Development of the high-resolution optical tomography capable for in vivo observation of biological tissue structure and the application to early-stage diagnosis of superficial cancer

我们的研究目标是提出并演示一种用于胃癌早期诊断的新型高分辨率光学相干断层扫描（Hi-OCT）。我们提出的技术用于聚焦成像方法在整个感兴趣的横截面积。该层析成像的空间分辨率为3μm，成像深度大于3mm。(1)采用锁模钛蓝宝石激光器（飞秒激光器）作为Hi-OCT的光源。通过对低相干干涉仪色散不平衡的补偿，得到了3.1μm飞秒激光的相干长度。(2)为了获得整个感兴趣横截面积的焦内成像，我们利用了样品聚焦透镜的聚焦效果。这种方法被称为聚焦OCT，其中通过移动组织内部物镜的焦平面，然后将OCT图像堆叠来获得多个OCT。成功获得了大于3mm的成像深度。(3)实现运动伪影最小化的实时OCT需要高速OCT成像。我们提出了采用PZM延迟线扫描的OCT成像系统，其中两个相同的PZM以推挽操作驱动。延迟线扫描速度为100次扫描/秒，一张OCT图像由400次扫描组成，图像数据采集时间为4秒。(4)在胃肠道应用中，Hi-OCT成像可以提供非常清晰的粘膜肌层成像，粘膜肌层是一种弯曲的膜状组织，厚度为几十微米，表明我们的方法对胃癌的早期诊断有用。

Our research target is proposal and demonstration of a novel high-resolution optical coherence tomography(Hi-OCT) for early-stage diagnosis of stomach cancer. Our proposed technique is used for in-focus imaging method over the entire cross-sectional area of interest. This tomography has the spatial resolution of 3μm with the imaging depth of more than 3mm.(1)A mode-locked Ti : sapphire laser (femto-second laser) is used as the light source of the Hi-OCT. The coherence length of femto-second laser of 3.1μm was obtained by compensation of unbalance of chromatic dispersion of the low-coherence interferometer.(2)In order to obtain in-focus imaging over the entire cross-sectional area of interest, we used the focusing effect of the focusing lens of the sample. This method is called in-focus OCT, in which multiple OCT is made by shifting the focal plane of the objective inside of tissue, followed by piling up of the OCT images. The imaging depth of more than 3mm was successfully obtained.(3)High-speed OCT imaging is required for a real-time OCT with minimization of motion artifact. We proposed the OCT imaging system with the PZM delay line scanning, where two identical PZMs are driven in push-pull operation. The delay-line scanning speed was 100 scans/sec, and an OCT image consists of 400 scans, providing us the image data acquisition time of 4 sec.(4)In the gastrointestinal application, the Hi-OCT imaging can provide very clear imaging of muscularis mucosae, which is a bending film-like tissue of a few tens micron thickness, showing that our method is useful for the early-stage diagnosis of stomach cancer.