Michael Marcus Lell MD, Presenter: Nothing to Disclose

Hendrik Ditt, Abstract Co-Author: Nothing to Disclose

Kambiz Nael MD, Abstract Co-Author: Nothing to Disclose

Ernst Klotz PhD, Abstract Co-Author: Employee, Siemens Medical Solutions

Pablo J. Villablanca MD, Abstract Co-Author: Nothing to Disclose

Christoph Panknin, Abstract Co-Author: Employee, Siemens AG

Algorithms for registered image subtraction can succeed where threshold based bone removal often fails due to HU overlap between contrast agent and bone: Areas where bone is in close proximity of intricate vessels or pathology. The purpose of this work was to evaluate the visualization of intracranial vessels with bone subtraction software commercially available for CT.

28 patients underwent intracranial CT angiography on 64 slice and dual source CT scanners. Two scans were performed: A low dose (mask) scan before, and a regular CTA scan after contrast agent administration. The images were processed with the subtraction software (Syngo Neuro DSA CT, Siemens Medical Solutions). Accuracy of the bone removal was verified by temporarily blending the removed bone back into the subtracted images. The image quality of 26 arterial segments in each subject (total: 728) was scored using a scale of 0-4 (0 not visible, 1: poor, 2: insufficient, 3: sufficient for diagnosis, 4: excellent). Arteries that showed algorithm induced gaps were rated 2 (insufficient).

Subtraction successful in all cases; average processing time was 5 minutes. 648/728 (89%) of arterial segments were scored with diagnostic image quality (median: 3, range: 3-4). Four arterial aneurysms (supraclinoid portion of internal carotid artery), one AVM and nine intracranial stenoses were identified. In 18 cases, artifactual stenoses exceeding 50% lumen diameter were found, but only for the ophthalmic arteries. No relevant stenoses of the ICA or vertebral artery were detected along their way through the skull base.

Automatic subtraction provides, in a fully automatic way, diagnostic image quality for 3D visualization of intracranial vessels. The radiation dose is increased only slightly for acquisition of the low dose mask scan. Operator independence and speed favorably impact clinical workflow.

Bone subtraction supports assessment of intracranial vessels and vessels of the neck. Automatic processing improves workflow without adding to the radiologists workload.

Lell, M, Ditt, H, Nael, K, Klotz, E, Villablanca, P, Panknin, C, DSA for CT: Automatic Bone Removal for 3D Visualization of Intracranial Structures.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5016324.html