Surgical Technique
HOT SPOT, COLD, -20
Eligible patients underwent preoperative lymphoscintigraphy with subdermal/peritumour injection of 15-20 MBq of technetium-99m the day before surgery. At the time of surgery after anaesthesia and immediately before the operation, 1 mL of InfracyanineFluorescence of ICG was elicited and detected by the near-infrared camera (SPY-PHI, STRYKER, Sydney, Australia). ICG generates fluorescence by contacting plasma proteins in the lymphovascular system. It absorbs near-infrared light and emits a fluorescent signal when particles return from an excited to ground state.Assessment of the surgical field using the near-infrared camera was applied continuously throughout the surgical exploration. Fluorescent lymphatic channels were dissected and followed to the first ICG avid lymph node. Fluorescent lymph nodes (“ICG-positive”) were then localised and excised. Excised ICG-positive nodes were then tested for radioactivity using the gamma-detecting probe and classified as “hot” (RI-positive”) or “cold” (“RI-negative”). SLN removal continued until no residual fluorescence was visible in the axilla.Finally, the axilla was inspected with the gamma-detecting probe to determine whether any radioactivity was left. If there was significant residual radioactivity the hot spot was removed and examined. The number of SLNs (“ICG-positive,” “RI-positive,” or both) removed from each patient were documented. This allowed for calculation of nodal detection rates for ICG alone and in combination with RI. A SLN was defined as any node with at least 10% of the hottest nodal counts in regards to radioactivity. All SLNs were sent for histopathology analysis.Patients in the BD-RI cohort underwent the same preoperative lymphoscintigraphy as the ICG-RI cohort. At the time of surgery after anaesthesia and immediately before the operation, 2.5 mL of Patent Blue V dye (125 mg/5 mL) was injected in the same manner. Identification of SLNs was performed as usual. The “blue” SLNs were excised and sent for histopathology analysis. The number of SLNs was recorded numerically and whether “blue,” “RI-positive,” or both, allowing calculation of nodal detection rates for BD alone and in combination with RI.