Introduction: Computerized tomography angiography (CTA) is commonly used to diagnose ruptured cerebral aneurysms with sensitivities as high as 97-100%. Studies validating CTA accuracy in the setting of subarachnoid hemorrhage (SAH) are scarce and limited by small sample sizes.
Methods: A single-center, retrospective cohort of 643 patients was reviewed. A total of 407 patients were identified whose diagnostic workup included both CTA and confirmatory diagnostic subtraction angiography (DSA). Aneurysms missed by CTA but diagnosed by DSA were further stratified by size and location.
Results: 306 aneurysms were detected by CTA while DSA detected a total of 433 aneurysms. False positive CTA results were seen for 24 aneurysms. DSA identified 127 aneurysms that were missed by CTA and 57.9% of those were determined to be <5mm. The sensitivity of CTA was 57.6% for aneurysms smaller than 5mm in size, and 45% for aneurysms originating from the ICA (p<0.001). The overall sensitivity of CTA in the setting of SAH was 70.7% (p<0.001).
Conclusions: The accuracy of CTA in the diagnosis of ruptured intracranial aneurysm may be lower than previously reported. CTA has a low sensitivity for aneurysms smaller than 5mm and in locations adjacent to bony structures and from small caliber parent vessels. It is our recommendation that CTA not be used alone in the diagnosis of ruptured intracranial aneurysms.
Patient Care: By using CTA for triage in the setting of suspected aneurysmal rupture as opposed to pure diagnosis. Cerebral angiogram must be the "gold standard" for diagnosing ruptured aneurysms
Learning Objectives: 1) Describe the limitations of CTA in the diagnosis of ruptured aneurysms
2) Understand the importance of cerebral angiography in the diagnosis and treatment of ruptured aneurysms