Abstract
Our purpose was to evaluate whether useful information was gained with 3D surface rendering and endoscopic visualisation post-processing techniques of MR angiographic data when compared to standard rotated MIP image sets in patients with intracranial aneurysms. We prospectively studied 49 patients with 55 intracranial aneurysms confirmed by digital subtraction angiography (DSA) using MR angiography performed on a 1.5-T system. Our protocol included 3D time-of-flight (TOF) with magnetisation transfer and 3D phase-contrast (PC) following contrast administration. Each image set consisted of either 28 or 60 slices. Post-processing on a SUN work-station with GE software included: MIP, 3D surface rendering, and “advantage navigator” software for endoluminal imaging. The sac, neck and parent arteries of all aneurysms were depicted on both MIP projection and 3D surface rendering images.
Objective evaluation demonstrated that surface rendering delineated aneurysm direction, shape, neck size, and spatial relationship to parent vessels; the MIP method was unable to depict this information. 3D TOF acquisition was superior to 3D PC in small vessel visualisation due to implementation of higher spatial resolution resulting in isometric submillimeter voxels. Magnetisation transfer, selective reconstruction, real-time rotation, and subtraction of data further optimised imaging. Endoluminal reconstructions (possible in 52/55 aneurysms) were particularly useful in identifying parent artery incorporation by the aneurysm. Surface rendering and endoluminal reconstruction techniques provide useful information for therapy planning of intracranial aneurysms not provided by MIP projections. Objective analysis of the value of endoluminal 3D imaging regarding aneurysm and parent artery wall morphology awaits further optimisation of the technique.
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