Clinically-compatible endoscopy for tumor detection with visible and infrared spectrum

Abstract

Early diagnosis of precancerous lesions in the colon with endoscopy has been shown to reduce mortality. While conventional white light endoscopy cannot provide information of molecular signature, molecular endoscopy with visible to IR spectrum may allow screening pre-cancerous lesions based on molecular contrast or physiology properties. This may provide effective tumor detection with fluorescently labeled organic fluorophores or inorganic fluorophores potentially allowing clinicians to spot invisible lesions. ICG and FITC are well-known FDA-approved fluorophores for human use. The AgInS2 QDs are deemed better candidates without highly toxic elements. The fluorescence signal in the neighborhood of the pseudo polyps was defined as the background. The effect of each fluorophore on contrast was determined by comprising TBR in the porcine colon in vivo. This study demonstrates the feasibility of multiple fluorescence endoscopic imaging of pseudo polyps composed of three biocompatible fluorophores in porcine colon towards clinical application. However, most cancer-targeting molecular imaging probes are targeted at preventing rapid clinical translation due to regulatory and safety concerns. Therefore, thermography has no exogenous probes and has been used for many years to analyze medical conditions related to changes in body or skin temperature. Passive thermal imaging provides a limited differentiation between a tumor and neighboring tissue as the temperature. Active thermal imaging (ATI) has emerged to provide new physiological biomarkers for early detection of a tumor without exogenous labeling. We developed an active thermal imaging modality and endoscopic approach with the hypothesis of differential physiological responses to thermos- modulation between the tumor and normal tissues using heating and cooling modulations. We performed ATI to evaluate physiologically relevant parameters, including the rate of temperature change and thermal recovery time with a murine xenograft skin tumor model and syngenic rectum tumor model. Combined with thermo-modulation, the developed infrared endoscopy can advance label-free non-invasive endoscopic screening.