A 53-year-old patient presented with acute headache. CT and intra/extracranial CT angiography were normal. A traumatic lumbar puncture showed 8,500 erythrocytes/mm3 and 24 leukocytes/mm3. MRI showed extensive sulcal fluid-attenuated inversion recovery (FLAIR) hyperintensities suggesting subarachnoid hemorrhage (figure). However, since T2*-weighted sequences were normal and the patient was wearing a face mask (for a possible meningeal infection), a radiologic artifact was suspected. Immediately after, MRI without face mask showed absence of FLAIR abnormalities, confirming the suspected susceptibility artifact probably caused by the metal part of the face mask.