In vivo visualisation of Charcot-Bouchard Aneurysms on lenticulostriate arteries using 7T MRI.

Background and purpose: Charcot-Bouchard Aneurysms (CBA) are tiny aneurysms arising from small perforating arteries. Despite the potentially catastrophic consequences of rupture of these aneurysms, the existence and prevalence of CBAs is controversial. The literature in this area is sparse with most previous studies based on radiological case reports of single hemorrhage or histopathological analysis. 7T MRI provides higher spatial resolution than 3T MRI that enables imaging of the small perforating arteries. We determined whether CBAs could be detected in vivo using 7T MRI.

Materials and methods: 94 patients with ischemic stroke collected in the Cam-SVD prospective cohort were retrospectively included; 75 of them had lacunar infarcts due to presumed small vessel disease and 19 had non-lacunar infarcts due to presumed cardioembolism or large artery disease. Contrast enhanced 3D time-of-flight (TOF) angiography (MRA) and structural sequences were performed by 7T MRI. Two neuroradiologists independently reviewed the MR scans to identify aneurysms on the lenticulostriate arteries (LSA) bilaterally.

Results: In 4 of the 94 subjects, CBAs were detected in the LSAs; of these three had a single CBA and one had two. The diameter of the parent vessel ranged from 0.26mm - 0.37mm, and the maximum diameter of the CBA ranged from 0.73mm - 1.39mm. Use of 3D images allowed differentiation of looped vessels, which could mimic aneurysms on 2D images, from true CBA.

Conclusions: We have demonstrated that 7T MRI can detect CBAs in vivo in humans. This technique could allow further longitudinal studies to determine the true prevalence and prognostic significance of CBAs.

Abbreviations: CBA: Charcot-Bouchard Aneurysms; LSA: lenticulostriate arteries; CamSVD: Cambridge 7T Cerebral Small Vessel Disease study; eGFR: estimated glomerular filtration rate; FA: flip angle.