Metal artifact reduction for flat panel detector intravenous CT angiography in patients with intracranial metallic implants after endovascular and surgical treatment.
BACKGROUND
Flat panel detector CT angiography with intravenous contrast agent injection (IV CTA) allows high-resolution imaging of cerebrovascular structures. Artifacts caused by metallic implants like platinum coils or clips lead to degradation of image quality and are a significant problem.


OBJECTIVE
To evaluate the influence of a prototype metal artifact reduction (MAR) algorithm on image quality in patients with intracranial metallic implants.


METHODS
Flat panel detector CT after intravenous application of 80 mL contrast agent was performed with an angiography system (Artis zee; Siemens, Forchheim, Germany) using a 20 s rotation protocol (200° rotation angle, 20 s acquisition time, 496 projections). The data before and after MAR of 26 patients with a total of 34 implants (coils, clips, stents) were independently evaluated by two blinded neuroradiologists.


RESULTS
MAR improved the assessability of the brain parenchyma and small vessels (diameter <1 mm) in the neighborhood of metallic implants and at a distance of 6 cm (p<0.001 each, Wilcoxon test). Furthermore, MAR significantly improved the assessability of parent vessel patency and potential aneurysm remnants (p<0.005 each, McNemar test). MAR, however, did not improve assessability of stented vessels.


CONCLUSIONS
When an intravenous contrast protocol is used, MAR significantly ameliorates the assessability of brain parenchyma, vessels, and treated aneurysms in patients with intracranial coils or clips.
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany.
Rastislav
R
Pjontek
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany.
Belgin
B
Önenköprülü
Healthcare, Imaging & Therapy Division, Siemens AG, Forchheim, Germany.
Bernhard
B
Scholz
Healthcare, Imaging & Therapy Division, Siemens AG, Forchheim, Germany.
Yiannis
Y
Kyriakou
Department of Neurosurgery, University Hospital RWTH Aachen, Aachen, Germany.
Gerrit A
GA
Schubert
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany.
Omid
http://orcid.org/0000-0002-2055-4217
O
Nikoubashman
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany.
Ahmed
A
Othman
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany.
Martin
M
Wiesmann
Department of Diagnostic and Interventional Neuroradiology, University Hospital RWTH Aachen, Aachen, Germany.
Marc A
MA
Brockmann
D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging; D002533:Cerebral Angiography / Q000379:methods*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002550:Cerebral Veins / Q000000981:diagnostic imaging; D000072226:Computed Tomography Angiography; D003287:Contrast Media; D003626:Data Display; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging; D008670:Metals; D019736:Prostheses and Implants; D015607:Stents; D013525:Surgical Instruments; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D008670:Metals
CT; CT Angiography; Technology