Indocyanine green (ICG) staining and demarcation of tumor margins in a rat glioma model.

The ability of indocyanine green (ICG) to stain and demarcate brain tumor margins was investigated using an intracerebral rat glioma model. Indocyanine green was injected intravenously into tumor-bearing rats and was found to stain the tumor intensely at 60 to 120 mg/kg for at least 1 hour after injection. Furthermore, gross tissue staining was found to coincide with the actual histologic tumor margins within 1 mm. After resection of stained tumor tissue, minimal residual tumor cells at the margins of the resection cavity were identified. This investigation established the capacity of indocyanine green to grossly delineate a rat brain tumor and its margins from adjacent normal parenchyma.