Tattoo removal is a burgeoning area of aesthetic practice, with Q-switched lasers revolutionizing the process.

By Mitchel P. Goldman, MD, and Heather Endicott, FNP-C

Tattoos aren't just a modern fascination. They've had a long lineage throughout the ages. In fact, the earliest markings were found on the body of an Iceman dating from 5,200 BC.

Today, 24 percent of Americans, ages 18 to 50, are tattooed, according to a 2006 study published in the Journal of the American Academy of Dermatology. That's almost one in four. But not all of these people want to keep their tattoos. A 2003 Harris Interactive Poll found that 17 percent of these Americans regretted having a tattoo.

The tattoo removal industry is projected to grow from approximately 1 million procedures in 2003 to more than 2.1 million procedures in 2008, generating more than $326 million in revenue, according to Medical Insight Inc., a medical and aesthetic industry analysis firm. As technology advances, the procedure is becoming more affordable. As such, tattoo removal is a service providers can easily integrate into their practices.

A Look at Tattooing

The most common method of tattooing is preformed with an electric tattoo machine. This device inserts ink into the skin via a group of needles, which rapidly place ink through the epidermis to the papillary dermis. Ideally, this procedure is done under sanitary conditions.

Amateur tattoos tend to be unsanitary. Someone simply places a needle dipped in ink or dye and inserts it into the skin. Best examples of these can be seen on gang members and prisoners.

During the tattoo process, the ink particles become imbedded into the skin where they're placed. But many particles have a migratory pattern after intradermal injection, traveling to lymph nodes. Ink depth and density are inconsistent and depend on the artist's skill level, although a study conducted by Lea and Pawlowski concluded that this didn't appear to affect ink dispersion in the epidermis and dermis.¹

The ink particles initially appear in the epidermis, epidermal-dermal junction and papillary dermis, during which time an inflammatory process occurs. Ink particles are ingested by phagocytic cells and eventually settle into the deeper dermis by the action of phagocytic cells, which may make the tattoo dull and blurry. Eventually, some of the ink migrates into the regional lymph nodes, which act as a filter to help remove ink particles.^2,3

In the past, treatment modalities have run the gamut from physical to thermal modalities of destruction. Unfortunately, these methods tend to produce scarring by destroying both tattooed and non-tattooed tissue.

Of removal methods, salabrasion is one of the earliest. It entails removing the superficial dermis by abrading the skin with course granule sodium chloride (table salt) and a moist gauze pad. A salt poultice is then left on the wound for 24 hours. This procedure can produce pain and scarring, with pigment still remaining on the skin.

Another method, dermabrasion, removes the surface of the epidermis and stratum corneum. A small electric diamond fraise wheel or wire brush abrades the skin and essentially "sands" the skin off. This method tends to be bloody and painful. It also produces scarring with residual tattoo pigment.

Another option is complete excision of the tattoo in areas of skin laxity. In places where excessive tissue is not available (as is with many tattoos), tissue expanders and grafts have been used.

Chemical destruction includes using phenol solutions and trichloroacetic acid 95 percent. This, too, has produced hypopigmented scars and burns, resulting in the need for a full-thickness skin graft.

Finally, thermal destruction has used everything from hot coals to cigarettes. Fortunately, as technology has progressed, we've replaced such primitive methods with the science of lasers.

Laser Tattoo Removal

In the 1970s, the carbon dioxide laser (CO2) and argon laser were first used to remove tattoos. The CO2 and argon laser removed tattoo pigment through direct tissue vaporization, thermal necrosis of adjacent tissue and loss of pigment in the exudative healing process.⁴ As with other methods of thermal destruction, the same risks existed with CO2 and argon lasers, including pain, scarring and hypo-pigmentaion of tissue.

The Q-switched laser (operating in the nanosecond range: one billionth of a second) has revolutionized tattoo removal, making scarless removal a possibility. These lasers target the tattoo pigment in the dermis, fragmenting it into particles. These particles are then released into the extracellular space and eliminated. Some particles are only partially removed through the crusting of the epidermis after treatment.⁴

The four wavelengths that remove tattoos are the Q-switched ruby (694 nm), the Q-switched alexandrite (755 nm) and the Q-switched Nd:YAG (532 nm and 1064 nm). Anderson and Parrish's principle of selective photothermolysis explains why lasers remove tattoo ink. The primary principle states that by choosing an appropriate wavelength (532 nm, 694 nm, 755 nm and/or 1064 nm) we can match the color of the tattoo particle. By choosing the pulse duration (nanoseconds), we can match the size of the tattoo particle. And with fluence, we can select the energy needed to explode the tattoo particle.

As a result, thermal injury is confined to a target (tattoo ink) while avoiding nonspecific thermal injury to the surrounding tissue.4 The type of laser to remove the tattoo depends on the color of the ink and surrounding skin pigmentation. (See table). Specific wavelengths destroy specific tattoo ink colors, while the competition from melanin in the epidermis decreases as wavelengths increase. Therefore, the longer the wavelength, the less likely depigmentation of the epidermis will occur.

The number of treatments to remove tattoos can vary greatly depending on color, depth and amount of tattoo pigment, as well as the person's ability to phagocytize the -tattoo pigment. It also depends on whether the tattoo is an amateur or professional one and whether it has one to two layers of -pigment on it.

The easiest colors to remove are black, green and blue because lasers are specifically tuned to these wavelength colors. All other colors are more difficult because we don't have lasers that are tuned to these color wavelengths.

The ability for the ink to absorb energy is a key concept. An unpublished study by a laser manufacturer in 1991 determined reflectance spectra for 17 different tattoo ink colors and six different variants of black ink. The company found that different colors of tattoo ink exhibited an optimal absorption laser wavelength.

For example, the ideal absorption wavelength for blue and green ink is 625 nm to 755 nm. Therefore, the Q-switched ruby (695 nm) or Q-switched alexandrite (755 nm) laser is the best choice for removing these colors. This is why successful tattoo removal often requires multiple lasers with different wavelengths.

On average, removing an amateur tattoo can take three to six sessions; a professional tattoo can take well over 10 treatments sessions.

New tattoos that are black usually require fewer treatments. In addition, they're easier to remove because the ink is superficial and has a strong absorption quality. Tattoos that are older (20 or more years), have multiple colors and are re-inked tend to be more challenging. Moreover, the patient's cellular ability to mobilize ink fragments and remove them affect the success of removal. Sometimes, completely removing the tattoo isn't possible, with the best result being a "ghost" tattoo�light shadow images of the original.

Ideally, treatments are spaced four to eight weeks apart. We've found that treatment intervals that occur less than one month apart don't accelerate tattoo removal. In fact, they can potentially interfere with the healing process, resulting in unwanted -tissue reactions, such as hypopigmentation or scarring.⁵

Initially, the ink pigment may show significant lightening on the first one to two treatments, then taper off. Others may be slower to lose color. This may be due to the person's ability to mobilize macrophages to remove the pigment fragments. As would be expected, the more superficial and less-dense the ink pigment, the fewer treatments required to lighten the tattoo.

Side Effects

Unlike past treatment options, Q-switched lasers offer greater success with fewer side effects. The concerns, however, are hypopigmentation, hyperpigmentation, textural changes, allergic reactions, residual tattoo pigment and tattoo ink darkening. Following are a few things to keep in mind when removing a tattoo.

· Always factor skin pigmentation (melanin concentration) into the treatment plan. If the surrounding tissue is darker than the tattoo, do not try to remove the tattoo. Doing so may cause permanent melanin destruction, resulting in hypopigmentation in the shape of the previous tattoo. The darker the skin type, the longer the wavelength should be. This will protect the surrounding tissue from scarring or hypopigmentation. Type V and VI skin types are best treated with a 1064 nm Nd:YAG laser.

· To avoid cutaneous textural change, do not space treatment sessions earlier than every four weeks. Furthermore, avoid excessive fluence, which can lead to permanent thermal injury to the tissue and scarring. An ideal treatment endpoint should be to produce an immediate whitening of the area treated, while avoiding bleeding, blistering and/or skin separation.

· Allergic reactions are rare, since tattoo ink pigment is surprisingly nonreactive. However, they are possible. Usually, the patient presents with a history of allergic-like reactions to the tattoo ink. An excessive immune response to ink fragments after being exposed to the Q-switched laser may result in a systemic allergic reaction.2 Thus, patients with an allergic reaction to tattoo ink should be treated with a carbon dioxide laser, excision or dermabrasion.

· Tattoo darkening can occur, particularly with "cosmetic" tattoos placed on the face. Pigments containing ferric oxide and titanium dioxide (as found in red, flesh colored or white tattoo inks) can turn black when exposed to temperatures above 1,400 F.^5,6 This is due to a chemical reaction that converts ferric oxide into ferrous oxide, which is black in color. The tattoo can still be removed because black is amenable to treatment. But patients must be warned that it may take more treatments to fully resolve.

On the Horizon

Q-switched lasers significantly improve tattoo removal while preserving surrounding tissue. New advances may be the development of a picosecond (millionth of one millionth of a second) laser, which may be more effective than nanosecond (Q-switched) laser. It's postulated that nanosecond lasers only produce 3 percent of the power a picosecond laser can. By thermolysis alone, the picosecond laser is superior.

In other advancements, a professor at Brown University developed a new polymer-coated microcapsuled tattoo ink. The ink is microcapsulated into tiny beads, which are reported to be safer, free of heavy metals and toxins. It's also reported to break down after one laser treatment, allowing the body to eliminate the ink trapped inside. This science may come to market late this year.

New tattoo ink must be universally adopted by all tattoo artists if it's to be beneficial to those who want removal. However, this potential new ink does nothing for the millions of Americans who want their tattoos removed now.

In the meantime, our best option is the Q-switched laser because it addresses many of the problems with earlier methods of tattoo removal.

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