title: The 'padlock sign' in computed tomography of the head.
abstract: In computed tomography (CT) of the head, some lesions may enhance after intravenous injection of contrast material as semisolid or semicystic lesions resembling a padlock. Thirty-five patients whose scans showed padlock-shaped enhancement patterns were followed up and proved to have the following: 12 gliomas, 9 abscesses, 8 metastases, 3 tuberculomas, 1 craniopharyngioma, 1 meningioma and 1 cystic prolactinoma. The sign is probably caused by excentric cavitation in a solid lesion, or partial-volume averaging of the capsule in an irregularly shaped cystic lesion.
mesh_terms: D000328:Adult; D001922:Brain Abscess / Q000000981:diagnostic imaging; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000503:physiopathology*; D005910:Glioma / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D014057:Tomography, X-Ray Computed / Q000379:methods*