Pantopaque mimicking spinal lipoma: MR pitfall

We present a patient with an intraspinal, high-signal-intensity lesion in the lumbosacral region on T1-weighted magnetic resonance images and a thin line of signal void between this region and the CSF on T2-weighted images. These findings were interpreted initially as representing an extradural spinal lipoma. However, CT revealed an intrathecal collection of iophendylate (Pantopaque), which was subsequently removed via a lumbar puncture. The apparent separation of Pantopaque from the CSF (seen on T2-weighted images and interpreted as the dura) was probably caused by chemical shift artifact, chemical shift contour, and/or CSF motion artifact.