Intraoperative evaluation of aneurysmal architecture: comparative study with transluminal images of 3D MR and CT angiograms.

BACKGROUND AND PURPOSE When exposure and visual access in aneurysmal microsurgery are limited, exact intraoperative information must be obtained regarding the whole shape of the aneurysm, property of the aneurysmal wall, vessels hidden behind the aneurysmal sac, and surrounding bony structures of the skull base. We developed a transluminal imaging technique that uses 3D MR and CT angiograms and applied it for intraoperative transparent evaluation of the angioarchitecture of cerebral aneurysms. METHODS Transluminal images were reconstructed from a perspective volume-rendering algorithm by selecting information on the luminal margin from the whole volume data sets of MR and CT angiograms. The images show the vessel and aneurysmal walls as a series of rings and provide direct visualization of the underlying objects through the spaces between the rings. By connecting a graphic workstation to the operative microscope, data were reconstructed intraoperatively and adjusted to coincide with the operative views by manipulating the projection and visual angle. The aneurysmal angioarchitecture could then be evaluated transparently on the reconstructed transluminal images through the operative approach. RESULTS Transluminal images provided direct transparent visualization of the aneurysmal architecture, including orifices at the neck, dome, and bleb and the parent arteries though the vessel and aneurysmal walls. The angioarchitecture of the neck complex was evaluated intraoperatively with transluminal 3D MR and CT angiograms through the operative approach before actual aneurysmal neck clipping. CONCLUSIONS Intraoperative exact evaluation of aneurysmal angioarchitecture with transluminal images would be a feasible and useful adjunct for aneurysmal microsurgery. Merging of data across modalities including 3D MR and CT angiography may improve preoperative or intraoperative evaluation of the angioarchitecture of cerebral aneurysms.