Ayako Ikemura

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.

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.

Time-resolved magnetic resonance angiography (TR-MRA) for the evaluation of post coiling aneurysms; A quantitative analysis of the residual aneurysm using full-width at half-maximum (FWHM) value

Magnetic resonance image (MRI) is now widely used for imaging follow-up for post coiling brain aneurysms. However, the accuracy on the estimation of residual aneurysm, which is crucial for the retreatment planning, remains to be controversial. The purpose of this study is to evaluate a new post-processing technique that provides improved estimation of the residual aneurysm after coil embolization. One hundred aneurysms on 93 patients who underwent coil embolization for brain aneurysm were evaluated using the 1.5 Tesla time-resolved magnetic resonance angiography (TR-MRA) one year after the treatment. To minimize the inter-observer variability caused by the window level adjustment, an automatic post processing protocol using the full-width at half-maximum (FWHM) value was utilized. The result was then compared with that from the conventional cerebral angiography. Of the 97 aneurysms that underwent both TR-MRA and DSA, 23 (23.7%) showed residual neck / dome during follow-up. After window level adjustment, the size of the parent artery in the TR-MRA was consistent with that in the DSA. The reconstructed Volume Rendering images provided clear contours of the residual aneurysms and contributed to the understanding the configuration of residual aneurysm. The largest and the smallest diameter of the residual aneurysms was larger in the TR-MRA than in the DSA (8.05 vs. 7.72 mm, p = 0.0004; 4.99 vs. 4.19 mm, p = 0.007 respectively). The sensitivity, specificity, and positive and negative predictive values of TR-MRA compared to DSA were 100%, 97%, 73%, and 100%, respectively. Using the FWHM value to optimize the window level adjustment, the size of the residual component observed in the TR-MRA was larger compared to that in the DSA whereas the size of neck and the parent artery showed consistency between the two modalities. This image processing technique can be used as an effective screening tool for evaluating residual component in post-coiling brain aneurysms.

E-032 High resolution cone beam ct for the assessment of stent apposition after flow diverterstent treatment

Purpose Incomplete stent apposition can lead to thromboembolic complications or post treatment endo-leak when a flow diverter (FD) stent treatment is performed. To facilitate the assessment of stent apposition during the procedure, a new imaging technique using a combination of high resolution cone-beam CT (CBCT) was developed. The purpose of this study is to review a series of large/giant aneurysm patient who underwent FD treatment, and evaluated using this new imaging method. Methods A total of 6 large/giant cavernous internal carotid artery (ICA) aneurysms were treated with a Pipeline stent. The procedures were performed using an angiosystem called Artis Q biplane (Siemens Healthcare GmbH, Forchheim, Germany). Immediately after the stent deployment, a 20 s high-resolution CBCT without contrast injection was performed followed by high resolution 6 s CBCT with contrast injection. The two acquisitions were then fused using a function called “identity mapping” to adjust the misalignment that occurs during the fusion process. After adjusting the window level to minimize inter-observed variability, volume rendering images of the treated vessel were created, and combined with the image of the deployed stent. If the post processing images revealed incomplete stent apposition, a stent-plasty using a super compliant balloon was performed. The quality of the CBCT images were retrospectively assessed. For those who underwent stent-plasty, the apposition/shortening of the delivered stent before and after the plasty were analyzed. Results All 6 patients successfully underwent the CBCT acquisitions immediately after the stent deployment. In all patients, the post reconstruction VR images clearly visualized the 3D structures of both stent and parent artery. Three patients showed incomplete stent apposition in the post processing images and consequently underwent stent plasty followed by another CBCT acquisitions. For these, the final CBCT images showed improved stent apposition with profound shorting of the stent. There was no symptomatic adverse event after the procedure. In four patients, the MRI performed the day after the procedure showed asymptomatic multiple DWI positive lesions, all of which disappeared in the 3 month follow up MRI. Conclusions The combination of high resolution CBCT acquisitions provided clear visualization of 3D structures of both stent and parent artery after the FD treatment. This imaging modality may contribute to the better understanding of stent apposition after the FD treatment. Abstract E-032 Figure 1 Disclosures I. Yuki: 1; C; Siemens Research Grant. T. Ishibashi: None. C. Dahmani: 5; C; employee : Siemens Healthcare Japan. Y. Abe: None. S. Hataoka: None. A. Ikemura: None. I. Kan: None. Y. Murayama: 1; C; Siemens Research Grant. 2; C; Stryker Japan.

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.

E-051 Combination of Contrast Enhanced Time-Resolved 3D MRA and 3D Neuroimaging Software for the Evaluation of Brain Aneurysms Treated with Coil Embolisation

Purpose To improve the visualisation of residual neck in the aneurysms treated with coil embolisation utilising the time-resolved contrast enhanced magnetic resonance angiography (4D MRA). Materials and Methods A total of 11 patients who underwent coil embolisation of brain aneurysm underwent 1.5 Tesla 4D MRA one year after the procedure. Of these, 6 patients were treated with stent assisted technique. The image information obtained from the 4D MRA was re-processed utilising a 3D Neuroimaging software (TeraRecon, Inc.) and compared to the images obtained from the cerebral angiograms. Results Six patients showed major recanalisation and five patients showed minimal residual neck of the treated aneurysm in the cerebral angiogram. The 4D MRA images obtained from each patient was consistent with the images from the cerebral angiogram. The susceptibility artifact induced by the coils and stents was significantly reduced as compared to the images of contrast enhanced time of flight (CE-TOF) images. The re-processed 3D images of 4D MRA in the Neuroimaging software showed great reproducibility of angiographical findings obtained from the cerebral angiograms. Conclusion The combination of the 4D MRA and utilisation of the 3D Neuroimaging software showed great visualisation of residual aneurysm. This imaging method can be a good alternative for the post-procedure follow up angiograms in the patients who underwent coil embolisation. Abstract E-051 Figure 1 Disclosures A. Ikemura: None. I. Yuki: None. T. Ishibashi: None. H. Arakawa: None. K. Irie: None. H. Takao: None. I. Kajiwara: None. K. Nishimura: None. I. Kan: None. Y. Murayama: None.

O-015 Double Catheter Technique : A Potential Alternative For The Stent Assisted Coil Embolisation For Wide Neck Aneurysms

Background and Purpose Double catheter coil embolisation (DCC) technique has been used for the treatment of wide neck aneurysms. Unlike Stent assisted Coil Embolisation (SAC), DCC does not require long term post-treatment anti-platelet therapy. Whether or not DCC can reduce the procedure related complications in SAC is not clear. In this series, consecutive unruptured wide neck aneurysm patients were treated primarily with the DCC. SAC was only used as a rescue therapy when the coil mass in the aneurysm was considered to be unstable. Clinical as well as angiographical outcomes of those who treated with DCC were reviewed. Methods A total of 597 unruptured aneurysm patients were treated in our institution between 2006 and 2012. Of these, 144 patients with wide neck (neck size >4.0 or dome-neck ratio<2.0) saccular aneurysm were primarily treated with DCC. Dual antiplatelet therapy was initiated 3 days prior to the procedure. If the treatment was completed with DCC, single antiplatelet therapy was continued for one month and then discontinued. Follow up MRI was performed at 3,6, and 12 months after the treatment. An angiogram was performed at 1 year, and the surveillance MRIs with every 6 to 12 months were continued. Results A total of 129 patients were treated with DCC only, and 5 patients were shifted to the SAC based on the intra-procedural findings. The average neck size and the average dome-neck ratio of the treated aneurysms were 6mm and 1.3 respectively. Every aneurysm treated with DCC was successfully embolised. Intra-operative hemorrhagic event occurred in 2 cases. There was no intra-operative thrombo-embolic event. During the average follow up period of 809 days, post operative symptomatic ischaemic events were seen in two cases (1.6%) and post operative hemorrhagic event (procedure unrelated) was seen in 1 case (0.8%). Permanent morbidity and mortality throughout was 2.4% and 0.8% respectively. Recanalisation that required re-treatment was seen in 14.7% but there was no procedure related complication during the re-treatment. Conclusion The angiographic outcomes of the aneurysms treated with DCC in this series were comparable to the historical controls of the wide neck aneurysms treated with other adjunctive techniques. To minimise procedure related ischaemic/haemorrhagic event associated with the SAC, DCC may be a potential candidate of alternative treatment. Abstract O-015 Figure 1 Disclosures I. Yuki: None. T. Ishibashi: None. H. Arakawa: None. K. Irie: None. H. Takao: None. I. Kajiwara: None. K. Misaki: None. K. Nishimura: None. A. Ikemura: None. T. Abe: None. Y. Murayama: None.