SAN DIEGO –
“A picosecond is to a second as 1 second is to 37,000 years,” Mathew M. Avram, MD, JD, said at the annual Masters of Aesthetics Symposium. “That’s equivalent to the total energy of the city of San Diego for 300-750 trillionths of a second.”
According to Dr. Avram, director of laser, cosmetics, and dermatologic surgery at Massachusetts General Hospital, Boston, picosecond lasers produce extreme cavitation and cell rupture, with a desired clinical endpoint of immediate dermal whitening of tattooed skin. The process causes transdermal elimination of the tattoo ink. Some of the ink flows into the lymphatic system, while the rest undergoes rephagocytosis by dermal scavenger cells.
Commercially available picosecond lasers include devices with wavelengths of 532 nm, 755 nm, and 1,064 nm that deliver energy in a range of 300-750 picoseconds. Nd:YAG lasers work best for red and black ink, while alexandrite lasers work best for green and blue ink. In Dr. Avram’s experience, picosecond lasers are generally more effective for tattoo removal, compared with nanosecond lasers. “There is some nonselective targeting of other pigments, and they’re particularly effective for faded tattoos, but the devices are more expensive,” he said.
Dr. Avram, who is also the faculty director for laser and cosmetic dermatology training at Harvard Medical School, also in Boston, advises against promising a certain number of laser treatments during initial patient consultations. “You will regret it,” he said. “Tattoos are notoriously unpredictable in how they respond. I often hear people say they get rid of these in three to five treatments. That isn’t my experience with these lasers. Often, all you’re going to be able to do is get significant clearing rather than tattoo removal. Professional tattoos are the most difficult to treat because they are the deepest and they have the most amount of ink.”
On the other hand, amateur tattoos, traumatic tattoos, and radiation tattoos require far fewer treatments. “The color is important,” he said. “Multicolored tattoos, regardless of the colors, are always going to be more difficult to clear than a single-color tattoo.” Black and dark-blue tattoos respond best to laser light; light-blue and green also respond well. Red responds well, while purple can be challenging. Yellow and orange do not respond very well, but they do respond partially.
According to a trial that analyzed variables influencing the outcome of tattoos treated by Q-switched lasers, 47% were cleared after 10 sessions, while 75% were cleared after 15 sessions (Arch Dermatol 2012;148:1364-9). “It’s very important to message to your patients how many treatments this might take, because there is going to be an annuity of patients who are unhappy because they have to keep coming back,” said Dr. Avram, who is the immediate past president of the American Society for Laser Medicine and Surgery. Skin type and pigmentation also affect treatment outcomes. “For darker skin types or tanned individuals, hyper- or hypopigmentation is a greater concern than in patients with lighter skin types,” he said. “A test spot may be beneficial. The 1,064-nm Q-switched Nd:YAG laser is least likely to affect skin pigment; it’s safest for skin types IV-VI . This is great if it’s a black tattoo. But if it’s a green, blue, or red tattoo, you have a problem because you’re not going to target it very effectively.”
Some degree of posttreatment hypopigmentation is likely to occur, regardless of skin type. “Let patients know this is going to happen, but over time, this usually resolves, because you’re not destroying the melanocytes, unless you’re going too strong,” Dr. Avram said. “It may take a few months. It may take a year or 2, but the pigment should recur.”
He emphasized that the key variable during laser treatment of tattoos is the clinical endpoint, not the energy setting of the device. “What you want to see is immediate whitening of the treated area,” he said. “With the 1,064-nm Nd:YAG, you may get a little pinpoint bleeding in addition to whitening. Do not memorize treatment settings. Many Q-switched lasers are not externally calibrated. Thus, energy levels may change day to day or before and after servicing [of the device]. Trust your eyes; trust your clinical skills.” If you see epidermal disruption and bleeding during treatment, you’re probably being too aggressive. If that happens, “decrease your fluence,” he recommended. “You also want to decrease fluences when treating tattoos that are placed over other tattoos.”
Another rule of thumb is to use larger spot sizes during treatment sessions. “The larger the spot size, the more efficient the energy is going to get more deeply, and less is going to be at the dermal-epidermal junction,” Dr. Avram said. “So you’re going to get less hypopigmentation and less hyperpigmentation. Follow your endpoints and you are less likely to get pigmentation changes.”
Posttreatment care typically includes the application of topical petroleum jelly and a Telfa dressing. “Wait about a week to heal, counsel patients to keep out of the sun, and avoid friction to the treated area during healing,” he said. Patients can be rescheduled for retreatment 6-8 weeks later.
Common adverse events during laser treatment of tattoos include erythema, blistering, hyperpigmentation, hypopigmentation, and scarring, which occurs in about 5% of cases. Less common adverse events include allergic reaction, darkening of cosmetic tattoos, immune reaction, and chrysiasis, which is a dark-blue pigmentation caused by Q-switched laser treatment in patients with a history of gold salt ingestion. “Any history of gold salt ingestion will produce this characteristic finding, even if they took it when they were 5 years old and they come to you when they’re 85,” Dr. Avram said. “All of our intake forms include a question about this, and before I treat patients I always ask if they have a history of gold ingestion, because it’s very difficult to treat.”
Surgical excision may be an alternative for smaller tattoos. “Another option is ablative fractional resurfacing as a solo treatment or in combination with the Q-switched or picosecond laser, which has better efficacy,” he said. “The ablative fractional laser also may help with fibrosis after multiple treatments in a recalcitrant tattoo.” He noted that cosmetic tattoos such as lip liner and blush tattoos might darken because of oxidation of ferric oxide or titanium oxide pigment. The best approach to such cases is to perform an inconspicuous test spot prior to treatment.
Clinicians continue to explore the optimal interval between treatments. For example, the “R20” method consists of four consecutive treatment passes separated by 20 minutes. The initial study found that this approach led to better outcomes, compared with conventional, single-pass laser treatment (J Am Acad Dermatol 2012;66:271-7). A follow-up study by Dr. Avram and his colleagues contradicted these findings, while another follow-up study was supportive.
Another technology playing a role in such repeat treatments is a perfluorodecalin-infused silicone patch, which is placed over the treatment area. According to Dr. Avram, the FDA-cleared patch helps reduce scatter during treatment and likely improves efficacy. It also allows for performing consecutive repeat laser treatments at the same visit. In one study, 11 of 17 patients had more rapid clearance on the side treated with the perfluorodecalin patch, compared with the side treated without the patch (Laser Surg Med 2015;47:613-8).
Dr. Avram disclosed that he has received consulting fees from Allergan, Merz, Sciton, Soliton, and Zalea. He also reported having ownership and/or shareholder interest in Cytrellis, Invasix, and Zalea.