A Multimode nonlinear optical imaging technique based on the combination of multichannel mode and Lambda mode is developed to investigate human dermis. Our findings show that this technique not only improves the image contrast of the structural proteins of extracellular matrix (ECM) but also provides an image-guided spectral analysis method to identify both cellular and ECM intrinsic components including collagen, elastin, NAD(P)H and flavin. By the combined use of multichannel mode and Lambda mode in tandem, the obtained in-depth two photon-excited fluorescence (TPEF) and second-harmonic generation (SHG) imaging and TPEF/SHG signals depth-dependence decay can offer a sensitive tool for obtaining quantitative tissue structural and biochemical information. These results suggest that the technique has the potential to provide more accurate information for determining tissue physiological and pathological states.

IMPORTANCE Lymph node status is the primary determinant in treatment decision making in early gastric cancer (EGC). Current evaluation methods are not adequate for estimating lymph node metastasis (LNM) in EGC. OBJECTIVE To develop and validate a prediction model based on a fully quantitative collagen signature in the tumor microenvironment to estimate the individual risk of LNM in EGC. DESIGN, SETTING, AND PARTICIPANTS This retrospective study was conducted from August 1, 2016, to May 10, 2018, at 2 medical centers in China (Nanfang Hospital and Fujian Provincial Hospital). Participants included a primary cohort (n = 232) of consecutive patients with histologically confirmed gastric cancer who underwent radical gastrectomy and received a T1 gastric cancer diagnosis from January 1, 2008, to December 31, 2012. Patients with neoadjuvant radiotherapy, chemotherapy, or chemoradiotherapy were excluded. An additional consecutive cohort (n = 143) who received the same diagnosis from January 1, 2011, to December 31, 2013, was enrolled to provide validation. Baseline clinicopathologic data of each patient were collected. Collagen features were extracted in specimens using multiphoton imaging, and the collagen signature was constructed. An LNM prediction model based on the collagen signature was developed and was internally and externally validated. MAIN OUTCOMES AND MEASURES The area under the receiver operating characteristic curve (AUROC) of the prediction model and decision curve were analyzed for estimating LNM. RESULTS In total, 375 patients were included. The primary cohort comprised 232 consecutive patients, in whom the LNM rate was 16.4% (n = 38; 25 men [65.8%] with a mean [SD] age of 57.82 [10.17] years). The validation cohort consisted of 143 consecutive patients, in whom the LNM rate was 20.9% (n = 30; 20 men [66.7%] with a mean [SD] age of 54.10 [13.19] years). The collagen signature was statistically significantly associated with LNM (odds ratio, 5.470; 95% CI, 3.315-9.026; P < .001). Multivariate analysis revealed that the depth of tumor invasion, tumor differentiation, and the collagen signature were independent predictors of LNM. These 3 predictors were incorporated into the new prediction model, and a nomogram was established. The model showed good discrimination in the primary cohort (AUROC, 0.955; 95% CI, 0.919-0.991) and validation cohort (AUROC, 0.938; 95% CI, 0.897-0.981). An optimal cutoff value was selected in the primary cohort, which had a sensitivity of 86.8%, a specificity of 93.3%, an accuracy of 92.2%, a positive predictive value of 71.7%, and a negative predictive value of 97.3%. The validation cohort had a sensitivity of 90.0%, a specificity of 90.3%, an accuracy of 90.2%, a positive predictive value of 71.1%, and a negative predictive value of 97.1%. Among the 375 patients, a sensitivity of 87.3%, a specificity of 92.1%, an accuracy of 91.2%, a positive predictive value of 72.1%, and a negative predictive value of 96.9% were found. CONCLUSIONS AND RELEVANCE This study's findings suggest th...

Collagen alteration is critical for epithelial tumor initiation and progression. Quantitatively linking collagen alteration and epithelial tumor progression is essential for developing an optical endoscopy to evaluate epithelial tumor progression. In this work, we established a quantitative link between collagen alteration and epithelial tumor progression using second harmonic generation (SHG) microscopy. It was found that SHG microscopy can provide quantitative features to effectively evaluate epithelial tumor progression, and to locate tumor and determine the margin of tumor regions. These results suggest that SHG microscopy has the potential in offering a noninvasive in vivo imaging tool to quantify epithelial tumor progression.

All the measurements were performed in backscattering geometry and demonstrated that nonlinear spectral imaging has the ability to differentiate hypertrophic scar tissue from normal skin based on noninvasive SHG imaging, and TPEF imaging revealed the microstructure and spectral features of collagen and elastin fibres. With the advances in spectral imaging apparatus miniaturization, we have good reason to believe that this approach can become a valuable tool for the in vivo pathophysiology study of human skin hypertrophic scars and for assessing the treatment responses of this disfiguring disease in clinic. It can also be used to track the development of hypertrophic scars and to study wound healing processes in a noninvasive fashion without biopsy, fixation, sectioning and the use of exogenous dyes or stains.

Multiphoton microscopy was used to study the extracellular matrix of keloid at the molecular level without tissue fixation and staining. Direct imaging of collagen and elastin was achieved by second harmonic generation and two-photon excited fluorescence, respectively. The morphology and quantity of collagen and elastin in keloid were characterized and quantitatively analyzed in comparison to normal skin. The study demonstrated that in keloid, collagen content increased in both the upper dermis and the deep dermis, while elastin mostly showed up in the deep dermis and its quantity is higher compared to normal skin. This suggests the possibility that abnormal fibroblasts synthesized an excessive amount of collagen and elastin at the beginning of keloid formation, corresponding to the observed deep dermis, while after a certain time point, the abnormal fibroblast produced mostly collagen, corresponding to the observed upper dermis. The morphology of collagen and elastin in keloid was disrupted and presented different variations. In the deep dermis, elastic fibers showed node structure, while collagen showed obviously regular gaps between adjacent bundles. In the upper dermis, collagen bundles aligned in a preferred direction, while elastin showed as sparse irregular granules. This new molecular information provided fresh insight about the development process of keloid.