Abstract 4048: Multiphoton tomographic imaging is an effective optical biopsy tool for detecting gastrointestinal inflammation and neoplasia

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Background: Improved early detection methods are needed to reduce the risk of gastrointestinal (GI) cancers for both average and high risk individuals. Standard colonoscopes and low magnification adjuncts (e.g., narrow band imaging) are unable to provide cellular resolution. Thus, any suspicious lesions must be biopsied. Individuals with longstanding inflammatory bowel disease (IBD) are at increased risk for colorectal cancer (CRC), requiring frequent colonoscopic evaluations including multiple random biopsies to exclude dysplasia. Technologies that facilitate directed biopsies should decrease both procedure-related morbidity and costs. Here, we explore the use of multiphoton microscopy (MPM) as a novel optical biopsy tool with several potential advantages: (1) no need for exogenous contrast; (2) greater depth of imaging; and (3) access to multiple signals from different tissue sources using a single illumination. Study design and results: Phase 1: Generating an MPM atlas of normal mouse GI tract. Tissues along the mouse GI tract from esophagus to anus were imaged using a single excitation wavelength; three distinct signals were collected, color-coded and overlaid to obtain cellular-resolution 3D images: (1) Second Harmonic Generation - a higher order scattering signal from collagen; (2) Short wavelength autofluorescence - from cytoplasm of epithelial and certain immune cells, and elastin; (3) Long wavelength autofluorescence - from macrophages, presumably originating from lipofuscin. After MPM imaging, each specimen was fixed, H&E stained, and images from both MPM and H&E-stained slides were archived and annotated by a pathologist. MPM provided sufficient histological details to identify all relevant tissue substructures. Phase 2: Imaging disease progression in mouse models of dextran sodium sulfate (DSS) induced colitis and azoxymethane (AOM) induced CRC. We identified both acute and resolving stages of colitis in the DSS model, which correlated with pathological findings. In the AOM model, we followed the progression from aberrant crypts to aberrant crypt foci to micro-adenoma to adenoma. Three independent pathologists identified all lesion types from the MPM images with 100% concordance. Phase 3: Translating mouse model findings to human disease. Patients with both IBD and celiac sprue are at increased risk of inflammation-related GI malignancy. Hence, both IBD and celiac sprue were evaluated. Additionally, adenomatous polyps and CRC were imaged. Normal tissue was imaged in each case as control, and all MPM images were compared with H&E slides prepared from the same specimens. MPM images demonstrated striking similarity to those generated by H&E staining. Conclusion: MPM is a promising optical biopsy technique that identifies relevant tissue substructures without exogenous contrast, and might have distinct advantages over competing technologies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4048. doi:1538-7445.AM2012-4048