Increased diagnostic accuracy and better morphology characterization of unruptured intracranial aneurysm by ultra-high-resolution photon-counting detector CT angiography

BACKGROUND: Accurate detection and morphology evaluation of unruptured intracranial aneurysms (UIAs) are essential for patient management. This study aimed to assess the efficacy of ultra-high-resolution (UHR) photon-counting detector-CT angiography (PCD-CTA) in detecting UIAs and characterizing their morphological features. METHODS: This prospective study recruited consecutive participants suspected of cerebral vascular diseases who underwent PCD-CTA and subsequent digital subtraction angiography (DSA) within 1 month from September 2023 to May 2024. Performance of UIA diagnosis using UHR PCD-CTA images (slice thickness 0.2 mm) and standard resolution (SR, reflecting clinical protocols) reconstructed images were compared with DSA as reference on a per-participant, per-vessel, and per-aneurysm basis. The inter-rater agreement for UIA detection and aneurysm morphology characterization using UHR/SR PCD-CTA was also evaluated. RESULTS: Among 95 participants, 50 UIAs were confirmed in 42 participants using DSA. The inter-rater agreement for UIA detection was: kappa 0.95 for UHR and 0.89 for SR (p<0.05). On a per-aneurysm basis, the sensitivity, specificity, and diagnostic accuracy of UHR (98.0%, 96.7%, 97.3%) were all significantly higher than SR (72.0%, 86.7%, 80.0%) (p<0.05). UHR PCD-CTA accurately identified 13 of the 14 aneurysms (93%) missed by SR PCD-CTA, including 3 cases (21%) larger than 3 mm. Furthermore, UHR identified more aneurysm irregularity (18/50, 36%) than SR (5/50, 10%) (p=0.004). UHR also revealed 4 (8.0%) more cases with wall calcification and 3 (6.0%) more cases with intra-aneurysmal hypointensity (possible thrombus) than SR. CONCLUSIONS: The advantages of UHR PCD-CTA, including enhanced reliability, improved diagnostic accuracy, and more comprehensive information, have the potential to significantly optimize UIA management.