Smooth muscle cells of human intracranial aneurysms assume phenotypic features similar to those of the atherosclerotic plaque.

OBJECTIVES: Characterize the phenotypic features of smooth muscle cells (SMCs) in the wall of human saccular intracranial aneurysms (sIAs). METHODS AND RESULTS: We investigated by means of immunohistochemistry the expression of the cytoskeletal differentiation markers α-smooth muscle actin (α-SMA), smooth muscle myosin heavy chains (SMMHCs), and smoothelin in 26 sIAs and 15 nonaneurysmal cerebral arteries. In addition, S100A4, a recently identified marker of dedifferentiated SMCs in atherosclerotic plaques, was also investigated. Six sIAs and 5 nonaneurysmal arteries were used for morphometric analysis. sIAs displayed a significant medial atrophy compared with nonaneurysmal cerebral arteries; moreover, sIA SMCs showed marked decrease of α-SMA and SMMHCs expression and disappearance of smoothelin. Unexpectedly, S100A4 was strongly up-regulated in media SMCs of sIAs. CONCLUSIONS: In sIAs, media SMCs acquire a dedifferentiated phenotype and show de novo expression of S100A4, characteristic features of atherosclerotic plaque SMCs.

Cerebral developmental venous anomalies: current concepts.

Cerebral developmental venous anomalies are the most frequently encountered cerebral vascular malformation, and as such, are frequently reported as fortuitous findings in computed tomography (CT) and magnetic resonance imaging (MRI) studies. Developmental venous anomalies (DVAs) are generally considered extreme anatomical variations of the cerebral vasculature, and follow a benign clinical course in the vast majority of cases. Here we review current concepts on DVAs with the aim of helping clinicians understand this complex entity. Morphological characteristics that are necessary to conceptualize DVAs are discussed in depth. Images modalities used in diagnosing DVAs are reviewed, including new MRI or CT techniques. Clinical presentation, association with other vascular malformations and cerebral parenchymal abnormalities, and possible physiopathological processes leading to associated imaging or clinical findings are discussed. Atypical forms of DVAs are also reviewed and their clinical significance discussed. Finally, recommendations as to how to manage asymptomatic or symptomatic patients with a DVA are advanced.

Regression of cerebral calcifications after endovascular treatment in a case of vein of Galen arteriovenous malformation.

The authors present the case of an infant harboring a vein of Galen arteriovenous malformation with conspicuous cerebral calcifications that progressively regressed after staged endovascular obliteration of the lesion. The role of venous hypertension and hydrocephalus secondary to the arteriovenous shunt are discussed to explain the formation and regression of the cerebral calcifications.

Developmental anatomy, angiography, and clinical implications of orbital arterial variations involving the stapedial artery.

Classical anatomists have provided detailed description of the arterial collateral pathways found in the head and neck. The small branches building this intricate network are difficult to access. The arterial map inherited from the anatomists has been put to the test with detailed high-resolution vascular imaging. Superselective angiography has helped rediscover the complexity of the craniocervical arterial network. The concept of dangerous collaterals or dangerous anastomoses was born with the advent of endovascular therapy. Although dangerous anastomoses of the skull base are described in the literature, variations and collateral pathways have been overlooked or misunderstood. This article reviews normal orbital arterial vascularization and its principal variations.

Whole-brain perfusion CT performed with a prototype 256-detector row CT system: initial experience.

PURPOSE: To preliminarily evaluate the feasibility and potential diagnostic utility of whole-brain perfusion computed tomography (CT) performed with a prototype 256-detector row CT system over an extended range covering the entire brain to assess ischemic cerebrovascular disease. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Eleven cases in 10 subjects (six men, four women; mean age, 64.3 years) with intra- or extracranial stenosis were retrospectively evaluated with whole-brain perfusion CT. Three readers independently evaluated perfusion CT data. The diagnostic performance of perfusion CT was visually evaluated with a three-point scale used to assess three factors. Differences between four axial perfusion CT images obtained at the basal ganglia level (hereafter, four-section images) and whole-brain perfusion CT images were assessed with the paired t test. In four subjects, the interval between perfusion CT and single photon emission computed tomography (SPECT) was 1-17 days (mean, 10.3 days). Correlation between perfusion CT findings and SPECT findings was assessed with the Spearman correlation coefficient. RESULTS: Three-dimensional perfusion CT images and axial, coronal, and sagittal whole-brain perfusion CT images were displayed, and the extent of ischemia was assessed. Mean visual evaluation scores were significantly higher for whole-brain images than for four-section images (4.27 +/- 0.76 [standard deviation] vs 2.55 +/- 0.87). The cerebral blood flow ratios of the ischemic lesions relative to normal regions scanned with perfusion CT (x) and SPECT (y) showed a significant positive correlation (R(2) = 0.76, y = 0.44 x + 0.37, P < .001). CONCLUSION: Perfusion CT performed with a 256-detector row CT system can be used to assess the entire brain with administration of one contrast medium bolus. Thus, ischemic regions can be identified with one examination, which has the potential to improve diagnostic utility.

Arterialization of cerebral veins on dynamic MDCT angiography: a possible sign of a dural arteriovenous fistula.

OBJECTIVE: MDCT angiography allows fast imaging of the cerebral vessels, and its potential as a noninvasive technique to detect vascular abnormalities on the basis of morphologic changes is well established. We analyzed vascular enhancement patterns of cerebral venous structures on MDCT angiography, which enabled us to diagnose dural arteriovenous fistula. CONCLUSION: MDCT angiography performed during an early arterial phase showed asymmetrically higher contrast intensity in the transverse or sigmoid sinus, or both, in five patients. In all patients, digital subtraction angiography confirmed the presence of a dural arteriovenous fistula on the side on which the higher contrast intensity appeared. Radiologists should actively look for this sign in the imaging workup of patients presenting with nonspecific symptoms that might be related to a dural arteriovenous fistula.