# High-resolution magnetic resonance imaging (HRMRI) for judging the location of paraclinoid aneurysms (PAs): assisting in diagnosis and treatment decision of PAs

## TL;DR

This study shows how high-resolution MRI can accurately determine the location of paraclinoid aneurysms, aiding diagnosis and treatment decisions.

## Contribution

The study introduces a specific HRMRI protocol and classification system for paraclinoid aneurysms to guide clinical decisions.

## Key findings

- HRMRI sequences effectively identified the location of paraclinoid aneurysms based on ICA segments.
- Most Type M and Type L aneurysms were located within the cavernous sinus.
- The HRMRI protocol is useful for radiation-free or iodine-free evaluation of aneurysm location.

## Abstract

Determining the location of paraclinoid aneurysms (PAs) is crucial. We aimed to evaluate the utility of paraclinoid high-resolution MRI (HRMRI) in determining PA locations.

We enrolled patients with suspected PAs who underwent our HRMRI sequence in 6 months. PAs were categorized into five types based on their origin from the internal carotid artery (ICA): Superior ophthalmic segment (Type S), Ventral ophthalmic segment (Type V), Medial clinoidal segment (Type M), Lateral clinoidal segment Type L, and Posterior clinoidal segment) (Type P). The paraclinoid HRMRI protocol included five main sequences: TOF-MRA, coronal and saggital high-resolution T2-weighted images, coronal and saggital enhanced high-resolution T1-weighted images. We utilized cerebrospinal fluid (CSF) notch and cavernous sinus enhanced signals to determine the location of PAs.

Sixty-nine patients with 75 PAs were included. Based on our classification, there were 10 Type S, 2 Type V, 45 Type M, 11 Type L, and 7 Type P PAs. Among the Type S PAs, 9 were fully located within the subarachnoid space, and 1 was in the juncture area. Both Type V PAs were situated within the cavernous sinus. Among the Type M PAs, 34 were located in the cavernous sinus, and 1 was in the juncture. Of the Type L PAs, 5 were within the cavernous sinus, and 1 was in the juncture area. All 7 Type P PAs were located within the cavernous sinus.

HRMRI sequences may assist in determining the location of PAs and could provide useful information for clinical decision-making, especially when radiation-free or iodine-free evaluation is preferred.

The clinical trial of China Internal Aneurysm Project (NCT03115905).