Estimating continuous 4D wall motion of cerebral aneurysms from 3D rotational angiography

This paper presents a technique to recover dynamic 3D vascular morphology from a single 3D rotational X-ray angiography acquisition. The dynamic morphology corresponding to a canonical cardiac cycle is represented via a 4D B-spline based spatiotemporal deformation. Such deformation is estimated by simultaneously matching the forward projections of a sequence of the temporally deformed 3D reference volume to the entire 2D measured projection sequence. A joint use of two acceleration strategies is also proposed: semi-precomputation of forward projections and registration metric computation based on a narrow-band region-of-interest. Digital and physical phantoms of pulsating cerebral aneurysms have been used for evaluation. Accurate estimation has been obtained in recovering sub-voxel pulsation, even from images with substantial intensity inhomogeneity. Results also demonstrate that the acceleration strategies can reduce memory consumption and computational time without degrading the performance.