应用光学相干层析术研究光动力治疗鲜红斑痣前后皮肤结构和光学参数的变化

Research on the Structure and Optical Parameter Changes of Port Wine Stain after Photodynamic Therapy Based on Optical Coherence Tomography

研究鲜红斑痣(PWS)组织结构和光学特性在光动力治疗(PDT)前后的变化有利于客观评价疗效及指导后续治疗。通过分析光学相干层析术(OCT)采集的光学相干信号在PWS不同组织结构中的特征,得到治疗前后PWS的表皮层厚度以及扩张血管的管径和深度;基于扩展的Huygens-Fresnel原理与最小二乘法对PWS的OCT纵向信号进行拟合,获取治疗前后组织的散射特性参数。分析上述参数在28例PWS患者PDT治疗前后的变化。治疗后表皮层厚度及各层散射系数无明显改变(p>0.05),扩张血管的平均管径减小,扩张血管的平均深度增加(p<0.05)。本研究实现了OCT对PWS结构参数和光学参数的在体无创测量。研究结果表明将PWS各参数在PDT治疗前后的变化作为评价治疗效果和调整治疗方案的参考依据具有一定的可行性。

Research on the changes of structure characteristics and optical properties of the port wine stain （PWS） skin after photodynamic therapy （PDT） can evaluate the treatment effect objectively and provide reference for the clinician to adjust the protocol. Based on optical coherence tomography （OCT）, the structure characteristics and scattering properties of the PWS skin are measured. Through analyzing the OCT signal characteristics shown in epidermis, dermis and blood, the thickness of epidermis, the diameter and depth of ectatic vessels in the PWS skin before and after PDT are calculated. An optical properties extraction algorithm is developed based on extended Huygens-Fresnel light propagation theorem, to extract the scattering coefficience of the PWS skin before and after PDT. The parameters of 28 PWS patients obtained before and after PDT are compared. The results show that the changes of epidermis thickness and scattering coefficients are not obvious （p〉0.05）. However, the mean ectatic vessels diameter is decreased and the locations of ectatic vessels in OCT images are deeper than those before PDT （p〈0.05）. This study indicates that OCT can be used as a noninvasive and in vivo measurement method to evaluate the structure and optical properties of PWS skin. The conclusions imply that this measurement method can be used to evaluate the treatment outcome and adjust PDT protocol individually.