Neurointervention.  2018 Sep;13(2):117-123. 10.5469/neuroint.2018.00976.

In Vitro Evaluation of Fusiform-Shaped Stents for Wide-Neck Intracranial Aneurysm Treatment

• Jia ZY
• Jiang YY
• Woo JM
• Hwang SM
• Lim OK
• Kim TI
• Park JC
• Lee HS
• Kim ES
• Lee DH

• KMID: 2424060
• DOI: http://doi.org/10.5469/neuroint.2018.00976

Abstract

PURPOSE
Wide-neck aneurysms (WNAs) associated with a dilated parent artery (PA) are not uncommon morphological abnormalities and usually cause inappropriate wall apposition and incomplete neck coverage of a tubular stent in stent-assisted coiling of aneurysms. We aimed to introduce a fusiform-shaped stent (FSS) and test its effectiveness in treating intracranial WNAs associated with a dilated PA using a three-dimensional (3D) model.
MATERIALS AND METHODS
Two FSS types were designed with the middle one-third segment dilated by 10% (FSS10) and 20% (FSS20) and were compared with the tubular-shaped stent (TSS). A patient-specific 3D WNA model was prototyped and produced, and in vitro stent placement was performed. Angiographic images of the three stent types were analyzed and compared using predetermined parameters.
RESULTS
The stent lumens were significantly larger in FSS10 and FSS20 than in TSS in the middle segments (P=0.046), particularly FSS20 (P=0.018). The non-covered area at the ostium tended to be smaller in FSS10 and FSS20 than in TSS, but the difference was not significant (P>0.05). The stent length was significantly longer in FSS10 and FSS20 than in TSS. The stent cell size was significantly larger in FSS than in TSS.
CONCLUSION
Better vessel wall apposition and aneurysmal neck coverage was observed for FSS than for TSS. No significant difference was observed between FSS10 and FSS20.

Keyword

Intracranial aneurysm; Endovascular procedure; Stents; Self-expandable metal stent; Proof of concept experiment

MeSH Terms

Aneurysm
Arteries
Cell Size
Endovascular Procedures
Humans
In Vitro Techniques*
Intracranial Aneurysm*
Neck
Parents
Stents*

Figure

• 

  Fig. 1. Stent-assisted WNA coiling and concept design. (A-C) Right internal carotid artery (ICA) ophthalmic segment WNA with PA dilation (aneurysm neck diameter 5.3 mm, proximal PA diameter 4.2 mm, distal PA diameter 2.9 mm, PA diameter at aneurysm neck 5.0 mm) underwent stent-assisted coiling (LVIS blue, 4.5×18 mm). Final three-dimensional angiography showed several loops of coil protruding into the gap between the stent and vessel wall (arrow in B), and the irregular residual space between the stent, coils, and vessel wall (curved arrow in B, stent was visible on C). (D) Illustrations of a TSS and a FSS for coiling of WNAs with a dilated PA. The FSS shows better wall apposition and aneurysmal neck coverage. (E) Prototypes of the TSS and the FSS with middle segment dilated by 10% and 20%. WNA, wide-neck aneurysm; PA, parent artery; TSS, tubular-shaped stent; FSS, fusiform-shaped stent.

• 

  Fig. 2. Centerline distance and stent expansion. (A, B) Three-dimensional (3D) volume-rendering image of the aneurysm and the 3D prototype of silicone aneurysm model. (C) Reconstructed 3D image showing the placed stent in the silicone model on the Leonardo workstation. A centerline was drawn along the stented segment of parent artery to measure the length of the stent (purple line). The position of 10 different cross sections perpendicular to the centerline at the aneurysm neck portion was shown, which was used for stent lumen area measurement. (D-L) Representative images (slices 3, 5, and 7 marked in image C) of each type of stent were compared and used for measuring the lumen area of the stents (cut-surface area). Note the gap between the TSS stent and the vessel wall (arrowheads in D), and the better wall apposition evolution from the TSS to FSS20 (arrow in E, H, and K). SL, slices; TSS, tubular-shaped stent; FSS, fusiform-shaped stent.

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  Fig. 3. Stent coverage at the aneurysm neck and cell area at the convex side. (A) Reconstructed 3D image showing the placed stent in the silicone model. (B) A cross section perpendicular to the centerline (corresponding to the white line shown in A). (C) A section at the aneurysm neck to measure the neck coverage of the stent (the blue cutting plane shown in A). The dashed lines between (B) and (C) showing the corresponding points in two planes. On image (C), the stent-covered area and non-covered area of the aneurysm neck can be measured. (D) Measuring the four-cell size at the convex side of the stent.

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  Fig. 4. Analytical results. (A) Comparison of the centerline distances of the stents showing that they are longer for FSS10 and FSS20 than for TSS. (B) Comparison of the stent lumen areas of the 10 sections along the stent among the three types of stents. FSS10 and FSS20 have significantly larger lumen areas than that of the TSS (P=0.024 and P=0.018, respectively). (C) Comparison of the non-covered area sizes at the aneurysmal neck (measured in Fig. 3C) showing no significant difference. (D) Comparison of the four-cell areas at the convex side showing better expansion for FSS10 and FSS20. FSS, fusiform-shaped stent; FSS10, FSS with middle segment dilated by 10%; FSS20, FSS with middle segment dilated by 20%; TSS, tubular-shaped stent.

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