Fluorescence-Guided Surgery and Biopsy in Gliomas with an Exoscope System

Abstract

Background. The introduction of fluorescence-guided resection allows a better identification of tumor tissue and its more radical resection. We describe our experience with a modified exoscope to detect 5 ALA-induced fluorescence in neuronavigation-guided brain surgery or biopsy of malignant brain tumors. Methods. Thirty-eight patients with a suspected preoperative diagnosis of high-grade astrocytoma were included. We used a neuronavigation device and a high-definition exoscope system with a built-in filter to detect 5-ALA fluorescence in all cases. Thirty patients underwent craniotomy with tumor resection and 8 underwent frameless stereotactic brain biopsy. Results. Histopathological diagnosis confirmed the presence of high-grade gliomas in 34 patients. Total resection was achieved in 23 cases and subtotal in 7. No relevant complications related to the administration of 5-ALA were detected. Conclusions. The use of the exoscope in 5-ALA fluorescence-guided tumor surgery has twofold implications: during brain tumor surgery it can be considered a valuable tool to achieve a more radical resection of the lesion, and when applied to a biopsy of a suspected brain high-grade glioma, it decreases the possibility of a negative biopsy.

Review of Neurosurgical Fluorescence Imaging Systems for Clinical Application

“…Piquer et al performed fluorescence-guided craniotomy with 5-ALA on patients with high-grade gliomas [48]. They used a high-definition exoscope system (HD-Xoscope, HDXO-SCOPE, Karl Storz Endoscopy, Tuttlingen, Germany) that includes a specially developed autoclavable rigid lens telescope and a fiber-optic light source channel.…”

“…Light in the UV/VIS spectral region (<700 nm) can penetrate superficial tissue only [47]. However, NIR light (700-900 nm) can propagate through tissue several centimeters thick because tissue does not absorb NIR radiation well [48]. Because of these features, multispectral fluorescence imaging of tissue is performed [49].…”

Fluorescence and Glioma Surgery

“…Therefore, it is imperative that robust biopsies are taken in order to appropriately treat patients. Research suggests that utilizing 5-ALA-induced fluorescence to guide biopsies yields more accurate biopsies with samples taken during surgery and with frameless MRI stereotactic biopsies [6,10]. Not only can PpIX fluorescence be utilized for resections and biopsies, 5-ALA has the capacity to guide resection surgeries of recurrent malignant gliomas.…”

“…The usual procedure of utilizing 5-ALA for resection surgery consists of administering 20 mg/kg body weight of 5-ALA orally to patients two to four hours prior to the procedure [4][5]10]. Preclinical data suggests that 5-ALA-induced fluorescence can last up to 12 hours and is optimal two to eight hours after it is administered [10][11].…”

“…Preclinical data suggests that 5-ALA-induced fluorescence can last up to 12 hours and is optimal two to eight hours after it is administered [10][11]. In order to observe the fluorescence, the region of interest must be illuminated with a blue xenon light (440 nm) to the excite PpIX molecules, allowing them to fluoresce in a red or pink color.…”