Determining X-ray projections for coil treatments of intracranial aneurysms

The endovascular coil embolization of intracranial saccular aneurysms requi res a set of specific X-ray images with which to view the aneurysm during c oiling. These two-dimensional (2-D) images, known as working projections, s hould be optimal for measuring the aneurysm sac diameter, inserting the fir st coil, and checking coil overhang into the surrounding vessels. At presen t the gantry tilt that produces these images is found by the radiologist by trial and error. In this pape, we present a method for automatically findi ng the angles that will produce the desired X-ray projections. Our method c onsists of four steps: 1) finding the location and orientation of the aneur ysm neck; (2) labeling the aneurysm sac; 3) determining the optimal tilts f or viewing the aneurysm during coiling; and 4) adjusting the optimal tilts for change in the patient orientation between pre-Guglielmi detachable coil (GDC) scanning and the coiling treatment. We discuss these steps and prese nt results of the algorithm applied to pathological examples in the form of simulated X-ray images. A final discussion is given for one example where our results have been applied in a clinical situation.