Ross V, Naseef G, Lin G, Kelly M, Michaud N, Flotte T J, Raythen J, Anderson R R
Department of Dermatology, Wellman Laboratories of Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, USA.
Arch Dermatol. 1998 Feb;134(2):167-71. doi: 10.1001/archderm.134.2.167.
To test the hypothesis that picosecond laser pulses are more effective than nanosecond domain pulses in clearing of tattoos.
Intratattoo comparison trial of 2 laser treatment modalities.
A large interdisciplinary biomedical laser laboratory on the campus of a tertiary medical center.
Consecutive patients with black tattoos were enrolled; all 16 patients completed the study.
We treated designated parts of the same tattoo with 35-picosecond and 10-nanosecond pulses from 2 neodymium:YAG lasers. Patients received a total of 4 treatments at 4-week intervals. All laser pulse parameters were held constant except pulse duration. Radiation exposure was 0.65 J/cm2 at the skin surface. Biopsies were performed for routine microscopic and electron microscopic analysis at the initial treatment session and 4 weeks after the final treatment in 8 consenting patients. Also, ink samples were irradiated in vitro.
In vivo, on the completion of treatment, a panel of dermatologists not associated with the study (and blinded to the treatment type) evaluated photographs to assess tattoo lightening. Formalin-fixed specimens were examined for qualitative epidermal and dermal changes as well as depth of pigment alteration. Electron micrographs were examined for particle electron density and size changes (in vivo and in vitro). The gross in vitro optical density changes were measured.
In 12 of 16 tattoos, there was significant lightening in the picosecond-treated areas compared with those treated with nanosecond pulses. Mean depth of pigment alteration was greater for picosecond pulses, but the difference was not significant. In vivo biopsy specimens showed similar electron-lucent changes for both pulse durations. In vitro results were similar for both pulse durations, showing increases in particle sizes and decreased electron density as well as gross ink lightening.
Picosecond pulses are more efficient than nanosecond pulses in clearing black tattoos. Black tattoos clear principally by laser-induced changes in the intrinsic optical properties of the ink.
验证皮秒激光脉冲在清除纹身方面比纳秒级脉冲更有效的假设。
两种激光治疗方式的纹身内比较试验。
一家三级医疗中心校园内的大型跨学科生物医学激光实验室。
连续纳入有黑色纹身的患者；所有16名患者均完成研究。
我们使用两台钕：钇铝石榴石激光的35皮秒和10纳秒脉冲治疗同一纹身的指定部位。患者每隔4周共接受4次治疗。除脉冲持续时间外，所有激光脉冲参数均保持不变。皮肤表面的辐射暴露为0.65 J/cm²。在8名同意的患者中，在初始治疗时和最终治疗后4周进行活检，用于常规显微镜和电子显微镜分析。此外，对墨水样本进行体外照射。
在体内，治疗完成后，一组与研究无关（且对治疗类型不知情）的皮肤科医生评估照片以评估纹身变淡情况。检查福尔马林固定标本的表皮和真皮定性变化以及色素改变深度。检查电子显微镜照片以观察颗粒电子密度和大小变化（体内和体外）。测量体外总体光密度变化。
在16个纹身中的12个中，与纳秒脉冲治疗的区域相比，皮秒治疗区域有明显变淡。皮秒脉冲的色素改变平均深度更大，但差异不显著。体内活检标本显示两种脉冲持续时间的电子透明变化相似。两种脉冲持续时间的体外结果相似，显示颗粒尺寸增加、电子密度降低以及墨水总体变淡。
皮秒脉冲在清除黑色纹身方面比纳秒脉冲更有效。黑色纹身主要通过激光诱导墨水固有光学性质的变化来清除。
