MRI-Based Separation of Congenital and Acquired Vertebrobasilar Artery Anomalies in Ischemic Stroke of the Posterior Circulation

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.

Predisposing factors in posterior circulation infarcts: a vascular morphological assessment

INTRODUCTION

The aim of the study is to assess the effect of shape, diameter, elongation and deviation criteria of basilar artery (BA), convergence angle and diameter variations of vertebral arteries, and concurrent chronic diseases on posterior circulation infarcts.

METHODS

Between January 2010 and May 2013, 186 patients who underwent brain and diffusion magnetic resonance imaging (MRI) with suspected cerebrovascular accident and were diagnosed with posterior circulation infarct and 120 infarct negative control subjects were included in this case-control retrospective study. Vertebral artery (VA) and BA diameter, right (R) and left (L) VA angles at the level of bifurcation, and BA elongation-deviation, and shape of BA were assessed in a total of 306 subjects. Ischemic lesions in the posterior circulation were classified according to their anatomical location and vascular perfusion areas.

RESULTS

No significant difference was noted between the control and patient groups with respect to BA diameter (p = 0.676). The most effective risk factors for posterior circulation infarcts were as follows: BA elongation of 2 or 3, BA transverse location of 2 or 3, increase in left VA angle, and history of hypertension, hypercholesterolemia, and diabetes mellitus.

CONCLUSION

Our results suggest that prominent elongation and deviation, C and J shape of BA, and increased L VA angle may be the predictors of at-risk patients in posterior circulation infarcts. Reporting marked morphological BA and VA variations detected at routine brain MRI will aid in selection of patients. Timely detection and treatment of at-risk patients may be life-saving.

Diagnosis of anterior inferior cerebellar artery occlusion on magnetic resonance angiography with reference to basiparallel anatomic scanning-magnetic resonance imaging

A 67-year-old woman presented with symptomatic infarction in the territory of the anterior inferior cerebellar artery manifesting as vertigo, vomiting, and right facial weakness. Basiparallel anatomic scanning (BPAS) magnetic resonance (MR) imaging combined with MR angiography demonstrated the occluded anterior inferior cerebellar artery. Common anatomic variations and limited detection of the smaller branches on MR angiography sometimes hinder evaluation of the occluded artery. BPAS-MR imaging may have a supplementary role to MR angiography in the diagnosis of cerebellar artery occlusions.

Hypoplasia or stenosis: Usefulness of high-resolution MRI

INTRODUCTION

Hypoplastic basilar (BA) and vertebral arteries (VA) can cause posterior circulation infarctions. Distinction between hypoplastic and atherosclerotic BA can be difficult with usual angiographic methods (MR, CT or conventional angiographies), only showing arterial luminogram. High-resolution MRI (HRMRI) of the arterial wall is promising in identifying intracranial artery plaques.

OBSERVATION

A 70-year-old man with vascular risk factors suddenly presented with vertigo. MRI showed no brain infarction. Contrast-enhanced MRA showed small and irregular BA lumen compatible with severe atherosclerotic stenosis. An associated persistent primitive trigeminal artery was noticed. HRMRI of the BA rectified the initial angiographic diagnosis by showing a normal vessel wall without any thickening that could suggest atherosclerotic plaque.

CONCLUSION

In the event of BA lumen narrowing, HRMRI may help distinguish between hypoplastic and atherosclerotic artery.