3D Cerebral Angiography

OsiriX and Horos Course · Vascular Surgery

In this video I show how to perform a cerebral angiography in OsiriX from a study with a well-opacified arterial phase. The case is a female patient with subclavian steal syndrome (visible in the reconstruction), but the focus of the lesson is visualizing the intracranial vessels and identifying a saccular aneurysm. 1) Choose the best dataset I select the arterial-phase dataset with the largest number of images (in the example: 477) Scrolling through the slices, I confirm that the cerebral vessels are well opacified 2) Open 3D Volume Rendering I go into 3D Volume Rendering I start with the three-dimensional reconstruction and adjust the viewing angle 3) “Clean up” the 3D to focus on what matters (Crop) To work faster and use less memory: I go into Crop and adjust the box (green dots) I cut away everything that is not of interest (sides, bottom and areas with no information) I make a cut to remove part of the skull so I can see “inside the head” This makes the computer lighter and faster when manipulating the 3D. 4) Improve quality and performance: CPU vs GPU To improve the 3D image: I switch the engine to GPU (Graphics Card) The GPU offloads processing to the graphics card, which is more efficient for 3D calculations, making the reconstruction smoother and, in many cases, of better quality than on the CPU. 5) Evaluate the intracranial vessels and find the aneurysm With the crop done: I zoom in I adjust the angle I evaluate the circle of Willis (in this case, it is not complete) I identify a saccular aneurysm in the M2 segment I can use the ruler to measure, if needed 6) Alternative to Crop: “trepanation” with the scissors Instead of Crop, you can also: Use the scissors to remove part of the skull cap (“trepanation” in 3D) This lets you see the aneurysm through the opening Caution: you need to be careful not to cut vessels you want to analyze. In the video I demonstrate both approaches (Crop and scissors) to reach the same goal: clearly seeing the intracranial vessels and the aneurysm in 3D.