[CT diagnostics of carotid artery stenosis]

CT angiography can be used to evaluate carotid artery stenosis with high diagnostic safety. In contrast to the gold standard digital subtraction angiography (DSA) it is a non-invasive procedure which yields information regarding the degree of stenosis as well as information about plaque morphology. Due to multiple reconstruction planes in 3 levels in maximum intensity projections (MIP) and the possibility to perform volume rendering (VR) reconstruction more information about the extent of carotid disease can be acquired. Due to the bolus tracking technique optimum contrast medium enhancement of the carotid artery with simultaneous minimization of venous artifacts is possible.

[Multiple aneurysms of intracranial arteries in neurofibromatosis Recklinghausen type 1]

We report on a 58 year old female patient with neurofibromatosis Recklinghausen type 1 (NF-1) in whom multiple intracranial aneurysms could be proven. Vascular changes in patients with NF-1 are frequent and concern primarily the aorta, the kidney arteries, the coronary and gastrointestinal arteries. Our case shows that in patients with NF-1 intracranial artery changes like aneurysms, maybe in need of treatment, are possible.

The Oxidation Behaviour of Ruthenium in the Presence of Platinum and its Effect on the Electrocatalytic Activity of Pt-Ru Fuel Cell Catalysts

Pt-Ru electrocatalysts are commonly applied anode materials for low-temperature fuel cells, as the addition of ruthenium improves the CO tolerance of the otherwise CO-sensitive platinum catalysts, either by an electronic effect or by electro-oxidation via oxygen-containing adsorbates in the so-called bifunctional mechanism. However, since bulk ruthenium oxidation already takes place at potentials of less than 1.0V vs. RHE and hydrous ruthenium oxide is suggested to be the active species in the bifunctional mechanism, the amount and specific nature of ruthenium oxides play an important role in fuel cell catalysis. Two Pt-Ru catalyst systems with distinctly different Pt-Ru separation have been studied: a carbon-supported Pt-Ru alloy electrocatalyst (Pt-Ru) and a mixture of carbon-supported Pt and carbon-supported Ru (Pt/Ru). Controlled heat-treatment experiments were carried out in air atmosphere at 100°C and 500°C to study the effect of deliberate ruthenium oxidation on the catalyst structure and electrochemical performance. At a heat-treatment temperature of 100°C, the Pt-Ru alloy appears less sensitive towards oxidation than the Pt/Ru mixture, although its lattice parameter increases from about 3.880Å to 3.907Å indicating that part of the ruthenium is pulled out of the alloy phase to form a (amorphous) ruthenium oxide. After heat-treatment at 500°C in air, X-ray patterns of the Pt-Ru alloy and the Pt/Ru mixture look almost alike. However, transmission electron micrographs reveal a distinctly different separation between the Pt and the Ru oxide phase with the Pt-Ru alloy system having many more Pt/Ru neighbour sites available. Complementary XPS measurements show a higher share of electrocatalytically inactive ruthenium oxide in the Pt/Ru mixture catalyst heat-treated at 100°C. The onset of the methanol oxidation reaction (MOR) for the different catalysts increases in the order Pt-Ru < Pt/Ru < Pt independent of the treatment underlining the importance of Pt/Ru site distribution and ruthenium oxide content for the electrocatalytic activity.

[Bilateral spontaneous carotid artery dissection in osteogenesis imperfecta (type I)]

We report on a 36-year-old patient with an acute cerebral infarction due to a spontaneous dissection of both internal carotid arteries in conjunction with type I osteogenesis imperfecta. Spontaneous dissections of cerebral arteries (DCA) represent a common cause of cerebral infarctions in younger patients. Our case shows that a hereditary connective tissue disorder should be considered in all patients with "spontaneous" DCA. The identification of an - initially unknown - hereditary connective tissue disorder may con-tribute to primary and secondary prophylaxis of cerebral ischemia.

Revascularization in acute ischaemic stroke using the penumbra system: the first single center experience

BACKGROUND AND PURPOSE

This is the first single center experience illustrating the effectiveness of the penumbra system (PS) in the treatment of large vessel occlusive disease in the arena of acute ischaemic stroke. The PS is an innovative mechanical thrombectomy device, employed in the revascularization of large cerebral vessel occlusions in patients via the utilization of an aspiration platform.

METHODS

This is a prospective, non-randomized controlled trial evaluating the clinical and functional outcome in 29 patients with acute intra-cranial occlusions consequent to mechanical thrombectomy by the PS either as mono-therapy or as an adjunct to current standard of care. Patients were evaluated by a neurologist and treated by our in house interventional neuro-radiologists. Primary end-points were revascularization of the occluded target vessel to TIMI grade 2 or 3 and neurological outcome as measured by an improvement in the NIH Stroke Scale (NIHSS) score after the procedure.

RESULTS

Complete revascularization (TIMI 3) was achieved in 21/29 (72.4%) of patients. Partial revascularization (TIMI 2) was established in 4/29 (13.8%) of patients. Revascularization failed in four (13.8%) patients. Nineteen (19) patients (65.5%) had at least a four-point improvement in NIHSS scores. Modified Rankin scale scores of < or =2 were seen in 37.9% of patients. There were no device-related adverse events. Symptomatic intra-cranial hemorrhage occurred in 7% of patients.

CONCLUSIONS

The PS has the potential of exercising a significant impact in the interventional treatment of ischaemic stroke in the future.

[Mechanical recanalization]

Although several studies and registries have focused on new interventional systems for the treatment of acute ischemic stroke, a standard procedure has not yet been established. The procedure itself is still controversially discussed but studies have shown that patients who were successfully treated with mechanical recanalization had a better clinical outcome.

[Magnetic resonance imaging and computed tomography findings in lacunar brain infarctions]

Lacunar brain infarctions belong to the most common causes of stroke and are typically located in basal ganglia with embolic, atheromatous or thrombotic etiology. Lipohyalinosis, often as a result of a long history of hypertension, can also be a cause of lacunar lesions. At present more than 20 different lacunar syndromes have been described. However clinical findings may be variable ranging from clinically"silent" to focal neurologic deficits to cognitive impairment. Magnetic resonance imaging (using diffusion-weighted sequences) generally allows diagnosis in most cases of acute lacunar infarcts and is superior to computed tomography especially in cases of additional leucoaraiosis.

[Acute disseminated encephalomyelitis]

Acute disseminated encephalomyelitis (ADEM) is an acute widespread autoimmune demyelinating condition, which principally affects the white matter of the brain and spinal cord. It usually follows an infection or vaccination. The typical presentation is that of multifocal neurologic disturbances accompanied by change in mental status. CSF analysis reveals lymphocytic pleocytosis and elevated protein content, but may also yield normal results. MRI is regarded as the diagnostic imaging modality of choice and typically demonstrates involvement of deep cerebral hemispheric and subcortical white matter as well as lesions in the basal ganglia, gray-white junction, diencephalon, brainstem, cerebellum and spinal cord. Unlike multiple sclerosis (MS), ADEM has a monophasic course and a favorable long-term prognosis.

[Magnetic resonance spectroscopy for inflammatory brain diseases]

Magnetic resonance spectroscopy (MRS) is a non-invasive method for investigation of cerebral metabolite concentrations in various pathologic conditions. The clinical use of MRS for intracranial disorders is well established. In this review the characteristic MRS findings for the most important inflammatory brain diseases will be discussed.

[Orbital tumors]

Computed tomography (CT) and magnetic resonance imaging are the modalities of choice in the assessment of orbital neoplasms. Careful interpretation of the characteristic radiological features usually leads to the correct diagnosis; however, some of the lesions look very similar and are difficult to differentiate from each other. This contribution provides an overview of tumors of the eye and orbit and their appearance on CT and magnetic resonance imaging.

Long-term results with Matrix coils vs. GDC: an angiographic and histopathological comparison

INTRODUCTION

The aim of the study was to compare standard platinum Guglielmi detachable coils (GDC) with coated platinum coils (Matrix; both Boston Scientific, Fremont, CA) regarding handling, complications, occlusion and recanalization rate after 3 and 6A months.

METHODS

Aneurysms in the right common carotid artery were created in 25 rabbits. The animals were divided into five groups of five animals each. The animals of group 1 (the control group) received no treatment of the induced aneurysms, the animals of groups 2 and 3 (killed at 3 and 6A months) were treated with standard GDC, and the animals of groups 4 and 5 (killed at 3 and 6A months) were treated with Matrix coils.

RESULTS

Histopathological evaluation showed organized thrombus formation and connective tissue with neovascularization around the implanted coils in all the treated groups. The achieved occlusion rates in groups 2 and 3 were identical to those in groups 4 and 5. Thus the long-term results of aneurysm treatment with GDC and Matrix coils show no differences regarding occlusion and recanalization rates. The only noticeable difference was the difference in handling. More force was required to pushing the Matrix coils forward through the microcatheter and there was more friction in coil interaction in the aneurysm.

CONCLUSION

The bioactive coating of the Matrix coil produces no significant benefit in achieving higher occlusion and lower recanalization rates, and the coil is more difficult to handle. Future bioactive coils must be shown to produce significantly better long-term results than GDC and their ease of handling has to be improved.

Bifunctional electrocatalysis in pt-ru nanoparticle systems

Pt-Ru alloys are prominent electrocatalysts in fuel cell anodes as they feature a very high activity for the oxidation of reformate and methanol. The improved CO tolerance of these alloys has been discussed in relation to the so-called ligand and bifunctional mechanisms. Although these effects have been known for many years, they are still not completely understood. A new approach that bridges the gap between single crystals and practical catalysts is presented in this paper. Nanoparticulate model systems attached to an oxidized glassy carbon electrode were prepared by combining both ligand-stabilized and spontaneously deposited Pt and Ru nanoparticles. These electrodes showed very different voltammetric responses for CO and methanol oxidation. The cyclic voltammograms were deconvoluted into contributions attributed to Pt, Ru, and Pt-Ru contact regions to quantify the contribution of the latter to the bifunctional mechanism. Scanning transmission electron microscopy confirmed the proximity of Pt and Ru nanoparticles in the different samples.

[Cavernous malformations]

Cavernomas of the CNS may involve brain parenchyma as well as the spinal cord and belong to those cerebrovascular malformations that have no arteriovenous shunt and thus are generally angiographically occult. Contrary to computed tomography (CT), which is generally suited to reveal calcifications or acute bleeding, magnetic resonance imaging (MRI) enables detection of even small cavernomas. A frequently associated venous anomaly is helpful for correct diagnosis.