The blister sign on non-contrast CT for detection of blood blister-like aneurysms in acute subarachnoid hemorrhage.

Authors

Atika El Attar, Andrea Bartolo, Romain Bourcier, Adel Menacere, Luca Scarcia, Erwah Kalsoum, Frédéric Clarençon, Pierre-Marie Chiaroni, François Zhu, Benjamin Gory, Stéphanie Condette-Auliac, Arturo Consoli

Published in

Neuroradiology. Jul 02, 2026. Epub Jul 02, 2026.

Abstract

Blood blister-like aneurysms (BBLAs) are rare, fragile lesions associated with a high risk of early rebleeding, yet they are frequently occult on initial non-invasive imaging. Early identification is therefore critical. This study introduces a novel non-contrast CT (NCCT) marker - the blister sign -for early recognition of BBLAs in acute subarachnoid hemorrhage (SAH).
We conducted a retrospective multicenter cohort study across five tertiary neurovascular centers, including consecutive patients presenting with non-traumatic SAH in 2023. The blister sign was defined on NCCT as a rounded hyperdense juxtavascular focus with a central iso/hypodense core, located at a non-branching segment of the parent artery. Digital subtraction angiography (DSA) served as the reference standard. Two experienced neuroradiologists independently assessed the blister sign on baseline NCCT; discrepancies were resolved by consensus.
Among 335 included patients (mean age 55.1 years; 69.8% women), 13 BBLAs were confirmed. The blister sign was present in 16 patients (13 with BBLAs and 3 saccular aneurysms). Sensitivity and specificity for BBLA detection were 100% and 99.1%, respectively, with a positive predictive value of 81% and a negative predictive value of 100%. No BBLA was found in blister-sign negative patients. Inter-observer agreement was substantial (κ = 0.79; 95% CI: 0.63-0.95).
The blister sign is an accurate and reproducible NCCT marker of BBLAs in acute SAH. Its identification may expedite targeted angiographic evaluation and intervention, whereas its absence may help exclude BBLA in SAH sine materia presentations. If validated prospectively, the blister sign could be incorporated into SAH diagnostic pathways.

PMID:
42390598
Bibliographic data and abstract were imported from PubMed on 02 Jul 2026.

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