A left temporal chemoradiation-treated glioblastoma on post-contrast T1-weighted imaging (arrows in A and B). Relative cerebral blood volume (rCBV) maps through this lesion from dynamic susceptibility contrast (DSC) perfusion-weighted imaging are shown in C and registered with and superimposed on post-contrast T1-weighted imaging in D. However, susceptibility-related signal loss in proximity to the petrous and mastoid temporal bones artifactually makes rCBV in the inferior temporal lobes appear to be zero (arrows in C and D). Since the treated glioblastoma is within this area of artifactual signal loss, it could falsely appear to be hypoperfusing and so it is unable to be evaluated with DSC.