Purpose With the advent of latest generation flat panel detectors, C-arm angiographic systems have the ability to provide high-resolution CT-like images of brain parenchyma, vasculature and deployed devices while the patient is still at the neuro-interventional suite.¹ However, the presence of high-density metallic implants (ie, aneurysm coils, clips, dental fillings etc) in the field of view can induce severe artifacts that affect the diagnostic quality of the reconstructed images. The purpose of this study is to report our preliminary results of metal artifact reduction algorithm in C-arm CT images acquired during embolization of intracranial aneurysms and arterio-venous malformations (AVMs).

Methods During aneurysm and AVM embolization procedures, C-arm CT (syngo DynaCT^®, Siemens AG, Healthcare Sector, Forchheim, Germany) images were acquired using the 20s-DR-H protocol. The acquired projection images were reconstructed using standard protocol at the clinical workstation (syngo XWP, VB15D). The same images were reconstructed at the research workstation using prototype software that reduces metal artifacts. The resulting images were retrospectively assessed for image quality and diagnostic information as compared to standard reconstruction. In addition, in-vitro studies using a metal phantom were carried out for quantitative assessment of the effects of metal artifact reduction reconstruction algorithm.

Results Abstract O-31 figure 1A shows the result of metal artifact reduction in our tube phantom (containing pipeline device and metal bead), with the line profile plot reflecting Hounsfield intensities along the vessel centerline. Abstract O-031 figure 1B shows the result of metal artifact reduction in cases of aneurysms treated with coils or clips and of AVM treated with Onyx^® (eV3, Plymouth, Minnesota, USA) liquid embolic agent. We observed that the individual strands of the pipeline device or stent struts could be visualized relatively better in the C-arm CT images after metal artifact reduction. In the AVM case with Onyx^® related artifacts, the algorithm improved the visualization of a resolving hematoma surrounding the AVM.

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Abstract O-031 Figure 1

Conclusions Our preliminary clinical and in-vitro results show the feasibility of reducing metal artifacts in C-arm CT images using special reconstruction algorithm. This prototype reconstruction software improves the visualization of intracranial metallic implants and better evaluation of adjacent brain parenchyma in C-arm CT images; however further quantitative validation is required.

Reference 1. Kamran M, Nagaraja S, Byrne JV. C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology. Neuroradiology 2010;52:319–27.

Competing interests P Chinna durai: Siemens Medical Solutions USA Inc., Full-time Employee (Research Collaborations, Angiography Division). G Chintalapani: Siemens Medical Solutions USA Inc. H Shaltoni: None. H Morsi: None. M Mawad: Siemens Medical Solutions USA Inc.