Applications of ICG Fluorescence Imaging for Surgery in Colorectal Cancers

Abstract

The use of indocyanine green (ICG) fluorescence imaging (IFI) for fluorescence-guided surgery has been expanding. In this study, we focus on the application of IFI in surgery for colorectal cancers. Recently, gastrointestinal cancers including colorectal cancers have been identified as new targets for sentinel node navigation surgery (SNNS). We examine the feasibility of sentinel lymph node (SLN) mapping guided by IFI in colorectal cancer. In colorectal surgery for early colorectal cancer, discerning tumor location is often difficult. Hence, endoscopic colorectal tattooing (ECT) with India ink is frequently performed. However, ECT with India ink has some complications. We showed the efficacy of a new tattooing method using IFI instead of India ink for effective tumor visualization without adverse effects. The number of harvested lymph nodes (LN) is very significant for the exact staging of colorectal cancer. We performed an evaluation of an IFI method of harvesting lymph nodes (LNs) from resected specimens. IFI allowed easy, highly sensitive, and real-time imaging-guided SLN mapping in patients with colorectal cancer. LN harvesting from resected specimens using IFI is a useful method with a highly improved number of LNs detected. We also found IFI-labeled LNs even when ICG solution was injected ex vivo and observed them in paraffin-embedded specimens that could provide a precise evaluation of the pathological status of LNs including sentinel LNs after surgery.