Comparative study of the efficacy of Q-switched neodymium-doped yttrium aluminum garnet laser alone versus ultra-pulse carbon dioxide laser along with Q-switched neodymium-doped yttrium aluminum garnet laser in patients with black tattoo

INTRODUCTION

Tattooing goes back thousands of years.¹ For ages, tattoos have been used as a form of expression of art.² Tattoo removal dates back to 534 BC, when salabrasion involved using salt for injury on tattoo. Furthermore, the use of sulfuric or nitric acid led to scar tissue formation.^3,4 Other methods included dermabrasion, electrocauterization, cryosurgery, and chemical peeling which resulted in scarring and lengthy recovery times.⁵

Although the Q-switched (QS) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is the established method for black tattoo removal, it often necessitates multiple sessions and may not fully eliminate the tattoo. Using an ultrapulse carbon dioxide (CO₂) laser to prepare the skin before the Nd:YAG laser can improve results and minimize side effects.⁵ There is, however, a paucity of literature regarding the use of combination lasers for tattoo removal. Furthermore, this study explores laser tattoo removal in a rural central Indian setting, a scarcely explored area addressing a significant void in existing research. However, this study only focused on black tattoos due to the infrequency of other colors such as red and yellow in this population.

MATERIAL AND METHODS

A prospective comparative study from September 2022 to February 2024 was conducted in the Department of Dermatology, Venereology, and Leprosy of a tertiary care hospital in rural central India.

The sample size was calculated using Cochran formula⁶ (based on study reference Vanarase et al.⁵), n = Zα/22. p.(1-p)/E2. Based on this, the sample size (n) came to be 25 in each group.

After approval from the institutional ethics committee, fifty patients with black tattoos were enrolled in this study. Inclusion criteria involved patients with professional and amateur black tattoos giving written informed consent for their removal. Exclusion criteria involved patients aged <18 years, any history of concurrent active skin disease at the site of the tattoo, current pregnancy, lactation, history of herpes simplex virus infection and its recurrence, bleeding disorders, the tendency of keloid formation, and intake drugs with photosensitizing potential within past 3 months.

Patient selection was done by systematic random sampling and was consecutively assigned to each group. There were 25 patients each in Groups A and B. Serological tests for human immunodeficiency virus and Hepatitis B and C virus were done. After obtaining consent, detailed history was documented, baseline photographs were taken with the same device at a fixed place and position, and Kirby Desai scoring was also done where numerical values were given to six factors: Skin type, location of the tattoo in the body, color of the tattoo ink used, amount of tattoo ink used, scarring, and layering. These values were then added together to give an estimate of the total number of sessions required.⁷ This was followed by the application of an eutectic mixture of local anesthesia (comprising 2.5% lidocaine and 2.5% prilocaine) for 45 min under occlusion. The area to be treated was cleaned with normal saline. Protective goggles were used by both patients and physicians. The QS Nd:YAG 1064 nm laser for the removal of dark pigments such as black and blue is considered versatile.⁷ Tattoo removal depends on wavelength, radiant exposure, spot size, pulse width, session intervals, and number of sessions. Radiant exposure (J/cm²) heats pigment, causing temporary whitening, creating gas or plasma and forming dermal vacuoles, which fade in hours.⁸

Group A was treated with QS Nd:YAG laser of VENUS PRO PLUS U.S.A. Inc. wavelength: 1064 nm; output power 1000 W; spot size 2–4 mm, pulse width 20 ns, frequency 2–4 Hz. Energy in the first sitting was taken at 250 mJ where visible whitening was seen. Energy dose was increased by 30 mJ in every sitting as preset in the laser. Skin type was adjusted depending on the patient profile.

Group B underwent combination laser treatment with QS Nd:YAG and ultra-pulse CO₂. At first, skin type was adjusted depending on the patient’s profile. Then, CO₂ laser was performed using ultra-pulse CO₂ fractional laser machine FRAX II with the following parameters power: 8 W, fluence - 1.2 J, pulse frequency 33.3 Hz, duration time 0.5 ms, distance 0.4 mm, shape adjusted according to tattoo. Following this, Group B was immediately treated with QS Nd:YAG 1064 nm laser. Parameters were the same as that of Group A. Immediate whitening of tattoo was considered the end point of treatment following which ice application was done over the site.

Patients were given post-procedure instructions which included photoprotection through the use of protective clothing and use of broad-spectrum sunscreens. Topical antibiotics were recommended for the care of a wound. Patients were informed that erythema and edema might stay for some time and to report back in the event of crusting, pigmentation, or blistering. Sessions were repeated every 6-week interval till complete clearance (if achieved in an earlier session) or a maximum 6 sessions. Most patients achieved removal within a lesser time frame. Very few patients who did not achieve their desired result within this time continued their follow-up till 6 sessions. On follow-up, photographs were captured with the same device settings on the 1^st, 2^nd, 3^rd, and 4^th sessions. Improvement percentage was assessed using a Visual Analog Scale (VAS) and tattoo ink lightening (TIL) grading system. VAS scores and TIL scores were similarly categorized as 1: poor (<25%), 2: fair (25–50%), 3: good (51–75%), 4: excellent (76-95%), and 5: clear (>96%).⁵ VAS scores were decided on patient assessments, whereas TIL scores were determined by evaluating the photographic evidence. The mean score was used for the purpose of statistical analysis. Any side effects were documented in a preset form.

RESULTS

Comparison between two groups

The majority of patients achieved satisfactory tattoo removal within four sessions. For analysis, we have focused on the data from the first four sessions. The study found that the combination laser treatment Group B showed significant improvement in VAS and TIL scores in subsequent visits compared to Visit 1, as shown in Tables 2 and 3. Both groups A and B showed an increasing trend in these scores over three visits as shown in Figures 1 and 2, indicating the effectiveness of both lasers in tattoo removal. Although Group B had higher scores, the difference was not statistically significant (P > 0.05). Group B had a higher percentage of tattoos with “excellent” to “clear” responses in both categories in comparison to Group A as depicted in Table 4. Side effects included pinpoint bleeding in Group B and tattoo darkening in Group A, with both groups experiencing equal instances of hypopigmentation as shown in Table 5.

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Figure 1:

Comparison of Visual Analog Scale score in groups neodymium-doped yttrium aluminum garnet (Nd:YAG) (Group A) and Nd:YAG + carbon dioxide (Group B) at visit 1, visit 2, visit 3, and visit 4 (Student’s unpaired t-test).

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Figure 2:

Comparison of mean difference in tattoo ink lightening score in neodymium-doped yttrium aluminum garnet (Nd:YAG) (Group A) and Nd:YAG + carbon dioxide (Group B) at visit 1, visit 2, visit 3, and visit 4.

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Table 2: Comparison of VAS score in group Nd: YAG+CO₂ (Group B) at visit 2, visit 3, and visit 4 with visit 1 (Student’s paired t-test).

Mean	n		Standard deviation	Standard error mean	Mean difference	t-value
Visit 1	20.53	28	17.33	3.27	-	-
Visit 2	48.21	28	20.19	3.81	27.67±14.74	9.93 P=0.0001, S
Visit 3	70.27	18	18.02	4.24	51.11±17.45	12.42 P=0.0001, S
Visit 4	80.83	12	14.74	4.25	65±18.09	12.44 P=0.0001, S

VAS: Visual Analog Scale, Nd: YAG: Neodymium-doped yttrium aluminum garnet, CO₂: Carbon dioxide, S: Significant

Table 3: Comparison of TIL score in Nd: YAG+CO₂ (Group B) at visit 2, visit 3, and visit 4 with visit 1 (Student’s paired t-test).

Visit	Mean	n	Standard deviation	Standard error mean	Mean difference	t-value
Visit 1	18.92	28	15.47	2.92	-	-
Visit 2	39.82	28	21.23	4.01	20.89±11.78	9.37 P=0.0001, S
Visit 3	59.44	18	20.35	4.79	41.66±14.55	12.14 P=0.0001, S
Visit 4	74.58	12	16.71	4.82	60.41±16.57	12.62 P=0.0001, S

TIL: Tattoo ink lightening, Nd: YAG: Neodymium-doped yttrium aluminum garnet, CO₂: Carbon dioxide, S: Significant

Table 4: Scoring of VAS of tattoos based on the assessment of patients and TIL based on the assessment by physician.

Grades (VAS and TIL) (%)	VAS Nd:YAG (Group A) (%)	TIL Nd:YAG (Group A) (%)	VAS Nd:YAG+CO2 (Group B) (%)	TIL Nd:YAG+CO2(Group B) (%)
Poor (<25)	0 (0)	0 (0)	0 (0)	0 (0)
Fair (25–50)	3 (13.04)	3 (13.04)	1 (4.17)	1 (4.17)
Good (51–75)	7 (30.43)	9 (39.13)	4 (16.67)	6 (25)
Excellent (76–95)	11 (47.83)	9 (39.13)	15 (62.5)	13 (54.17)
Clear (≥96)	2 (8.70)	2 (8.70)	4 (16.67)	4 (16.67)
Total	23 (100)	23 (100)	24 (100)	24 (100)

VAS: Visual Analog Scale, TIL: Tattoo ink lightening, Nd:YAG: Neodymium-doped yttrium aluminum garnet, CO₂: Carbon dioxide

Table 5: Distribution of patients in two groups according to side effects.

Side Effects	Nd:YAG (Group A) n=25 (%)	Nd:YAG+CO2(Group B) n=25 (%)	Chi-square-value
Tattoo darkening	1 (4)	0 (0)	2.92 P=0.23, NS
Pinpoint bleeding	0 (0)	2 (8)
Hypopigmentation	3 (12)	3 (12)
Total	4 (16)	5 (20)

Nd:YAG: Neodymium-doped yttrium aluminum garnet, CO₂: Carbon dioxide, NS: Not significant

DISCUSSION

Tattoo removal poses a significant challenge for dermatologists due to the various complications that can arise, including infections, allergic reactions, and the potential for neoplastic conditions.⁹

This study found the mean patient age in Group A to be 23.84 ± 8.27 while it was 25.32 ± 6.13 in Group B which is consistent with the findings of Sardana et al.¹⁰ where the mean age was 27.6 and Padhiar et al.¹¹ where the mean 21.9 years with a standard deviation of 3.4 years. The current study had a higher number of male patients in both groups in comparison with female patients, similar to the findings of Sardana et al.¹⁰ and Bencini et al.¹² However, this contrasts with the study done by Radmanesh and Rafiei¹³ and Aurangabadkar et al.¹⁴ which reported more female participants than male participants. The present study found that 92% of patients in Group A and 80% of patients in Group B had Fitzpatrick skin type IV while 8% in Group A and 20% of patients in Group B had Fitzpatrick skin type V which is similar to the results obtained in studies done by Radmanesh and Rafiei¹³ and Vanarase et al.⁵ where a greater number of patients were in Fitzpatrick skin type IV and equal number of patients in Fitzpatrick skin type III and IV, respectively. The study revealed that the majority of participants had amateur tattoos (33 in Group A and 29 in Group B) than professional tattoos (2 in Group A and 8 in Group B). These findings align with similar studies by Vanarase et al.,⁵ Sardana et al.,¹⁰ Padhiar et al.,¹¹ and Rolaniya et al.¹⁵ which reported a higher number of amateur tattoos in their studies. In addition, this study found that most tattoos were located on the forearm in both Group A (60%) and Group B (70.27%), followed by the hand (10.81%) in Group B and hand (20%) as well as forehead (20%) in Group A. Similar results were reported by Vanarase et al.,⁵ Padhiar et al.,¹¹ and Aurangabadkar et al.¹⁴ where the most common sites for tattoos were distal extremity and forearm, respectively. The mean size of tattoos in this study in Group A was 4.05±3.28 cm with a size ranging from 0.5 to 14 cm whereas in Group B, the mean size of tattoos was 4.36 ± 2.29 with size ranging from 0.5 cm to 11 cm. This finding was in contrast to Vanarase et al.⁵ where 16.6% of patients had tattoo size more than 20 cm. In the present study, in Group A, the duration of tattoos ranged from 1.5 to 20 years while in Group B, it was <1 year–28 years which is in line with the study done by Rolaniya et al.¹⁵ which also had many tattoos of duration more than 10 years and Yang et al.¹⁶ where age of tattoos ranged from <12 months to 20 months and more.

None of the patients in both groups had positive viral markers and no systemic illness was reported. The end point of laser treatment was post procedure edema and whitening as shown in Figure 3.

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Figure 3:

Post-procedure edema and whitening after both neodymium-doped yttrium aluminum garnet and carbon dioxide laser suggesting end point of treatment.

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In Group A, amateur tattoo showed improvement in both VAS and TIL in every visit as shown in Figures 4 a-c, while professional tattoo showed minimal improvement in both VAS and TIL as shown in Figures 5 a-c. In Group B, amateur tattoo showed 'clear' response in both VAS and TL as shown in Figures 6 a-c, while professional tattoo showed good response in both VAS and TIL in every visit as shown in Figures 7 a-c. Group A experienced paradoxical tattoo darkening as shown in Figure 8a and b. This is usually seen in tattoos containing titanium dioxide or iron oxide, which react to laser energy by oxidizing rather than breaking down, thus darkening instead of lightening the tattoo. Both groups had the same rate of tattoo hypopigmentation as shown in Figure 9a and b as the laser can inadvertently disrupt melanin in the skin while targeting the tattoo pigment. Group B, treated with a combination laser, developed pinpoint bleeding as shown in Figure 10. This is due to the heat generated by the laser which causes vasodilation and subsequent rupture of small vessels. This contrasts with the Cannarozzo et al.¹⁷ study showing that 25% of tattoos had paradoxical darkening. Unlike the results obtained by Vanarase et al.,⁵ this study did not observe scarring, tissue splatter, mottled depigmentation. The effectiveness of tattoo removal depends on several factors, including age, tattoo type, location, size, and the amount of ink. Tattoos present over the hands were first to get cleared followed by tattoos over the neck followed by the forehead followed by the arm. Tattoos over the forearm were last to get cleared. In comparison to amateur ink, minimal ink was 0.48 times less likely and moderate ink was 0.45 less likely to achieve therapy success which is comparable to findings described by Zhang et al.¹⁸ The CO₂ laser aids in tattoo removal by targeting superficial pigments in the papillary dermis, promoting their extrusion. With the epidermis removed, less laser light is absorbed by the epidermis and melanin, enhancing penetration and absorption by the pigment particles. This results in more effective tattoo removal.^5,13

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Figure 4:

(a) Baseline; (b) Visit 2; (c) Visit 4. Nd:YAG Group A- Amateur tattoo, in comparison to (a) baseline, (b) showing improvement in Visit 2 and (c) Visit 4.

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Figure 5:

(a) Baseline; (b) Visit 2; (c) Visit 4. Neodymium-doped yttrium aluminum garnet (Group A) – Professional tattoo showing minimal improvement in Visit 2(b) and Visit 4(c) in comparison to baseline (a).

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Figure 6:

(a) Baseline; (b) Visit 2; (c) Visit 4. Neodymium-doped yttrium aluminum garnet + carbon dioxide (Group B) – Amateur tattoos showing improvement in Visit 2 (b) and Visit 4 (c) in comparison to baseline (a) with clearance of tattoo.

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Figure 7:

(a) Baseline; (b) Visit 2; (c) Visit 4. Neodymium-doped yttrium aluminum garnet + carbon dioxide (Group B) – Professional tattoos showing improvement in Visit 2 (b) and Visit 4 (c) in comparison to baseline (a).

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Figure 8:

(a) Baseline; (b) Paradoxical tattoo darkening seen in amateur tattoo in neodymium-doped yttrium aluminum garnet Group A in Visit 1.

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Figure 9:

(a) Baseline; (b) Hypopigmentation of amateur tattoo seen in neodymium-doped yttrium aluminum garnet + carbon dioxide Group (B) in Visit 2.

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Figure 10:

Pinpoint bleeding of professional tattoo seen in neodymium-doped yttrium aluminum garnet + carbon dioxide Group (B).

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Most of the patients had their tattoos removed in lesser sessions in comparison to the number of sessions depicted by Kirby-Desai scale indicating that the combination laser is efficacious for faster tattoo removal. Pincelli et al.⁸ reported similar findings. Most patients were satisfied with combination laser treatment as indicated by the VAS scores. This is similar to studies by Vanarase et al.,⁵ Sardana et al.,¹⁰ Cannarozzo et al.,¹⁷ and Yang et al.¹⁶ reported similar results where patients were satisfied with the combination therapy.

In addition, the higher number of tattoos in Group B treated by combination laser achieved clearance in a lesser number of sessions in comparison to Group A indicating its superior effect as indicated by the TIL scores.

CONCLUSION

QS lasers, though commonly used, require multiple sessions and may be less effective, especially for those with darker skin tones. Combining different lasers enhances results and reduces the number of sessions, as shown in recent studies in comparison to the Kirby-Desai Score. Future research should involve larger, well-designed studies with extended follow-up to assess the efficacy and safety of Nd:YAG and CO₂ laser combinations for tattoo removal. In addition, exploring factors such as tattoo characteristics and patient-specific variables could be beneficial. This study underscores the potential of laser technology, helping clinicians make more informed recommendations for tattoo removal.