Hyperintensity of Subarachnoid Space on FLAIR Images Caused by Supplemental Oxygen

ABSTRACT

A hyperintensity in the subarachnoid space on fluid-attenuated inversion-recovery (FLAIR) images is often caused by diseases such as subarachnoid hemorrhage or meningitis. Oxygen has a known paramagnetic effect and also causes signal changes in the subarachnoid space on FLAIR images. These changes usually develop when the inspired air contains a high oxygen fraction. Here we present a patient with a hyperintensity in the subarachnoid space on FLAIR images whose inspired air contained only a low oxygen fraction.