Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors arising in the digest tract. It brings a challenge to diagnosis because it is asymptomatic clinically. It is well known that tumor development is often accompanied by the changes in the morphology of collagen fibers. Nowadays, an emerging optical imaging technique, second-harmonic generation (SHG), can directly identify collagen fibers without staining due to its noncentrosymmetric properties. Therefore, in this study, we attempt to assess the feasibility of SHG imaging for detecting GISTs by monitoring the morphological changes of collagen fibers in tumor microenvironment. We found that collagen alterations occurred obviously in the GISTs by comparing with normal tissues, and furthermore, two morphological features from SHG images were extracted to quantitatively assess the morphological difference of collagen fibers between normal muscular layer and GISTs by means of automated image analysis. Quantitative analyses show a significant difference in the two collagen features. This study demonstrates the potential of SHG imaging as an adjunctive diagnostic tool for label-free identification of GISTs.

Precisely distinguishing between hyperplastic and adenomatous polyps and normal human colonic mucosa at the cellular level is of great medical significance. In this work, multiphoton laser scanning microscopy (MPLSM) was used to obtain the high-contrast images and the morphological characteristics from normal colonic mucosa, hyperplastic polyps and tubular adenoma. By integrating the length and area measurement tools and computing tool, we quantified the difference of crypt morphology and the alteration of nuclei in normal and diseased human colonic mucosa. Our results demonstrated that the morphology of crypts had an obvious tendency to cystic dilatation or elongated in hyperplastic polyps and tubular adenoma. The content and number of mucin droplets of the scattered goblet cells had a piecemeal reduction in hyperplastic polyps and a large decrease in tubular adenoma. The nuclei of epithelial cells might be elongated and pseudostratified, but overt dysplasia was absent in hyperplastic polyps. Nevertheless, the nuclei showed enlarged, crowded, stratified and a rod-like structure, with loss of polarity in tubular adenoma. These results suggest that MPLSM has the capacity to distinguish between hyperplastic and adenomatous polyps and normal human colonic mucosa at the cellular level.