The emergency department incidence of incidental intracranial aneurysm on computed tomography angiography (EPIC-ACT) study

Abstract

Background Subarachnoid hemorrhage has been traditionally ruled-out in the emergency department (ED) through computed tomography (CT) followed by lumbar puncture if indicated. Mounting evidence suggests that non-contrast CT with CT angiography (CTA) can safely rule-out subarachnoid hemorrhage and obviate the need for lumbar puncture, but adoption of this approach is hindered by concerns of identifying incidental aneurysms. This study aims to estimate the incidence of incidental aneurysms identified on CTA head and neck in an ED population. Methods This was a health records review of all patients ≥ 18 years who underwent CTA head and neck for any indication at four large urban tertiary care EDs over a 3 month period. Patients were excluded if they underwent CT venogram only, had previously documented intracranial aneurysms, or had intracranial hemorrhage with or without aneurysm. Imaging reports were reviewed by two independent physicians before extracting relevant demographic (age, sex), clinical (CTAS level, CEDIS primary complaint) and radiographic (number, size, and location of aneurysms) information. The incidence rate of incidental aneurysms was calculated. Results A total of 1089 CTA studies were reviewed with a 3.3% (95% CI 2.3-4.6) incidence of incidental intracranial aneurysms. The median size of incidental aneurysms was 4 mm (0.7-11) and 10 (27.7%) patients had multiple aneurysms. Patients with incidental aneurysms did not differ based on mean age, sex, and CTAS levels. Conclusions The "risk" of discovering an incidental aneurysm is 3.3%. Clinicians should not be deterred from using CTA in the appropriate clinical settings. These estimates can inform shared decision-making conversations with patients when comparing subarachnoid hemorrhage rule-out options.

Shifts in Diagnostic Testing for Headache in the Emergency Department, 2015 to 2021

“…[55][56][57] The 2019 ACEP endorsement of CTCA as a substitute for LP was based on very high (97%-98%) overall sensitivity and specificity of CTCA for cerebral aneurysms, including case-series suggesting 100% sensitivity of CTCA for causative aneurysms in patients with CT-negative/LP-positive SAH. 10,23,30,[35][36][37][58][59][60] One criticism of a CT-CTCA approach is lower sensitivity for very small aneurysms (Յ3 mm), which account for up to 18% of ruptured aneurysms, whereas CT-LP is essentially 100% sensitive for aneurysmal SAH. 11,12,[25][26][27][61][62][63] These differences in test characteristics, however, must be balanced against the low incidence of CT-negative aneurysmal SAH in clinical practice.…”

“…As a retrospective study using diagnostic codes to define outcomes, the results are subject to coding errors and incomplete outcome capture. However, assuming that misclassifications were equally distributed over time, the temporal basis of analysis mitigated these risks . Although we did not assess magnetic resonance imaging, since this is not a recommended screening modality for SAH and had variable availability between EDs and over time, a proportion of UIAs were ostensibly diagnosed using magnetic resonance angiography.…”

“…30 However, debate persists over the appropriateness of the CT-CTCA approach owing to concerns over cost, radiation exposure, missed alternative diagnoses (eg, meningitis), increased detection of unruptured intracranial aneurysms (UIA), and no clear advantage in cost-benefit analyses. [31][32][33][34][35][36][37][38] Since there is little to no direct evidence supporting a CT-CTCA approach to SAH diagnosis in practice, updated 2023 guidelines from the American Heart and Stroke Associations (AHA/ASA) made a strong recommendation in favor of a CT-LP approach but no recommendation for a CT-CTCA approach. 8 To help further inform clinical practice, we examined temporal trends in and correlations between second-line testing (LP or CTCA) for SAH and newly detected UIA among ED patients with headaches.…”

“…In 2019, the American College of Emergency Physicians (ACEP) issued a weak recommendation for the use of either a CT-LP or CT-CTCA approach to exclude aneurysmal SAH . However, debate persists over the appropriateness of the CT-CTCA approach owing to concerns over cost, radiation exposure, missed alternative diagnoses (eg, meningitis), increased detection of unruptured intracranial aneurysms (UIA), and no clear advantage in cost-benefit analyses . Since there is little to no direct evidence supporting a CT-CTCA approach to SAH diagnosis in practice, updated 2023 guidelines from the American Heart and Stroke Associations (AHA/ASA) made a strong recommendation in favor of a CT-LP approach but no recommendation for a CT-CTCA approach …”

Weighing the negatives, CT/LP or CT/CTA for patients at risk of aneurysmal subarachnoid hemorrhage

“…The article by Wong, et al in the March (2022) issue titled "The Emergency Department Incidence of Incidental Intracranial Aneurysms on Computed Tomography Angiography (EPIC-ACT) Study" adds to our knowledge base [1]. The result is not unexpected, but it is valuable to define the "incidental" aneurysmal rate at 3.3% in patients presenting to Canadian emergency departments.…”