Automated Three-dimensional Volume Rendering of Helical Computed Tomographic Angiography for Aneurysms: An Advanced Application of Neuronavigation Technology

Abstract

Abstract OBJECTIVE: To introduce the possibility of volume-rendered helical computed tomographic (CT) angiographic data sets by use of Medtronic StealthStation Treon surgical navigation technology (Medtronic Surgical Navigation Technologies, Louisville, CO) and to evaluate the clinical usefulness of the method in planning and performing surgical treatment of intracranial aneurysms. METHODS: Between November 2002 and July 2003, we studied 15 patients with suspected intracranial aneurysms. All patients but two received conventional digital subtraction angiography, which failed to provide the requested information. Helical CT angiography was performed in all patients, and data sets were transferred to the StealthStation system across an electronic network to be automatically postprocessed by use of three-dimensional (3-D) volume rendering. The 3-D volume-rendered images were accurately analyzed to obtain more complete information about the aneurysm and to provide accurate treatment planning. In all patients, the 3-D volume-rendered model was displayed on the screen of the StealthStation system for the duration of the surgical procedure and compared with the intraoperative image. RESULTS: Data sets from CT angiography were automatically postprocessed by the StealthStation in seconds with excellent results, providing us, before and during surgery, with additional information not always available on traditional digital subtraction angiographic investigation. Because of the very short time necessary to complete this process (<5 min to obtain 3-D volume-rendered images), it was possible to perform emergency clipping of the aneurysms in two patients who had been admitted in very compromised neurological conditions. In 12 patients, integrated digital subtraction angiography and automated 3-D volume-rendered images allowed an accurate presurgical evaluation. Furthermore, in all patients on whom surgery was performed, aneurysms were found in the exact location and with the same anatomic features as depicted by the 3-D volume-rendered models. CONCLUSION: Reports in the literature indicate that information gathered by CT angiography with volume rendering shows a significant impact on aneurysm management. The StealthStation system upgraded with the adequate algorithm seems to provide a time- and cost-effective method of performing automated 3-D volume rendering of CT angiography and provides an interesting alternative to the available investigation modalities in case of emergency.