MET-11 NEAR-INFRATED OPTICAL CONTRAST OF INDOCYANINE GREEN CAN LOCALIZE METASTATIC BRAIN TUMORS


 
 
 The utility of intraoperative real-time fluorescent navigation of indocyanine green (ICG) for cerebrospinal tumors has been demonstrated in gliomas, schwannomas, and meningiomas. We reported the usefulness of the existing Second window ICG (SWIG) for metastatic brain tumors, in which 5 mg/kg is administered 24 hours before the day before surgery. Subsequently, we developed a Delayed window ICG (DWIG) administered 1 hour before observation intraoperatively and report our experience.
 
 
 
 The subjects were 28 patients from August 2019 to March 2022, with an average age of 67 years, diagnosed with metastatic brain tumors. Eighteen patients were in the SWIG group and 10 in the DWIG group. Iridium (Visionsense) and KINEVO (Carl Zeiss) were used for near-infrared irradiation and observation.
 
 
 
 Near-infrared light was irradiated during surgery, and in all cases, fluorescence from the tumor was confirmed. Fluorescence emission could be confirmed as far as 10 mm from the brain surface. The Signal Background Ratio (SBR) of tumor to brain parenchyma was 3.4 in SWIG and 4.2 in DWIG. There is no significant difference between them.(P=0.15) All patients had contrast areas on preoperative contrast MRI, and the ratio of contrast area to brain parenchyma (T1BR) was 2.5. After intraoperative resection, all resected patients showed no contrast lesions on immediate postoperative MRI. No perioperative complications due to I CG administration were noted.
 
 
 
 Metastatic tumors may be difficult to distinguish from the normal brain visually due to the inaccuracy of the navigation system caused by intraoperative brainshift and blurring of the boundaries under an optical microscope. Intraoperative fluorescence angiography is useful in such cases because it allows tumor localization and removal in real time. DWIG is useful for metastatic brain tumors because it is simple and easy to use, with no significant difference compared to existing SWIG.
