# True versus pseudo-occlusion of the cervical internal carotid artery in acute stroke: A multicenter MR angiography study

## TL;DR

This study shows that CE-MRA can help distinguish true from pseudo-occlusion of the cervical ICA in stroke patients, but accuracy improves with radiologists' experience.

## Contribution

The study evaluates CE-MRA's diagnostic accuracy for differentiating true and pseudo-occlusion of the cervical ICA in acute stroke patients.

## Key findings

- Board-certified radiologists had higher sensitivity and specificity compared to fellows in identifying pseudo-occlusion.
- Inter-reader agreement was moderate overall but substantial among board-certified radiologists.
- Correct differentiation helps in selecting appropriate materials for endovascular treatment.

## Abstract

Differentiating true from pseudo-occlusion of the cervical internal carotid artery (ICA) in acute ischemic stroke patients undergoing thrombectomy is crucial but challenging. We aimed to investigate the ability of contrast-enhanced magnetic resonance angiography (CE-MRA) to differentiate true from pseudo-occlusion (defined as an isolated thrombus of the intracranial ICA suppressing ascending blood flow) of the cervical ICA in acute ischemic stroke patients.

Multicenter, retrospective analysis of acute ischemic stroke patients with true or pseudo-occlusion of the cervical ICA and subsequent thrombectomy. Patients with preprocedural CE-MRA showing a lack of contrast filling in the cervical ICA on the symptomatic side were included. Six readers (three radiology fellows and three board-certified radiologists) independently evaluated the CE-MRA images for true or pseudo-occlusion of the cervical ICA using a rating scheme. Their assessments were compared with DSA results as the reference standard. Diagnostic accuracy measures, as well as inter- and intra-reader reliability for detecting pseudo-occlusion, were calculated and compared between subgroups.

A total of 41 patients were included. The median age was 73 years, and 39% were female. According to the reference standard, 16 of 41 (39%) patients had a pseudo-occlusion of the cervical ICA, while the remainder had a true occlusion. The aggregated sensitivity and specificity from all readers were 72% (95% confidence interval [CI]: 62%–81%) and 86% (95% CI: 79%–91%), respectively. Board-certified radiologists performed better, with a sensitivity of 81% (95% CI: 67%–91%) and specificity of 92% (95% CI: 83%–97%). Overall, inter-reader agreement was moderate (κ = 0.48; 95% CI: 0.31–0.65) and reached substantial agreement within the board-certified radiologists subgroup (κ = 0.65; 95% CI: 0.45–0.85).

Differentiating true occlusion from pseudo-occlusion of the cervical ICA using CE-MRA is feasible but requires training in specific imaging characteristics as well as experience in interpreting them, as evidenced by the higher diagnostic accuracy of board-certified radiologists. Correct distinction help in optimal material selection (e.g. size and type of guiding catheter) prior to endovascular treatment.

Graphical abstract