Value of dual-energy CT angiography in patients with treated intracranial aneurysms

To evaluate the ability of dual-energy CT angiography (DECTA) in metal artifact reduction in patients with treated intracranial aneurysms by comparing DECTA-based virtual monoenergetic extrapolations (VMEs) and mixed images (MI). Thirty-five patients underwent prospectively a dual-source DECTA (Somatom Force, Siemens Medical Solutions, Forchheim, Germany) after aneurysm repair. A total number of 40 aneurysms (23 treated by coil embolization and 17 treated by surgical clipping) were analyzed. Mixed images (equivalent to a conventional single-energy CT angiography) were compared to VMEs at 75, 95, and 115 keV. Artifact severity was assessed quantitatively by measuring the mean attenuation value and standard deviation within regions of interest placed in the most hypodense coil or clip artifact area. Artifact severity score and contrast vessel score were also assessed qualitatively by two independent blinded readers. In those aneurysms treated by surgical clipping, quantitative and qualitative analyses showed significant reduction of artifacts on VMEs compared to MI with the best compromise being obtained at 95 keV in order to keep an optimal vessel contrast in the adjacent vessel. In those aneurysms treated by coil embolization, there was no significant reduction of artifacts both on quantitative and qualitative analyses. Dual-source DECTA was helpful in order to reduce clip artifacts on VMEs with the optimal adjacent vessel visualization obtained at 95 keV, whereas this technique was not helpful in aneurysms treated by coiling. (orig.)