Transversal PMCT after previous intrathecal contrast agent application in a 55-year-old patient with orthostatic headache without epidural CSF collection (SLEC(−)) demonstrating opacification of the renal pelvis and a density measurement using a circular ROI with a mean of 64 Hounsfield units. CSF cerebrospinal fluid, PMCT postmyelography computed tomography, ROI region of interest