Introduction: Near infrared laser reflectance confocal microscopy (NIRC) is a new non-invasive technology that produces high-magnification cross-sectional optical images of tissue down to the cellular level at a depth of 200 microns.. The current laboratory study was to investigate the surface imaging of the cerebral cortex of the micro-vascular structures of the rabbit.

Methods: IACUC approval obtained. Three rabbits in separate laboratory sessions were subjected to identical wide vertex craniectomies under general anesthesia. The dura was opened and the surface of cerebral cortex exposed. A NIRC 1cm diameter smooth surface probe (Caliber-FDA approved) was gently applied to the surface of the cortex in the high parietal region. Images of real time microvascular flow were gathered and stored on the accompanied hard drive. The probe was moved to different point on the cortical surface. No indocyanine or other agent was administered.

Results: Surface cortical flow in real time was visible in micro-venous and micro-arterial vasculature to 15 micron diameter. The vessel wall was also discernible. Red blood cells auto-fluoresced and could be seen traversing the vessels. Various velocities of flow could be detected and feeding systems from small to large vessels were visible. The walls of the vessels were visible as well.

Conclusions: This is the first report of NIRC visualizing in real time the flow of the micro-vasculature of the surface of the cerebral cortex with a non-enhancement model. A method of calculating flow velocity and perfusion is in progress. This system has promise for applications in measuring relative micro-vascular surface flow in humans at craniotomy.

Patient Care: Determine changes in cortical flow and perfusion in real time during cerebrovascular procedures in neurosurgery.

Learning Objectives: New device (NIRC) for measuring real time micro-vascular flow of the cerebral cortex. Possible applications to humans in neurosurgical procedures Ability to view in real time micro-vascular flow in the cerebral cortex and determine alterations.

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