Anatomy and frequency of large pontomesencephalic veins on 3D CT angiograms of the circle of Willis.

Background And Purpose: The pontomesencephalic veins (PMVs), especially the anterior PMV, are sometimes large enough that they could potentially affect the interpretation of CT angiograms of the circle of Willis. We investigated the frequency and anatomy of visible PMVs on 3D CT angiograms.

Methods: CT angiograms of 211 consecutive patients who underwent CT angiography for a variety of clinical indications were evaluated retrospectively.

Gadolinium enhancement of spinal subdural collection on magnetic resonance imaging after lumbar puncture.

We report a 35-year-old male with an unusual contrast-enhancing sterile spinal subdural collection on magnetic resonance imaging (MRI), apparently occurring as a complication of lumbar puncture. Follow-up MRI after 4 weeks demonstrated spontaneous resolution of the collection without intervening treatment.