia. Pre-treatment might include the application of an anesthetic cream under occlusion for 45 to 90 minutes prior to the laser treatment session. If complete anesthesia is desired, it can be administered locally by injections of 1% to 2% lidocaine with epinephrine. Anecdotal reports have noted that patients receiving anesthesia by local injection will require additional treatments as the injection causes mechanical edema, spreading out the tattoo ink, which in turn makes it more difficult for the laser light to act on specific ink particles. It has been reported that infiltration of local anesthesia will add an additional treatment or two.

Post-Treatment Considerations
Immediately after laser treatment, a slightly elevated, white discoloration with or without the presence of punctuate bleeding is often observed. This white color change is thought to be the result of rapid, heat-formed steam or gas, causing dermal and epidermal vacuolization. Pinpoint bleeding represents vascular injury from photoacoustic waves created by the laser’s interaction with tattoo pigment. Minimal edema and erythema of adjacent normal skin usually resolve within 24 hours. Subsequently, a crust appears over the entire tattoo, which sloughs off at approximately 14 days post treatment. As noted above, some tattoo pigment may be found within this crust. Post-operative wound care consists of topically applied antibiotic ointment and a non-occlusive dressing. Fading of the tattoo will be noted over the next 6 to 8 weeks and retreatment energy levels can be tailored depending on the clinical response observed.

Side Effects and Complications
About half of the patients treated with Q-switched lasers for tattoo removal will show some transient changes in the normal skin pigmentation. These changes usually resolve in 6 to 12 months but may be rarely be permanent.

Hyperpigmentation is related to the patient’s skin type, with skin types IV, V and VI more prone regardless of the wavelength used. Twice daily treatment with hydroquinones and broad-spectrum sunscreens usually resolves the hyperpigmentation within a few months, although, in some patients, resolution can be prolonged.

Transient textural changes are occasionally noted but often resolve within a few months, however, permanent textural changes and scarring very rarely occur. If a patient is prone to pigmentary or textural changes, longer treatment intervals are recommended. Also, if a patient forms a blister or crust post treatment, it is imperative that they not manipulate this secondary skin change. Early removal of a blister of crust increases the chances of developing a scar. Additionally, patients with a history of hypertrophic or keloidal scarring should be warned of increased risk of scarring.

Local allergic responses to many tattoo pigments have been reported, and allergic reactions to tattoo pigment after Q-switched laser treatment are also possible.32 Rarely, when yellow cadmium sulfide is used to “brighten” the red or yellow portion of a tattoo, a photoallergic reaction may occur.33 The reaction is also common with red ink, which may contain cinnabar (mercuric sulphide).24 Erythema, pruritus, and even inflamed nodules, verrucose papules, or granulomas may present. The reaction will be confined to the site of the red/yellow ink. Treatment consists of strict sunlight avoidance, sunscreen, interlesional steroid injections, or in some cases, surgical removal. Unlike the destructive modalities described, Q-switched lasers mobilize the ink and may generate a systemic allergic response. Oral antihistamines and anti-inflammatory steroids have been used to treat allergic reactions to tattoo ink.

Studies of various tattoo pigments have shown that a number of pigments (most containing iron oxide or titanium dioxide) change color when irradiated with Q-switched laser energy. Some tattoo colors including flesh tones, light red, white, peach and light brown containing pigments as well as some green and blue tattoo pigments, changed to black when irradiated with Q-switched laser pulses.35 The resulting gray-black color may require more treatments to remove. If tattoo darkening does occur, after 8 weeks the newly darkened tattoo can be treated as if it were black pigment. Darkening of cosmetic ink are shown in the photos on page 75.

Q-switched lasers can rupture blood vessels and aerosolizes tissue requiring a plastic shield or a cone device to protect the laser operator from tissue and blood contact.36 Lastly, protective eyewear should be donned at all times during treatment.

Future Trends
Beyond the currently available treatments, topical treatment modalities for tattoo removal are currently being studied. In 2002, Solis et al. performed a study in which imiquimod (Aldara) was evaluated for removal of tattoos in guinea pigs. Imiquimod cream 5% was applied to guinea pigs 6 hours after an application of tattoo ink. Applications were applied every 6 hours for 7 days. At 28 days after initiation of treatment, the pigment was barely perceptible on microscopy but both inflammation and fibrosis was observed.37 More research is needed to determine whether topical immune response modifiers can effect mature tattoos in humans.

Additionally, in the future it may be possible to define tattoo pigment reflectance characteristics on an individual basis and then choose a wavelength of laser light that will maximize absorption of a particular pigment color theoretically resulting in a faster, more complete laser treatment regime.

Better Options for Patients
Methods of tattoo ink removal have been around nearly as long as tattoos themselves. Previous removal modalities left patients with pain, discoloration, tissue texture changes, and residual pigment. Our ability to remove tattoos, however, has advanced greatly in the last decade and previous modalities for tattoo removal have been replaced by highly selective laser techniques. The use of Q-switched lasers has been able to help the vast majority of patients seeking tattoo removal by offering a low risk, highly effective therapy with minimal side effects. Because they offer bloodless, low risk, effective treatment, Q-switched lasers have replaced other methods and are now considered standard treatment for patients seeking tattoo removal. In the coming years, we’ll hopefully have even more options available for our patients.