Hypoplasia or stenosis: Usefulness of high-resolution MRI

The Role of High-Resolution Magnetic Resonance Imaging in Cerebrovascular Disease: A Narrative Review

High-resolution magnetic resonance imaging (HRMRI) is the most important and popular vessel wall imaging technique for the direct assessment of vessel wall and cerebral arterial disease. It can identify the cause of stroke in high-risk plaques and differentiate the diagnosis of head and carotid artery dissection, including inflammation, Moya Moya disease, cerebral aneurysm, vasospasm after subarachnoid hemorrhage, reversible cerebral vasoconstriction syndrome, blunt cerebrovascular injury, cerebral arteriovenous malformations, and other stenosis or occlusion conditions. Through noninvasive visualization of the vessel wall in vitro, quantified assessment of luminal stenosis and pathological features of the vessel wall can provide clinicians with further disease information. In this report, technical considerations of HRMRI are discussed, and current clinical applications of HRMRI are reviewed.

Clinical Importance of the Persistent Primitive Trigeminal Artery in Vascular Lesions and Its Role in Endovascular Treatment

The persistent primitive trigeminal artery (PPTA) extends from the internal carotid artery to the basilar artery between the origins of the anterior inferior cerebellar artery and superior cerebellar artery. PPTAs have complex anatomical characteristics. Salas and Saltzman classifications are most often used in PPTAs. The PPTA can play many roles in vascular lesions, including intracranial aneurysms, brain arteriovenous malformations, trigeminal artery-cavernous fistulas, Moyamoya disease, and large vessel occlusion. For these lesions, surgical treatment is difficult due to the deep location and complex anatomy of the PPTA, but endovascular treatment (EVT) has emerged as a good alternative. Currently, a complete review of the clinical importance of the PPTA in terms of its role in the development and EVT of vascular lesions is lacking. Therefore, we conducted a PubMed search, performed a review of the relevant extracted literature and cataloged our experience with PPTAs. By review, we found that a thorough understanding of the anatomical and angiographic features of this PPTA is of utmost importance when making therapeutic decisions for any of these pathological conditions.

Endovascular recanalization for chronic symptomatic intracranial vertebral artery total occlusion: Experience of a single center and review of literature

OBJECTIVE

The optimal treatment of chronic symptomatic total occlusion of the intracranial vertebral artery (ICVA) remains undefined. We report a single-center experience of endovascular recanalization for patients with chronic symptomatic ICVA occlusion who were refractory to medical therapy.

METHODS

From Jan 2009 to Jan 2017, we retrospectively reviewed 14 consecutive patients presenting with recurrent symptoms attributed to the chronic ICVA occlusion. We searched previous literature using PubMed databases during the same period as comparison.

RESULTS

Eleven patients out of 14 presented initial symptoms to intervention less than 90days. The occlusion course was extrapolated on simultaneous two-vessel injection angiography or high-resolution MR imaging (HRMRI) in 13 cases. Nine patients had the occlusion beyond the origin of posterior inferior cerebellar artery (PICA) and 5 had the occlusion proximal to the PICA origin. The technical success rate of recanalization was 85.7% (12/14). Two patients (14.3%, 2/14) had peri-procedural complications: 1 developed TIA and 1 presented with perforator occlusion syndrome. Using the keyword-based search, we identified 6 studies at the same period. A total of 34 patients underwent recanalization with the successful recanalization rate at 94.1%, peri-procedural complication rate at 17.6% and mortality at 2.9%, respectively.

CONCLUSION

Our single-center study illustrated the feasibility and safety of ICVA recanalization. Great care should be taken as revascularization is of high risk. When patient selection, occlusion course and stage as well as neuroimaging evaluation are considered, endovascular recanalization may be a useful therapeutic modality.

Increased risk for posterior circulation ischaemia in patients with vertebral artery hypoplasia: A systematic review and meta-analysis

Introduction

Although several study protocols reported that vertebral artery hypoplasia can predispose to posterior circulation ischaemia, the role of vertebral artery hypoplasia in the risk of posterior circulation ischaemia still remains controversial. The aim of the present meta-analysis was to investigate the association of vertebral artery hypoplasia and posterior circulation ischaemia.

Patients and methods

We performed a systematic review and random effects meta-analysis of all eligible observational study protocols reporting prevalence rates of vertebral artery hypoplasia in patients with anterior circulation ischaemia and posterior circulation ischaemia.

Results

We identified eight study protocols including a total of 3875 acute ischemic stroke patients (mean age: 64.2 years, 61.3% males) and reporting a pooled prevalence of vertebral artery hypoplasia 18.6% (95%CI: 10.8-30.0%). In the overall analysis, a significantly higher probability of vertebral artery hypoplasia presence was found in posterior circulation ischaemia patients compared to patients with anterior circulation ischaemia (risk ratio = 2.12, 95%CI: 1.60-2.82, p < 0.001). In the subsequent sensitivity analysis, vertebral artery hypoplasia was again found to be significantly more prevalent in patients with posterior circulation ischaemia compared to anterior circulation ischaemia (risk ratio = 1.81, 95%CI: 1.58-2.06, p < 0.001), with no evidence of heterogeneity (I²= 0%, p for Cochran Q = 0.55) between included studies.

Discussion

The present report is a meta-analysis of retrospective observational study protocols, with all the inherent limitations of included studies. The heterogeneity on the reported rates of vertebral artery hypoplasia could be attributed to differences in population age, sex, race, imaging protocols and vertebral artery hypoplasia definition between included studies.

Conclusion

Our meta-analysis provides further evidence for a possible causal relationship between vertebral artery hypoplasia and cryptogenic posterior circulation ischaemia, an association which undoubtedly deserves further investigation in future prospective study protocols.

Wall Imaging for Unilateral Intracranial Vertebral Artery Hypoplasia with Three-dimensional High-isotropic Resolution Magnetic Resonance Images

BACKGROUND

There are few studies for evaluating wall characteristics of intracranial vertebral artery hypoplasia (VAH). The aim of this study was to determine wall characteristics of VAH with three-dimensional volumetric isotropic turbo spin echo acquisition (3D VISTA) images and differentiate between acquired atherosclerotic stenosis and VAH.

METHODS

Thirty patients with suspicious VAH by luminograms were retrospectively enrolled between January 2014 and February 2015. The patients were classified as "acquired atherosclerotic stenosis" or "VAH" based on 3D VISTA images. The wall characteristics of VAH were assessed to determine the presence of atherosclerotic lesions, and the patients were classified into two subgroups (VAH with atherosclerosis and VAH with normal wall). Wall characteristics of basilar arteries and vertebral arteries were also assessed. The clinical and wall characteristics were compared between the two groups.

RESULTS

Five of 30 patients with suspicious VAH were finally diagnosed as acquired atherosclerotic stenosis by 3D VISTA images. 25 patients were finally diagnosed as VAH including 16 (64.00%) patients with atherosclerosis and 9 (36.00%) patients with normal wall. In the 16 patients with atherosclerosis, plaque was found in 9 patients, slight wall thickening in 6 patients, and thrombus and wall thickening in 1 patient. Compared with VAH patients with normal wall, VAH patients with atherosclerosis showed atherosclerotic basilar arteries and dominant vertebral arteries more frequently (P = 0.000).

CONCLUSIONS

Three-dimensional VISTA images enable differentiation between the acquired atherosclerotic stenosis and VAH. VAH was also prone to atherosclerotic processes.