Practical Role of Three-Dimensional Computed Tomographic Angiography in Planning the Surgery for Intracranial Aneurysm

Park, Hyeon Seon; Kim, Eun Young; Cho, Young Kook; Sohn, Mun Joon; Park, Hyung Chun

Abstract

OBJECTIVES
The aim of this study is to evaluate the practical role of 3D-CTA in planning the surgery for intracranial aneurysm from a viewpoint of operator.
METHODS
Since May 1997 to April 1998, a total of 65 patients who were suspected to have intracranial aneurysms were studied with 3D-CTA using a General Electric Hispeed Advantage helical scanner. Conventional intraarterial digital subtraction angiographies(IA-DSAs) were performed in all patients except four who were in urgent situation. With the images obtained from the 3D-CTA, we performed preoperative assessments for the targeted aneurysms and evaluated its usefulness for planning the aneurysm surgery.
RESULTS
3D-CTA revealed 69 intracranial aneurysms in 55 patients and the size of aneurysms detected were 2-17mm in diameter. The sensitivity of 3D-CTA(95.8%) which was based on the comparison with IA-DSA and supplemented by microsurgical finding was similar to that of IA-DSA(94.1%) and its specificity(81.8%) was lower than that of IA-DSA(100%). Time consuming for getting images from 3D-CTA was no more than 20 minutes and this rapidity was very useful in the emergent situation such as cases of large intracerebral hematoma or massive intraventricular hemorrhage. 3D-CTA proffered various perspective views including surgical view, which were valuable to estimate the degree of head rotation and the direction of clip insertion and to determine the permanent clip type preoperatively. Careful reviewing of 3D-CTA made it possible to minimize surgical procedures. We could omit routine rectus gyrus resection in twelve of 16 surgeries for A-com aneurysm and could operate sixteen of 19 ICA aneurysms successfully without routine extracranial carotid artery preparation. On the basis of 3D-CTA, we could select the appropriate surgical approach in cases of ophthalmic aneurysm or posterior circulation aneurysm. Moreover, in cases of bilateral multiple aneurysms, 3D-CTA was helpful for evaluating the possibility of visualizing contralateral aneurysm through unilateral approach. The extent of bone work could be determined preoperatively through reviewing the 3D-CTA images and possible rupture of MCA aneurysm during bone work could be avoidable. However, 3D-CTA had some limitations for the describing fine vascular architecture such as the teat of aneurysm, a clue for the ruptured aneurysm in multiple aneurysms and most of fine caliber vessels such as hypoplastic posterior communicating artery or anterior choroidal artery was missed on the 3D-CTA. 3D-CTA lacked description for the hemodynamics of cerebral circulation.
CONCLUSIONS
Although the 3D-CTA is still insufficient to be the complete substitute for conventional intraarterial digital subtraction angiography, it may be excellent adjunctive tool in planning the surgery of intracranial aneurysm considering that understanding the exact relationship of aneurysm with surrounding structure is mandatory for minimizing the possible risk during surgery.