Application of indocyanine green (ICG) fluorescence for endoscopic biopsy of intraventricular tumors

Many reports have already indicated the benefit of pathological diagnosis of intra- and periventricular tumors with neuroendoscopic biopsy. However, it is also well known that studies can be occasionally inconclusive because of the small and/or inadequate samples for identification of abnormal tissues. The application of indocyanine green (ICG) fluorescence for endoscopical tumor biopsy under the intraventricular surroundings is a new area not previously reported. We attempted visual differentiation of intraventricular lesions from the surrounding structure using ICG fluorescence and considered the most appropriate region for biopsy. Three cases (13-14 year-old boys) with secondary hydrocephalus caused by intra- and periventricular tumors were operated for endoscopic transventricular biopsy combined with endoscopic third ventriculostomy. Final pathological diagnoses were suprasellar malignant lymphoma and germ cell tumors in two patients, both associated with intraventricular dissemination. Enhanced tumor visualization with 12.5 mg of ICG administration was obtained using the D-light P light equipment and ICG telescope 5.8 mm/19 cm. It was possible to identify the tumor mass margins themselves and detect the differences of intratumoral ICG accumulation. The areas of tumor dissemination were identifiable by neuroendoscopy but unable to be visualized by ICG fluorescence. We were able to obtain an ICG fluorescence imaging inside the cerebral ventricles by new D-light P system comprised of a camera head telescope. ICG fluorescence with neuroendoscopy can provide useful information for choosing the point of biopsy of intra- and periventricular tumors. However, we need to assess if the ICG accumulation site is the most appropriate for biopsy.