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Case ReportpISSN 1738-2637 / eISSN 2288-2928J Korean Soc Radiol 2015;72(5):364-367http://dx.doi.org/10.3348/jksr.2015.72.5.364

INTRODUCTION

Conventional angiography is essential to assess intraluminal flow and define aneurysm neck and angio-architecture in treat-ment planning. However, when giant aneurysms are supplied by more than one parent artery, the precise relationship of the an-eurysm to adjacent arterial structures might not be clearly dem-onstrated even with three-dimensional (3D) rotational angiog-raphy, because of the preferential flow to the giant aneurysmal sac (1). We present a case in which each rotational angiogram with 3D reconstruction of both parent arteries was fused with each other to guide the treatment strategy for a giant, partially calci-fied, lower basilar trunk aneurysm.

CASE REPORT

A 54-year-old female was referred to our neurointervention clinic

for a giant aneurysm of the basilar top. The aneurysm had been previously detected during an evaluation for a lateral neck mass. The mass was resected and was ultimately proven to be a thoracic duct cyst. The patient reported no past medical history, except for hyperlipidemia. Neurologic examination and primary labo-ratory investigations were all within the normal limits. Contrast-enhanced computed tomography angiography revealed a 25-mm, partially calcified, intracranial aneurysm in the ventral aspect of the lower basilar trunk (Fig. 1A). Conventional and rotational angiograms obtained using digital biplane angiography with an AXI-OM Artis Zee apparatus (Siemens Medical Solution, Erlan-gen, Germany) showed the large basilar trunk aneurysm above the level of the anterior inferior cerebellar artery (AICA). How-ever, the angiograms obtained from each vertebral artery showed incomplete filling in both of the aneurysmal sac and the basilar artery above the aneurysm because of the preferential flow from equally developed, balanced vertebral arteries on both sides. There

Three-Dimensional Fusion Angiography of a Giant Basilar Aneurysm for Coil Embolization기저동맥 거대동맥류 색전술을 위한 3차원 융합영상

Joo Yeon Lee, MD, Dae Chul Suh, MDDepartment of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea

A giant aneurysm was unexpectedly found on computed tomography angiogram in a 54-year-old female. Cerebral angiogram showed a giant aneurysm at the ventral side of the lower basilar artery trunk. However, it was difficult to demonstrate the pre-cise relationship between the aneurysmal sac and the parent artery because of the in-complete filling of the contrast medium secondary to the preferential flows from a well-balanced development of both vertebral arteries. Three-dimensional (3D) fusion angiography revealed complete filling of the aneurysm as well as the basilar trunk it-self beyond the aneurysm, which was dysplastic. Coiling of the aneurysm was safely and completely accomplished based on the fusion images. In this report, we demon-strate a case of giant basilar aneurysm with 3D fusion angiography proving useful in assisting with treatment planning.

Index termsAneurysmAngiographyEmbolization

Received August 18, 2014 Accepted February 17, 2015Corresponding author: Dae Chul Suh, MDDepartment of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Korea.Tel. 82-2-3010-4366 Fax. 82-2-476-0090E-mail: dcsuh@amc.seoul.kr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distri-bution, and reproduction in any medium, provided the original work is properly cited.

Joo Yeon Lee, et al

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were also uncertainties regarding the aneurysm neck and the angled basilar trunk due to the ventrally-located, giant aneurysm at the basilar artery. Moreover, it was difficult to define the pre-cise relationship of the aneurysmal sac to the origin of the adja-cent branches (Fig. 1B), which necessitated further study to de-velop a treatment plan. The main focus was to define the detailed angio-architecture of the aneurysm and the basilar artery, and to demonstrate the precise relationship of the origin of the AICA to the aneurysm neck. Fusion images were obtained using the VB21C fusion application software of a Syngo X Workplace ap-paratus (Siemens Medical Solution) to reconstruct the aneurysm and the adjacent segment of the vertebra-basilar system. The full dimension of the aneurysm sac and the basilar artery was dem-onstrated in 3D fusion images using different color coding ac-cording to the orientation of the vertebral artery (Fig. 1C). The origin of the right AICA arose just proximal to the aneurysmal sac on the right side (Fig. 1C). Based on the 3D fusion images, the giant aneurysm was safely treated with coil embolization using the double-catheter technique. Post-procedural angiography re-vealed dysplastic changes of the distal basilar artery (Fig. 1D), which might not be directly related to the giant aneurysm and were not clearly seen before coiling due to incomplete filling of the contrast agent to the basilar artery distal to the aneurysm. There was no adverse event during the peri-procedural period or after the procedure and a 3D time-of-flight magnetic resonance an-

giogram obtained 8 months following the procedure showed suc-cessful coiling of the basilar aneurysm.

DISCUSSION

A giant intracranial aneurysm is diagnosed when the aneurys-mal sac is larger than 2.5 cm in size and represents approximate-ly 5–8% of the intracranial aneurysm (2). A giant aneurysm at the top of the basilar trunk accounts for approximately 15% of all giant intracranial aneurysms and the vertebral artery accounts for approximately 5% of the lesions. Giant aneurysms notoriously remain one of the most difficult to treat intracranial vascular le-sions, and can have a dramatic clinical presentation including sub-arachnoid hemorrhage (25%), intra-aneurysmal thrombosis, subsequent stroke and distant emboli (2–5%) and mass effects that include visual disturbance, cranial nerve dysfunction, sei-zure, headache and hemiparesis (2). Surgical management of gi-ant aneurysms has been associated with a higher morbidity and mortality (20–30%) than those of smaller lesions (3) and no sin-gle technique is effective for treating all giant aneurysms. Cur-rent treatment options for these lesions include direct surgical techniques, endovascular techniques and combined approaches (2). Therefore, it is important to determine the precise angio-ar-chitecture as a treatment planning for every kind of the treatment modalities, especially for complex vascular lesions, such as giant

Fig. 1. A 54-year-old female with giant aneurysm of basilar artery.A. Sagittal CT angiogram shows a partially calcified, saccular aneurysm (arrow) at the ventral aspect of the lower basilar trunk with 2.5-cm in maxi-mal diameter.B. Vertebral angiogram shows the giant basilar trunk aneurysm, however, the aneurysmal sac is not completely filled, which hinder our accurate assessment of the relationship between the aneurysmal sac and the origin of the branches in vicinity.C. 3D-fusion image obtained from the right vertebral (grey color) and left vertebral (red color) arteries shows the different-colored filling of each part of the aneurysm and the basilar trunk beyond the aneurysm.D. Post-embolization vertebral angiogram shows a dysplastic distal basilar artery is clearly seen in the left vertebral angiogram. It was not demon-strated on pre-procedural angiogram because of an incomplete filling of contrast media to the basilar artery distal to the aneurysm, although this morphological change was not directly related to the giant saccular aneurysm.3D = three-dimensional

A B C D

Three-Dimensional Fusion Angiography of a Giant Basilar Aneurysm for Coil Embolization

366 jksronline.orgJ Korean Soc Radiol 2015;72(5):364-367

aneurysms. Attempts to classify giant aneurysms have included morphol-

ogy and the location (4) and fourth-dimension magnetic reso-nance imaging to demonstrate the influence of lesion size and morphology on aneurysm hemodynamics (5). Our pre-proce-dural planning was feasible based on the 3D fusion images that revealed the detailed angio-architecture, especially the aneurysm and its major branch arising from the parent artery. We were able to clarify the origin of the AICA arising from the dorsally dis-placed, lower basilar trunk secondary to the giant aneurysm, which otherwise was not possible using only 3D rotational ce-rebral angiography. Additional roles of fusion images based on 3D rotational angiography could be to simultaneously determine the relationship between vascular and osseous structures, espe-cially near the skull base, and to detect calcified tissue near the aneurysmal neck, neither of which is otherwise possible using only 3D rotational cerebral angiography (1, 6). Moreover, in-creasing attention is being given to the use of computational flu-id dynamics to ascertain the association between some specific intra-aneurysmal hemodynamics that can increase the risk of an-eurysmal rupture (7).

The 3D rotational angiography fusion technique has some limitations. First, considering the deterministic and random ef-fects of the radiation, it is necessary to reduce the radiation dose in additional 3D rotational angiography scans. Second, an inher-ent limitation of the volume-rendering technique used in 3D fu-sion can be that it overestimates the aneurysmal neck size com-pared with two-dimensional digital subtraction angiography images (8). Last, the additional fusion imaging technique requires more processing time, although it cannot impede the subsequent pro-cedure.

In conclusion, the fusion technique of 3D rotational angiogra-phy revealed the complete filling of a giant aneurysm near the con-fluent junction area of the lower basilar trunk, which was filling from both sides of the vertebral artery. Complete understanding of the angio-architecture of an aneurysm as well as the neck, in-cluding the relationship between the origin of the branching ar-

tery and the aneurysmal sac, assisted us in performing the neuro-interventional procedure accurately and safely.

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Joo Yeon Lee, et al

367jksronline.org J Korean Soc Radiol 2015;72(5):364-367

기저동맥 거대동맥류 색전술을 위한 3차원 융합영상

이주연 · 서대철

54세 여자에서 뇌기저동맥 하부 복측에 2.5 cm 크기의 거대 뇌동맥류(giant aneurysm)가 확인되었으나, 양측이 비슷한

크기로 발달한 척추동맥에서 얻은 혈관조영상에서는 각 척추동맥에서의 선택적 혈류흐름으로 인해 동맥류낭과 원위부 혈

관이 완전 충만이 되지 않았다. 3차원 융합혈관조영술을 통해 기저동맥과 동맥류목 및 주위 혈관과의 관계, 동맥류와 원

위부 뇌기저동맥과의 관계 등을 확인할 수 있었으며, 코일색전술을 성공적으로 시행하였고 6개월 임상추적검사에서 특기

할 이상소견은 발견되지 않았다. 본 증례에서는 치료가 어려운 희귀 뇌혈관질환의 하나인 기저동맥의 거대동맥류에서 3

차원 융합혈관조영술을 이용하여 정확히 혈관구조를 분석하여 성공적인 코일색전술을 할 수 있었다.

울산대학교 의과대학 서울아산병원 영상의학과