Gadolinium Enhancement of the Aneurysm Wall in Extracranial Carotid Artery Aneurysms

Abstract

Background and purpose: The natural history and optimal treatment of extracranial carotid artery aneurysms are unknown. Gadolinium enhancement of the aneurysm wall may reflect aneurysm wall inflammation and instability. In this study, we investigated the feasibility of extracranial carotid artery aneurysm wall imaging and explored a potential relationship of aneurysm wall enhancement with aneurysm growth and the presence of (silent) brain infarcts and white matter lesions.

Materials and methods: Fourteen conservatively treated patients with 15 asymptomatic extracranial carotid artery aneurysms underwent gadolinium-enhanced 3T MR imaging at 2 time points with a 12-month interval. Primary outcome was growth of the aneurysm sac (≥2.0 mm); secondary outcomes were the presence of (silent) brain infarcts and white matter lesions at baseline and follow-up. MR images were reviewed by 2 independent observers, and inter- and intraobserver reproducibility was assessed.

Results: Seven (50%) patients were men; the median age was 55 years (range, 40-69 years). Eleven extracranial carotid artery aneurysms (73%) were saccular (median size, 11 mm; range, 5.0-38.5 mm), and 4 were fusiform (median size, 21.5 mm; range, 10.0-40.0 mm). Eleven of 15 aneurysms (73%) exhibited gadolinium enhancement at baseline. Four aneurysms (27%) showed growth at follow-up imaging, 2 gadolinium-positive (+) and 2 gadolinium-negative (-) (P = .245). Three patients (21%) had ipsilateral brain infarcts at baseline; 1 of them showed a new silent brain infarct at follow-up imaging (gadolinium+). Nine patients (64%) showed bilateral white matter lesions at baseline. In 3 patients, increased white matter lesion severity was observed at follow-up (2 gadolinium+). All observations showed excellent inter- and intraobserver reproducibility.

Conclusions: In this explorative study, we demonstrated that extracranial carotid artery aneurysm wall imaging was feasible. Future well-powered studies are needed to investigate whether extracranial carotid artery aneurysm gadolinium enhancement predicts aneurysm growth and thromboembolic complications.

© 2020 by American Journal of Neuroradiology.

Figures

Fig 1.

Schematic examples of diameter measurements of ECAAs, perpendicular to the nonaffected vessel. Left: fusiform ECAA length × width. Right: saccular ECAA length × width × neck (round arrow).

Fig 2.

Examples of aneurysm wall enhancement (solid arrow) on 3T MR imaging with aneurysm wall imaging on the transaxial plane. B, D, F, and H, The sequence after administration of gadolinium. A and B, A 66-year-old woman with a 11.0- mm saccular left internal carotid artery aneurysm without enhancement (dashed arrow). C and D, A 54-year-old man with a 9.0-mm saccular right internal carotid artery aneurysm without enhancement (dashed arrow). E and F, A 51-year-old woman with a 7.5-mm saccular left internal carotid artery aneurysm with aneurysm enhancement (solid arrow). G and H, A 59-year-old woman with a 10.0-mm fusiform left internal carotid artery aneurysm with enhancement (solid arrow). The asterisk indicates the parent ICA; e, branches of the external carotid artery; v, internal jugular vein.

Fig 3.

Bland-Altman plot of interobserver agreement. The solid line in the middle represents the mean difference of the diameter measurements between the 2 observers; the dashed line represents the upper and lower limits of agreement (mean difference ± 1.96 × SD).

Fig 4.

Overview baseline 3T Gd-enhanced MR imaging of 66-year-old woman with a saccular ECAA of the right internal carotid artery. At baseline, enhancement of the aneurysm wall was observed after contrast administration, indicated by the white arrows. T2 FLAIR and T2 TSE show both periventricular and deep white matter lesions and Fazekas 3 and multiple bilateral lacunar infarctions. adm indicates contrast administration.