Key points

Introduction

Body art, such as tattoos, have fascinated mankind for centuries and have already been found in ancient Egyptian, Greek, and Roman cultures. In the past, such body markings served to enhance beauty, provide healing, declare belongings, and were even used to identify criminals and slaves.

The symbolic importance of tattoos has endured through the present day. However, although tattooing in ancient times was a slow and tedious process reserved for a select few, the invention of electric tattooing machines in the 20th century made tattooing available and affordable for the mainstream. Thus, tattoos have become an important part of the modern lifestyle. According to statistics published the Pew Research Center, an American think tank organization, 38% of men and women between the ages of 18 and 29 years have at least one tattoo. Around 50% of these individuals have 2 to 5 tattoos, whereas 18% indicate that they have 6 or more tattoos. The reasons cited for getting a tattoo include “impulsive decision making”, “to be part of a group”, “just wanted one”, and “for the heck of it”, but people also strive for individuality and uniqueness when making such a decision.

Throughout the course of the past 20 years, the prevalence of tattoos has significantly increased. Consequently, the demand for tattoo removal has increased as well. Although surveys suggest that up to 20% of owners may be dissatisfied with their tattoo, 11% consider removal and approximately 6% actually seek tattoo removal. Reasons cited for tattoo removal vary, but patients reported feelings of embarrassment, low self-esteem, problems with clothing, changing of life roles, medical problems, and stigmatization.

Introduction

Body art, such as tattoos, have fascinated mankind for centuries and have already been found in ancient Egyptian, Greek, and Roman cultures. In the past, such body markings served to enhance beauty, provide healing, declare belongings, and were even used to identify criminals and slaves.

The symbolic importance of tattoos has endured through the present day. However, although tattooing in ancient times was a slow and tedious process reserved for a select few, the invention of electric tattooing machines in the 20th century made tattooing available and affordable for the mainstream. Thus, tattoos have become an important part of the modern lifestyle. According to statistics published the Pew Research Center, an American think tank organization, 38% of men and women between the ages of 18 and 29 years have at least one tattoo. Around 50% of these individuals have 2 to 5 tattoos, whereas 18% indicate that they have 6 or more tattoos. The reasons cited for getting a tattoo include “impulsive decision making”, “to be part of a group”, “just wanted one”, and “for the heck of it”, but people also strive for individuality and uniqueness when making such a decision.

Throughout the course of the past 20 years, the prevalence of tattoos has significantly increased. Consequently, the demand for tattoo removal has increased as well. Although surveys suggest that up to 20% of owners may be dissatisfied with their tattoo, 11% consider removal and approximately 6% actually seek tattoo removal. Reasons cited for tattoo removal vary, but patients reported feelings of embarrassment, low self-esteem, problems with clothing, changing of life roles, medical problems, and stigmatization.

Tattoo removal

Tattoos are made by inserting indelible ink into the dermis layer of the skin to change the pigment. Although these body marks were once considered to be permanent, the technical and scientific progress in recent years has made it possible to remove tattoos partly or fully by various treatment modalities. Today, tattoo removal is a frequently performed procedure in dermatologic practices.

The methods for tattoo removal can be distinguished into 2 groups, namely ablative and nonablative tattoo removal procedures.

Ablative tattoo removal

Historically, several ablative techniques were used to remove tattoos. One of the earliest methods, salabrasion, was introduced by the Greek physician Aetius in 543 ad . Salabrasion is a process incorporating the application of salt and abrasion to rub off the top layers of the skin. Tattoo removal with an abrasive devise was also performed earlier by using dermabrasion, a process by which a wire brush or diamond fraise was used to mechanically abrade the tattooed skin. Another approach used trichloroacetic acid to chemically remove the top layers of the skin up to the dermal layers where the tattoo ink resides.

A significant innovation in the area of tattoo removal was the use of lasers in dermatology. In 1965, Leon Goldman first demonstrated the ability of the quality-switched (QS) ruby laser to selectively destroy pigments in the skin. However, because the mechanisms and medical potential for selectively absorbed, high-energy QS lasers were not well understood, the dermatologic use of ruby lasers was abandoned for some time.

In the early 1970s, a variety of continuous lasers were developed for scientific and industrial purposes, including carbon dioxide (far infrared, 10.6-μm wavelength) and argon-ion (Ar-ion; visible spectrum, 488 and 514-nm). These laser approaches used water as the targeted chromophore and removed the tattooed skin by ablating the epidermal layers up to the dermis. Ablative carbon dioxide and argon-ion lasers became the treatment of choice for tattoo removal for quite some time.

Although ablative laser treatment modalities for tattoo removal were somewhat successful, they were often accompanied by a wide range of unwanted side effects, including scarring and dyspigmentation. Additionally, the clinical outcome was often unpredictable and results were not satisfying. For this reason, the demand for safer and less ablative treatments became evident.

Nonablative tattoo removal

The groundbreaking theory of selective photothermolysis, described by Anderson and Parrish in the early 1980s, paved the way for a new generation of laser-based tattoo removal. This theory of selective photothermolysis refers to the precise targeting of chromophores, such as melanin, water, or oxyhemoglobin, using a specific wavelength of light with the intention of absorbing light into the specific target area while leaving surrounding areas relatively untouched.

The method of selective photothermolysis implies that the laser causes targeted heating of exogenous chromophores in the skin, the tattoo pigments, by means of selectively absorbed wavelengths. The high-temperature gradient produced by the laser results in the formation and propagation of acoustic waves that cause mechanical destruction of surrounding structures. Therefore, the target chromophore has to be heated very quickly and for no longer than its thermal relaxation time, which is defined as the time required for the target chromophore to lose 50% of its heat. Very small structures, such as the tattoo pigment, require rapid heating. In practice this can be accomplished by Q-switching, a technique that produces nanosecond (10 ⁻⁹ s) laser pulses by suddenly releasing all of the excited-state energy from the laser medium. Therefore, contemporary technology involves the use of QS lasers that are considered to be the gold-standard treatment option for the removal of unwanted tattoo ink in the skin.

Quality-switched lasers

The QS ruby laser, introduced by William H. Reid in 1983, was the first commercially available QS laser for tattoo removal, followed by the QS Nd:YAG and QS alexandrite laser. All 3 lasers are still used today in dermatologic practice. However, because the tattooed pigment comes in a wide range of colors, multiple wavelengths of laser light are required to successfully remove tattoos.

Studies have shown that dark pigmented tattoos can theoretically be treated by any laser, because black absorbs virtually every wavelength of light. However, Leuenberger and colleagues and others found the QS 694-nm ruby and QS 755-nm alexandrite laser to be superior in lightening black-blue tattoos compared with the 1064-nm QS Nd:YAG, but these treatments are frequently associated with transient pigmentary changes, including rare depigmentation. Although the 1064-nm QS Nd:YAG laser is slightly less efficient in the removal of black ink, dyspigmentation and textual changes are much less frequent due to its lower absorption by melanin and keratinocytes in the epidermis; this makes the 1064-nm Nd:YAG laser an excellent choice of therapy for tattoo removal in darker pigmented skin.

The light emitted from the 1064-nm QS Nd:YAG laser may also be frequency-doubled to produce light with a wavelength of 532-nm. Orange, red, and red-brown pigments, in particular, respond well to this wavelength. The 532-nm option of the QS YAG laser was also found to be superior to the QS 694-nm ruby and the 1064-nm option of the YAG laser in the removal of red colors in professional tattoos. The QS 755-nm alexandrite and the QS 694-nm ruby laser were considered the treatment modalities of choice for the removal of green-colored tattoos, whereas purple and violet ink respond best to the QS 694-nm ruby laser.

New advancements in laser-assisted tattoo removal

Laser-assisted tattoo removal with various QS laser devises still remains the gold-standard therapy in tattoo clearance. However, multiple treatment sessions are required until reaching full or acceptable lightening of the pigmented skin. The number of treatment sessions depends on pigment color, composition, density, depth, age of the tattoo, body location, and the amount of tattoo ink present. On average, 4 to 6 treatment sessions, which are typically spaced 1 to 2 months apart, are required for the complete removal of amateur tattoos, whereas up to 20 sessions are required for professional tattoos. Mediocre clinical results as well as prolonged and costly treatment sessions leave more to be desired from both patient and clinician. Therefore, newer unconventional laser-assisted techniques and treatment approaches have been developed to achieve faster and more effective removal of unwanted tattoos.

Multipass treatment

Recently published studies have focused on the possibility to effectively remove tattoos in fewer treatment sessions using a multipass method. In order for this method to be effective, immediate laser-induced cutaneous whitening reactions, likely resulting from thermally induced cavitation bubble formation in the dermis, must subside before delivery of each pass, which can be achieved in 1 of 2 ways: either by waiting for spontaneous resolution of whitening reactions, which requires an average of 20 minutes time after each pass (R20 method) or by application of topical perfluorodecalin (PFD), a highly gas soluble liquid fluorocarbon that resolves the whitening reaction within seconds (R0 method).

In a comparative study, Kossida and colleagues paralleled the efficacy of the conventional single-pass laser tattoo removal, using the 755-nm QS alexandrite laser, to treatment in 4 consecutive passes separated by a 20-minute interval (R20 method). Results demonstrated that the multi-pass R20 method is a safe and far more effective method in lightening tattoos in a single treatment session when compared with conventional single-pass laser treatment. Reddy and colleagues used the QS 694-nm ruby or 1064-nm Nd:YAG laser to compare the conventional single-pass treatment with the R20 and R0 method. Results indicated that the multiple-pass tattoo removal method, using PFD to deliver rapid sequential passes, is as effective as the R20 method, but in a significantly reduced treatment time. Moreover, tattoo clearance of both the R0 and R20 methods are superior to the traditional single-pass laser method with comparable safety potential.