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1.
Nervenarzt ; 91(10): 902-907, 2020 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-32930814

RESUMO

BACKGROUND: In order to treat the complete spectrum of neurovascular diseases at a high level of quality, which goes beyond the purely acute treatment of stroke, the German Stroke Society (DSG) together with the German Societies for Neurosurgery and Neuroradiology developed a certification procedure for neurovascular networks (NVN). Structurally, a NVN consists of a coordinating center with at least three neurovascular network partners with a certified stroke unit. From 2018 to 2020 a total of 15 NVN have so far been audited and certified according to this new standard. OBJECTIVE: How efficient are the NVN? Are high standards maintained? MATERIAL AND METHODS: The reports of the audits were analyzed. The data were taken from the period 2017-2019. RESULTS: The 15 NVN treated a total of 86,510 stroke patients in the years examined and were networked with a total of 107 partner clinics, which were situated an average of 25 km from the coordinating center and transferred a total of 2726 patients. The coordinating centers performed 2463 thrombectomies and treated 2383 patients with nontraumatic intracerebral bleeding. In 712 patients with acute aneurysmatic subarachnoid hemorrhages endovascular treatment was carried out and clipping in 401. The audit was successful in the majority of the NVN. CONCLUSION: The certification process of NVN has been successfully established and the audits proved to be a useful instrument for quality control and improvement. The 15 NVN are highly efficient and treat more than one quarter of stroke patients in German stroke units.


Assuntos
Acidente Vascular Cerebral , Trombectomia , Certificação , Humanos , Acidente Vascular Cerebral/terapia
2.
Phys Chem Chem Phys ; 21(16): 8342-8351, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30933196

RESUMO

By employing ab initio computed intermolecular potential energy surfaces we calculate the radiative association probabilities and rates for two different associative mechanisms involving trapped molecular ions N2+(2Σg) interacting either directly with ultracold Rb atoms or undergoing charge-exchange (CE) processes leading to the formation of complexes of the strongly exothermic products N2(X1Σg) plus Rb+(1S0). The two processes are expected to provide possible paths to ion losses in the trap within the timescale of experiments. The present calculations suggest that the associative rates for the 'vibrational' direct process are too small to be of any significant importance at the millikelvin temperatures considered in the experiments, while the 'vibronic' path into radiatively associating the CE products has a probability of occurring which is several orders of magnitude larger. However the reaction rate constants attributed to non-adiabatic CE [F. H. J. Hall and S. Willist, Phys. Rev. Lett., 2012, 109, 233202] are in turn several orders of magnitude larger than the radiative ones calculated here, thereby making the primary experimental process substantially unaffected by the radiative losses channel.

3.
Strahlenther Onkol ; 192(7): 489-97, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27245820

RESUMO

INTRODUCTION: For both patients with high-grade gliomas and multiple cerebral metastases, radio(chemo)therapy is the standard therapy. Neurological decline during treatment is rarely attributed to infections of the brain but to tumor progression or side effects of radiotherapy. CASE REPORTS: We present 4 cases of cytomegalovirus (CMV) viremia associated with neurological deterioration, which occurred during or shortly after radiotherapy and/or chemotherapy of the brain (brain metastases 2, high-grade glioma 1, carcinoma infiltrating brain 1). In all cases, neurological decline was sudden and unexpected, and causes such as increased intracranial pressure or tumor progression could be excluded radiologically. Treatment with dexamethasone and mannitol had no or only very short-term effects. General infections were either excluded or receding before the neurological symptoms occurred. All patients presented with decreasing levels of thrombocytes. In all cases, CMV (re)activation could be proven using blood test for CMV-DNA. The anti-CMV-IgG status suggested reactivation rather than a primary infection. One patient died within 72 h of onset of the symptoms (results of CMV tests were received postmortem). Diagnosis of 3 patients allowed successful administration of antiviral treatment, which greatly improved the general and neurological conditions of the patients within 48 h. DISCUSSION: Neurological deterioration during RT is hardly ever attributed to viral infections. These cases suggest that CMV reactivation and subsequent infection might actually be causative and has to be considered and treated. CONCLUSION: Further prospective studies verifying and investigating this observation in terms of frequency and clinical relevance seem indicated.


Assuntos
Neoplasias Encefálicas/terapia , Quimiorradioterapia/efeitos adversos , Infecções por Citomegalovirus/tratamento farmacológico , Infecções por Citomegalovirus/etiologia , Doenças do Sistema Nervoso/etiologia , Doenças do Sistema Nervoso/prevenção & controle , Idoso , Antivirais/administração & dosagem , Neoplasias Encefálicas/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Doenças do Sistema Nervoso/diagnóstico , Resultado do Tratamento , Viremia/diagnóstico , Viremia/tratamento farmacológico , Viremia/etiologia
4.
Radiologe ; 55(8): 654-62, 2015 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-26245985

RESUMO

Flat detectors (FD) have completely replaced image intensifiers in angiography. Due to this development not only the image quality of 2D digital subtraction angiography series (2-D-DSA) could be improved but also the acquisition of computed tomography (CT)-like cross-sectional images (FD-CT) within the angio suite became feasible. These techniques are now being used in daily clinical routine. Only little information about effective doses of these applications to patients has been published in the literature. We describe the effective patient dose of current applications in the field of angiography and demonstrate strategies to minimize the dose to the patient. In addition, we compare FD-CT applications to standard multislice CT applications.


Assuntos
Angiografia Cerebral/instrumentação , Neurorradiografia/instrumentação , Segurança do Paciente , Proteção Radiológica/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Ecrans Intensificadores para Raios X , Angiografia Cerebral/métodos , Desenho de Equipamento , Segurança de Equipamentos , Humanos , Neurorradiografia/métodos , Doses de Radiação , Tomografia Computadorizada por Raios X/métodos
6.
Fortschr Neurol Psychiatr ; 82(3): 149-54, 2014 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-24615586

RESUMO

Immunologically mediated heparin-induced thrombocytopenia (HIT) is a thrombotic disease caused by antibodies occurring after heparin exposure. Thrombocytopenia occurs within a few days after heparin exposure, about half of HIT-patients develop venous or arterial thrombotic complications. Neurological complications of HIT are mainly ischaemic stroke and sinus vein thrombosis. To ensure the primary clinical diagnosis functional and immunological assays for antibody detection are available. The probability for the occurrence of HIT depends on the nature of heparin employed (LMWH vs. UFH) and individual patient characteristics such as gender and primary disease (medical vs. surgical patients). In the case of suspected HIT heparin administration should be discontinued immediately and replaced by an alternative anticoagulation to prevent the expansion or development of further thrombotic complications. Herein we report a case of a patient suffering from HIT-associated embolic cerebral ischaemic stroke.


Assuntos
Anticoagulantes/efeitos adversos , Transtornos Cerebrovasculares/etiologia , Heparina/efeitos adversos , Trombocitopenia/complicações , Trombocitopenia/imunologia , Idoso , Anticorpos/análise , Anticorpos/imunologia , Anticoagulantes/química , Isquemia Encefálica/etiologia , Transtornos Cerebrovasculares/epidemiologia , Ecocardiografia Transesofagiana , Heparina/química , Heparina de Baixo Peso Molecular/efeitos adversos , Heparina de Baixo Peso Molecular/uso terapêutico , Humanos , Trombose Intracraniana/etiologia , Trombose Intracraniana/prevenção & controle , Masculino , Trombose dos Seios Intracranianos/etiologia , Acidente Vascular Cerebral/etiologia , Trombocitopenia/induzido quimicamente
7.
Acta Neurol Scand ; 127(4): 274-80, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22882005

RESUMO

PURPOSE: This study aims to investigate the contributions of magnetoencephalography (MEG) in magnetic resonance imaging (MRI)-negative patients. METHODS: A total of 18 MRI-negative patients diagnosed with refractory epilepsy, subjected to MEG investigation, and subsequently underwent surgery were selected for retrospective analysis. A 1.5-tesla Magnetom Sonata with an eight-channel head array coil was used. MEG data were obtained using a 74/248-channel system. RESULTS: A total of 16 patients (16/18) had positive MEG results, comprising 12 patients with monofocal localizations, five with multifocal localizations, and one with unremarkable results in MEG. In addition, 12 patients had indicative single photon-emission computed tomography (SPECT), five had indicative fluorodeoxyglucose positron emission tomography (FDG-PET), and all the patients had intracranial electroencephalography (EEG) (14 with subdural electrodes and four with electrocorticography). The intracranial EEG recordings of nine patients were guided by MEG informative results. Among these 18 patients, 10 exhibited good postoperative outcomes (Engel I and II), four of which were completely seizure-free. All these ten patients had clear monofocal localization in MEG, including nine with accordant indicative metabolic changes in either SPECT or FDG-PET, or both. None of the five patients with multifocal localizations achieved good postoperative outcomes. CONCLUSION: For cases with negative MRI findings, epilepsy surgery may be an alternative option for pharmaco-resistant patients if epileptogenic focus localizations by MEG are present in multimodal evaluation.


Assuntos
Encéfalo , Epilepsia/diagnóstico , Imageamento por Ressonância Magnética , Magnetoencefalografia , Adulto , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Encéfalo/fisiopatologia , Eletroencefalografia , Epilepsia/fisiopatologia , Feminino , Fluordesoxiglucose F18 , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada de Emissão , Gravação em Vídeo , Adulto Jovem
8.
Radiologe ; 53(3): 246-50, 2013 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-23435623

RESUMO

CLINICAL/METHODICAL ISSUE: Therapy of carotid stenosis should be based on an accurate assessment of the stenosis and a differentiation between symptomatic and asymptomatic patients. STANDARD RADIOLOGICAL METHODS: According to current guidelines carotid artery stenting (CAS) can be considered as an established therapeutic alternative to carotid endarterectomy (CEA). METHODICAL INNOVATIONS: For the therapy of carotid stenosis CAS has become established as a minimally invasive alternative to CEA because the complication rate has been reduced due to growing experience, technical innovations and external quality assessment. PERFORMANCE: The CAS procedure should be performed in centers with documented complication rates of < 3 % for asymptomatic and < 6 % for symptomatic stenoses. ACHIEVEMENTS: Overall there are no significant differences between CAS and CEA in the treatment of carotid stenosis concerning the secondary prophylactic effect. PRACTICAL RECOMMENDATIONS: Ideally an interdisciplinary approach should be chosen for the therapy regime. Revascularization of asymptomatic stenoses should be considered critically as these patients might profit from optimized conservative medicinal therapy.


Assuntos
Angiografia/métodos , Prótese Vascular , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/cirurgia , Radiografia Intervencionista/métodos , Stents , Humanos , Desenho de Prótese
9.
AJNR Am J Neuroradiol ; 44(4): 474-480, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36997283

RESUMO

BACKGROUND AND PURPOSE: Flow diverters with antithrombotic coatings are increasingly used to improve the safety of flow diverter treatments of intracranial aneurysms. This study aimed to investigate the safety and short-term efficacy of the new FRED X flow diverter. MATERIALS AND METHODS: Medical charts and procedural and imaging data of a consecutive series of patients with intracranial aneurysms who were treated with the FRED X at 9 international neurovascular centers were retrospectively analyzed. RESULTS: One hundred sixty-one patients (77.6% women; mean age, 55 years) with 184 aneurysms (11.2% acutely ruptured) were included in this study. Most aneurysms were located in the anterior circulation (77.0%), most frequently at the ICA (72.7%). The FRED X was successfully implanted in all procedures. Additional coiling was performed in 29.8%. In-stent balloon angioplasty was necessary in 2.5%. The rate of major adverse events was 3.1%. Thrombotic events occurred in 7 patients (4.3%) with 4 intra- and 4 postprocedural in-stent thromboses, respectively (1 patient had both peri- and postprocedural thrombosis). Of these thrombotic events, only 2 (1.2%) led to major adverse events (ischemic strokes). Postinterventional neurologic morbidity and mortality were observed in 1.9% and 1.2%, respectively. The rate of complete aneurysm occlusion after a mean follow-up of 7.0 months was 66.0%. CONCLUSIONS: The new FRED X is a safe and feasible device for aneurysm treatment. In this retrospective multicenter study, the rate of thrombotic complications was low, and the short-term occlusion rates are satisfactory.


Assuntos
Embolização Terapêutica , Procedimentos Endovasculares , Aneurisma Intracraniano , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Resultado do Tratamento , Fibrinolíticos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/terapia , Estudos Retrospectivos , Procedimentos Endovasculares/métodos , Stents , Embolização Terapêutica/métodos
10.
Klin Monbl Augenheilkd ; 229(2): 143-8, 2012 Feb.
Artigo em Alemão | MEDLINE | ID: mdl-22334412

RESUMO

BACKGROUND: In primary open angle glaucoma (POAG) and its non-barotraumatic subgroup, normal tension glaucoma (NTG), the pathophysiological differences are not clear. A participation of the 4th neuron of the visual pathway (optic radiation) appears possible on the basis of related experimental studies. The goal of the present study was the evaluation of the optic radiation by diffusion tensor imaging (DTI), which is based on the magnetic resonance imaging. The diffusion and anisotropy parameters of the optic radiation as a marker of axonal integrity and demyelination/damage of glial cells, respectively, were used to investigate the relation between the morphology of the papilla (BLDF, linear discriminant function of Burk) and the contrast sensitivity (FDT, frequency doubling test). PATIENTS AND METHODS: In this prospective observational study 13 POAG patients, 13 NTG patients, and 7 control patients of the same mean age were included. For segmentation of the optic radiation a semi-automated algorithm was applied and the diffusion and anisotropy parameters were calculated. The importance of the covariates age, BLDF, and FDT for the DTI parameters was determined using partial correlation analysis. RESULTS: Analysis of the covariates partially showed a clear autocorrelation. The correlations between the DTI parameters and BLDF were significant in all groups after correction of the measurement values for the covariates. FDT correlated with DTI parameters in controls and POAG. The NTG group did not show this correlation due to a strong spreading of the FDT values. CONCLUSION: After statistical elimination of the autocorrelation of the covariates age, BLDF, and FDT the morphology of the papilla correlated with the axonal integrity and demyelination/glia cell impairment of the optic radiation in controls and glaucoma. In NTG the impaired contrast sensitivity is highly variable and is not associated with the condition of the 3rd or 4th neuron, respectively, as compared to POAG. The autocorrelation between individual covariates represents an important element for the judgement of the visual pathway.


Assuntos
Sensibilidades de Contraste/fisiologia , Doenças Desmielinizantes/diagnóstico , Imagem de Difusão por Ressonância Magnética , Glaucoma de Ângulo Aberto/diagnóstico , Interpretação de Imagem Assistida por Computador , Glaucoma de Baixa Tensão/diagnóstico , Fibras Nervosas/patologia , Disco Óptico/patologia , Nervo Óptico/patologia , Retina/patologia , Vias Visuais/patologia , Adulto , Idoso , Algoritmos , Axônios/patologia , Axônios/fisiologia , Doenças Desmielinizantes/patologia , Doenças Desmielinizantes/fisiopatologia , Feminino , Glaucoma de Ângulo Aberto/patologia , Glaucoma de Ângulo Aberto/fisiopatologia , Humanos , Glaucoma de Baixa Tensão/patologia , Glaucoma de Baixa Tensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Neurônios/patologia , Neurônios/fisiologia , Disco Óptico/fisiopatologia , Nervo Óptico/fisiopatologia , Estudos Prospectivos , Sensibilidade e Especificidade , Estatística como Assunto , Vias Visuais/fisiopatologia
11.
Minim Invasive Neurosurg ; 54(4): 187-90, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21922449

RESUMO

BACKGROUND: Epistaxis is one of the most common emergencies of ENT surgery and can be managed conservatively in most cases. However, transarterial embolization is an accepted treatment option for intractable epistaxis, if conservative management fails. But often, direct detection of the bleeding point by obvious contrast extravasation is not possible in conventional subtracted angiographic series (DSA). Then the suspected bleeding point is treated by endovascular embolization based on the clinical suspicion. CASE REPORT: We here present the case of a young woman with intractable epistaxis where hemorrhage with contrast extravasation was only faintly visible. We used the new imaging modality of flat detector computed tomography (FD-CT) to visualize acute hemorrhage and treatment effect accurately. CONCLUSION: FD-CT was helpful to visualize both irregular branches of the bleeding mucosa and active hemorrhage and also to monitor an effective embolization within the angio suite. Acquisition of FD-CT imaging in addition to conventional 2-D imaging with the same system enhances the possibility to a better understanding of the individual patient's anatomy and could be beneficial in the accurate depiction of active bleeding, and it might also improve surgical management, if endovascular attempts should fail.


Assuntos
Embolização Terapêutica/métodos , Procedimentos Endovasculares/métodos , Epistaxe/diagnóstico por imagem , Epistaxe/terapia , Doença Aguda , Adulto , Angiografia , Feminino , Humanos , Tomografia Computadorizada por Raios X , Resultado do Tratamento
12.
Fortschr Neurol Psychiatr ; 79(11): 642-6, 2011 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-22048857

RESUMO

BACKGROUND: The contribution of potential treatable dementia aetiologies diagnosed using cerebral imaging varied considerably in previous studies and was not evaluated in a recent larger German sample of patients from a memory clinic. MATERIAL AND METHODS: MRI images of 502 patients were retrospectively reassessed. Beside the proportion of potentially treatable dementia aetiology, the extent of whole brain atrophy (semiquantitative) and vascular white matter lesions were assessed. RESULTS: Mean age of the patients was 63.7 ± 13.1 years; 49 % were female, mean MMST was 24.2 ± 5.5. In 74 % there was an agreement between the clinical dementia syndrome and MRI. 9 % (45 patients) had clearly discrepant imaging results, according to MRI criteria (21 × ischaemia, 20 × normal pressure hydrocephalus (NPH), 4 × intracerebral haemorrhage). These patients could not not be differentiated using age and MMST alone as clinical criteria. There was a significant correlation between global brain atrophy and MMST (r = -0.32; p < 0.001) and white matter lesion score (r = 0.28; p < 0.001). CONCLUSION: In 9 % there was a clear discrepancy between MRI results and the clinical syndrome diagnosis in memory-clinic patients. As known from earlier studies and current German 3 rd generation guidelines, it is reasonable to perform MRI imaging in dementia to improve the aetiological and differential diagnoses and to detect a different aetiology that can be missed using the clinical dementia criteria alone.


Assuntos
Demência/diagnóstico , Demência/psicologia , Imageamento por Ressonância Magnética , Transtornos da Memória/diagnóstico , Transtornos da Memória/psicologia , Idoso , Doença de Alzheimer/patologia , Apolipoproteínas E/genética , Atrofia , Encéfalo/patologia , Infarto Cerebral/patologia , Infarto Cerebral/psicologia , Demência/líquido cefalorraquidiano , Demência/patologia , Depressão/complicações , Depressão/psicologia , Diagnóstico Diferencial , Feminino , Genótipo , Humanos , Hidrocefalia/complicações , Hidrocefalia/diagnóstico , Hemorragias Intracranianas/complicações , Hemorragias Intracranianas/diagnóstico , Masculino , Transtornos da Memória/líquido cefalorraquidiano , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos Retrospectivos , Teste de Sequência Alfanumérica
13.
Contemp Clin Trials Commun ; 22: 100770, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34041413

RESUMO

BACKGROUND: Tumor necrosis factor inhibitors (TNFi) signify a major advance in the treatment of rheumatoid arthritis (RA). However, treatment success initially remains uncertain as approximately half of the patients do not respond adequately to TNFi. Thus, an unmet need exists to better predict therapeutic outcome of biologicals. OBJECTIVES: We investigated whether brain activity associated with arthritis measured by functional magnetic resonance imaging (fMRI) of the brain can serve as a predictor of response to TNFi in RA patients. METHODS: PreCePRA is a multi-center, randomized, double-blind, placebo-controlled fMRI trial on patients with RA [1] [2]. Active RA patients failing csDMARDs therapy with a DAS28 > 3.2 and at least three tender and/or swollen joints underwent a brain BOLD (blood-oxygen-level dependent) fMRI scan upon joint compression at screening. Patients were then randomized into a 12-week double-blinded treatment phase with 200 mg Certolizumab Pegol (CZP) every two weeks (arm 1: fMRI BOLD signal activated volume > 2000 voxel, i.e. 2 cm3; arm 2: fMRI BOLD signal activated volume <2000 voxel) or placebo (arm 3). DAS28 low disease activity at 12 weeks was assigned as primary endpoint. A 12-week follow-up phase in which patients were switched from the placebo to the treatment arm followed the blinded phase. fMRI was carried out at screening as well as after 12 and 24 weeks of receiving CZP or placebo. CONCLUSION: We hypothesize that high-level central nervous representation of pain in patients with rheumatoid arthritis predicts response to the TNFi CZP which we further investigate in the PreCePRA trial.

14.
Fortschr Neurol Psychiatr ; 78(2): 101-6, 2010 Feb.
Artigo em Alemão | MEDLINE | ID: mdl-20146154

RESUMO

Up to 25 % of all acute ischemic strokes (AIS) occur during sleep with the patients or relatives becoming aware of their neurological deficits as they wake up. Because of the unclear time of stroke onset patients with stroke on awakening are usually not considered for acute therapies and excluded from most treatment trials. We give an overview of the published data regarding ischemic wake up strokes (WUS). In particular we focused on baseline characteristics, imaging methods and therapy strategies. Comparing WUS patients and patients with known stroke onset there were no major differences found regarding patient characteristics, etiology, clinical and radiological characteristics. Even though there is no existing gold standard multiparametric neuroimaging (CT; MRI) appears to be helpful for decision making whether to treat a WUS patient with thrombolysis or not. Especially multiparametric MRI which proved to be safe in patients within an extended time window might serve as an adequate diagnostic tool. The results of first pilot studies analyzing treatment of WUS demonstrate that a substantial number of these patients can be treated with IV thrombolysis (IVT) successfully. Large randomized, controlled, prospective clinical trials for patients with WUS are needed to test safety and efficacy of IVT and to evaluate the assumed benefit of multiparametric neuroimaging techniques in this patient group. The results of first pilot studies may be instrumental to help plan and design such trials.


Assuntos
Isquemia Encefálica/diagnóstico , Isquemia Encefálica/terapia , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/terapia , Vigília/fisiologia , Isquemia Encefálica/patologia , Isquemia Encefálica/psicologia , Humanos , Imageamento por Ressonância Magnética , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/psicologia
15.
J Phys Condens Matter ; 32(18): 185302, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31952050

RESUMO

The compelling physical properties of the recently discovered ferroelectric phase in thin film Hf x Zr1-x O2 have opened a window for applications such as non-volatile resistive switching memory devices with high retention known as ferroelectric tunnel junctions. In this article, we investigate the stability of these two-terminal, polarization induced resistance-switching devices with respect to the statistical reproducibility of constitutive electrical parameters based on surface thickness inhomogeneities. We provide a straightforward, quantitative model to estimate tunneling currents dependent on thickness variations, and the resulting tunneling electroresistance (TER) ratios and breakdown probability. An analytical expression for the probability distribution of tunneling currents for normally distributed thicknesses is given. Using material parameters of a TiN/HZO/Pt heterostructure, practical design requirements are deduced and an estimation with respect to the surface roughness is given for practical ferroelectric layer thicknesses and voltages below 4 nm and 1 V, respectively. In this regime, the simple model of a ballistic, direct tunneling mechanism can be used to adequately model the thickness and voltage dependence of the resistivity.

16.
J Neurol Neurosurg Psychiatry ; 80(2): 196-200, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18838399

RESUMO

OBJECTIVE: Mesial temporal lobe epilepsy (MTLE) constitutes a heterogenic entity with different clinical histories, pathomorphological hippocampal findings and varying postoperative outcome. METHOD: 64 patients with MTLE, scheduled for hippocampal resection, were included. Initial precipitating injuries (IPI), structural and functional findings and neuropathological classification of hippocampal specimens were related to prediction of surgical outcome. RESULTS: Patients with severe hippocampal sclerosis (mesial temporal sclerosis (MTS) type 1b) became completely seizure free (80% Engel Ia) significantly more often compared with approximately 40% of seizure freedom in other types of MTS or in patients without hippocampal cell loss (non-MTS), irrespective of the extent of hippocampal resection. Age at IPI was found to be related to MTS variants (p<0.01) and significantly correlated with cell loss in the CA1 sector and the dentate gyrus (p<0.05). Presurgical MRI discriminated between MTS and non-MTS, but did not discriminate between different MTS subtypes. The most reliable predictors of MTS type 1b were the Wada memory scores combined with interictal and ictal EEG. CONCLUSIONS: A particular cohort of MTLE patients benefit most from surgical treatment. These patients are clinically best recognised as presenting with (1) very early IPI; (2) a silent period of about 5 years; (3) unequivocal unilateral EEG localisation; (4) MRI signs of MTS; and (5) Wada Test indicates contralateral memory compensation and ipsilateral reduced memory capacity. MTS type 1b, characterised by severe cell loss in all hippocampal subfields including the dentate gyrus, and associated with optimal postoperative seizure control, was preoperatively clinically best differentiated from other MTS types by the Wada Memory Test.


Assuntos
Epilepsia do Lobo Temporal/diagnóstico , Epilepsia do Lobo Temporal/cirurgia , Hipocampo/patologia , Hipocampo/cirurgia , Complicações Pós-Operatórias , Convulsões/etiologia , Adulto , Eletroencefalografia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Procedimentos Neurocirúrgicos , Cuidados Pré-Operatórios , Estudos Prospectivos , Esclerose/patologia , Convulsões/diagnóstico , Índice de Gravidade de Doença , Resultado do Tratamento
17.
Radiologe ; 49(9): 811-9, 2009 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-19701623

RESUMO

Flat detectors (FDs) have been developed for use in radiography and fluoroscopy to replace standard X-ray film, film-screen combinations and image intensifiers (II). In comparison to X-ray film and II, FD technology offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. FDCT has meanwhile become widely accepted for interventional and intra-operative imaging using C-arm systems. Additionally, the introduction of FD technology was a milestone for soft-tissue CT imaging in the interventional suite which was not possible with II systems in the past. This review focuses on technical and performance issues of FD technology and its wide range of applications for CT imaging. FDCT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations, but it has already proven unique for a number of dedicated CT applications offering distinct practical advantages, above all the availability of immediate CT imaging during an intervention.


Assuntos
Imageamento Tridimensional/instrumentação , Intensificação de Imagem Radiográfica/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Transdutores , Desenho de Equipamento , Análise de Falha de Equipamento , Avaliação da Tecnologia Biomédica
18.
Rofo ; 180(10): 891-8, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19238639

RESUMO

Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range than available with X-ray film or film-screen combinations, flat-panel detector technology has become widely accepted for neuroangiographic imaging. In particular flat-panel detector computed tomography (FD-CT) which uses rotational C-arm-mounted flat-panel detector technology is capable of volumetric imaging with high spatial resolution. As "Angiographic CT" FD-CT may be helpful during many diagnostic and neurointerventional procedures, i.e. intracranial stenting for cerebrovascular stenoses, stent-assisted coil embolization of wide-necked cerebral aneurysms and embolizations of arteriovenous malformations. By providing morphologic, CT-like images of the brain within the angio suite, FD-CT is able to rapidly visualize periprocedural hemorrhage and may thus improve rapid complication management without the need for patient transfer. In addition, myelography and postmyelographic FD-CT imaging can be carried out using a single machine. Spinal interventions, such as kyphoplasty or vertebroplasty might also benefit from FD-CT. This paper briefly reviews the technical principles of FD technology and then focuses on possible applications in diagnostic and interventional neuroradiology.


Assuntos
Doenças do Sistema Nervoso Central/diagnóstico por imagem , Angiografia Cerebral/instrumentação , Processamento de Imagem Assistida por Computador/instrumentação , Imageamento Tridimensional/instrumentação , Neuronavegação/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Doenças do Sistema Nervoso Central/terapia , Malformações Vasculares do Sistema Nervoso Central/diagnóstico por imagem , Malformações Vasculares do Sistema Nervoso Central/terapia , Embolização Terapêutica/instrumentação , Humanos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/terapia , Malformações Arteriovenosas Intracranianas/diagnóstico por imagem , Malformações Arteriovenosas Intracranianas/terapia , Sensibilidade e Especificidade , Estenose Espinal/diagnóstico por imagem , Estenose Espinal/terapia , Espondilose/diagnóstico por imagem , Espondilose/terapia , Stents , Vertebroplastia/instrumentação
19.
Clin Neuroradiol ; 28(3): 367-376, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28265679

RESUMO

PURPOSE: To evaluate the performance of an innovative image processing approach for detection of T2-weighted hyperintense multiple sclerosis (MS) lesions. METHODS: In this study 20 consecutive patients with inflammatory demyelinating lesions were retrospectively evaluated of whom 10 patients featured progressive disease and 10 a stable lesion load. 3 mm transversal FLAIRfusion imaging was processed and archived. Image processing was performed through landmark-based 3D co-registration of the previous and current isotropic FLAIR examination followed by inversion of image contrast. Thereby, the hyperintense signals of the unchanged MS plaques extinguish each other, while newly developed lesions appear bright on FLAIRfusion. Diagnostic performance was evaluated by 4 experienced readers. Consensus reading supplied the reference standard. Sensitivity, specificity, NPV (negative predictive value), PPV (positive predictive value), interreader agreement and reading time were the outcome measures analyzed. RESULTS: Combined sensitivity was 100% at a specificity of 88.2%, with PPV ranging from 83.3% to 90.1% and NPV at 100%. Reading time was nearly 5­fold faster than conventional side by side comparison (35.6 s vs. 163.7 s, p < 0.001). Cohen's kappa was excellent (>0.75; p < 0.001) and Cronbach's alpha was 0.994. CONCLUSION: FLAIRfusion provides reliable detection of newly developed MS lesions along with strong interreader agreement across all levels of expertise in 35 s of reading time.


Assuntos
Encéfalo/diagnóstico por imagem , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico por imagem , Adulto , Feminino , Alemanha , Humanos , Masculino , Pessoa de Meia-Idade , Leitura , Estudos Retrospectivos , Sensibilidade e Especificidade , Adulto Jovem
20.
Seizure ; 16(3): 248-53, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17276092

RESUMO

PURPOSE: In this study 30 patients with symptomatic epilepsy caused by cavernomas were investigated in a postoperative follow up study to assess predictors for postoperative outcome with respect to indications, time and approach of surgery. METHODS: Thirty patients with cavernomas refractory to medical treatment were scheduled for surgery based on the findings of high-resolution MR imaging and intensive EEG-video monitoring. Postoperative outcome of epilepsy was assessed by follow-up examinations based on the basis of classification by Engel and the International League against epilepsy (ILAE). RESULTS: The following variables were associated with good postoperative outcome: (1) complete resection of hemosiderin fringe surrounding the cavernoma was correlated to less postoperative seizure frequency versus incomplete resection of the hemosiderin fringe according to the outcome protocol of ILAE. (2) Lower duration of epilepsy at the time of operation was correlated to a better postoperative outcome with a benefit for recovery. (3) Absence of hemorrhage before surgery and unifocal seizure onset was a predictor for a favorable outcome, whereas bilateral or multifocal seizure onset zones showed poorer postoperative outcomes. (4) In patients with dual pathology (hippocampal sclerosis in addition to a cavernoma), lesionectomy plus hippocampectomy as opposed to lesionectomy only, had a better outcome than single lesionectomy. CONCLUSION: Postoperative outcome in patients with cavernomas should be the topic of further prospective multicenter studies involving a large number of patients. In addition to the ideal operation time and handling of dual pathology the role of extended resection including perilesional hemorrhages should be taken into account.


Assuntos
Encéfalo/cirurgia , Epilepsia/etiologia , Hemangioma Cavernoso do Sistema Nervoso Central/cirurgia , Hemossiderina/metabolismo , Adolescente , Adulto , Hemorragia Cerebral/etiologia , Criança , Pré-Escolar , Eletroencefalografia , Epilepsia/metabolismo , Feminino , Hemangioma Cavernoso do Sistema Nervoso Central/complicações , Hipocampo/patologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esclerose , Resultado do Tratamento , Gravação em Vídeo
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