Ichiro Yuki

Natural Course of Dissecting Vertebrobasilar Artery Aneurysms without Stroke

More than 100 conservatively managed nonstroke dissecting vertebrobasilar artery aneurysms were followed on average for 3 years. Ninety-seven percent of patients remained clinically unchanged and the 3 patients who deteriorated clinically had aneurysm enlargement. The natural course of these lesions suggests that acute intervention is not always required and close follow-up without antithrombotic therapy is reasonable. Patients with symptoms due to mass effect or aneurysms of >10 mm may require treatment. BACKGROUND AND PURPOSE: The natural history and therapeutic management of dissecting vertebrobasilar aneurysms without ischemic or hemorrhagic stroke (nonstroke dissecting vertebrobasilar aneurysms) are not well-established. We conservatively followed patients with nonstroke dissecting vertebrobasilar aneurysms and evaluated the factors related to clinical and morphologic deterioration. MATERIALS AND METHODS: One hundred thirteen patients were enrolled and divided by clinical presentation at diagnosis: asymptomatic (group 1, n = 52), pain only (group 2, n = 56), and mass effect (group 3, n = 5). Patients were conservatively managed without intervention and antithrombotic therapy. Clinical outcomes and morphologic changes were analyzed. RESULTS: A total of 113 patients who were diagnosed with nonstroke dissecting vertebrobasilar aneurysm had a mean follow-up of 2.9 years (range, 27 days to 8 years). Throughout that period, 1 patient in group 1 (1.9%) and 1 patient in group 2 (1.8%) showed clinical deterioration due to mass effect, and 1 patient in group 3 (20%) developed ischemic stroke followed by subarachnoid hemorrhage. Most patients (97.3%) were clinically unchanged. Three patients who had clinical deterioration showed aneurysm enlargement (P < .001). Aneurysms remained morphologically unchanged in 91 patients (80.5%). Aneurysm enlargement was seen in 5 patients (4.4%); risk of enlargement was significantly associated with either maximum diameter (hazard ratio = 1.30; 95% CI, 1.11–11.52; P = .001) or aneurysm ≥10 mm (hazard ratio = 18.0; 95% CI, 1.95–167; P = .011). CONCLUSIONS: The natural course of these lesions suggests that acute intervention is not always required and close follow-up without antithrombotic therapy is reasonable. Patients with symptoms due to mass effect or aneurysms of >10 mm may require treatment.

Immunohistochemical Analysis of Debris Captured by Filter-Type Distal Embolic Protection Devices for Carotid Artery Stenting

BACKGROUND Little is known about the micro-debris captured in filter-type distal embolic protection devices (EPD) used for carotid stenting (CAS). This study aimed to determine the histological and immunohistochemical characteristics of such debris by using a new liquid-based cytology (LBC) technique. METHODS Fifteen patients who underwent CAS using a filter-type distal EPD (FilterWire EZ; Boston Scientific, Marlborough, MA, USA) were included in the study. After gross inspection of each recovered filter device, micro-debris were collected using a new LBC technique (SurePath; TriPath Imaging, Inc., Burlington, NC). Histological and immunohistochemical analysis of the recovered debris was performed. The pre- and postoperative brain magnetic resonance imaging and neurological status of each patient were also reviewed. RESULTS No patient developed ipsilateral symptomatic stroke due to a thromboembolic event. All 15 patients (100%) had microscopically identifiable debris in the filters, whereas gross inspection detected visible debris only in 5 patients (33.3%). Histological analysis revealed various types of structural components in an advanced atheromatous plaque, including fragments of fibrous cap, calcified plaque, smooth muscle cells, and necrotic tissue fragment infiltrated with monocytes and macrophages. CONCLUSIONS Filter-type EPDs may contribute to reducing the risk of CAS-related embolic events by capturing micro-debris even when gross inspection of the recovered filter shows no visible debris in the device.

High-Resolution C-Arm CT and Metal Artifact Reduction Software: A Novel Imaging Modality for Analyzing Aneurysms Treated with Stent-Assisted Coil Embolization.

BACKGROUND AND PURPOSE: Combination of high-resolution C-arm CT and novel metal artifact reduction software may contribute to the assessment of aneurysms treated with stent-assisted coil embolization. This study aimed to evaluate the efficacy of a novel Metal Artifact Reduction prototype software combined with the currently available high spatial-resolution C-arm CT prototype implementation by using an experimental aneurysm model treated with stent-assisted coil embolization. MATERIALS AND METHODS: Eight experimental aneurysms were created in 6 swine. Coil embolization of each aneurysm was performed by using a stent-assisted technique. High-resolution C-arm CT with intra-arterial contrast injection was performed immediately after the treatment. The obtained images were processed with Metal Artifact Reduction. Five neurointerventional specialists reviewed the image quality before and after Metal Artifact Reduction. Observational and quantitative analyses (via image analysis software) were performed. RESULTS: Every aneurysm was successfully created and treated with stent-assisted coil embolization. Before Metal Artifact Reduction, coil loops protruding through the stent lumen were not visualized due to the prominent metal artifacts produced by the coils. These became visible after Metal Artifact Reduction processing. Contrast filling in the residual aneurysm was also visualized after Metal Artifact Reduction in every aneurysm. Both the observational (P < .0001) and quantitative (P < .001) analyses showed significant reduction of the metal artifacts after application of the Metal Artifact Reduction prototype software. CONCLUSIONS: The combination of high-resolution C-arm CT and Metal Artifact Reduction enables differentiation of the coil mass, stent, and contrast material on the same image by significantly reducing the metal artifacts produced by the platinum coils. This novel image technique may improve the assessment of aneurysms treated with stent-assisted coil embolization.

Thermoreversible gelation polymer as an embolic material for aneurysm treatment: a delivery device for dermal fibroblasts and basic fibroblast growing factor into experimental aneurysms in rats

Background This study evaluates whether thermoreversible gelation polymer (TGP) can be used as a delivery device to deploy dermal fibroblasts and cytokines into experimental aneurysms in rats. Methods The right common iliac artery of rats was surgically ligated and an experimental aneurysm was created by applying exogenous elastase. Seven days later, two aneurysms were harvested and used as controls (Group A), two were embolized with pure TGP (Group B), two were embolized with TGP and basic fibroblast growth factor (bFGF) (Group C) and two were embolized with TGP loaded with rat dermal fibroblasts (Group D). The aneurysms were also embolized with TGP mixed with dermal fibroblasts and bFGF at different concentrations (10 ng/ml: Group E (n=2), 100 ng/ml: Group F (n=2), 1000 ng/ml: Group G (n=2)). Each aneurysm sample was harvested after 7 days and histologic analyses were performed. Results The most advanced thrombus organization in the aneurysm, such as prominent fibroblast proliferation and collagen deposition, was observed in Groups E, F and G, although there was no noticeable difference between the groups. Moderate thrombus organization was seen in Group D and minimal thrombus organization was seen in Groups B and C. Conclusions TGP mixed with both dermal fibroblasts and bFGF induced the most advanced thrombus organization in the experimental aneurysms followed by TGP mixed only with dermal fibroblasts. TGP may be useful as a delivery device to deploy fibroblasts and cytokines into aneurysms.

Hybrid Operating Room for Combined Neuroendovascular and Endoscopic Treatment of Ruptured Cerebral Aneurysms with Intraventricular Hemorrhage

BACKGROUND Intraventricular hemorrhages (IVHs) caused by ruptured cerebral aneurysms often have poor outcomes. Treatment challenges include comorbidities, increased intracranial pressure caused by IVH, and risk of rebleeding. CASE DESCRIPTION Two cases of severe IVH accompanied by acute hydrocephalus caused by ruptured aneurysm were treated with coil embolization followed by endoscopic hematoma evacuation as a single treatment session in a hybrid operating room (OR) equipped with a multipurpose angio biplane system. The first case was an 84-year-old woman with a ruptured basilar top aneurysm, who presented with Hunt and Hess (H&H) grade 5 subarachnoid hemorrhage (SAH) with packed IVH. The second case was a 43-year-old man with a ruptured anterior communicating artery aneurysm who presented with H&H grade 5 SAH with packed IVH. In both cases, endovascular coil embolization was performed first to prevent intraoperative bleeding. The coiled aneurysms suddenly appeared on the screen of the endoscope during the hematoma removal, which could have led to massive rebleeding if not treated previously. Neither patient needed a reinsertion of the ventricular drainage or developed chronic hydrocephalus during hospitalization. The hybrid OR enabled the 2 treatment approaches to be performed without the need to transfer the patient, thereby minimizing the transition time between the modalities. Intraoperative cone-beam computed tomography contributed to the evaluation of residual clots. CONCLUSIONS A hybrid OR may contribute to a combined neuroendoscopic and endovascular treatment for ruptured cerebral aneurysms with severe intraventricular hemorrhage.

O-019 4d digital subtraction angiography: the advantages and limitations in the evaluation of brain arteriovenous malformation and brain aneurysms

Purpose To evaluate the potential advantages and limitations of 4D-DSA image acquisition, the acquired images on the patients with arteriovenous malformations (AVMs) and aneurysms were reviewed and analyzed. Methods Brain arteriovenous malformation (AVM) and brain aneurysm patients who underwent 4D-DSA during the pre and post assessment for the endovascular / surgical treatment were included. The obtained source image information of the 4D-DSA was transferred to a dedicated workstation and reconstructed using a software, “Syngo Dyna4D©”. The results were reviewed and interpretation of each image finding was evaluated. The radiation dose required for each examination was calculated, and compared with that required for conventional 5-second 3D-DSA acquisitions. Results 10 aneurysm patients and 4 AVM patients underwent 4D-DSA. One patient had both an intracranial aneurysm and an AVM. 6 aneurysm patients underwent 6-second acquisition protocol. 12-second acquisition was used for all AVM patients as well as 4 aneurysm patients. For aneurysm evaluation, with a temporal sampling of 28.7-volumes/sec and a region of interest (ROI) of 42 cm x× 42 cm, the quality of the image was not sufficient to evaluate contrast flow patterns in the aneurysm although the sizes of all aneurysms were less than 10 mm in the largest diameter. With 12-second acquisition, anatomical information of both arteries and veins were simultaneously obtained in one scan, which was useful for the pre-operative evaluation of surgical clipping. For AVMs, temporal change in the appearance of each feeding artery clearly differentiated the different feeding patterns of each artery to the nidus component. Detailed anatomical structures, e.g. a stenosis in the main drainer which was not detected in the 2D-DSA and difficult to see in the conventional 3D angiogram, were better depicted in the 4D-DSA images. Average surface dose of the radiation was 115 mGy in the 6-second acquisition, 225 mGy in the 12-second acquisition and 105 mGy in the conventional 3D angiogram. Conclusions 4D-DSA provides useful information for the treatment planning of AVM patients by depicting the temporal change in the 3D-DSA. Current temporal resolution was not sufficient for the evaluation of contrast flow patterns in the small aneurysms. The 12-second acquisition which covers the entire arterial phase to the venous phase required approximately double the radiation dose of the conventional 5-second 3D-DSA. However, the dose required for the 6-second acquisition, which mainly covers the arterial phase, was similar to the conventional 3D-DSA.Abstract O-019 Figure 1 Temporal change in the 3D DSA images of an AVM Disclosures I. Yuki: 1; C; Siemens Grant. T. Ishibashi: None. A. Ikemura: 1; C; Siemens Grant. Y. Kambayashi: None. I. Kan: None. Y. Abe: None. C. Dahmani: 5; C; Siemens K. K.. S. Kaku: None. K. Nishimura: None. Y. Murayama: 1; C; Siemens Grant.

O-001 A Novel Metal Artefact Removal Software for C-arm CT; A Novel Imaging Modality to Analyze Aneurysms Treated with Stent Assisted Coil Embolization

Purpose Stent assisted coil embolization recently became a common treatment strategy for the wide neck aneurysms. Normal digital subtraction angiography (DSA), however, does not allow visualization of the deployed stents. With a combination of novel Metal Artefact Removal software (MAR) and C-arm CT, the coil mass, stent, and contrast material can be differentiated. In this study, experimental aneurysms were treated with stent assisted coil embolization and image analysis was performed using the C-arm CT and MAR. I. V. injection of the contrast to obtain the images was also performed. Methods A total of 12 experimental aneurysms were created in 6 swine. The aneurysms were treated with coil embolization using stent assisted technique. High Resolution (HR) C-arm CT with intra-arterial injection of the contrast dye (20%) was performed immediately after the treatment and obtained images were processed with MAR. Intra venous contrast injection (non-diluted) from femoral vein was also performed in 3 swine. Visualization of the residual aneurysms as well as coil loops protruded into the stent lumen was evaluated. Two patients previously treated with stent assisted coil embolization underwent the same image acquisition protocol, and the obtained images were evaluated. Results Coil loops protruded into the stent lumen, which were not visible before the MAR due to the significant metal artefact, were well visualised after the MAR. Likewise, Contrast filling into the residual aneurism was observed after the MAR in every aneurysm. Intravenous injection of the contrast material reproduced similar image quality as compared to the intra arterial injections. The C-arm CT images of the two patients showed remarkable reduction of the metal artefacts after the MAR processing. Conclusions The combination of the C-arm CT and MAR enables the differentiation of the coil mass, stent and contrast material by markedly reducing the metal artefact produced by the coils. This novel image modality may contribute to the evaluation of aneurysms treated with stent assisted coil embolization. Abstract O-001 Figure 1 Disclosures I. Yuki: 1; C; Siemens Grant. Y. Kambayashi: 1; C; Siemens Grant. A. Ikemura: 1; C; Siemens Grant. I. Kan: 1; C; Siemens Grant. Y. Abe: None. A. Mohamed: 5; C; Siemens Japan KK. C. Dahmani: 5; C; Siemens Japan KK. T. Ishibashi: 1; C; Siemens Grant. I. Kajiwara: 1; C; Siemens Grant. K. Nishimura: 1; C; Siemens Grant. Y. Murayama: 1; C; Siemens Grant.

Estimated pretreatment hemodynamic prognostic factors of aneurysm recurrence after endovascular embolization

BACKGROUND: Hemodynamic factors play important roles in aneurysm recurrence after endovascular treatment. OBJECTIVE: Predicting the risk of recurrence by hemodynamic analysis using an untreated aneurysm model is important because such prediction is required before treatment. METHODS: We retrospectively analyzed hemodynamic factors associated with aneurysm recurrence from pretreatment models of five recurrent and five stable posterior communicating artery (Pcom) aneurysms with no significant differences in aneurysm volume, coil packing density, or sizes of the dome, neck, or Pcom. Hemodynamic factors of velocity ratio, flow rate, pressure ratio, and wall shear stress were investigated. RESULTS: Among the hemodynamic factors investigated, velocity ratio and flow rate of the Pcom showed significant differences between the recurrence group and stable group (0.630 ± 0.062 and 0.926 ± 0.051, P= 0.016; 56.4 ± 8.9 and 121.6 ± 6.7, P= 0.008, respectively). CONCLUSIONS: Our results suggest that hemodynamic factors may be associated with aneurysm recurrence among Pcom aneurysms. Velocity and flow rate in the Pcom may be a pretreatment prognostic factor for aneurysm recurrence after endovascular treatment.

E-032 Combination of High Resolution Cone-beam CT and 3D DSA for the Evaluation of Intracranial Stents used for Aneurysm Treatment

Purpose Incomplete stent apposition after the treatment of brain aneurysm can increase the risk of thromboembolic complications and remains to be the major concern during the procedure. Utilizing the high resolution cone-beam CT (HR-CBCT) and metal artifact reduction software (MAR), the metal artifact produced by the coil mass is reduced and the visualization of the deployed stent is optimized. After combining with the 3D digital subtraction angiography (3D-DSA), the resulting image is used for the evaluation of the stent apposition in the artery. Initial clinical experience of this novel imaging method is reported. Methods A total of 24 aneurysm patients who underwent the stent assisted coil embolization was selected for this study. All patients were treated using either Neuroform® stent or Enterprise® stent system. Artis PURE® Platform (Siemens) was used in this study. Acquisition protocols are follows. A HR-CBCT acquisition was performed to obtain the image of stent and coil mass. The dataset was then reconstructed using MAR. A 3 D DSA acquisition was performed for the visualization of the vasculature. The two datasets were combined using a dedicated software. A 3D volume rendering (VR) image was created and the stent apposition of each treated patient was evaluated. Results All 24 patients underwent the image acquisition successfully. Relationship between the deployed stent and the wall of the parent artery was well visualized in every patient although partial image defect of the stent due to the metal artifact was observed in the relatively large aneurysms. The incomplete stent apposition was frequently seen near the carotid siphon, especially at the inner curve of the target vessel. Conclusion Combination of high resolution cone-beam CT and 3D DSA for the evaluation of intracranial stents provided sufficient visualization of the deployed stent and parent artery. This imaging method can be used for the evaluation of stent apposition during/after the treatment of brain aneurysms.Abstract E-032 Figure 1 Disclosures I. Yuki: 1; C; Siemens Grant. S. Hataoka: None. T. Ishibashi: 1; C; Siemens Grant. C. Dahmani: 5; C; Employee of Siemens Healthcare. A. Ikemura: None. Y. Kambayashi: None. I. Kan: None. Y. Abe: None. S. kaku: None. K. Nishimura: None. T. Kodama: None. Y. Sasaki: None. Y. Murayama: 1; C; Siemens Grant.

E-071 Initial Experimental Result of a Novel, Low Profile Stent for Aneurysm Treatment

Introduction Stent assisted coil therapy has been developed for treatment of wide neck aneurysms. However, several reports show that recanalization rate of 10–15% after therapy is still observed. A novel low profile, flow diverter stent has been developed, and initial experience with it in an experimental wide-neck aneurysm swine model is reported. Method The novel stent is self-expandable with radiopaque markers on both ends and 0.023 inch inner size compatible microcatheter. Eighteen aneurysms in 9 swine were surgically created using vein auto-grafts. Embolizations were performed in following device combinations: Novel Stent with coil (Group1: Novel stent, n = 6), commercially available stent (Group2: Neuroform stent, n = 6) with coil, and coil alone (Group3: coil, n = 6). Swine were sacrificed 14 days after stent deployment. Results Mean aneurysm neck size was 6.24 mm (4.3–8.26 mm), and average aneurysm fundus size was 9.0 mm (5.8–10.9 mm). All cases in Group2 were treated by Neuroform stent. Average VER (volume embolization ratio) of Group1, Group2, and Group3 was 10.1%, 10.9%, and 10.5%, respectively. There were no technical complications during novel stent deployment, such as migration, occlusion, etc. Favorable angiographic outcome, such as complete aneurysm thrombosis, was observed in 50% of group3, and there was no favorable outcome in both group2 and 3. Recanalization rate of group1, 2, and 3 is 50% (n = 3), 100% (n = 6), and 66% (n = 4), respectively. Aneurysmal rupture after procedure was observed in three cases from group 2, and two cases from group 3. Conclusion The present study showed promising initial experience with the novel stent, particularly for its role as a low profile flow diverting stent and as an assisting stent for coil therapy. Disclosures I. Kan: 1; C; Japan Agency for Medical Research and Development. Y. Murayama: 1; C; Japan Agency for Medical Research and Development. K. Karagiozov: None. A. Ikemura: None. I. Yuki: None. H. Takao: None. T. Kodama: None.