CT Angiography, MR Angiography, and Their Combined Use for Detection of Unruptured Intracranial Aneurysms: Comparison with Digital Subtraction Angiography and 3-dimensional Rotational Angiography.

Purpose: To compare the diagnostic accuracy of CT angiography (CTA), MR angiography (MRA), and their combined use for detecting unruptured intracranial aneurysms (UIAs).

Methods: Between September 2019 and August 2023, 235 patients suspected of having UIA underwent CTA, MRA, and digital subtraction angiography (DSA)/3-dimensional rotational angiography (3DRA). Two neuroradiologists retrospectively reviewed these images for UIA presence. The value of combining modalities was assessed using confidence rating scores for each. The sensitivity, specificity, and accuracy of these modalities were calculated on a per-aneurysm basis and compared using DSA/3DRA as the reference standard. Subgroup analyses were performed based on aneurysm size (≤ 3 or > 3 mm).

Results: DSA/3DRA detected 252 UIAs in 182 patients, no aneurysms detected in 53 (mean age: 61.9 years ±11.6, 83 men). The overall sensitivity/specificity/accuracy of the combined analysis of CTA and MRA were 91.3%/88.7%/90.7%, respectively, which were significantly higher than those of CTA alone (86.9%/71.8%/83.6%) (P = 0.006/0.003/<0.001) and MRA alone (86.9%/80.3%/85.5%) (P =0.003/0.041/<0.001). No significant differences were found in sensitivity, specificity, or accuracy between the use of CTA and MRA (P = 1/0.26/0.45). CTA and MRA sensitivity and accuracy for aneurysms ≤3 mm were significantly lower than for those aneurysms larger. (P < 0.001, each).

Conclusion: Combining CTA and MRA analysis improves sensitivity, specificity, and accuracy for UIA detection compared to using each modality alone.