At present, this exploratory study has preliminarily achieved the set goals, and the subsequent data analysis is currently underway to determine whether it is necessary to continue recruiting participants.

According to the latest global cancer epidemiological data published by the International Agency for Research on Cancer, colorectal cancer (CRC) ranks 3rd in total incidence and 2nd in total mortality among all malignancies worldwide. The prognosis of CRC is directly related to tumor stage. The 5-year survival rate for early CRC can reach 90%, while less than 14% for advanced CRC. Therefore, early diagnosis of CRC is particularly important. Gastrointestinal (GI) endoscopy is an important method in the diagnosis of CRC. Currently, diagnosis of GI endoscopy is mainly based on morphological changes of tumors, while early-stage tumors are difficult to be detected because of the indistinguishable morphology. Studies have shown that the molecular function of cancer cells can be altered in early-stage tumors. The development of a new endoscopic system that can identify early tumor molecular function changes and improve the accuracy of morphological diagnosis will greatly improve the early diagnosis rate of CRC, which is the future direction of GI endoscopic system design and development.

The combination of high-definition white light endoscopy, endoscopic cerenkov luminescence imaging (ECLI) and probe-based confocal laser endomicroscopy (pCLE) is ideal for future new GI endoscopy. High-definition white light endoscopy is helpful to quickly find and locate suspected abnormal mucosa; on top of this, ECLI enables molecule-specific functional imaging for accurate identification and determination of GI lesions; and further relies on pCLE for high-precision "cellular-level" lesion images for optical biopsy of lesions. Through the multimodal digestive endoscopy, structural imaging and functional imaging can be accomplished simultaneously, playing the innate advantage of multimodal information fusion diagnosis and facilitating the identification of early-stage tumors.

In this clinical trial, patients with colorectal lesions who underwent PET-CT in Xijing Hospital were enrolled. Multimodal digestive endoscopy, combination of high-definition white light endoscopy, ECLI and pCLE, was used to perform for each patient's colorectal lesion. ECLI images were compared with PET-CT images, and pCLE images were compared with lesion histopathology, which evaluate the actual imaging effect of multimodal digestive endoscopy in human.

Inclusion Criteria:

1. Age >18 years old.
2. Clinical diagnosis of colorectal cancer, colorectal polyps, colorectal adenomas and enteritis.
3. No allergy to relevant imaging agents.
4. Person who is able to understand and sign the informed consent form.
5. Person who is willing to participate in this experiment.

Exclusion Criteria:

1. Patient who has been treated for colorectal lesions (endoscopic treatment, surgery , targeted therapy, and radiotherapy, etc.)
2. Patients with severe, progressive, or uncontrolled diseases of the kidneys, liver, blood, gastrointestinal tract, endocrine system, lungs, heart, or nervous system.
3. Women who are pregnant or breastfeeding.
4. Person without personal freedom and independent civil capacity.

grade III A hospital