Wall imaging of cerebral aneurysms with a modified surface-rendering technique of spiral CT

Background. There has been no detailed documentation of the advantages of t hree-dimensional (3D) wall imaging of cerebral aneurysms. The usefulness of such endoscopic images obtained with modified spiral computed tomography a ngiography (CTA) was therefore examined in comparison with conventional spi ral CTA and digital subtraction angiography (DSA). Methods. Fifteen of 45 patients who underwent conventional spiral CTA in ou r department in the past 4 years, were further studied with a technical mod ification of surface-rendering reconstruction in spiral CT. Endoscopic imag es were obtained by regulating the lower and higher thresholds of spiral CT scans in processing. Digital subtraction angiography was also performed fo r 14 of the 15 patients. The 3D wall images of the cerebral aneurysms were assessed in comparison with findings from conventional CTA and DSA. Findings. The true orifice of the aneurysms could be visualized with the en doscopic mode in all of the 15 cases. In paraclinoid aneurysms, particularl y below the anterior clinoid process, the relationships to associated vesse ls and bone structures were more clearly disclosed with this mode. The endo scopic images of aneurysms with rigid clots or neighboring distended veins were not as adversely affected as conventional CTA. In 4 of the 15 the wall imaging precisely located the branches arising from the dome of aneurysms which DSA could not. Interpretation. Wall imaging of complex or small cerebral aneurysms provide d valuable information on their relationships to associated arteries and su rrounding bony structures. The endoscopic mode, a simple modification of su rface rendering, is easily available in commercial CT processing packages.