[Noninvasive carotid plaque characterization by black blood MRI].

Management of atherosclerotic carotid arteries requires both plaque characterization and determination of the degree of stenosis, especially when carotid stenting (CAS) is being considered for severe carotid stenosis. Recent studies have demonstrated that high-resolution MRI can identify plaque components, such as the lipid-rich necrotic core, intraplaque hemorrhage, fibrous tissue, and the calcification present in human carotid atherosclerosis. The purpose of this study was to assess the feasibility of black blood MRI (BB-MRI) for accurately identifying the plaque components in vivo. Twenty-six consecutive patients scheduled for carotid endarterectomy (CEA) underwent a BB-MRI examination within 2 weeks before the surgical procedure using a 1.5-T Philips scanner with a protocol that generated 2 contrast weightings (T1 and T2). The MR images were acquired using cardiac gating to minimize motion artifact and fat suppression to reduce MR signals from subcutaneous fatty tissue. The plaque evaluations obtained by BB-MRI were compared with the intra-operative video recordings, the excised specimens, and the histological sections. With BB-MRI, the combination of the signal intensities in the T1- and T2-weighted images for each component (lipid deposits, intra-plaque hemorrhage, fibrous plaque, and calcification) showed findings that corresponded with the excised specimens. Complex morphological features could also be assessed by BB-MRI. BB-MRI is a useful method for noninvasively imaging and characterizing atherosclerotic carotid arteries. This MRI technique can provide valuable information that can be used to decide whether to perform a CEA or a CAS in patients with severe carotid stenosis. Furthermore, BB-MRI appears to be a useful tool for the investigation of the pathogenesis and natural history of carotid atherosclerosis.

[Bilateral vertebral artery dissection and its chronological changes detected by MR angiography: a case report].

A case of intracranial bilateral vertebral artery (VA) dissection presenting with ischemic symptoms which following unilateral dissection is presented. A 42-year-old male with an occipital headache was pointed out right vertebral artery stenosis with magnetic resonance (MR) angiography 8 day before admission. He admitted to our hospital complaining of severe vertigo and tinnitus. MR images and cerebral angiograms revealed bilateral VA dissection with infarcts in light lower surface of cerebellum perfused by posterior inferior cerebellar artery and right hypothalamus. Conservative therapy was adopted and serial MR angiography was performed. His symptoms were improved gradually and MR angiograms obtained 2 months later revealed improvement of bilateral VA stenosis. It is generally accepted that VA dissection presenting ischemic symptoms has good outcome by conservative therapy only. However, its pathological process of progression is still unknown. Based on the serial MR findings, we discuss the mechanisms of bilateral VA dissection. In this case, we consider that unilateral VA dissection extended to contralateral vertebral artery through the vertebrobasilar junction. Frequent MR angiography in acute phase could be of great use for monitoring the progression of dissection.

[Fenestration of the extracranial internal carotid artery: report of two cases].

Fenestration of the internal carotid artery (ICA) is extremely rare on clinical settings. Six cases of fenestration in intracranial and 8 in extracracranial ICA have ever been reported in literature. Authors describe two cases of fenestration at the extracranial ICA that were initially suspected of the dissection of ICA on MRA/I. Both angiography and CT angiography (CTA) disclosed the fenestration, which located at C2 vertebral levels. To confirm the fenestration at extracranial ICA is important in such an occasion that mimic the dissection of ICA, especially in patients who complain of cervical pain, mass and other related symptoms. Differences in the fenestration, the dissection and atherosclerosis on imaging, were reviewed and discussed.