结肠早癌自体荧光内镜诊断系统研究Ⅱ.肿瘤组织与正常组织自体荧光机制研究

A STUDY ON AUTOFLUORESCENCE ENDOSCOPIC DIAGNOSTIC SYSTEM FOR EARLY COLONIC CANCER (Ⅱ MECHANISM OF AUTOFLUORESCENCE DIFFERENCES BETWEEN NEOPLASM TISSUE AND NORMAL TISSUE)

正常结肠组织和癌组织的自体荧光存在差异 ,主要表现在正常组织的荧光强度高于癌组织 ,二者有各自的特征峰 ,这是自体荧光光谱分析用于早期诊断的前提。现主要从两个方面解释产生这种荧光差异的原因。一是癌变后组织的生化环境发生了改变 ,如癌组织能特异性聚集血卟啉 ,所以癌组织的荧光谱在 6 90nm处存在特征峰和荧光强度高于正常组织。其二是肠壁粘膜和粘膜下层形态结构的改变 ,由于粘膜下胶原组织被癌组织代替和粘膜增厚的滤网效应 ,使从组织粘膜表面所能采集的荧光减少。到目前为止结肠组织内荧光分子和他们的空间分布尚未完全清楚 ,所以产生这种荧光差异的确切原因有待于进一步研究。

There is difference of laser-induced autoflurescence between colonic carcinoma tissue and normal tissue. The fluorescence intensity of colonic carcinoma tissue is significant lower than normal tissue. And the carcinoma tissue and normal tissue have their characteristic peaks in their spectral curves, respectively. As a result, the laser-induced autofluorescence can be used for the early diagnosis of colonic carcinoma. There are two main causes to explain the difference from the investigated results. First, the biochemical circumstance changes after the colon tissue changes from normal to cancer. For instance, the carcinoma tissue can accumulate endogenous hematoporphrin so that there is a characteristic peak in 690nm, but the fluorescence intensity is lower than normal tissue and the normal tissue has not a typical peak in 690nm. On the other hand, the morphological architectures of the colonic mucosa and submucosa change after cancer occurs. The fluorescence quantum collected from the surface of the colon mucosa reduces because the collagen, which is one of the main fluorophores, is replaced by the cancer cells, and the screening effect of the thicker mucosa in colonic cancer when the fluorescence escapes through the mucosa. However, the reason which results in the differences is waiting for further investigation for the exact fluorophore molecules and their spatial distribution inside the colon tissue are not yet known.