[MRI localization of paraclinoid carotid aneurysms].
OBJECTIVE
The distal dural ring plane (DDRP) separates the intracavernous from the supracavernous paraclinoid internal carotid artery. The purpose of this MRI protocol is to evaluate the position of this plane for the characterization of paraclinoid aneurysms.


METHODS
The protocol uses a T2 weighted sequence in two orthogonal planes (diaphragmatic and carotid planes) and two correlation lines in each plane. These lines pass through anatomo-radiological reference points correlated with the medio-lateral and antero-posterior margins of the DDRP. We use the intersection angle of these lines as the inferior radiological limit of the DDRP curve.


RESULTS
An aneurysm located above this angle is supracavernous; an aneurysm located below this angle is intracavernous; an aneurysm crossing this angle is transitional.


CONCLUSIONS
In difficult cases, this MRI protocol could help better characterize the exact localization of paraclinoid aneurysms on both sides of the cavernous sinus roof.
Thines
L
L
Clinique Neurochirurgicale, Hôpital Roger-Salengro, CHRU, rue du Professeur Emile Laine, 59037 Lille Cedex. Laurent.Thines@wanadoo.fr
Delmaire
C
C
Le Gars
D
D
Pruvo
J P
JP
Lejeune
J P
JP
Lehmann
P
P
Francke
J P
JP
D002340:Carotid Artery Diseases / Q000175:diagnosis*; D004388:Dura Mater; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*