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6.2 OCT在临床疾病诊断中的应用 在皮肤科，OCT图像可清楚地分辨角质层、表皮与真皮接合处、毛囊、皮脂腺、汗腺等附属物,测量皮肤各层的厚度，并可以检测皮肤疾病、评价治疗效果［27］。 在口腔科，OCT可定量检测龋齿中矿物质的变化。OCT检测早期龋的原理：龋损釉质中有机成分的增加导致该部位釉质的光学散射系数低于周围正常牙釉质，在OCT图像上显示为较周围正常釉质灰度高的白色影像。根据定量测量图像的灰度值可以定量测定龋损组织的脱矿程度［28］。牙OCT图像上还可以观测到牙龈结合上皮的精细结构，因此还可以用于牙周疾病的诊断。在心血管疾病中，以往的成像技术无法迅速而明确地得到心血管粥样硬化、梗塞、心肌缺血坏死等病情。在冠状动脉光学相干层析成像中，由于该系统的分辨率和灵敏度都很高，冠状动脉组织有较大的后向散射和脂肪钙化斑状的阴影效应，使脂肪钙化斑状层、纤维动脉粥样化和正常动脉壁对比十分明显。OCT与内窥镜相结合，可用于活体获得与心脏结构和功能有关的定性、定量信息，如节拍率、室壁位置、心脏收缩和舒张期间心室容积等，可用于临床鉴别动脉粥样硬化及用于诊断血管内由于动脉粥样硬化而导致的血管堵塞及破裂情况［29］。在胃肠道疾病，Sivak等［30］将OCT探头从内窥镜中插入，对38例患者进行成像，获得包括胃小凹、十二指肠绒毛等黏膜及黏膜下血管细微结构的图像，且与活检病理结果一致。在另一项对患者进行经内窥镜OCT成像的研究中，表明OCT图像在胃黏膜与食管黏膜及食管与正常食管和Barret食管黏膜间均有明显不同。表明OCT对黏膜层的鉴别能力有一定的临床意义，尤其是对肿瘤的早期发现。
6.3 OCT在癌症诊断中的应用 癌症是威胁人类健康的主要疾病，OCT提供了一种高灵敏度、高空间分辨的光学活检手段，通常健康的皮肤组织为明显的层状结构，而癌组织为匀质结构，OCT则依据癌变组织具有与健康组织不同的光谱特性和结构，得到组织清晰的像，由此实时而准确地进行诊断。研究发现［31］，OCT技术可以广泛应用于探测软组织的早期癌变。陈绍维等[32]采用OCT技术对正常口腔黏膜和癌前病变进行活体厚度测量，并与组织学切片测量结果比较，发现OCT活体测量和组织学测量结果基本相同，无统计学意义。即可通过OCT技术，建立一种灵敏、无创的组织形态学观测手段，为上皮病损的诊断和治疗提供新途径。OCT技术也可监测癌症切除手术，通过实时成像保证癌变组织被完全切除。
7展望
OCT自应用于临床以来，得到了迅速的发展，为临床和科研提供了更精确可靠的检测检测手段。相信随着OCT技术的不断完善和开发，其分辨率、扫描速度、扫描深度将进一步提高，其在生物医学领域的前景也将更为广阔。
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