gms | German Medical Science

Objective: Augmented reality is the overlay of virtual images upon real structures. In the operating theatre, it can be visualized through head-up display, stereoscopic glasses or through the microscope’s ocular, and can be used for image-guidance during surgical procedures. As careful preoperative analysis of angiographic imaging sequences is essential for the successful clipping of cerebral aneurysms, we considered a novel technique of intraoperative injection of angiographic images into the microscope to guide both dissection and clipping.

Method: Virtual segmentations of patients' vessels, aneurysms and aneurysm necks were acquired from preoperative 3D image datasets (angio-MRI, angio-CT, 3D DSA) – using BrainLAB's Iplannet interface (BrainLAB, Feldkirchen, Germany) – and intraoperatively injected into the neuronavigated operating microscope's eyepiece (Zeiss, Oberkochen, Germany), to optimize patient positioning, to tailor the craniotomy and to guide dissection and clipping.

Results: Four illustrative case examples are presented:

1.

Same-session clipping, through a right pterional approach, and without optic nerve mobilization, of a left carotido-ophthalmic aneurysm, an aneurysm of the anterior communicating artery, an aneurysm of the right middle cerebral artery bifurcation and a right M1 aneurysm;

2.

clipping of a large aneurysm of the left anterior choroidal artery, without direct visualization of the artery itself;

3.

same-session clipping, through a left pterional approach, of an aneurysm of the right posterior communicating artery, through a narrow corridor between the optic nerves, and of an aneurysm of the left middle cerebral artery bifurcation;

4.

clipping of an aneurysm of the right superior cerebellar artery through a narrow right pterional approach with limited aneurysm exposition and without III^rd cranial nerve mobilization.

Conclusions: Aneurysm clipping with augmented reality appears as a feasible and safe technique if immediate intra-operative angiographic control is available. It adds to the surgeon's confidence during the procedure, thereby possibly impacting positively on patients' outcome. Further technical advances are needed before routine use.