Technical Note
DynaCT imaging for intraprocedural evaluation of flow-diverting stent apposition during endovascular treatment of intracranial aneurysms

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Abstract

The treatment of large, complex intracranial aneurysms is being increasingly performed using flow-diverting stents (FDS) such as the Pipeline Embolization Device (PED; ev3, Irvine, CA, USA). Malapposition of a FDS to the parent artery wall decreases the likelihood of aneurysm obliteration and increases the risk of both immediate and delayed complications. DynaCT scanning (Siemens Medical Solutions, Erlangen, Germany) is a novel imaging modality which uses a flat plane detector to generate CT images using the same C-arm employed for digital subtraction angiography. We present a 40-year-old woman with an unruptured, 11 mm cavernous internal carotid artery aneurysm who was treated with endovascular obliteration using a PED. Intraprocedural DynaCT scan performed after PED deployment demonstrated incomplete stent apposition to the parent vessel which could not be detected on digital subtraction angiography alone. Balloon angioplasty was performed to improve apposition of the stent to the vessel wall. There were no procedural or clinical complications. The aneurysm shrank in size at follow-up angiography 6 months after the procedure and will be monitored for progressive occlusion. While gross stent malapposition is readily evident after stent deployment, minor instances of malapposition may be undetectable by standard angiography. Therefore the use of DynaCT imaging may improve intraprocedural stent visualization and potentially avert long-term endovascular aneurysm treatment complications associated with inadequate stent apposition.

Introduction

Endovascular reconstruction of giant or complex intracranial aneurysms using flow diverting stents (FDS), such as the Pipeline Embolization Device (PED; ev3, Irvine, CA, USA) has been utilized with increasing frequency since the turn of the decade [1], [2]. Proper apposition of a PED to the wall of the parent vessel is critical for optimizing endovascular aneurysm outcomes using flow diversion techniques. Stent malapposition creates a false lumen between the stent exterior and vessel wall thereby potentially allowing for persistent filling of the aneurysm sac, in-stent stenosis or thrombosis, parent vessel occlusion, and distal thromboembolic complications [3]. DynaCT (Siemens Medical Solutions, Erlangen, Germany) imaging utilizes flat panel detector technology to generate high-resolution CT images while allowing three dimensional rotational digital subtraction angiography (DSA) to be performed with the same C-arm [4], [5]. DynaCT allows improved intraprocedural visualization of intracranial stents compared to DSA [6]. We present a unique case in which intraprocedural DynaCT scan was used to diagnose malapposition of a PED during endovascular embolization of a cavernous internal carotid artery (ICA) aneurysm.

Section snippets

Case presentation

A 40-year-old woman with a history of neurofibromatosis type 1 was incidentally diagnosed with an unruptured, left-sided cavernous ICA aneurysm on MRI, including MR angiography (MRA), during work-up for trigeminal neuralgia (Fig. 1). After discussing the risks and benefits of surgical clipping, endovascular treatment, and conservative management, the patient elected to proceed with endovascular therapy. Based on the location and size of the lesion, the decision was made to treat the aneurysm

Discussion

Significant stent malapposition can be identified immediately after deployment. However, minor malapposition, such as in the presented case, frequently cannot be detected with standard DSA. While these relatively small degrees of stent malapposition are unlikely to result in immediate intraprocedural or postprocedural complications, they may potentially contribute to the development of long-term treatment failures, such as endoleak leading to incomplete aneurysm obliteration, and complications,

Conclusions

DynaCT imaging allows intraprocedural evaluation of stent apposition to the vessel wall which is crucial to optimizing the efficacy of FDS. While the emerging role of this novel imaging modality has yet to be completely defined, we present a patient in whom DynaCT imaging was used to diagnose minor malapposition of a PED during endovascular aneurysm treatment. In this patient, the application of DynaCT imaging allowed for intraprocedural adjustment of stent apposition with balloon angioplasty.

Conflicts of Interest/Disclosures

The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.

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