Flow Re-direction Endoluminal Device in treatment of cerebral aneurysms: initial experience with short-term follow-up results

Clinical article

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Object

Flow diverter (FD) stents are relatively new and important devices in the treatment of cerebral aneurysms. The Flow Re-Direction Endoluminal Device has been recently released for clinical use. The authors' aim in this paper is to report their initial single-center FRED experience with short-term results.

Methods

Between February 2012 and May 2013, 33 patients with 37 aneurysms (35 unruptured and 2 previously ruptured aneurysms) were treated with the FRED. Clinical and radiological data of the patients were retrospectively reviewed.

Results

In all patients only 1 device was used without any additional device or material, such as a stent or coil. All procedures were successfully performed. The procedural complication rate was 3% (1 of 33). Thirty patients underwent clinical and radiological follow-up. During the follow-up period, changes in stent morphology, such as “fish mouth” and “foreshortening” phenomena, occurred in 5 patients. The mortality and permanent morbidity rates were 0%. The complete occlusion rates were 32% (6 of 19) at 0–1 month, 67% (8 of 12) at 2–3 months, 80% (4 of 5) at 4–6 months, and 100% (8 of 8) at 7–12 months. The rates for some aneurysms were assessed at more than one time point.

Conclusions

The FRED has an ability to serve neurointerventionalists in the treatment of cerebral aneurysms with its different technical advantages. The occlusion rates with FRED are similar to those with other FD devices. However, these short-term results need to be confirmed with mid- and long-term follow-up results of multicenter large series.

Abbreviations used in this paper:ACA = anterior cerebral artery; DS = digital subtraction; DSA = DS angiography; FRED = Flow Re-Direction Endoluminal Device; FD = flow diverter; FDCT = flat-detector CT; FDCTA = flat-detector CT angiography; ICA = internal carotid artery; mRS = modified Rankin Scale; PED = Pipeline Embolization Device; TIA = transient ischemic attack; VA = vertebral artery.

Object

Flow diverter (FD) stents are relatively new and important devices in the treatment of cerebral aneurysms. The Flow Re-Direction Endoluminal Device has been recently released for clinical use. The authors' aim in this paper is to report their initial single-center FRED experience with short-term results.

Methods

Between February 2012 and May 2013, 33 patients with 37 aneurysms (35 unruptured and 2 previously ruptured aneurysms) were treated with the FRED. Clinical and radiological data of the patients were retrospectively reviewed.

Results

In all patients only 1 device was used without any additional device or material, such as a stent or coil. All procedures were successfully performed. The procedural complication rate was 3% (1 of 33). Thirty patients underwent clinical and radiological follow-up. During the follow-up period, changes in stent morphology, such as “fish mouth” and “foreshortening” phenomena, occurred in 5 patients. The mortality and permanent morbidity rates were 0%. The complete occlusion rates were 32% (6 of 19) at 0–1 month, 67% (8 of 12) at 2–3 months, 80% (4 of 5) at 4–6 months, and 100% (8 of 8) at 7–12 months. The rates for some aneurysms were assessed at more than one time point.

Conclusions

The FRED has an ability to serve neurointerventionalists in the treatment of cerebral aneurysms with its different technical advantages. The occlusion rates with FRED are similar to those with other FD devices. However, these short-term results need to be confirmed with mid- and long-term follow-up results of multicenter large series.

Despite the fact that endovascular coiling has been proven to be an effective method in the treatment of cerebral aneurysms, certain types of cerebral aneurysms, particularly wide-neck, large, and fusiform aneurysms, are still considered to be challenging for endovascular treatment.10,11 In treatment of these types of aneurysms, endovascular coiling is associated with a high recurrence rate.4 Self-expandable intracranial stents have been increasingly used to treat these challenging aneurysms with satisfying clinical and anatomical results.9,13 However, the recurrence rate remains significant.15

Recently, flow diverter (FD) devices have been introduced into neurointerventional practice. These devices provide endoluminal aneurysm occlusion by causing flow disruption.5,17 Two well-known and most commonly used FD devices are the Pipeline Embolization Device (PED; Covidien, FDA approved and CE marked) and SILK stent (Balt Extrusion, CE marked). These devices are single-layer, low-porosity, self-expandable stents, forming high-coverage mesh that covers the aneurysm neck and then simultaneously induces thrombosis of the aneurysm sac while preserving the patency of the adjacent small vessels. Alternatively, the Flow Re-Direction Endoluminal Device (FRED; MicroVention, Inc.) is a novel FD stent and has been recently released for clinical use. It has a unique dual-layer design composed of a low-porosity inner FD mesh and a high-porosity outer stent, mainly focusing on the neck of the aneurysm with its inner part while preserving the adjacent small vessels with its outer part. Here, we present our preliminary clinical experience with the FRED in 33 patients with 37 aneurysms.

Methods

Patient Population

Between February 2012 and May 2013, 33 patients with 37 cerebral aneurysms were treated with FRED placement in our interventional neuroradiology department. Our treatment indications with FRED were the same as those of other FDs and are as follows: 1) complex wide-necked (neck diameter > 4 mm) saccular aneurysms in the anterior circulation below the anterior choroidal artery, 2) small aneurysms (< 2 mm) that are untreatable with other techniques, 3) giant aneurysms or aneurysms presenting with mass affect, 4) fusiform aneurysms, and 5) dissecting aneurysms (regardless of aneurysm location, for example, anterior or posterior cerebral circulation).

There were 27 women and 6 men with a mean age of 50.6 years (range 32–68 years). Overall, 22 patients had only 1 cerebral aneurysm, and 11 patients had more than 1 aneurysm. Among these 11 patients, 4 had 2 adjacent aneurysms in the same location, and these were treated with a single device. Fifteen patients were asymptomatic, and 18 patients were symptomatic. Of the symptomatic patients, 17 presented with headache and 1 presented with sixth cranial nerve palsy due to mass effect of the aneurysm. Detailed characteristics of the patients are presented in Table 1. This retrospective study was approved by the institutional ethics committee. Written informed consent was obtained for each patient in advance of the treatment.

TABLE 1:

Detailed characteristics of patients and aneurysms*

Case No.Age (yrs), SexClinical PresentationAneurysm Characteristics
Ruptured/UnrupturedSideLocationNo. of Aneurysms TreatedTypeSize (mm)Neck Size (mm)
138, Fincidentalunrupturedrtparaophthalmic ICA1saccular4.4 × 4.7 × 4.94.2
247, MCN VI nerve palsyunrupturedrtpetrous ICA1dissecting fusiform6.2 × 4.5 × 5.8no neck
367, FincidentalunrupturedltA1-A2 junction of ACA1fusiform7.5 × 4.8 × 6.8no neck
446, Mincidentalunrupturedltparaophthalmic ICA1saccular3.7 × 4 × 4.14
561, Mincidentalunrupturedrtparaophthalmic ICA2saccular2.9 × 2.9 × 4.32.9
saccular4.6 × 5.4 × 5.53.4
655, Mheadacheunrupturedltparaophthalmic ICA1saccular5.8 × 6.1 × 8.85.6
744, Fheadacheunrupturedrtparaophthalmic ICA1fusiform15 × 8.4 × 10.1no neck
832, Fincidentalunrupturedrtparaophthalmic ICA1saccular3.4 × 3.9 × 5.74
954, Fincidentalunrupturedrtparaophthalmic ICA1saccular2.1 × 3.8 × 3.44.7
1045, Fheadacheunrupturedltparaophthalmic ICA1saccular5.9 × 5.5 × 6.85.4
1168, Fheadacheunrupturedltparaophthalmic ICA1saccular11 × 13 × 8.84.3
1259, Mheadacheunrupturedltparaophthalmic ICA1saccular13 × 15 × 156.3
1343, Fheadacheunrupturedltparaophthalmic ICA1saccular9.6 × 4.8 × 6.26.9
1457, Fincidentalunrupturedltparaophthalmic ICA1saccular2.6 × 3.2 × 4.32.9
1558, Fheadacheunrupturedrtpetrous ICA1dissecting fusiform9.1 × 4.2 × 8.9no neck
1633, Fincidentalunrupturedrtparaophthalmic ICA1saccular3.6 × 4.1 × 4.54
1737, Fheadacheunrupturedltparaophthalmic ICA1saccular6.7 × 7.3 × 8.77.1
1863, Fheadacheunrupturedrtparaophthalmic ICA1saccular5.4 × 5.7 × 7.95.2
1963, Fheadacheunrupturedltparaophthalmic ICA1saccular6.1 × 6.4 × 7.36.5
2035, Fincidentalunrupturedrtparaophthalmic ICA1saccular2.7 × 3.7 × 7.15.8
2150, Fheadacheunrupturedrtparaophthalmic ICA2saccular4 × 5.6 × 4.1no neck
fusiform6.9 × 4.1 × 6.12
2259, Fheadacheunrupturedrtparaophthalmic ICA1saccular9.9 × 13 × 13.65.2
2348, FincidentalunrupturedltC1-C2 segment of ICA1fusiform3.9 × 1.7 × 3.1no neck
2445, Fincidentalunrupturedltparaophthalmic ICA1saccular5.1 × 5.6 × 7.14.1
2557, Fheadacheunrupturedltparaophthalmic ICA1fusiform8.5 × 6.8 × 7.9no neck
2655, Fincidentalunrupturedrtparaophthalmic ICA1saccular3 × 5.2 × 5.32.8
2742, Fincidentalunrupturedrtparaophthalmic ICA1saccular3.9 × 5 × 6.14.7
2849, Fheadacheunrupturedltparaophthalmic ICA1saccular6.3 × 6.5 × 6.75.8
2958, Fheadacheunrupturedrtparaophthalmic ICA (previously coiled)2saccular6.5 × 5.5 × 86.5
residual neck4 × 4 × 3.56.9
3064, Fincidentalunrupturedltparaophthalmic ICA2saccular7 × 4 × 3.54
fusiform2 × 2.5 × 2.7no neck
3152, FincidentalunrupturedrtV4 segment of VA1dissecting fusiform6.7 × 6 × 6.4no neck
3239, Mheadachepreviously rupturedltV4 segment of VA (previously coiled)1dissecting fusiform w/ saccular component13 × 13 × 5no neck
3348, Fheadachepreviously rupturedltparaophthalmic ICA (previously coiled)1fusiform8.6 × 5.6 × 7no neck

CN = cranial nerve.

Device

The FRED (MicroVention, Inc.) is a braided self-expandable FD stent with a stent-in-stent design that is composed of an outer stent with high porosity and an inner FD mesh with lower porosity and higher pore density (Fig. 1). The device is composed of 48 braided nitinol inner strands and 16 outer struts, forming a dual-layer coverage to focus mainly on the aneurysm neck. The FRED has 4 radiopaque markers on each end of the outer stent and 2 interwoven helical marker strands that attach inner and outer stents and run the entire length of the inner stent. The second-generation FRED is available with a nominal diameter ranging from 3.5 to 5.5 mm and lengths varying according to the parent vessel diameter (presented as working length/total length: range minimum 7 mm/13 mm to maximum 48 mm/55 mm). The FRED system includes an introducer sheath and a detachable delivery wire. It is delivered through a microcatheter with a 0.027-inch inner diameter. The FRED is of close-cell design and can be resheathed up to 50% deployment of its total length. It has European Community approval (that is, CE marking).

Fig. 1.
Fig. 1.

Angled view of FRED. Published with permission from MicroVention, Inc.

Two generations of the FRED system were used in this study; the first-generation devices were used only in the first 8 patients (9 aneurysms). The main differences between the first and second generations of the FRED are 1) the presence of a distal support wire, which is absent in the first generation of FRED; 2) the configuration of attachment zones of the inner stent to the outer stent, which are only proximally in the first generation, whereas those are interwoven in the second generation; and 3) the wire diameter of the outer stent, which is smaller in the first generation, and is similar to an LVIS stent (MicroVention, Inc.).

Endovascular Procedure

A biplane flat panel digital subtraction unit (Allura Xper20/20, Philips Healthcare) was used for all endovascular procedures. All procedures were performed under general anesthesia and systemic heparinization with the protocol described below.

Unilateral femoral access was used in all patients. A distal access-guiding catheter was placed within a long introducer sheath to reach the petro-cavernous segment of the internal carotid artery (ICA) or the V2-V3 segments of the vertebral artery (VA). Then, a Headway (MicroVention, Inc.) microcatheter with a 0.027-inch inner diameter was placed in a distal safe vessel segment to avoid any damage with the distal tip of the stent support wire. At the appropriate location, the stent was loaded and pushed through the microcatheter; the catheter was then pulled back to unsheathe the stent simultaneously while forward tension was maintained on the pusher system of the stent to keep it in place. To obtain a good stent opening and a satisfying apposition on the vessel wall, the stent was pushed on slightly at the time of implantation to attain a position in the middle of the parent artery. In addition, careful attention was given to check whether the distal segments of the stent had been opened well before opening the detachment zone. When an unopened segment was observed, thanks to the retrievability and repositionability features of the FRED system, it was reopened without removing the microcatheter and the stent from the body. Most often the distal support wire of the stent helped renavigate the microcatheter distal to the aneurysm.

To evaluate the expanded stent morphology and the apposition of the stent in the vessel wall in much greater detail, intraarterial flat-detector CT angiography (FDCTA; VasoCT, Philips Healthcare) was performed in all patients during or after deployment (Fig. 2). In addition, a flat-detector CT (FDCT; XperCT, Philips Healthcare) examination was performed routinely immediately after the treatment.

Fig. 2.
Fig. 2.

Case 21. Images obtained in a 50-year-old woman with 2 right-sided paraophthalmic ICA aneurysms and an ipsilateral anterior choroidal artery aneurysm. This patient also had a history of a left-sided paraophthalmic ICA aneurysm that was treated with Onyx 6 years earlier. A–C: Three-dimensional DS angiograms showing the right-sided wide-necked paraophthalmic ICA aneurysm (A and B), which is laterally oriented at the curve of the tight carotid siphon. The anterior choroidal artery aneurysm (A) and superior hypophysial artery (C) aneurysms are visible in the right ICA in addition to the Onyx cast on the left side. D–F: After coiling of the anterior choroidal artery aneurysm, nonsubtracted images show that the FRED covers both the superior hypophysial artery and paraophthalmic segment aneurysms. The Onyx cast is also visible on the left side. Note the opening difficulties and manipulation of the microcatheter and system. G: Postembolization FDCTA image showing good apposition of the stent.

Periprocedural Angiographic Evaluation

All imaging studies were evaluated by at least 2 experienced interventional neuroradiologists (N.K., C.I., and O.K.). Preprocedural morphological characteristics of the aneurysms and parent arteries were measured using 3D reconstructed images derived from rotational angiography. All measurements were performed using an XtraVision Workstation (Philips Healthcare).

Intraaneurysmal flow modification after stent deployment was assessed using digital subtraction angiography (DSA). A modified O'Kelly-Marotta grading scale was used for classification of intraaneurysmal flow modification as follows:12 1, complete stasis (if no contrast medium entered the aneurysm); 2, significant stasis (if the contrast medium stagnation was seen at the late venous angiographic phase); 3, moderate stasis (if contrast medium stagnation was only seen at early venous angiographic phases); and 4, no stasis (if contrast stagnation was not seen even at the early angiographic phase).

Based on contrast medium filling in the aneurysm, the occlusion grade of the aneurysms during radiological follow-up was assessed using either DSA or intravenous FDCTA, which is a much less invasive imaging technique compared with the intraarterial counterpart.8 The occlusion grade was classified using the O'Kelly-Marotta grading scale as follows:12 A, complete filling (> 95% filling; no change in aneurysm occlusion status); B, incomplete filling (5%–95% filling; incomplete occlusion); C, neck remnant (< 5% filling); and D, no filling (0% filling; complete occlusion).

Antiplatelet and Anticoagulation Protocol

Before the procedure, the patients were prescribed 75 mg clopidogrel together with 100 mg aspirin daily for at least 7 days before the procedure. Clopidogrel resistivity was checked a few times for all patients to maintain at least a 40% platelet inhibition rate. In patients whose platelet inhibition rates were unable to reach 40%, the initial aspirin dose was increased to 300 mg daily. Among the patients who still were unable to maintain an appropriate platelet inhibition rate, the clopidogrel dose was then doubled (150 mg) or exchanged with ticlopidine (250 mg twice daily) and was taken along with aspirin (300 mg daily). If the platelet inhibition rate was still less than 40%, ticlopidine was exchanged for prasugrel (10 mg daily) and was taken along with aspirin (300 mg daily).

All stenting procedures were performed under systemic heparinization. Heparin was given after insertion of the femoral sheath. The adequacy of systemic anticoagulation was monitored by obtaining frequent measurements of the activated clotting time. A baseline activated clotting time was obtained before the bolus infusion of 5000 IU heparin and hourly thereafter. The bolus infusion of heparin was followed by continuous drip (1000–1500 IU/hour) to double the baseline activated clotting time.

After treatment, systemic heparinization was continued until control DSA was performed 1 day postoperatively. Postprocedural dual antiplatelet medication including clopidogrel (75 mg/day) and aspirin (100–300 mg/day) was taken for at least 6 months. Nonetheless, in patients with in-stent stenosis, dual antiplatelet medication was continued.

Follow-Up

For optimum imaging follow-up, 6- and 12-month DSA and 1-, 3-, 6-, and 12-month VasoCT (FDCTA) examinations were planned for each patient. In addition to these examinations, before discharging the patient, control DSA was performed 1 day postoperatively to evaluate the aneurysm and stent morphologies in patients whose femoral introducer sheath had not been removed.

Clinical follow-up was performed at 1, 3, 6, and 12 months by the interventional neuroradiologists at the same time as assessment of the imaging studies. Clinical assessment was carried out using modified Rankin Scale (mRS) scores at baseline, at discharge, and at follow-up clinical assessments.

Results

Aneurysm Characteristics

Thirty-seven cerebral aneurysms in 33 patients were treated using the FRED. In 4 patients, the treated vascular segment involved 2 aneurysms in each patient. All aneurysms except 2 dissecting VA aneurysms were in the anterior circulation. Thirty-one aneurysms were located at the paraophthalmic ICA. Other locations were the petrous ICA (n = 2), A1-A2 junction of the anterior cerebral artery (ACA; n = 1), the C1-C2 segment of the ICA (n = 1), and the V4 segment of the VA (n = 2). Twenty-six aneurysms were saccular in shape, of which 1 aneurysm was a recurrent aneurysm that had undergone previous coil treatment. Eleven aneurysms were fusiform, and 4 aneurysms of these aneurysms were dissecting in nature. Two of the 11 fusiform aneurysms that had undergone previous coil treatment were recurrent aneurysms. Two of 37 aneurysms had previously ruptured, whereas the remaining aneurysms were unruptured. Based on the maximum aneurysm diameter, the mean aneurysm size was 7.37 mm (range 2.7–15 mm). The mean neck size of the saccular aneurysms was 4.81 mm (range 2–7.1 mm). For the fusiform-type aneurysms, the mean length of the aneurysm segment was 8.4 mm. Detailed characteristics of the aneurysms are presented in Table 1.

Technical and Procedural Results

In all patients, a single FRED was placed successfully without any additional device or material, such as stents or coils. In 2 patients (Cases 9 and 11), the FRED could not be advanced through the hub of the microcatheter proximally. Thus, the detached stents in the hub were exchanged for new ones.

In one patient (Case 11), there was an air bubble in the aneurysm sac without any clinical consequence, probably caused by trapped air between layers of the FRED. In another patient (Case 25), the first 2 stents that were oversized compared with the parent artery could not be deployed because of the unfavorable angle of the parent vessel. To overcome this problem, a shorter and undersized stent was chosen. However, this resulted in the “foreshortening” phenomenon 1 day after the procedure.

Considering the 0.3-mm additional enlargement over the maximum diameter (unpublished data), the stents were sized in according to the parent vessel diameter. For the proximal parent artery, the stents were oversized in 9 patients, sized in 16 patients, and undersized in 8 patients. For the distal parent artery, the stents were oversized in 25 patients, sized in 7 patients, and undersized in 1 patient (Table 2).

TABLE 2:

Detailed characteristics of parent artery and device used for treatment*

Case No.Parent Artery DiameterDevice Characteristics
Proximal (mm)Distal (mm)Generation of DeviceDiameter (mm)Total Length (mm)Working Length (mm)Device Size Compared w/ Parent Artery
ProximalDistal
14.92.71st4.253318UO
24.13.51st4.253318SO
31.92.31st2.752716OU
43.82.61st3.252816UO
54.23.31st3.753018UO
64.341st4.253018SS
73.13.51st3.252816SS
83.73.51st3.51812SS
94.23.42nd4.52013OO
104.53.82nd4.52518SO
114.63.52nd41812UO
124.34.72nd4.52013SS
134.73.82nd4.52518SO
143.83.32nd41812SO
1553.62nd52114SO
164.43.12nd41812UO
173.92.752nd42317SO
183.73.42nd41812OO
194.13.82nd4.52013OO
203.32.92nd3.52216SO
213.93.12nd42317SO
2243.82nd41812SS
23342nd4.52518OO
242.53.42nd3.52216OS
254.73.52nd41812UO
264.33.22nd41812UO
274.33.72nd41812UO
283.42.72nd3.52216SO
294.13.32nd4.52518OO
304.02.82nd41812SO
312.83.32nd3.52216OS
3243.82nd4.52518OO
333.61.92nd3.52216SO

O= oversize; S= size; U= undersize.

One procedural complication occurred in 33 procedures (3%). In this patient (Case 21), a petrous ICA dissection occurred during distal access catheter manipulations, causing a cerebral transient ischemic attack (TIA). Detailed technical and procedural results are presented in Tables 2 and 3.

TABLE 3:

Technical, procedural, immediate angiographic, and clinical results*

Case No.Technical ComplicationProcedural ComplicationContrast Stasis & Stent Morphology After FRED ImplantationImmediate Clinical Outcome
Contrast Stasis on Immediate DSAContrast Stasis on 1-Day Postop DSAStent Morphology on 1-Day Postop DSA
1moderatemoderateno changenormal
2no changeno changeno changenormal
3moderatemoderateno changenormal
4moderatemoderateno changenormal
5significantsignificantno changenormal
significantsignificant
6significantsignificantno changenormal
7significantsignificantno changenormal
8moderatemoderateno changenormal
9stent detached at hubno changeno changeno changenormal
10moderatemoderateno changenormal
11stent detached at hub; intraaneurysmal air bubblesignificantsignificantno changenormal
12significantsignificantno changenormal
13moderatemoderateno changenormal
14moderatemoderateno changenormal
15significantsignificantno changenormal
16no changeno changeno changenormal
17significantsignificantno changenormal
18significantsignificantno changenormal
19moderatemoderateno changenormal
20moderatemoderateno changenormal
21nonstenosing dissection of petrous ICAmoderatemoderateno changecerebral TIA
moderatemoderate
22significantsignificantno changenormal
23no changeno changeno changenormal
24significantsignificantno changenormal
25failure during deployment of 1st 2 stentsno changeno changeforeshorteningnormal
26moderatemoderateno changenormal
27no changeNANAnormal
28significantsignificantno changeophthalmic TIA
29significantsignificantno changenormal
significantsignificant
30no changeNANAnormal
no changeNA
31significantNANAnormal
32moderatemoderateno changenormal
33significantsignificantno changenormal

The mRS scores remained the same from baseline to discharge. NA = not available.

Angiographic Results

Immediately after FRED implantation, contrast stasis in the aneurysm sac was complete in none of the aneurysms, significant in 16 aneurysms, and moderate in 13 aneurysms. There was no stasis in 8 aneurysms. One-day control angiography was performed in 30 patients with 33 aneurysms. There was no difference between immediate and 1-day postoperative DSA in terms of contrast medium stasis (Fig. 3).

Fig. 3.
Fig. 3.

Case 12. Images obtained in a 59-year-old man with an unruptured left-sided paraophthalmic ICA aneurysm. A: Three-dimensional DS angiogram showing the left-sided paraophthalmic ICA aneurysm. B: Significant stasis is shown in the late venous angiographic phase after stent deployment. C: Intraarterial FDCTA reconstruction clearly showing the inner portion of the FRED that covers the neck. D: Intravenous FDCTA image obtained at the 1-month follow-up, showing incomplete occlusion (75%) with no morphological change in the stent itself.

There was no change in stent morphology on 1-day postoperative DSA compared with the immediate posttreatment DSA study except in 1 patient (Case 25) in whom the FRED was foreshortened due to the use of an undersized stent in relation to the proximal parent artery. Because of this foreshortening phenomenon, the proximal part of the stent moved forward so that the inner stent covered the neck of the aneurysm just at the edge.

Thirty patients with 33 aneurysms underwent DSA or FDCTA follow-up studies. The mean angiographic follow-up period was 3.6 months (range 1–12 months). Graphs showing the occlusion status of the aneurysms are shown in Fig. 4. Based on these angiographic results, there was an obvious increase in complete occlusion rates with time. The complete occlusion rates were 32% (6 of 19) at 0–1 month, 67% (8 of 12) at 2–3 months, 80% (4 of 5) at 4–6 months, and 100% (8 of 8) at 7–12 months (Fig. 5). The rates for some aneurysms were assessed at more than one time point.

Fig. 4.
Fig. 4.

Graphs showing the aneurysm occlusion status during angiographic follow-up. Upper: Aneurysm occlusion status with patient numbers. Lower: Aneurysm occlusion status with rates.

Fig. 5.
Fig. 5.

Case 6. Images obtained in a 55-year-old man with a left-sided paraophthalmic ICA aneurysm. A: Left ICA DS angiogram showing the left-sided wide-necked paraophthalmic ICA aneurysm. B: Coronal thin-section FDCTA image showing good apposition of the stent to the vessel wall. C and D: Digital subtraction angiogram obtained at the 7-month follow-up showing total occlusion of the aneurysm with a patent ophthalmic artery and no morphological change in the stent.

In 26 patients, there was no change in stent morphology and the parent artery during the follow-up period. However, the “fish mouth” phenomenon (that is, inward crimping of the proximal, distal, or both ends of the stent18) occurred in 4 patients (Cases 1, 3, 4, and 8) in whom only first-generation FREDs were used (Fig. 6). Of these patients, 3 (Cases 1, 3, and 4) had only a distal fish mouth phenomenon, and the remaining patient (Case 8) had the phenomenon at the proximal and distal ends. In 1 patient (Case 1), the distal “fish mouth” phenomenon was significant on follow-up images obtained at 3 months. However, it improved to moderate on 12-month images. In another patient (Case 4), the fish mouth phenomenon improved from significant to moderate between the 1- and 6-month images. However, on follow-up images obtained at 12 months, the fish mouth phenomenon was no longer visible. In Case 3, the fish mouth phenomenon remained unchanged as moderate on the 2-month and 12-month images. In Case 8, although the distal fish mouth phenomenon remained as moderate on the images obtained at 2 and 10 months, a significant proximal fish mouth phenomenon with visible intimal hyperplasia was noted on the images obtained at 10 months.

Fig. 6.
Fig. 6.

Case 4. Images obtained in a 46-year-old man with an unruptured left-sided paraophthalmic ICA aneurysm and a proximal A1 segment aneurysm treated in the same session. A: Left ICA injection angiogram showing the aneurysms. B: Three-dimensional DS angiogram obtained at the 6-month follow-up demonstrating total occlusion of both aneurysms. Note the slight narrowing at the C2 segment of the left ICA, which is covered by the FRED. C: Immediate posttreatment nonsubtracted DS angiogram showing a well-opened stent. D: FDCTA reconstruction obtained at the 1-month follow-up showing a significant fish mouth phenomenon and enlargement of one-third middle segment of the FRED at the aneurysm segment. E and F: Nonsubtracted DS angiogram obtained at the 6-month follow-up (E) and FDCTA image obtained at the 12-month follow-up (F) showing gradual improvement of the fish mouth phenomenon. Also note that there is no visible neointimal hyperplasia.

In 28 patients, the ophthalmic arteries were covered by the inner FD mesh of the FRED. Furthermore, in 11 patients, the anterior choroidal arteries were covered. In 9 patients these arteries were covered by the outer high porosity part of the stent and in 2 patients they were covered by the inner FD mesh. The ophthalmic and anterior choroidal arteries were both patent in all of these patients during the follow-up period. Nonetheless, 1 patient (Case 28) experienced an ophthalmic TIA immediately after the procedure, although this patient had an angiographically patent ophthalmic artery. Detailed angiographic results are presented in Tables 3 and 4.

TABLE 4:

Radiological and clinical follow-up results*

Case No.Radiological & Clinical Follow-Up Duration (mos)Imaging Studies Used During Follow-Up (timing of study)Radiological Follow-UpClinical Follow-Up Outcome
Aneurysm Occlusion StatusAneurysm Occlusion Time (mos)Morphology of Parent Artery & Stent
112DSA (6 mos); FDCTA (3 mos, 12 mos); CT (1 wk)complete3sig distal FM (3 mos); mod distal FM (12 mos)normal
26DSA (6 mos); FDCTA (2 mos)complete2no changenormal
312DSA (6 mos); FDCTA (6 mos, 12 mos)complete12mod distal FM (2 mos, 12 mos)normal
412DSA (6 mos); FDCTA (1 mo, 12 mos)complete1sig distal FM (1 mo); mod distal FM (6 mos); no FM (12 mos)normal
57DSA (1 mo); FDCTA (7 mos)complete7no changenormal
complete7
67DSA (7 mos)complete7no changenormal
77FDCTA (1 mo, 7 mos)complete7no changenormal
810DSA (6 mos); FDCTA (2 mos, 10 mos); CT (2 mos)complete2mod distal FM (2 mos); sig proximal & mod distal FM (10 mos); intimal hyperplasia at 1/3 proximal part of stent (10 mos)normal
92FDCTA (2 mos)no changeno changenormal
102FDCTA (2 mos)complete2no changenormal
112FDCTA (2 mos)incompleteno changenormal
121FDCTA (1 mo); MRI (1 mo)incompleteno changenormal
132FDCTA (2 mos)incompleteno changenormal
141FDCTA (1 mo)no changeno changenormal
151FDCTA (1 mo)neck remnantno changenormal
161FDCTA (1 mo); CT (1 wk)incompleteno changenormal
171FDCTA (1 mo)incompleteno changenormal
183FDCTA (3 mos)complete3no changenormal
193FDCTA (3 mos)no changeno changenormal
203FDCTA (3 mos)complete3no changenormal
211MRI (1 day); FDCTA (1 mo)neck remnantno changenormal
complete1
223FDCTA (3 mos)complete3no changenormal
233DSA (3 mos)complete3no changenormal
241FDCTA (1 mo)incompleteno changenormal
251FDCTA (1 mo)no changeno changenormal
261FDCTA (1 mo)complete1no changenormal
271FDCTA (1 mo)incompleteno changenormal
281FDCTA (1 mo)complete1no changenormal
291FDCTA (1 mo)neck remnantno changenormal
complete1
30NANANANANA
NA
311FDCTA (1 mo)complete1no changenormal
32NANANANANA
33NANANANANA

The mRS scores remained the same from baseline to follow-up. FM = fish mouth phenomenon; mod = moderate; sig = significant.

Clinical Results

Thirty patients with 33 aneurysms underwent clinical follow-up. Two patients (Cases 21 and 28) experienced a TIA. In Case 21, cerebral TIA causing hemiparesis (4/5) occurred, and was related to the petrous ICA dissection that took place during distal access catheter manipulations, which had resolved on follow-up angiographic images. Immediate control MRI showed ipsilateral multiple embolic foci in both cortical and subcortical areas (Fig. 7). However, the patient's symptoms disappeared in 2 hours. In the other patient (Case 28) in whom the ophthalmic artery originated from the sac itself, an ophthalmic TIA occurred, possibly due to emboli. The patient's symptoms disappeared the same day as the symptoms of the other patient (Case 21).

Fig. 7.
Fig. 7.

Case 21. Axial diffusion-weighted image showing multiple small emboli in the right MCA territory.

In patients with the fish mouth phenomenon and intimal hyperplasia, no neurological sign corresponded to the cerebral perfusion abnormality.

There were no cases of mortality or permanent morbidity. Overall, all patients including the 2 patients who suffered TIAs were neurologically normal during follow-up. There was in turn no change in mRS scores between baseline and follow-up clinical assessments. Detailed clinical results are presented in Tables 3 and 4.

Discussion

The PED and SILK flow diverter devices have been available for clinical use for nearly 6–7 years.1,19 Recently, a few new devices have been introduced into the neurointerventional realm. These devices are the FRED, Surpass Flow Diverter (Stryker Neurovascular), and P64 Flow Modulation Device (Phenox). To the best of our knowledge, this is the first study that evaluates the technical, radiological, and clinical aspects of the use of FREDs with short-term follow-up.

Technical Considerations

The dual-layer design composed of inner and outer stents is a distinguishing feature of the FRED. The inner part, which determines the working length, is a low-porosity stent that neurointerventionalists can use as an active FD segment at the neck region of the aneurysms, particularly at the inflow zone. The outer part, which determines the total length, is a high-porosity stent like an LVIS stent with 16 wires and serves as a scaffold for the inner stent.7 The outer stent is 3 mm longer than the inner FD mesh at each end so that the proximal and distal parts of the FRED can be used to cover the adjacent perforating arteries or side branches of the parent vessel with the advantage of high porosity, which helps to maintain the antegrade flow for those important small vessels. Furthermore, the outer stent is able to decrease the friction that occurs during navigation in the microcatheter since the outer stent has fewer wires (16 wires) than other FD devices.

Retrievability of the system is another important feature of the FRED. Although the company informs neurointerventionalists that the FRED can be retrieved into the microcatheter and repositioned if less than 50% of its total length has been deployed, in our in vitro and in vivo experience we found that the device can still be retrieved even if 80%–85% of its length has been deployed. In tortuous vascular anatomy, this feature allows the neurointerventionalist to renavigate and reposition the microcatheter without pulling the device and microcatheter out of the body, preventing additional exchange manipulations. The SILK stent can be retrieved and repositioned if less than 90% of its total length has been extruded from the microcatheter.6 However, the PED is not retrievable, but at any point up to final deployment it may be captured and removed from the body.16

The second-generation FRED has a stronger outer wire than the first generation and a radial force nearly equal to that of the PED (unpublished data). This feature can help ensure full expansion and good apposition of the stent even in stenotic segments of the parent arteries. Because of this feature, no opening problem at the distal end occurred during our procedures even though the device was oversized compared with the distal parent artery in 25 patients (75%).

In one patient (Case 11) in the second-generation FRED group, an air bubble was seen in the aneurysm after deployment of the stent even though a meticulous back flush of the introducer sheath had been performed before navigating it into the hub. Then, it was realized that simple “finger massaging” in saline before inserting the catheter may be helpful in eliminating possible air bubbles left between stent struts. This manipulation can be done in vitro when 50% of the length of the stent has been extruded from the microcatheter.

With regard to size selection, the FRED is not available in a tapered version and therefore it needs to be oversized distally in the vast majority of cases, as seen in our series (75%), depending on the morphology of the parent vessel. This distal oversizing, especially more than 1 mm, may cause opening problems at tight curves. To overcome these problems, in some cases a repetitive back and forth movement of the stent in the microcatheter and changing the position of the microcatheter may be a solution (Fig. 2). Nonetheless, to avoid oversizing more than 1 mm according to the parent vessel is key in preventing this problem.

To choose the properly sized FRED, we usually follow 3 essential steps that were developed based on our increasing experience. The first step is to choose an optimal stent diameter for the proximal parent artery to prevent endoleak, keeping in mind that the stent can expand an additional 0.3 mm over the stated nominal diameter. The second step is to determine a proper working length to fully cover the neck of the aneurysm. This step is of utmost importance because the FRED expands maximally at very wide necks and in long fusiform segments, and thus the possible foreshortening phenomenon should be kept in mind. In addition, one should be aware that the neurointerventionalist can gain slightly more working length coming from a distal oversized segment. The possibility of those conditions affects the third step of the size selection, which is to select the proper total length.

Radioanatomical Considerations

The complete occlusion rates were 32% at 0–1 month, 67% at 2–3 months, 80% at 4–6 months, and 100% at 7–12 months. In the majority of the aneurysms, contrast stasis in the aneurysm was moderate or significant on immediate posttreatment and 1-day postoperative DS angiograms, which may be a leading factor for the remarkable occlusion rates observed during the follow-up period. Despite the fact that the number of patients who underwent follow-up for at least 6 months was somewhat fewer than that reported in other FD studies, based on the results of a recent meta-analysis, the complete occlusion rates were comparable and almost similar to those of 6-month follow-up images.2

One of the important issues of FD treatment is unavoidable coverage of the side branches adjacent to the aneurysm neck. Only a few studies have examined the effect of FDs on side branches. In a study by Szikora et al.,16 there were 1 immediate and 2 delayed (at 6-month control) ophthalmic artery occlusions among 17 ophthalmic arteries covered with the PED. The immediate occlusion resulted in a retinal branch occlusion, and the other 2 occlusions in which multiple stents had been used were clinically silent. In that study, 4 anterior choroidal arteries were covered with PEDs and no occlusion was reported. In another PED study with a mean follow-up of 8.7 months, 4 occlusions in 19 ophthalmic arteries were reported, and all were asymptomatic.14 In that study, the authors also noted that ophthalmic artery occlusion was not correlated with the use of multiple stents. In another FD study, 15 ophthalmic and 12 anterior choroidal arteries were covered with the Surpass Flow Diverter.3 At 6-month follow-up, 2 of the ophthalmic arteries (13%) lost their antegrade flow without any neurological consequence. In that study, 12 covered anterior choroidal arteries were patent at 6-month angiography. In our series, 28 ophthalmic and 2 choroidal arteries were covered by the inner FD mesh of the FRED, whereas 9 anterior choroidal arteries were covered with the outer part of the FRED. All arteries covered by the outer stent were angiographically patent during the follow-up period. Nonetheless, 1 patient (Case 28) experienced an ophthalmic TIA immediately after the procedure even though the ophthalmic artery was patent on angiography.

In 1 patient (Case 25), the stent foreshortened because the stent was undersized in diameter and there was too much room for expansion at the very wide neck of the aneurysm. However, this event could have been prevented by selecting a somewhat longer stent.

There was no change in stent morphology and parent artery in 26 of 30 patients who underwent angiographic follow-up. However, the fish mouth phenomenon, which can be defined as inward crimping of proximal, distal, or both ends of the stent,18 occurred in 4 patients. The mechanism behind the development of the fish mouth phenomenon is unknown. There were, however, no such parent vessel curves in any of our 4 patients in whom the phenomenon occurred. In addition, no similar sizing pattern was observed in these patients. That is, for example, the stent diameter in relation to the distal parent artery was oversized in 2 patients, sized in 1 patient, and undersized in 1 patient. Nevertheless, it is interesting to note that the first-generation FRED was used in all of these patients. However, it would be misleading to conclude that this phenomenon is associated with features of the first-generation FRED since the mean follow-up period of patients treated with second-generation FREDs is relatively small compared with that of patients treated with first-generation FREDs. We thought that there might be other factors that could be associated with the fish mouth phenomenon, such as the length of the flare ends, wire size, parent vessel size, geometric features of the stented segment, and healing reaction.

Future Expectations

Based on our initial experience, new generations of the FRED could be better with a few features. An increased stent length could allow the neurointerventionalist to reconstruct longer aneurysm segments with a single stent. A more robust outer stent and increased radial force can provide better opening and apposition at the tight vessel curves. With a tapered version, a better reconstruction could be achieved in parent arteries with prominent proximal and distal diameter discrepancies. A possible short-long and asymmetrical design of the inner stent that is close to the proximal or distal end in a longer outer stent could allow neurointerventionalists to use this kind of FD device for aneurysms located more distally, such as anterior communicating artery or middle cerebral artery bifurcation aneurysms. In the future, our indication spectrum may be enhanced with the mid- and long-term results of use of these kinds of evolved devices.

Study Limitations

Our study was retrospective in nature and therefore suffers from the limitations of such studies. Another limitation is that the patients treated with FREDs were selected patients in that the aneurysms were mostly located at the paraophthalmic segment of the ICA. Furthermore, this is a single-center study with an unblinded study design, the follow-up period is short, the mean aneurysm size is relatively small, and the patient population is small.

Conclusions

Despite the fact that this preliminary study has a few obvious limitations mentioned in the paper, the results derived from the study are comparable to those of PED and SILK studies in terms of occlusion and complication rates. It appears that this novel FD device has the ability to serve neurointerventionalists in the treatment of cerebral aneurysms with its different technical advantages. Nonetheless, those results need to be confirmed with mid- and long-term follow-up results of multicenter large series. In addition, this new technology needs to be improved with a few new features mentioned in the paper.

Disclosure

Naci Kocer has a proctoring and consultancy agreement with MicroVention, Inc. Civan Islak has a consultancy agreement with MicroVention, Inc. The other authors have no conflict to report.

Author contributions to the study and manuscript preparation include the following. Conception and design: Kocer. Acquisition of data: all authors. Analysis and interpretation of data: Kocer, Kocak. Drafting the article: Kocer, Kocak, Saglam. Critically revising the article: Kocer, Islak, Kızılkılıç, Kocak, Tureci. Reviewed submitted version of manuscript: Kocer, Islak, Kızılkılıç, Kocak, Tureci. Approved the final version of the manuscript on behalf of all authors: Kocer. Study supervision: Kocer.

References

  • 1

    Becske TKallmes DFSaatci IMcDougall CGSzikora ILanzino G: Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial. Radiology 267:8588682013

    • Search Google Scholar
    • Export Citation
  • 2

    Brinjikji WMurad MHLanzino GCloft HJKallmes DF: Endovascular treatment of intracranial aneurysms with flow diverters: a meta-analysis. Stroke 44:4424472013

    • Search Google Scholar
    • Export Citation
  • 3

    De Vries JBoogaarts JVan Norden AWakhloo AK: New generation of flow diverter (surpass) for unruptured intracranial aneurysms: a prospective single-center study in 37 patients. Stroke 44:156715772013

    • Search Google Scholar
    • Export Citation
  • 4

    Ferns SPSprengers MEvan Rooij WJRinkel GJvan Rijn JCBipat S: Coiling of intracranial aneurysms: a systematic review on initial occlusion and reopening and retreatment rates. Stroke 40:e523e5292009

    • Search Google Scholar
    • Export Citation
  • 5

    Fiorella DWoo HHAlbuquerque FCNelson PK: Definitive reconstruction of circumferential, fusiform cerebral aneurysms with the pipeline embolization device. Neurosurgery 62:111511202008

    • Search Google Scholar
    • Export Citation
  • 6

    Gross BAFrerichs KU: Stent usage in the treatment of intracranial aneurysms: past, present and future. J Neurol Neurosurg Psychiatry 84:2442532013

    • Search Google Scholar
    • Export Citation
  • 7

    Islak CKocer NAlbayram SKizilkilic OUzma OCokyuksel O: Bare stent-graft technique: a new method of endoluminal vascular reconstruction for the treatment of giant and fusiform aneurysms. AJNR Am J Neuroradiol 23:158915952002

    • Search Google Scholar
    • Export Citation
  • 8

    Kizilkilic OKocer NMetaxas GEBabic DHoman RIslak C: Utility of VasoCT in the treatment of intracranial aneurysm with flow-diverter stents. Clinical article. J Neurosurg 117:45492012

    • Search Google Scholar
    • Export Citation
  • 9

    Lubicz BBandeira ABruneau MDewindt ABalériaux DDe Witte O: Stenting is improving and stabilizing anatomical results of coiled intracranial aneurysms. Neuroradiology 51:4194252009

    • Search Google Scholar
    • Export Citation
  • 10

    McDougall CGSpetzler RFZabramski JMPartovi SHills NKNakaji P: The Barrow Ruptured Aneurysm Trial. Clinical article. J Neurosurg 116:1351442012

    • Search Google Scholar
    • Export Citation
  • 11

    Molyneux AKerr RStratton ISandercock PClarke MShrimpton J: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 360:126712742002

    • Search Google Scholar
    • Export Citation
  • 12

    O'Kelly CJKrings TFiorella DMarotta TR: A novel grading scale for the angiographic assessment of intracranial aneurysms treated using flow diverting stents. Interv Neuroradiol 16:1331372010

    • Search Google Scholar
    • Export Citation
  • 13

    Piotin MBlanc RSpelle LMounayer CPiantino RSchmidt PJ: Stent-assisted coiling of intracranial aneurysms: clinical and angiographic results in 216 consecutive aneurysms. Stroke 41:1101152010

    • Search Google Scholar
    • Export Citation
  • 14

    Puffer RCKallmes DFCloft HJLanzino G: Patency of the ophthalmic artery after flow diversion treatment of paraclinoid aneurysms. Clinical article. J Neurosurg 116:8928962012

    • Search Google Scholar
    • Export Citation
  • 15

    Shapiro MBecske TSahlein DBabb JNelson PK: Stent-supported aneurysm coiling: a literature survey of treatment and follow-up. AJNR Am J Neuroradiol 33:1591632012

    • Search Google Scholar
    • Export Citation
  • 16

    Szikora IBerentei ZKulcsar ZMarosfoi MVajda ZSLee W: Treatment of intracranial aneurysms by functional reconstruction of the parent artery: the Budapest experience with the pipeline embolization device. AJNR Am J Neuroradiol 31:113911472010

    • Search Google Scholar
    • Export Citation
  • 17

    Turowski BMacht SKulcsár ZHänggi DStummer W: Early fatal hemorrhage after endovascular cerebral aneurysm treatment with a flow diverter (SILK-Stent): do we need to rethink our concepts?. Neuroradiology 53:37412011

    • Search Google Scholar
    • Export Citation
  • 18

    Valdivia y Alvarado MEbrahimi NBenndorf G: Study of conformability of the new LEO plus stent to a curved vascular model using flat-panel detector computed tomography (DynaCT). Neurosurgery 64:3 Supplons130ons1342009

    • Search Google Scholar
    • Export Citation
  • 19

    Velioglu MKizilkilic OSelcuk HKocak BTureci EIslak C: Early and midterm results of complex cerebral aneurysms treated with Silk stent. Neuroradiology 54:135513652012

    • Search Google Scholar
    • Export Citation

If the inline PDF is not rendering correctly, you can download the PDF file here.

Article Information

Address correspondence to: Naci Kocer, M.D., Department of Radiology, Division of Neuroradiology, Cerrahpasa Medical Faculty, Istanbul University, Kocamustafapasa/Istanbul 34098, Turkey. email: nkocer@istanbul.edu.tr.

Please include this information when citing this paper: published online March 14, 2014; DOI: 10.3171/2014.1.JNS131442.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Angled view of FRED. Published with permission from MicroVention, Inc.

  • View in gallery

    Case 21. Images obtained in a 50-year-old woman with 2 right-sided paraophthalmic ICA aneurysms and an ipsilateral anterior choroidal artery aneurysm. This patient also had a history of a left-sided paraophthalmic ICA aneurysm that was treated with Onyx 6 years earlier. A–C: Three-dimensional DS angiograms showing the right-sided wide-necked paraophthalmic ICA aneurysm (A and B), which is laterally oriented at the curve of the tight carotid siphon. The anterior choroidal artery aneurysm (A) and superior hypophysial artery (C) aneurysms are visible in the right ICA in addition to the Onyx cast on the left side. D–F: After coiling of the anterior choroidal artery aneurysm, nonsubtracted images show that the FRED covers both the superior hypophysial artery and paraophthalmic segment aneurysms. The Onyx cast is also visible on the left side. Note the opening difficulties and manipulation of the microcatheter and system. G: Postembolization FDCTA image showing good apposition of the stent.

  • View in gallery

    Case 12. Images obtained in a 59-year-old man with an unruptured left-sided paraophthalmic ICA aneurysm. A: Three-dimensional DS angiogram showing the left-sided paraophthalmic ICA aneurysm. B: Significant stasis is shown in the late venous angiographic phase after stent deployment. C: Intraarterial FDCTA reconstruction clearly showing the inner portion of the FRED that covers the neck. D: Intravenous FDCTA image obtained at the 1-month follow-up, showing incomplete occlusion (75%) with no morphological change in the stent itself.

  • View in gallery

    Graphs showing the aneurysm occlusion status during angiographic follow-up. Upper: Aneurysm occlusion status with patient numbers. Lower: Aneurysm occlusion status with rates.

  • View in gallery

    Case 6. Images obtained in a 55-year-old man with a left-sided paraophthalmic ICA aneurysm. A: Left ICA DS angiogram showing the left-sided wide-necked paraophthalmic ICA aneurysm. B: Coronal thin-section FDCTA image showing good apposition of the stent to the vessel wall. C and D: Digital subtraction angiogram obtained at the 7-month follow-up showing total occlusion of the aneurysm with a patent ophthalmic artery and no morphological change in the stent.

  • View in gallery

    Case 4. Images obtained in a 46-year-old man with an unruptured left-sided paraophthalmic ICA aneurysm and a proximal A1 segment aneurysm treated in the same session. A: Left ICA injection angiogram showing the aneurysms. B: Three-dimensional DS angiogram obtained at the 6-month follow-up demonstrating total occlusion of both aneurysms. Note the slight narrowing at the C2 segment of the left ICA, which is covered by the FRED. C: Immediate posttreatment nonsubtracted DS angiogram showing a well-opened stent. D: FDCTA reconstruction obtained at the 1-month follow-up showing a significant fish mouth phenomenon and enlargement of one-third middle segment of the FRED at the aneurysm segment. E and F: Nonsubtracted DS angiogram obtained at the 6-month follow-up (E) and FDCTA image obtained at the 12-month follow-up (F) showing gradual improvement of the fish mouth phenomenon. Also note that there is no visible neointimal hyperplasia.

  • View in gallery

    Case 21. Axial diffusion-weighted image showing multiple small emboli in the right MCA territory.

References

  • 1

    Becske TKallmes DFSaatci IMcDougall CGSzikora ILanzino G: Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial. Radiology 267:8588682013

    • Search Google Scholar
    • Export Citation
  • 2

    Brinjikji WMurad MHLanzino GCloft HJKallmes DF: Endovascular treatment of intracranial aneurysms with flow diverters: a meta-analysis. Stroke 44:4424472013

    • Search Google Scholar
    • Export Citation
  • 3

    De Vries JBoogaarts JVan Norden AWakhloo AK: New generation of flow diverter (surpass) for unruptured intracranial aneurysms: a prospective single-center study in 37 patients. Stroke 44:156715772013

    • Search Google Scholar
    • Export Citation
  • 4

    Ferns SPSprengers MEvan Rooij WJRinkel GJvan Rijn JCBipat S: Coiling of intracranial aneurysms: a systematic review on initial occlusion and reopening and retreatment rates. Stroke 40:e523e5292009

    • Search Google Scholar
    • Export Citation
  • 5

    Fiorella DWoo HHAlbuquerque FCNelson PK: Definitive reconstruction of circumferential, fusiform cerebral aneurysms with the pipeline embolization device. Neurosurgery 62:111511202008

    • Search Google Scholar
    • Export Citation
  • 6

    Gross BAFrerichs KU: Stent usage in the treatment of intracranial aneurysms: past, present and future. J Neurol Neurosurg Psychiatry 84:2442532013

    • Search Google Scholar
    • Export Citation
  • 7

    Islak CKocer NAlbayram SKizilkilic OUzma OCokyuksel O: Bare stent-graft technique: a new method of endoluminal vascular reconstruction for the treatment of giant and fusiform aneurysms. AJNR Am J Neuroradiol 23:158915952002

    • Search Google Scholar
    • Export Citation
  • 8

    Kizilkilic OKocer NMetaxas GEBabic DHoman RIslak C: Utility of VasoCT in the treatment of intracranial aneurysm with flow-diverter stents. Clinical article. J Neurosurg 117:45492012

    • Search Google Scholar
    • Export Citation
  • 9

    Lubicz BBandeira ABruneau MDewindt ABalériaux DDe Witte O: Stenting is improving and stabilizing anatomical results of coiled intracranial aneurysms. Neuroradiology 51:4194252009

    • Search Google Scholar
    • Export Citation
  • 10

    McDougall CGSpetzler RFZabramski JMPartovi SHills NKNakaji P: The Barrow Ruptured Aneurysm Trial. Clinical article. J Neurosurg 116:1351442012

    • Search Google Scholar
    • Export Citation
  • 11

    Molyneux AKerr RStratton ISandercock PClarke MShrimpton J: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 360:126712742002

    • Search Google Scholar
    • Export Citation
  • 12

    O'Kelly CJKrings TFiorella DMarotta TR: A novel grading scale for the angiographic assessment of intracranial aneurysms treated using flow diverting stents. Interv Neuroradiol 16:1331372010

    • Search Google Scholar
    • Export Citation
  • 13

    Piotin MBlanc RSpelle LMounayer CPiantino RSchmidt PJ: Stent-assisted coiling of intracranial aneurysms: clinical and angiographic results in 216 consecutive aneurysms. Stroke 41:1101152010

    • Search Google Scholar
    • Export Citation
  • 14

    Puffer RCKallmes DFCloft HJLanzino G: Patency of the ophthalmic artery after flow diversion treatment of paraclinoid aneurysms. Clinical article. J Neurosurg 116:8928962012

    • Search Google Scholar
    • Export Citation
  • 15

    Shapiro MBecske TSahlein DBabb JNelson PK: Stent-supported aneurysm coiling: a literature survey of treatment and follow-up. AJNR Am J Neuroradiol 33:1591632012

    • Search Google Scholar
    • Export Citation
  • 16

    Szikora IBerentei ZKulcsar ZMarosfoi MVajda ZSLee W: Treatment of intracranial aneurysms by functional reconstruction of the parent artery: the Budapest experience with the pipeline embolization device. AJNR Am J Neuroradiol 31:113911472010

    • Search Google Scholar
    • Export Citation
  • 17

    Turowski BMacht SKulcsár ZHänggi DStummer W: Early fatal hemorrhage after endovascular cerebral aneurysm treatment with a flow diverter (SILK-Stent): do we need to rethink our concepts?. Neuroradiology 53:37412011

    • Search Google Scholar
    • Export Citation
  • 18

    Valdivia y Alvarado MEbrahimi NBenndorf G: Study of conformability of the new LEO plus stent to a curved vascular model using flat-panel detector computed tomography (DynaCT). Neurosurgery 64:3 Supplons130ons1342009

    • Search Google Scholar
    • Export Citation
  • 19

    Velioglu MKizilkilic OSelcuk HKocak BTureci EIslak C: Early and midterm results of complex cerebral aneurysms treated with Silk stent. Neuroradiology 54:135513652012

    • Search Google Scholar
    • Export Citation

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