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A pneumatized anterior clinoid mimicking an aneurysm on MR imaging. Report of two cases
A D Gean1, J Pile-Spellman, R C Heros
1Department of Neuroradiology, Massachusetts General Hospital, Boston.
Abstract:
The advent of magnetic resonance (MR) imaging has marked a new era in neuroimaging--particularly in terms of diminishing the need for more invasive diagnostic procedures. A cautionary note should be sounded, however, about an important limitation of standard spin-echo MR studies. Two patients were referred for angiography because MR imaging indicated the presence of a "paraclinoid aneurysm." In retrospect, these findings were due instead to a pneumatized anterior clinoid. Angiography could have been avoided had this pitfall been recognized, and had a gradient-echo flow-imaging protocol been utilized. This latter approach (which does not replace spin-echo imaging) is more sensitive to flowing blood and thus allows differentiation of an air space from a nonthrombosed aneurysm.
Insights
Magnetic resonance (MR) imaging can misdiagnose pneumatized anterior clinoids as aneurysms. Utilizing gradient-echo flow imaging can help differentiate these conditions, avoiding unnecessary angiography.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Magnetic resonance (MR) imaging has revolutionized neuroimaging, reducing the need for invasive procedures.
- Standard spin-echo MR studies have limitations that can lead to misinterpretations.
- Accurate differentiation of vascular structures is crucial in neurodiagnostic imaging.
Observation:
- Two patients were referred for angiography based on MR findings suggestive of a paraclinoid aneurysm.
- In retrospect, the MR findings were attributed to a pneumatized anterior clinoid, an anatomical variant.
- This highlights a potential pitfall in standard spin-echo MR imaging interpretation.
Findings:
- A pneumatized anterior clinoid can mimic a paraclinoid aneurysm on spin-echo MR imaging.
- Gradient-echo flow imaging is more sensitive to blood flow than spin-echo techniques.
- Gradient-echo imaging allows for the differentiation between an air space (pneumatized clinoid) and a nonthrombosed aneurysm.
Implications:
- Recognizing the potential for misinterpretation can prevent unnecessary invasive procedures like angiography.
- Gradient-echo flow imaging should be considered as a complementary technique to spin-echo MR imaging in specific neurodiagnostic scenarios.
- Improved diagnostic accuracy in neuroimaging can lead to more efficient and effective patient management.