A 22-year-old woman with a history of headaches underwent brain imaging to exclude structural causes of headache. After magnetic resonance angiography suggested a basilar artery aneurysm, she was referred to our institution for further diagnostic workup. A conventional angiogram was performed and showed a possible aneurysm of the midbasilar segment (Figure A, arrow). Three-dimensional reconstructed images, however, demonstrated that this abnormality was clearly a fenestrated basilar artery without aneurysm. The image simulated an “ok” hand sign (Figure B, arrow) and no further intervention was taken.
Prabhakaran S, Lopes DK. The “OK” SignAn Unusual Angiographic Appearance of Basilar Artery Fenestration. Arch Neurol. 2008;65(6):836. doi:10.1001/archneur.65.6.836