Purpose: To correlate computed tomographic (CT) or magnetic resonance (MR) images with dissections of normal inferior petrosal sinuses (IPS).
Materials and methods: Postmortem dissection was performed in 12 individuals, one of whom had undergone CT and MR imaging 3 months before death. Seven patients underwent IPS venography, CT, and MR imaging. One hundred sixteen patients with normal IPS underwent MR imaging; 40, CT and MR imaging; and two, CT, MR imaging, and arteriography.
Results: Images showed that the IPS and basilar plexus formed conspicuous, enhanced structures that provide much of the border between the clivus and cerebrospinal fluid. Axial, cross-sectional IPS dimensions were as large as 9 x 16 mm. The larger sinuses were contained by deep grooves of bone that sometimes showed marked cortical thinning. Sixty-nine (39%) of the 175 individuals studied had markedly asymmetric IPS.
Conclusion: CT and MR images showed that normal IPS and basilar plexus vary in size and are frequently asymmetric. This range of normal measurements and appearances should be taken into account before abnormalities in this region are diagnosed.