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

doi:10.1016/j.jocn.2014.04.003

Journal of Clinical Neuroscience

Volume 21, Issue 11, November 2014, Pages 1981-1983

https://doi.org/10.1016/j.jocn.2014.04.003 Get rights and content

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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Cited by (24)

Virtual diluted cone beam CT for device apposition assessment during endovascular treatment of intracranial aneurysm: A technical note
2024, Journal of Neuroradiology
The increasing use of embolization devices with suboptimal radio-opacity to treat intracranial aneurysm underscores the need for advanced imaging techniques to characterize device-vessel interactions more accurately. Contrast-diluted cone-beam CT is commonly used in neurointervention but requires additional technical refinements to improve endovascular treatment assessment. In this technical note, we describe the virtual dilution cone beam CT (VDCBCT), a technique that synthetizes non-contrast and contrast-enhanced CBCT images to virtually dilute iodinated contrast agents, thereby facilitating a more accurate assessment of embolization device apposition.
Through a set of intracranial aneurysms treated with different embolization devices, we describe the VDCBCT protocol and its usefulness for device apposition confidence.
VDCBCT may enhance the global understanding of neurovascular embolization treatments by providing improved visualization of target vessels and low-radio-opacity embolization devices, obviating the need for contrast dilution.
Flow Diverter Apposition in Patients with Large or Giant Intracranial Aneurysms Evaluated on Three-Dimensional Fusion Images Acquired by High-Resolution Cone-Beam Computed Tomography and Digital Subtraction Angiography
2021, World Neurosurgery
Citation Excerpt :
Cone-beam computed tomography (CBCT) has been widely used for assessing FD location and apposition, because most endovascular treatments are performed with angiography systems capable of acquiring CBCT images. CBCT acquired after the administration of low-concentration contrast medium can visualize vessels and FD structures on the same image and has proven useful for evaluating stent apposition after stent placement in stent-assisted coil treatment,7-11 as well as for intraprocedural evaluation of apposition during FD deployment when stent-plasty can be performed to improve FD wall apposition.9 However, this imaging technique generates only 2-dimensional (2D) slice images, and the spatial relationship of the FD, aneurysm, and surrounding vessels may be difficult to determine.6,8,9
To investigate flow diverter (FD) apposition on fused images acquired by high-resolution cone-beam computed tomography (CBCT) and 3-dimensional (3D) digital subtraction angiography.
Patients with large or giant internal carotid artery aneurysms treated with Pipeline FDs who underwent CBCT imaging at our institution between October 2016 and May 2019 were included. Two neurosurgeons measured the maximum malapposition between FDs and vessel walls on 3D fusion images of high-resolution CBCT images displaying the FD and 3D digital subtraction angiography images displaying the vessels. Associations between the relative malapposition, FD diameter, vessel diameter, proximal and distal vessel diameter discrepancy, and siphon angle were evaluated by linear regression analysis. Inter-rater and intermethod (3D and 2D image) agreements of the malapposition measurements were assessed by Bland-Altman analysis and by interclass correlation coefficients.
Images of 2 patients were excluded because of image artifacts or fusion errors, and 3D fusion images were acquired in the remaining 26 patients. Our results did not suggest that relative malapposition was associated with vessel diameter (P = 0.12), vessel diameter discrepancy (P = 0.60), or syphon angle (P = 0.34), but relative malapposition increased by an estimated 13% (95% confidence interval: 4%–23%, P = 0.006) for each 1 mm increase in FD diameter. Inter-rater and intermethod agreements for apposition measurements were excellent and good, respectively.
Three-dimensional fusion images provided clear visualization of structures of both the stent and parent artery with excellent diagnostic reliability. Careful deployment may be needed for FDs with larger diameters, as they tended to have larger relative malapposition.
Intimal Hyperplasia After Aneurysm Treatment by Flow Diversion
2019, World Neurosurgery
Citation Excerpt :
Stent malapposition could occur at any point along the stent, causing various flow alterations and subsequent posttreatment complications during the follow-up. At the present time, high precision methods have been developed for assessment of flow diverter malapposition allowing the evaluation of stent apposition in vivo, such as DynaCT, VasoCT, and optical coherence tomography.19,20 King et al.21 recently investigated the effect of so-called communicating malapposition (i.e., a continuous malapposition beginning from the proximal segment along the aneurysm neck) and found a correlation with poor rates of early aneurysm occlusion.
Flow diverter stents have become a useful tool for treatment of complex intracranial aneurysms. A serious complication is incomplete wall apposition after flow diverter placement. The aim of this study was to present a comprehensive investigation of hemodynamic changes induced by incomplete expansion of a flow diverter.
A case of a patient treated for an internal carotid artery aneurysm by flow diversion with incomplete wall apposition was virtually investigated. The effect of incomplete flow diverter expansion was studied using image-based blood flow simulations under physiologically relevant flow conditions based on patient-specific clinical data.
The numerical results revealed that incomplete expansion at the proximal end of the stent had minimal impact on the intra-aneurysmal blood flow alteration. A region of nonphysiologically high wall shear stress was observed near the contact area between the incompletely expanded proximal end of the flow diverter and the parent artery, which caused an intimal hyperplasia in this region. These simulation results were consistent with the real-life clinical course and outcome.
The results of this study can be considered during treatment planning of complex cases where the risk of incomplete flow diverter expansion exists. Further studies are required before results can also be used to support the decision process about antiplatelet therapy and additional interventions to improve wall apposition.
SMART coils for intracranial aneurysm embolization: Initial outcomes
2018, Clinical Neurology and Neurosurgery
Citation Excerpt :
Our data bolsters the currently sparse literature for the SMART coil, and supports the overall safety and efficacy of this technology. Despite the rising popularity and increasingly widespread use of flow-diverting stents, coil embolization retains an important role in the endovascular treatment of aneurysms, particularly those which are small- to medium-sized (maximum diameter <10 mm) with a narrow neck (dome to neck ratio ≥2) and ruptured ones [17–23]. Increased aneurysm packing density and coil mass uniformity has been associated with improved aneurysm impermeability, which may facilitate occlusion and decrease the risk of recurrence [6,13].
Endovascular technology for the treatment of intracranial aneurysms continues to rapidly evolve. The SMART coil (Penumbra Inc., Alameda, CA, USA) is a novel microcoil designed to enhance deliverability. The aim of this single-center, retrospective cohort study is to assess the initial outcomes after aneurysm embolization using SMART coils.
We reviewed consecutive patients with intracranial aneurysms who underwent endovascular embolization using SMART coils from June 2016 to January 2017. Baseline and initial outcomes data were analyzed.
The study cohort was comprised of 32 patients with 33 aneurysms. The mean age was 55.8 years. The majority (85%) of aneurysms were located in the anterior circulation. The mean aneurysm maximum diameter and neck width were 6.0 mm and 3.1 mm, respectively. Dome irregularity and fusiform aneurysm morphology were noted in 33% and 9% of aneurysms, respectively, and 15% presented with subarachnoid hemorrhage. No serious procedural complications occurred, including microcatheter prolapse, intraprocedural aneurysm rupture, or thromboembolism. Device malfunction occurred in one case (3%). The mean packing density was 25%, and the degree of immediate post-embolization aneurysm occlusion was a modified Raymond-Roy grade I, II, IIIa, and IIIb in 48%, 27%, 18%, and 6%, respectively.
Our preliminary findings suggest that the SMART coil has a favorable initial risk to benefit profile for the embolization of appropriately selected aneurysms. Additional studies of larger cohorts are necessary to determine the mid-term and long-term clinical and angiographic outcomes of aneurysm patients treated with the SMART coil.
Flat detector CT and its applications in the endovascular treatment of wide-necked intracranial aneurysms—A literature review
2017, European Journal of Radiology
Citation Excerpt :
Therefore, achieving proper wall apposition of the flow-diverter is essential for aneurysm closure and parent vessel reconstruction. FDCT performed at the end of the procedure enables an accurate evaluation of device deployment, aneurysm neck coverage, and patency of side branches (Fig. 3) [32–36]. In comparison with SAC, the implantation of a flow diverter device is rarely accompanied by coiling, thus the problem of coil streak artifacts becomes a minor issue.
Flat detector CT (FDCT) provides cross sectional imaging within an angiographic suite and is increasingly gaining popularity in various areas of interventional radiology, as an alternative imaging modality. Its relatively high spatial resolution improves visualization of intraluminal devices such as intracranial stents or flow-diverters. Device deployment and positioning, in relation to the parent vessel and surrounding structures, are easily assessible with FDCT. Furthermore, with contrast agent administration, it expands the diagnostic capabilities of this new imaging tool. However, beam-hardening artifacts is a major limitation in some cases. The examination can be performed both during the endovascular procedure and for pre- and post-treatment imaging. Intravenous contrast agent injection reduces the risk of complications, making it possible to perform this examination in the outpatient settings. The aim of this paper is to present an overview of published studies reporting experience with FDCT in the field of endovascular neurosurgery and in particular, FDCT's contribution in treatment of wide-necked intracranial aneurysms. The authors have focused specifically on stent-assisted coiling and flow-diverter implantation, since obtaining proper parent vessel wall apposition of these devices is essential for short- and long-term procedural outcomes.
Surgical treatment of unruptured middle cerebral artery aneurysms: Complication avoidance
2017, Clinical Neurology and Neurosurgery

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

Abstract

Introduction

Section snippets

Case presentation

Discussion

Conclusions

Conflicts of Interest/Disclosures

Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial

Radiology

The pipeline embolization device for the intracranial treatment of aneurysms trial

AJNR Am J Neuroradiol

Incomplete stent apposition in Enterprise stent-mediated coiling of aneurysms: persistence over time and risk of delayed ischemic events

J Neurosurg

Three-dimensional imaging and cone beam volume CT in C-arm angiography with flat panel detector

Diagn Interv Radiol

C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology

Neuroradiology

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