ABSTRACT NUMBER: ESOC2026A2216 VISUALIZATION OF ANTERIOR CHOROIDAL ARTERY USING PHOTON COUNTING DETECTOR CT ANGIOGRAPHY: A RETROSPECTIVE COHORT STUDY

Abstract Background and aims The anterior choroidal artery (AChA) is a small but critical branch of the proximal intracranial internal carotid artery supplying eloquent deep brain regions. Accurate visualization is essential for the management of aneurysms and ischemic events involving the AChA. To that end, digital subtraction angiography (DSA) remains the gold standard. Photon-counting detector CT angiography (PCD-CTA) offers improved spatial resolution and signal-to-noise ratio over conventional energy-integrating detector CT angiography (EID-CTA). This study evaluated the performance of PCD-CTA and EID-CTA in visualizing the AChA compared with DSA. Methods This single-center retrospective study included patients with subarachnoid hemorrhage who underwent both CTA (either EID-CTA or PCD-CTA) and DSA between 2021 and 2024. Two experienced readers independently assessed AChA presence, visualized trajectory, and subjective image quality using standardized scales. Comparative analyses were performed using conventional statistics. Interobserver agreement was assessed using Cohens kappa. Results 159 patients were included. PCD-CTA demonstrated significantly higher AChA detection rates and image quality ratings compared with EID-CTA. PCD-CTA AChA detection rates were comparable to DSA. Median visualized trajectory scores did not differ significantly between PCD-CTA and DSA, while DSA maintained a slightly superior subjective image quality. Interobserver agreement was moderate to low across modalities. Conclusions PCD-CTA enables noninvasive detection of the AChA with a performance approaching that of DSA and substantially exceeding EID-CTA. These findings suggest that PCD-CTA may serve as a feasible alternative to DSA for diagnostic or preoperative AChA assessment in neurovascular patients. Conflict of interest Thomas G. Flohr is a former employee of Siemens Healthineers. A.A. Postma reports an institutional grant from Siemens Healthineers. J.E. Wildberger reports institutional grants from Abbott, Anaconda Biomed, Asklepios, Bayer, Becton & Dickinson Medical, Bentley, Boston, Brainlab, GE Healthcare, Gleamer, Hologic, Inari Medical, Johnson & Johnson, LCRB, Medtronic, Merit Medical Systems, Microvention, Nico-Lab, Nova Techs, Oldelft Benelux, Ontario Association of Radiologists, Penumbra, Philips, Screenpoint Medical, Siemens Healthineers, Stryker, and Tajpan Sro, as well as speaker fees (paid to the institution) from Bayer and Siemens Healthineers. H.D. Boogaarts received consultation fees from Stryker Neurovascular (paid to the institution). W.H. van Zwam received consultation fees from Stryker, Nicolab and Cerenovus (paid to the institution), and is a DSMB member of the We-Trust study, Solonda study, and In Extremis study (all funding paid to the institution).