In vitro observation of air bubbles during delivery of various detachable aneurysm embolization coils

Intra-aneurysmal air after flow diversion treatment in intracranial aneurysms: incidence, characteristics and clinical significance

OBJECTIVE

To describe the rate and characteristics of air bubble retention (ABR) within cerebral aneurysms treated by flow diversion.

METHODS

Procedural flat detector CT (FDCT) studies were scrutinized for the presence of air bubbles (density < - 200 HU) in patients treated by flow diversion. Patients with intrasaccular treatment or previous clipping were excluded. Clinical outcomes, procedural angiograms, aneurysm characteristics and imaging features of air within the aneurysm were evaluated.

RESULTS

Bubbles were noted in 17.1% of 105 aneurysms in 85 FDCTs. Aneurysms with ABR were significantly larger (mean diameter: 18.9 versus 7.5 mm, P < 0.0001). There was a trend for the use of multiple devices during the treatment of these aneurysms (72.2% vs 49.4%, P = 0.071). All of the bubbles were located rostrally in the aneurysm sac and were smaller than 6 mm (mean diameter: 2.1 ± 1.3 mm). None of the patients had post-procedural neurological deterioration. The air had spontaneously disappeared on follow-up CT images (available in 12 patients) obtained at a mean follow-up duration of 48 h.

CONCLUSIONS

ABR is not infrequent in cerebral flow diversion procedures. It is a clinically silent and self-limited technical complication. We propose air entrapment or filtration through the flow diverter as causative factors.

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

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.

Microembolism after endovascular coiling of unruptured cerebral aneurysms: incidence and risk factors

OBJECTIVE

The incidence and risk factors of microembolic lesions on MR diffusion-weighted imaging (DWI) were analyzed after the endovascular coiling of unruptured intracranial aneurysms (UIAs).

METHODS

Data obtained from 271 consecutive patients (70 men and 201 women; median age 57 years; range 23-79 years) who presented with UIA for coil embolization between July 2011 and June 2013 were analyzed. Two independent reviewers examined the DWI and apparent diffusion coefficient maps obtained the following day for the presence of restrictive diffusion spots and counted the number of spots. Multivariate analysis was then performed to identify independent risk factors for developing microembolism following the coiling of an aneurysm.

RESULTS

Microembolic lesions were noted in 101 of 271 patients (37.3%). The results of the multivariate analysis showed that the following factors significantly influenced the risk for microembolism: age, diabetes, previous history of ischemic stroke, high-signal FLAIR lesions in the white matter, multiple aneurysms, and the insertion of an Enterprise stent (all ORs > 1.0 and all p values < 0.05). Previously known risk factors such as prolonged procedure duration, aneurysm size, and decreased antiplatelet function did not show any significant influence.

CONCLUSIONS

The incidence of microembolism after endovascular coiling of UIA was not low. Lesions occurred more frequently in patients with vascular status associated with old age, diabetes, and previous stroke. Aneurysm multiplicity and the type of stent used for treatment also influenced lesion occurrence.

Microembolism after Endovascular Treatment of Unruptured Cerebral Aneurysms: Reduction of its Incidence by Microcatheter Lumen Aspiration

PURPOSE

Diffusion-weighted MR images (DWI) obtained after endovascular treatment of cerebral aneurysms frequently show multiple high-signal intensity (HSI) dots. The purpose of this study was to see whether we could reduce their incidence after embolization of unruptured cerebral aneurysms by modification of our coiling technique, which involves the deliberate aspiration of the microcatheter lumen right after delivery of each detachable coil into the aneurysm sac.

MATERIALS AND METHODS

From January 2011 to June 2011, all 71 patients with unruptured cerebral aneurysms were treated using various endovascular methods. During the earlier period, 37 patients were treated using our conventional embolization technique (conventional period). Then 34 patients were treated with a modified coiling technique (modified period). DWI was obtained on the following day. We compared the occurrence of any DWI HSI lesions and the presence of the symptomatic lesions during the two time periods.

RESULTS

The incidence of the DWI HSI lesions differed significantly at 89.2% (33/37) during the conventional period and 26.5% (9/34) during the modified period (p < 0.0001). The incidence of symptomatic lesions differed between the two periods (29.7% during the conventional period vs. 2.9% during the modified period, p < 0.003).

CONCLUSION

Aspiration of the inner content of the microcatheter right after detachable coil delivery was helpful for the reduction of the incidence of microembolisms after endovascular coil embolization for the treatment of unruptured cerebral aneurysms.

Design and biocompatibility of endovascular aneurysm filling devices

The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.

Thromboembolic Events Associated with Electrolytic Detachment of Guglielmi Detachable Coils and Target Coils : Comparison with Use of Diffusion-Weighted MR Imaging

Objective

The purpose of this study was to retrospectively evaluate and compare the incidence of diffusion-weighted image (DWI) lesions between the Guglielmi detachable coil (GDC) and the Target coil for treating unruptured intracranial aneurysm.

Methods

From 2010 to 2011, consecutive 222 patients with an intracranial aneurysm underwent coil embolization. Inclusion criterias were : 1) unruptured intracranial aneurysm, 2) one or more GDC or Target coils used with or without other coils, 3) DWI examination within 24 hours after coiling, and 4) coiling performed without a balloon or stent.

Results

Ninety patients (92 cases) met the inclusion criteria. DWI lesions were detected in 55 (61.1%) of 90 patients. In the GDC group (n=44), DWI lesions were detected in 31 (70.5%). The average number of DWI lesions was 5.0±8.7 (mean±SD; range, 1-40) in aneurysm-related territory. In the Target coil group (n=48), DWI lesions were detected in 24 (50.0%). The number of DWI lesion was 2.1±5.4 (range, 1-32) in aneurysm-related territory. There was no significant correlation between a number of coils and DWI lesions. No significant differences were also observed in the number of DWI lesions in each group.

Conclusion

The GDC and Target coils, which have an electrolytic detachable system, showed no differences in the incidence of DWI lesion.