The aerated anterior and posterior clinoid processes: A pictorial review of potential pitfalls in MR imaging

John F. Healy, MD

View content online at: http://www.appliedradiology.com/Issues/2003/01/Articles/The-aerated-anterior-and-posterior-clinoid-processes--A-pictorial-review-of-potential-pitfalls-in-MR-imaging.aspx

Abstract:  Knowledge of the anatomy of the anterior clinoid processes is important, as an aerated anterior clinoid process may be a confusing pitfall in modern magnetic resonance (MR) imaging— it may mimic a tumor, an aneurysm, blood or calcium, or an abnormal vessel. This article presents an illustrated review of the MR appearance of the anatomy and diseases of this region.
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Dr. Healy is a Professor of Radiology at the University of California San Diego Medical Center, San Diego, CA.

The purpose of this article is to summarize pitfalls in the interpretation of magnetic resonance (MR) imaging due to aeration of the anterior or posterior clinoid processes.

In the bygone days of plain-film neuroradiology, careful examinations of the anterior clinoid processes were of diagnostic importance. Knowledge of anatomy in this region is still important, as an aerated anterior clinoid process may be a confusing pitfall in modern MR imaging; it may mimic a tumor (Figure 1), an aneurysm (Figures 2 and 3), blood (Figure 4), calcium, or an abnormal vessel. Less frequently, an aerated dorsum sella or a posterior clinoid process may cause similar diagnostic confusion (Figures 3 and 4). Figure 5 illustrates a potential pitfall in the interpretation of a maximum intensity algorithm cerebral angiogram caused by normal fat in a nonaerated anterior clinoid process.

An aerated clinoid process may also be subject to diseases that typically occur in other paranasal sinuses, such as mucocoele (Figure 6), that may cause marked visual loss due to proximity to the optic nerve and ophthalmic artery.

Endoscopic surgeons need to be aware of the anterior clinoid process because surgical instruments in an aerated clinoid process are quite close to the optic nerve and the carotid and ophthalmic arteries. AR

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