In-vivo histopathological study of YouLaser MT interaction with the skin. A laser device emitting combined 1540 and nm wavelengths.

Transcription

1 Histology report No. 02/04-12, date April 2nd, 2012 Page 1 In-vivo histopathological study of YouLaser MT interaction with the skin. A laser device emitting combined 1540 and nm wavelengths. Paolo Sbano MD, Dermatology Department of Siena University Hospital (Siena, Italy) INTRODUCTION The Fractional Skin Resurfacing is typically performed in Ablative or in Non-Ablative mode. Both the techniques have well known advantages and disadvantages in terms of final results and patient s recovery time. These fractional devices have an handpiece that produces small point of laser-tissues interaction called micro thermal zones. Depending on the wavelength of 1540 or nm, the laser creates a different amount of thermal damage to the skin. This process trigger a wound healing process from the spared side healthy tissues to the thermally damaged micro zones of skin results in the formation of new dermal collagen using 1540 nm and also new epidermis using nm. The 1540 nm laser is considered a no-down-time device with excellent results in acne scars and skin toning treatments but with limited clinical outcomes on deep wrinkle reduction and superficial pigmentations treatments. The nm CO 2 laser is typically more effective than 1540 nm on wrinkles and superficial pigmentations but delivering also a down- time to the patients of some days. A new ideal laser device must take the benefits of both this modalities to maximize results and reduce as much as possible the recovery time. OBJECTIVE This study evaluates the ablation and coagulation depth, the healing time and safety of YouLaser MT (Quanta System, Italy), a fractional laser device able to mix, in sequential or simultaneous emission, 1540 and nm laser wavelengths in order to asses the potentials in fractional skin resurfacing treatments. METHODS The laser beam was focused by the fractional scanner in selected areas (fig. 2) with fixed 1x1 cm squared pattern and 100 dot/cm 2 of density. Biopsies were taken at 1 hour, 3 and 14 days post treatment. Both the lasers were tested at different range of energy on pig s skin. The pigs used, five delay Fig. 1 Sequential emission of nm and 1540 nm with independent pulse and variable delay between the two pulses Simultaneous emission of nm and 1540 nm with variable pulse Coaxial delivery of the 1540 and laser beams

2 Histology report No. 02/04-12, date April 2nd, 2012 Page 2 months old, was four, one for each of the three follow-up time and one as back-up. Table N.3 Simultaneous emission 1540 and nm Diode 1540 nm CO nm Test (N ) Pause n/a n/a n/a n/a n/a n/a n/a The number of tests where totally 26, composed by 3 steps of CO nm energy and other 3 steps for diode 1540 nm (see table n.1, n.2 and n.3 for details). These steps have been combined in sequential or simultaneous emissions (fig. 1) in the same dot generated by the fractional scanner Test (N ) Table N.1 Sequential emission than 1540 nm CO nm Pause Diode 1540 nm Test (N ) Table N.2 Sequential emission 1540 than nm Diode 1540 nm Fig. 2 - treatment areas Pause CO nm RESULTS n/a The laser treatment produce a fractional pattern of micro-dots separated by an average of 500µm of untreated tissue (with selected scanner density). Table N.1, N.2 and N.3 summarize the laser parameters and the pulse structures of each of the 26 tests performed. Table N.4 shows the results of the histology examination at 1 hour, 3 and 14 day post treatment. Tests n.1 and n.19 produced no visible wounds at the 1 hour examination but visible coagulation at 3 days probably due to the low laser energy dose, not able to create immediate coagulation but a subsequent very limited thermal necrosis. The histology images at 14 days are in some cases not available due to the complete healing of the skin at that time. In This study, we publish just the images with visible wound reparation processes. At 1 hour post treatment, the lasers effect, depending by the energy delivered by each one, generates from a superficial coagulation to an immediate ablation of the treated area. The diode 1540 nm laser tested at 21, 42 and 63 mj per micro-dot is the major responsible of the amount of coagulation, the CO nm at 5, 10, and 22.5 mj per micro-dot is the only laser responsible of the ablation and for a minimal amount of the coagulation. The Table N.4 shows the amount of ablation and coagulation depth as well as the diameter of the ablated and coagulated skin delivering the laser energy in just a single pulse and all the three mixed configurations. The results through indicate that the skin ablation depth is related with energy delivered, the energy depends by the power and the pulse and increases efficiently up to 22.5mJ per pulse with

3 Histology report No. 02/04-12, date April 2nd, 2012 Page nm and 63mJ with 1540nm (the maximum tested parameters). In general increasing the energy of both lasers in simultaneous emission, the ablation depth increase more efficiently if compared with the results of the same energy but delivered in sequential mode. This is the consequent of a cumulative effect: the 1540nm laser has a lower water absorption compared to 10600nm and is not able to ablate epidermis but increase efficiently the dermis temperature up to coagulation (around C for irradiation of few ms), now the 10600nm laser delivered simultaneously with 1540nm needs a lower amount of energy to ablate a certain amount of skin. Comparing the results in Table N.4 with the histology results of YouLaser CO 2 (YouLaser CO 2 histology rev.2 - author Paolo Mezzana) is evident that the energy needed by 10600nm, when simultaneously combined with 42mJ of 1540nm, to ablate 600µm of skin is about ~60% of the energy needed by 10600nm alone. At 21mJ of 1540nm, the 10600nm needs ~80% of usual energy (if used alone) to reach the same ablation depth, at 63mJ of 1540 the 10600nm energy is just about ~40% than 10600nm alone (see Table N.5 for 10600nm histology results). This synergic effect is not so evident using the two laser in sequence because of the delay between the pulses overtakes the thermal relaxation time of the skin than has now time to cool down before the second pulse. The diameter of the ablation (Wa) and coagula- Table N.4 Histology measurements Test (n) Da Dc Wa Wc Da Dc Wa Wc Da Dc Wa Wc notes Lesion not found Lesion not found at 1 hour. Healing visible at 3 days Da: Depth of ablation; Dc: Depth of coagulation; Wa: Width of ablation; Wc: Width of coagulation

4 Histology report No. 02/04-12, date April 2nd, 2012 Page 4 Table N.5 YouLaser CO 2 histology results per dot Ablation Diameter Ablation depth Coagulation depth tion is influenced by the energy delivered and the 10600nm laser is responsible of the ablation diameter that compared to Table N.5 has not remarkable differences, while the 1540 is the major responsible of the coagulation diameter (Wc). The average Wa diameter was 256µm and the Wc diameter was 345µm. At 3 days post treatment a collection of necrotic debris is visible when the nm is associated to 1540nm, the wound healing was in all the cases evident with a compete reepithelization visible in all the samples. At 14 days post treatment the repair is always complete. At the highest settings tested is visible some residual necrotic debris Test N.2-5mJ@10600nm; 2 ms delay than 42mJ@1540nm Test N.3-5mJ@10600nm; 2 ms delay than 63mJ@1540nm

5 Histology report No. 02/04-12, date April 2nd, 2012 Page 5 Fig. 4 - Test N.4-10mJ@10600nm; 2 ms delay than 21mJ@1540nm Fig. 5 - Test N.5-10mJ@10600nm; 2 ms delay than 42mJ@1540nm Fig. 6 - Test N.6-10mJ@10600nm; 2 ms delay than 63mJ@1540nm

6 Histology report No. 02/04-12, date April 2nd, 2012 Page 6 Test N mJ@10600nm; 2 ms delay than 21mJ@1540nm Test N mJ@10600nm; 2 ms delay than 42mJ@1540nm Test N mJ@10600nm; 2 ms delay than 63mJ@1540nm

7 Histology report No. 02/04-12, date April 2nd, 2012 Page 7 Test N.10-21@1540nm; 2 ms delay than 5mJ@10600nm Test N.11-42@1540nm; 2 ms delay than 5mJ@10600nm Test N.12-63@1540nm; 2 ms delay than 5mJ@10600nm

8 Histology report No. 02/04-12, date April 2nd, 2012 Page 8 Test N.13-21@1540nm; 2 ms delay than 10mJ@10600nm Test N.14-42@1540nm; 2 ms delay than 10mJ@10600nm Test N.15-63@1540nm; 2 ms delay than 10mJ@10600nm

9 Histology report No. 02/04-12, date April 2nd, 2012 Page 9 Test N.16-21@1540nm; 2 ms delay than 22.5mJ@10600nm Test N.17-42@1540nm; 2 ms delay than 22,5mJ@10600nm Test N.18-63@1540nm; 2 ms delay than 22,5mJ@10600nm N/P

10 Histology report No. 02/04-12, date April 2nd, 2012 Page 10 Test simultaneously Test simultaneously Test simultaneously N/P

11 Histology report No. 02/04-12, date April 2nd, 2012 Page 11 Test simultaneously Test simultaneously Test simultaneously

12 Histology report No. 02/04-12, date April 2nd, 2012 Page 12 Test simultaneously Test simultaneously CONCLUSIONS The YouLaser MT laser device when is used at different settings is able to produce different amount of ablation and coagulation into the skin. Increasing energy of both and 1540nm lasers, ablation coagulation and diameter of wound increase progressively up to less than 1mm in depth and around 350µm in diameter. To maximize the ablation depth the simultaneous emission mode of the two wavelengths is preferable. To maximize the coagulation depth with minimal ablation the sequential emission mode with 1540nm starting before is the ideal pulse configuration. In conclusion, the tested laser device is able to ablate and coagulate the skin at predictable layers with reproducible precision and can be used safely and effectively in human medical field. REFERENCES Kamat BR, Carney JM, Arndt KA, Stern RS, Rosen S. Cutaneous tissue repair following CO2 laser irradiation. J Invest Dermatol 1986 Aug; 87(2): Ross EV, Grossman MC, Duke D, Grevelink JM. Long-term results after CO2 laser skin resurfacing: A comparison of scanned and pulsed systems. J Am Acad Dermatol 1997;37 (5 Pt 1): Ross EV, McKinlay JR, Anderson RR. Why does carbon dioxide resurfacing work? Arch Dermatol 1999;135: Richert SM, Bridenstine J. Transepidermal elimination of elastic fibers after carbon dioxide laser resurfacing. A report of two cases. Dermatol Surg 1998;24(2):

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