Time-lapse imaging of sentinel lymph node using indocyanine green with near-infrared fluorescence imaging in early endometrial cancer

OBJECTIVE Indocyanine green with near-infrared fluorescence imaging (NIR-ICG) is a new tracer modality in the limelight used for lymphatic mapping. The advantage of this method is to provide real-time image during surgery. To use ICG for image guided lymph node dissection, a surgeon needs to know initial appearing time and duration. METHODS A 52-year-old woman undertook surgery diagnosed with endometrial cancer. She had no past medical history and her body mass index was 25.3 kg/m². Preoperative magnetic resonance imaging examination revealed 2.7 cm sized cancerous mass in the endometrial cavity with superficial myometrial invasion without lymph node enlargement. Four mL (1.25 mg/mL) of ICG solution was prepared for injection. For each site, 1 mL of solution was injected superficially, 2-3 mm into the cervical submucosa and another 1 mL was injected deep, 1-2 cm into the stroma of the cervix. We recorded video with 30° 10 mm scope equipped with a specific lens and light source emitting both visible and NIR light (KARL STORZ GmbH & Co. KG, Tuttlingen, Germany). RESULTS Pelvic lymph node was visualized from around 5 minutes. ICG was dispersed into organs after hysterectomy (53 minutes after ICG injection), yet we could clearly identify sentinel lymph node (SLN). Pathology revealed endometriod adenocarcinoma grade I, myometrial invasion with less than half of myometrium and no lymph node metastasis. CONCLUSION Cervical injection of ICG provides good visualization of SLN from 5 minutes to over an hour. Our film gives an idea about time management to make a plan for surgery and not to miss SNLs.