Patient population

A total of 18 patients were enrolled between January 1, 2015 to January 1, 2016. There were 10 males and 8 females, aging 34–76 years, with a mean age of 58. All patients presented with sudden severe headache, with the following H & H grades: grade 1 in 2 cases, grade 2 in 6 cases, grade 3 in 8 cases, grade 4 in 2 cases. All of their emergency cranial CTs showed subarachnoid hemorrhage (SAH), including 3 cases accompanied with hematoma. All patients underwent CTA and DSA examination within 3 days: anterior communicating artery aneurysms in 8 cases, middle cerebral artery aneurysms in 5 cases, posterior communicating artery aneurysms in 3 cases, carotid artery bifurcation aneurysm in 2 cases.

Surgical technique

We performed whole neck cerebral angiography with Siemens Artis zee biplane Universal interventional radiology machine (DSA machine), in the Interventional Center. Orthophoric and lateral intracranial angiography, 3D–DSA angiography and three-dimensional reconstruction were performed in all patients under general anesthesia, with Seldinge’s technique, in femoral artery approach, with 5F imaging catheter. These 18 patients aborted interventional operations due to unsuccessful interventional embolization or demand for craniotomy clipping by family members.

We simulated and designed the 3D–DSA operation path pattern with the Syngo system on DSA machine when sending the patients to the operating room. In this process, we identified blood vessels, nerves, brain, skull logo, and the location, shape, size, neck, pointing, rupture site of the aim aneurysms, and the relationship between the aneurysms and their parent arterys, adjacent blood vessels and tissues. Finalize operation plans after slight adjustment based on the classic pterion approach. Meanwhile, the patients were sent to the operating room, and got ready to craniotomy for aneurysm clipping.

Approach and path design

Design

2D–DSA is not adequate to provide a comprehensive local anatomical information. In contrast, with the use of 3D–DSA, a surgeon can fully understand the spatial structure of anterior communicating artery aneurysms and parent artery before operation. This is vital to improving the safety of clipping and reducing complications [3, 4]. 3D–DSA can provide the surgeon with full understanding of the local anatomy and simulate surgical conditions, such as relationship between the aneurysm and the parent artery, adjacent blood vessels and tissues. Therefore, we took full advantage of 3D–DSA when designing. Firstly, we identified the location, shape, size, neck, pointing, rupture site of the ruptured aneurysm, and payed attention to the local anatomical relationship between the aneurysm, relevant blood vessels, nerves, brain tissue, and skull marks. Secondly, we observed the visual angle of approach after adjustment based on the classic pterion approach to determine the surgical path, the clip angle and choose the aneurysm clip. Like the cases in this study, the paths we designed before the surgery were used as the actual microscopic surgery operating position (Fig. 1). Doing so not only enhanced the confidence of surgeons, but also improved the safety and operability of the surgery.

The surgical procedure

All the operations were bridging operations, namely the doctors who performed the intervention and designed the 3D–DSA simulated path also performed the craniotomy. It was safer and more feasible, since the surgeon understood the surgical path and the aneurysm anatomy better than others.

Body position and approach

By using the simulation of both sides of pterion position, surgeons could better predict and judge the intraoperative local situation, and decide the most convenient approach to expose and clip the aneurysm. This preoperative prediction and judgment of local anatomy is significant in generating surgical strategies and preventing unexpected situations [5]. This group of patients were placed in body position and the head position based on 3D–DSA simulated approach. The surgeons sought, exposed, isolated aneurysms according to simulated approach. It could reduce unnecessary separation and tractive injury of brain tissue in the operation, and improve the operation efficiency, shorten the operation time and reduce the surgical injury.

Regional anatomy

We decided to adopt the non blood-supply dominating side pterion approach after judging the difficulty in blood-supply dominating side approach and the advantage in local exposure of the contralateral approach with the 3D–DSA. Intraoperative findings of regional anatomy was very close to 3D–DSA simulated vascular anatomy which was proved to be a good guidance [5]. The regional anatomy between the aneurysm, the parent artery and the perforating branches was very important. When we isolated the parent artery, we sought the aneurysm according to the spatial positional relationship between aneurysm and parent artery we acquired before. It greatly reduced the time we spent to separate and dissect the aneurysms, and reduced the risk of aneurysm rupture during separation. That was the reason why we were able to find and separate the aneurysm quickly, and avoid clipping other arteries by mistake (Fig. 2).

Aneurysm clipping

The aneurysm pointing must firstly be identified in 3D–DSA image reconstruction, and secondly we identified the rupture position. In this way, the surgeons knew clearly the shape, size, structure, pointing and rupture position of the aneurysms before the craniotomy. Consequently, we were able to avoid injuring the structures surrounding the rupture position when exposing the aneurysm. We were able to clip the aneurysms after the neck, the parent artery, the surrounding tissue of the aneurysms were all fully exposed, thus minimize the risk of secondary ruptures (Fig. 1). In this study, one case of intraoperative bleeding occurred, but it was not during the process of separating the aneurysm.

Teaching and demonstration

Application of 3D–DSA simulated surgery path technique makes it possible for us to get better observation of stereoscopic vessel images from any angle. Also, doctors can directly understand the condition of the brain parenchyma, the parent artery and the skull base of diseased region. All of these are conducive to safer aneurysm clipping, and to intuitive teaching and display. We teach young doctors, students and interns with 3D–DSA image combined with operative video after operation.

We believe that the mechanized 3D–DSA images simulated surgical path effectively makes up for the defects of 2D–DSA. It can not only guide bridging operation in emergency ruptured intracranial aneurysm, but also help in teaching. It displayed high feasibility and reliability.

Researches abroad

Researchers abroad showed the importance of 3D–DSA in the evaluation and the treatment of aneurysms [6–8]. In our study, we applied 3D–DSA to evaluate aneurysms in bridging surgery to ensure a smooth and safe process of transit.