MRI location of the distal dural ring plane: anatomoradiological study and application to paraclinoid carotid artery
Laurent Thines1, Christine Delmaire, Daniel Le Gars
1Department of Neurosurgery, University Hospital, Lille, France. Laurent.Thines@wanadoo.fr
Abstract:
The distal dural ring plane (DDRP) separates the intradural from the extradural paraclinoid internal carotid artery. The purpose of this study was to evaluate its position with MR imaging. The protocol used a T2-weighted sequence in two orthogonal planes: diaphragmatic (DIA-P) and carotid (CAR-P). The DDRP passes through four anatomoradiological reference points (RefP). We developed on a cadaveric model a correlation method supported by correlation lines and angles (CA) projecting the RefP toward the DDRP. RefP were correlated to the DDRP in 65-84% of cases in the DIA-P and 60-76% of cases in the CAR-P. CA were identified and correlated to the DDRP, respectively, in 87% and 60% of cases in the DIA-P, and 60% and 51% of cases in the CAR-P (failure often related to a lack of visibility of just one RefP). A higher tissular contrast in living subjects allowed the identification of CA in 90% and 80% of cases, respectively, in the DIA-P and the CAR-P. We propose that CA, when identified, should be considered as an approximation of the inferior radiological limit of the DDRP curve. In difficult angiographical cases, this MRI protocol could help to locate paraclinoid aneurysms on both sides of the cavernous sinus roof.
Insights
This study introduces a novel MRI method to precisely locate the distal dural ring plane (DDRP), crucial for identifying internal carotid artery aneurysms. The technique utilizes correlation angles (CA) for improved surgical planning.
Area of Science:
- Neurosurgery
- Radiology
- Anatomy
Background:
- The distal dural ring plane (DDRP) is a critical anatomical landmark separating intradural and extradural segments of the paraclinoid internal carotid artery.
- Accurate localization of the DDRP is essential for surgical planning, particularly for paraclinoid aneurysms.
Observation:
- A T2-weighted MRI sequence in diaphragmatic (DIA-P) and carotid (CAR-P) planes was used to evaluate the DDRP's position.
- Anatomoradiological reference points (RefP) and correlation lines/angles (CA) were developed and tested on cadaveric models.
- Correlation between RefP and DDRP ranged from 60-84%, while CA correlation varied from 51-87%.
Findings:
- Correlation angles (CA) demonstrated higher accuracy in identifying the DDRP compared to reference points alone, especially in living subjects with better tissue contrast (90% in DIA-P, 80% in CAR-P).
- The proposed MRI protocol effectively visualizes the DDRP and its associated correlation angles.
- Correlation angles (CA) can approximate the inferior radiological limit of the DDRP curve.
Implications:
- This MRI protocol offers a valuable tool for precisely locating the DDRP, aiding in the diagnosis and surgical management of paraclinoid aneurysms.
- Improved visualization of the DDRP can enhance surgical navigation and reduce risks associated with complex neurovascular procedures.
- The findings support the use of specific MRI sequences and correlation angles for detailed anatomical assessment in neurosurgical contexts.
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