Figure 2.

Standard protocol for fluorescence lymph node mapping (FLNM). (A) The endoscopic submucosal indocyanine green (ICG) injection procedure for tattooing was performed 12–18 h before surgery on two sites, as close as possible to the distal margin of the colon cancer. Indocyanine green injection protocols were standardized using an injection of 0.5–1 mL of minimal ICG concentration dose (0.25 mg/mL). (B) The FLNM exploration facilitated visualization of the tumor location, fluorescent lymphatic drainage pathway, and distribution of D3 lymph nodes under laparoscopic near-infrared (NIR) camera. (C) The suspicious metastatic lymph node was partially stained with ICG, which expressed weak fluorescent lymph node (FLN). (D) The D3 lymph nodes were harvested under the visualization provided by the laparoscopic NIR camera and labeled the fluorescence D3 lymph nodes, according to the colic arteries for pathologic assessment. (E) After the radical D3 lymph node dissection (LND) was completed, the absence of any residual FLN was confirmed to assess the completeness of the radical D3 LND. (F) Pathologic evaluations were conducted separately for the labeled fluorescent and non-fluorescent D3 lymph nodes to assess the presence of metastatic lymph nodes (hematoxylin and eosin staining, ×20). Black circle is the cancer infiltration area in the metastatic lymph node.