Intracranial Infrared Fluorescence Angiography for Neurovascular Surgery 

Conventional angiography involves a series of radiographic images of the blood vessels of the head and neck. A small catheter or tube is inserted into an artery, usually in the groin. An x-ray video, known as fluoroscopy, guides the catheter through the artery to the large blood vessels that lead to the brain. A contrasting dye is inserted through the catheter into the artery, and radiographic images are taken as the contrast circulates through the arteries, capillaries and veins of the head and neck. 

Cerebral angiography can detect abnormal blood circulation to the brain, such as a clot or obstruction inside a vessel or swelling of a vessel. 

Infrared technology allows the neurosurgeon performing neurovascular procedures such as aneurysm clipping to directly visualize the blood vessels and actually see the flow of blood inside the vessels. Instead of x-rays, a special microscope with infrared vision is used for the surgery. After exposing the aneurysm or vascular abnormality by conventional microsurgical methods, a dye is injected into the IV site by the anesthesiologist. At this time the infrared video camera is activated. While in the bloodstream the dye fluoresces, or glows, at an infrared wavelength just outside the visible spectrum of light so human eyes cannot observe it. 

However, the video camera in the microscope can see it and the image is observed on the video screen attached to the microscope. In this way, the surgeon can see blood flow inside the vessels both before and after placing an aneurysm clip across the lesion. 

As a result, the surgeon can evaluate the effectiveness of clip placement, i.e., if the clip is completely occluding the aneurysm or blood is still entering the aneurysm sac, and whether blood flow past the aneurysm or through important vessels near the aneurysm has been compromised. 

The surgeon can readjust the clip if necessary within minutes of placement, preserving blood flow to the brain while occluding and rendering the aneurysm harmless.