AbstractID: 9007 Title: Micro-cone-beam CT for determination of stent coverage of aneurysm
orifice
Minimally invasive approaches are being developed for treatment of cerebrovascular diseases such as stent placement at aneurysms. We are
developing asymmetric stents with low porosity mesh regions to cover the aneurysm orifice, reduce flow into the aneurysm, and initiate
thrombosis. To evaluate the extent of aneurysm coverage, we have developed techniques for quantitative analysis of micro-CT 3D data. After
placement of the stent/mesh in the vessel, projection images are acquired with the micro-CT system (x-ray tube, rotary stage, and microangiographic detector with 43 micron pixels) as the vessel is rotated 360 degrees about its long axis. The 3D data is reconstructed using a
Feldkamp algorithm. The vessel centerline is automatically calculated, and a range of radial distances from the centerline is selected which
includes the stent/mesh and the neck of the aneurysm. For each slice in planes perpendicular to the vessel centerline, maximum- and
minimum-intensity projections (MIP and MinIP) are generated by projecting radially outward from the centerline, thus un-wrapping the vessel.
Regions corresponding to the aneurysm neck and stent/mesh regions are segmented in the MIP and MinIP images, respectively. The two
images are then fused. The coverage of the aneurysm neck is found by counting the pixels in the orifice region that correspond to the
stent/mesh. The calculated stent porosity agreed well within 2% of the porosity determined using a microscope. Micro-CT offers a reliable
means for determination of stent placement and coverage. (Support received from NIH Grant 1RO1NS38746, Toshiba Corporation, Oishei
Foundation and Guidant Corporation.)