Comparison Between CTA and Digital Subtraction Angiography in the Diagnosis of Ruptured Aneurysms

BACKGROUND: Computerized tomography angiography (CTA) is commonly used to diagnose ruptured cerebral aneurysms with sensitivities reported as high as 97% to 100%. Studies validating CTA accuracy in the setting of subarachnoid hemorrhage (SAH) are scarce and limited by small sample sizes. OBJECTIVE: To evaluate the diagnostic accuracy of CTA in detecting intracranial aneurysms in the setting of SAH. METHODS: A single-center, retrospective cohort of 643 patients was reviewed. A total of 401 patients were identified whose diagnostic workup included both CTA and confirmatory digital subtraction angiography (DSA). Aneurysms missed by CTA but diagnosed by DSA were further stratified by size and location. RESULTS: Three hundred and thirty aneurysms were detected by CTA while DSA detected a total of 431 aneurysms. False positive CTA results were seen for 24 aneurysms. DSA identified 125 aneurysms that were missed by CTA and 83.2% of those were <5 mm in diameter. The sensitivity of CTA was 57.6% for aneurysms smaller than 5 mm in size, and 45% for aneurysms originating from the internal carotid artery. The overall sensitivity of CTA in the setting of SAH was 70.7%. CONCLUSION: The accuracy of CTA in the diagnosis of ruptured intracranial aneurysm may be lower than previously reported. CTA has a low sensitivity for aneurysms less than 5 mm in size, in locations adjacent to bony structures, and for those arising from small caliber parent vessels. It is our recommendation that CTA should be used with caution when used alone in the diagnosis of ruptured intracranial aneurysms.