The purpose of the study is to test the feasibility of obtaining interpretable in vivo endomicroscopy images which can be compared with traditional histopathology.

Hypothesis: That a rigid confocal endomicroscope can be used during neurosurgery to provide in vivo histology that enables differentiation of tumour tissue from normal adjacent brain tissue.

Confocal endomicroscopy is a medical imaging modality that allows real-time microscopy to be performed on living tissue in vivo. It is already in clinical use in the fields of gastroenterological endoscopy, laparoscopy, dermatology, gynecology and respiratory medicine. This study represents the first time that confocal endomicroscopy will be evaluated for intraoperative imaging in neurosurgery.

The procedure involves a small endoscope which is placed gently into contact with the brain, providing significant in vivo magnification on a scale similar to that obtained by the pathology laboratory microscope. The captured confocal images will be compared with corresponding histology (tissue that is being removed as part of the indicated neurosurgical procedure). The images will be visually compared among each other and with histology images to detect possible clinically relevant information.

Inclusion Criteria:

• All patients with neurosurgical pathology requiring surgery in which tumor resection might be evaluated by using biopsy.

Exclusion Criteria:

• Pregnant women
• Inability to give informed consent
• History of allergy to fluorescein
• Patients on beta-blockers or ACE inhibitors