Computed tomographic angiography as an adjunct to digital subtraction angiography for the pre-operative assessment of cerebral aneurysms

Abstract

Objectives: Computerized tomographic angiography (CTA) has emerged as a valuable diagnostic tool for the management of patients with cerebrovascular disease. The use of CTA in lieu of, or as an adjunct to, conventional cerebral angiography in the management of cerebral aneurysms awaits further experience. In this study, we evaluated the role of CTA specifically for the pre-operative assessment and planning of cerebral aneurysm surgery.

Patients and methods: We reviewed the relevant neuroimaging of all patients treated at Dartmouth Hitchcock Medical Center between January, 2001 and December, 2004 with a diagnosis of cerebral aneurysm and diagnostic evaluation with both CTA and conventional digital subtraction angiography (DSA) using standard imaging protocols. 32 patients underwent both CTA and DSA during the study period for a total of 36 aneurysms. Images were independently re-assesed by two neurosurgeons for information valuable for pre-operative surgical planning.

Results: In 26 of 36 aneurysms (72%), the CTA was felt to provide the best image quality in defining the morphology of the aneurysm. In 14 aneurysms (39%), CTA provided clinically valuable anatomic detail not demonstrated on DSA, largely due to better visualization of parent and perforating vessel relationships at the aneurysm neck. There were no instances where a lesion was seen on DSA but missed on CTA. The DSA was of most clinical value in determining flow dynamics, such as the arterial supply of an anterior communicating artery aneurysm and distal anterior cerebral branches via the two A1 segments.

Conclusion: CTA with three-dimensional reconstructions is a valuable adjunct to the preoperative evaluation of cerebral aneurysms. We advocate routine use of CTA in all patients in whom surgical aneurysm repair is planned, even when DSA has already been performed.

Keywords: Computed tomographic angiography; cerebral aneurysm; digital subtraction angiography; magnetic resonance angiography; pre-operative assessment..

Fig. (1)

Right superior cerebellar artery aneurysm as visualized by conventional digital subtraction angiography (DSA, left) compared with the same aneurysm visualized by computerized tomographic angiography (CTA, right). Note the high degree of anatomic resolution and the imaging detail of the parent/daughter vessel relationships at the aneurysm neck.

Fig. (2)

Right posterior inferior cerebellar artery (PICA) aneurysm as imaged by DSA (left) and CTA (right). The right vertebral was not amenable to selective catheterization, and the subsequent innominate artery injection does not reveal much detail to the aneurysm and its vascular relationships compared with the result from the CTA. Note the relationship to the basilar artery, not seen with DSA, and PICA take-off at the base of the aneurysm (arrow) seen on CTA.

Fig. (3)

Anterior communicating artery aneurysm seen by DSA (A and B, arrows) and CTA (C-E, arrows). The lobular/saccular morphology of the aneurysm is more clearly seen on CTA, and the ability for rotational views allows visualization of the anatomy from above (A), the side (B), and below (C) to provide a valuable three-dimensional representation of the aneurysm.

Fig. (4)

Aneurysm at the tip of the basilar artery seen on CTA. Aneurysm projection and relationship to the skull base bony anatomy is unambiguously seen.

Fig. (5)

Fusiform basilar artery aneurysm with a saccular aneurysm at the left vertebrobasilar junction. Note how this aneurysm is poorly seen on DSA (A and C, arrow shows probable location) and was initially missed using this modality, whereas it is unequivocally visualized on CTA (B and D, arrows). A and B represent anterior-posterior (AP) views, C and D represent lateral views.