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1.
Nat Commun ; 15(1): 3973, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38729944

RESUMO

Ultra-fast single-photon detectors with high current density and operating temperature can benefit space and ground applications, including quantum optical communication systems, lightweight cryogenics for space crafts, and medical use. Here we demonstrate magnesium diboride (MgB2) thin-film superconducting microwires capable of single-photon detection at 1.55 µm optical wavelength. We used helium ions to alter the properties of MgB2, resulting in microwire-based detectors exhibiting single-photon sensitivity across a broad temperature range of up to 20 K, and detection efficiency saturation for 1 µm wide microwires at 3.7 K. Linearity of detection rate vs incident power was preserved up to at least 100 Mcps. Despite the large active area of up to 400 × 400 µm2, the reset time was found to be as low as ~ 1 ns. Our research provides possibilities for breaking the operating temperature limit and maximum single-pixel count rate, expanding the detector area, and raises inquiries about the fundamental mechanisms of single-photon detection in high-critical-temperature superconductors.

2.
Nano Lett ; 24(7): 2282-2288, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38345381

RESUMO

The rapid development of infrared spectroscopy, observational astronomy, and scanning near-field microscopy has been enabled by the emergence of sensitive mid- and far-infrared photodetectors. Superconducting hot-electron bolometers (HEBs), known for their exceptional signal-to-noise ratio and fast photoresponse, play a crucial role in these applications. While superconducting HEBs are traditionally crafted from sputtered thin films such as NbN, the potential of layered van der Waals (vdW) superconductors is untapped at THz frequencies. Here, we introduce superconducting HEBs made from few-layer NbSe2 microwires. By improving the interface between NbSe2 and metal leads, we overcome impedance mismatch with RF readout, enabling large responsivity THz detection (0.13 to 2.5 THz) with a minimal noise equivalent power of 7 pW/ Hz and nanosecond-range response time. Our work highlights NbSe2 as a promising platform for HEB technology and presents a reliable vdW assembly protocol for custom bolometer production.

3.
Inorg Chem ; 63(1): 247-255, 2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38101323

RESUMO

To elucidate the impact of a high entropy elemental distribution of the lattice site on the magnetic properties in oxide compounds, a series of complex perovskites BaBO3 (B = Y, Fe, Ti, Zr, Hf, Nb, and Ta) with different Fe content ratios (0, 0.2, 0.3, and 0.4) have been synthesized and thoroughly characterized. In this complex oxide series, superconducting quantum interference device magnetometry reveals a gradual change of a well-defined magnetic phase transition and B-site magnetic moment, which correlates with the Fe content. More importantly, a comprehensive analysis of the sample with a 0.4-Fe content (40% on the B-site) including magnetization, heat capacity, neutron diffraction, and muon-spin rotation measurements suggests that in the low-temperature state, a short-range antiferromagnetic correlation may exist, which could result from the magnetic interaction of Fe ions and consequent redistribution of associated d-electrons.

4.
Emerg Microbes Infect ; 12(1): 2179348, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36757188

RESUMO

Human bornavirus encephalitis is an emerging disease caused by the variegated squirrel bornavirus 1 (VSBV-1) and the Borna disease virus 1 (BoDV-1). While characteristic brain magnetic resonance imaging (MRI) changes have been described for BoDV-1 encephalitis, only scarce diagnostic data in VSBV-1 encephalitis exist. We systematically analysed brain MRI scans from all known VSBV-1 encephalitis patients. Initial and follow-up scans demonstrated characteristic T2 hyperintense lesions in the limbic system and the basal ganglia, followed by the brainstem. No involvement of the cerebellar cortex was seen. Deep white matter affection occurred in a later stage of the disease. Strict symmetry of pathologic changes was seen in 62%. T2 hyperintense areas were often associated with low T1 signal intensity and with mass effect. Sinusitis in three patients on the first MRI and an early involvement of the limbic system suggest an olfactory route of VSBV-1 entry. The viral spread could occur per continuitatem to adjacent anatomical brain regions or along specific neural tracts to more distant brain regions. The number and extent of lesions did not correlate with the length of patients' survivals. The overall pattern closely resembles that described for BoDV-1 encephalitis. The exact bornavirus species can thus not be deduced from imaging results alone, and molecular testing and serology should be performed to confirm the causative bornavirus. As VSBV-1 is likely of tropical origin, and MRI investigations are increasingly available globally, imaging techniques might be helpful to facilitate an early presumptive diagnosis of VSBV-1 encephalitis when molecular and/or serological testing is not available.


Assuntos
Vírus da Doença de Borna , Bornaviridae , Encefalite , Animais , Humanos , Vírus da Doença de Borna/genética , Bornaviridae/genética , Zoonoses , RNA Viral/genética , Imageamento por Ressonância Magnética , Sciuridae
5.
Comput Methods Programs Biomed ; 225: 107085, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36044801

RESUMO

BACKGROUND AND OBJECTIVE: Tracking of anatomical structures in time-resolved medical image data plays an important role for various tasks such as volume change estimation or treatment planning. State-of-the-art deep learning techniques for automated tracking, while providing accurate results, require large amounts of human-labeled training data making their wide-spread use time- and resource-intensive. Our contribution in this work is the implementation and adaption of a self-supervised learning (SSL) framework that addresses this bottleneck of training data generation. METHODS: To this end we adapted and implemented an SSL framework that allows for automated anatomical tracking without the necessity for human-labeled training data. We evaluated this method by comparison to conventional- and deep learning optical flow (OF)-based tracking methods. We applied all methods on three different time-resolved medical image datasets (abdominal MRI, cardiac MRI, and echocardiography) and assessed their accuracy regarding tracking of pre-defined anatomical structures within and across individuals. RESULTS: We found that SSL-based tracking as well as OF-based methods provide accurate results for simple, rigid and smooth motion patterns. However, regarding more complex motion, e.g. non-rigid or discontinuous motion patterns in the cardiac region, and for cross-subject anatomical matching, SSL-based tracking showed markedly superior performance. CONCLUSION: We conclude that automated tracking of anatomical structures on time-resolved medical image data with minimal human labeling effort is feasible using SSL and can provide superior results compared to conventional and deep learning OF-based methods.


Assuntos
Abdome , Imageamento por Ressonância Magnética , Humanos , Imageamento por Ressonância Magnética/métodos , Movimento (Física) , Radiografia , Aprendizado de Máquina Supervisionado
6.
J Med Imaging (Bellingham) ; 8(5): 054003, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34660843

RESUMO

Purpose: We introduce and evaluate deep learning methods for weakly supervised segmentation of tumor lesions in whole-body fluorodeoxyglucose-positron emission tomography (FDG-PET) based solely on binary global labels ("tumor" versus "no tumor"). Approach: We propose a three-step approach based on (i) a deep learning framework for image classification, (ii) subsequent generation of class activation maps (CAMs) using different CAM methods (CAM, GradCAM, GradCAM++, ScoreCAM), and (iii) final tumor segmentation based on the aforementioned CAMs. A VGG-based classification neural network was trained to distinguish between PET image slices with and without FDG-avid tumor lesions. Subsequently, the CAMs of this network were used to identify the tumor regions within images. This proposed framework was applied to FDG-PET/CT data of 453 oncological patients with available manually generated ground-truth segmentations. Quantitative segmentation performance was assessed for the different CAM approaches and compared with the manual ground truth segmentation and with supervised segmentation methods. In addition, further biomarkers (MTV and TLG) were extracted from the segmentation masks. Results: A weakly supervised segmentation of tumor lesions was feasible with satisfactory performance [best median Dice score 0.47, interquartile range (IQR) 0.35] compared with a fully supervised U-Net model (median Dice score 0.72, IQR 0.36) and a simple threshold based segmentation (Dice score 0.29, IQR 0.28). CAM, GradCAM++, and ScoreCAM yielded similar results. However, GradCAM led to inferior results (median Dice score: 0.12, IQR 0.21) and was likely to ignore multiple instances within a given slice. CAM, GradCAM++, and ScoreCAM yielded accurate estimates of metabolic tumor volume (MTV) and tumor lesion glycolysis. Again, worse results were observed for GradCAM. Conclusions: This work demonstrated the feasibility of weakly supervised segmentation of tumor lesions and accurate estimation of derived metrics such as MTV and tumor lesion glycolysis.

7.
Int J Cardiovasc Imaging ; 35(12): 2177-2188, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31321655

RESUMO

Longitudinal right ventricular (RV) function is substantial and might be reflected by free wall longitudinal strain (FWLS). Software solutions for FWLS analysis by two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) are available, but data on validation are sparse. In this study, a novel method for FWLS analysis on 3D meshes ("mesh surface", MS-FWLS,) was tested for feasibility and compared to available parameters. 80 patients undergoing left-sided cardiac valve surgery with intraoperative TEE were included retrospectively. 2D-FWLS, 3D-derived (3Dd)-FWLS (assessed in optimized four-chamber views after volume analysis) and MS-FWLS were measured and compared to conventional parameters (3Dd-TAPSE, FAC and RVEF). The mean FWLS values did not differ significantly between methods (- 19.0 ± 6.1%, - 20.0 ± 7.3%, - 19.5 ± 7.3% for 2D-, 3Dd- and MS-FWLS, respectively). No significant differences in the mean FWLS between patients with normal or increased pulmonary artery pressures as well as normal or reduced left ventricular ejection fraction were observed. Agreement was best between 3Dd- and MS-FWLS (r = 0.89, bias = - 1.0%, LOA ± 6.9%). Conventional echocardiographic parameters yielded poorer intermodality agreement. In patients with discrepant results between 2D- and 3Dd-FWLS, 3Dd-FWLS and MS-FWLS yielded similar results (r = 0.82, bias = - 0.3%, LOA ± 8.6%), while 2D-FWLS and MS-FWLS did not. Intra- and interobserver variabilities of strain analyses were low. MS-FWLS might represent a promising method to overcome artefacts associated with 2D analysis. Its prognostic relevance needs to be investigated in prospective studies.


Assuntos
Ecocardiografia Tridimensional , Ecocardiografia Transesofagiana , Contração Miocárdica , Disfunção Ventricular Direita/diagnóstico por imagem , Função Ventricular Direita , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Período Intraoperatório , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Estudos Retrospectivos , Disfunção Ventricular Direita/fisiopatologia
8.
J Cardiothorac Vasc Anesth ; 33(6): 1527-1532, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30867108

RESUMO

OBJECTIVES: In daily echocardiographic practice, the right ventricle (RV) is assessed using mostly 2-dimensional (2D) echocardiography. Parameters measuring longitudinal shortening (eg, tricuspid annular plane systolic excursion) or changes in areas (eg, fractional area change) are used as surrogates for right ventricular function. Three-dimensional (3D) echocardiography-based techniques allow for cardiac magnetic resonance imaging-validated assessment of the RV. Depiction of regional right ventricular function is of increasing clinical interest. This study aimed to calculate regional volumetric changes in the right ventricular inlet, apical section, and outflow tract. Correlations between traditional parameters and regional right ventricular function were studied. DESIGN: Retrospective cohort study on patients scheduled for cardiac surgery. SETTING: Tertiary care university hospital. PARTICIPANTS: The study comprised 80 patients scheduled for cardiac surgery. MEASUREMENTS AND MAIN RESULTS: Based on 3D echocardiographic datasets, mesh models of the RV were generated on a vendor-independent platform. The meshes were further cut into the following 3 regions: the inlet part, the apical section, and the outflow tract. The regional volumes and ejection fractions were compared with the global right ventricular and left ventricular functions. Regional volumes were correlated linearly with the global end-diastolic volume. The right ventricular outflow tract demonstrated a significantly lower ejection fraction than the inlet part (34% ± 11% v 28% ± 11%; p = 0.0054). The function in the right ventricular outflow tract was reduced significantly compared with the global right ventricular function in patients with severely reduced left ventricular ejection fraction (<20%). CONCLUSION: The different parts of the RV seem to have different ejection fractions. Different regions of the RV are affected differently by reduced left ventricular ejection fraction. Regional right ventricular analyses could help clinicians better understand pathologic states of the RV.


Assuntos
Volume Cardíaco/fisiologia , Ecocardiografia Tridimensional/métodos , Ecocardiografia Transesofagiana/métodos , Ventrículos do Coração/diagnóstico por imagem , Volume Sistólico/fisiologia , Função Ventricular Direita/fisiologia , Idoso , Procedimentos Cirúrgicos Cardíacos , Diástole , Feminino , Seguimentos , Ventrículos do Coração/fisiopatologia , Humanos , Período Intraoperatório , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sístole
9.
J Phys Condens Matter ; 28(27): 276001, 2016 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-27195766

RESUMO

We report on the magnetic properties of CsCo2Se2 with ThCr2Si2 structure, which we have characterized through a series of magnetization and neutron diffraction measurements. We find that CsCo2Se2 undergoes a phase transition to an antiferromagnetically ordered state with a Néel temperature of [Formula: see text] K. The nearest neighbour interactions are ferromagnetic as observed by the positive Curie-Weiss temperature of [Formula: see text] K. We find that the magnetic structure of CsCo2Se2 consists of ferromagnetic sheets, which are stacked antiferromagnetically along the tetragonal c-axis, generally referred to as A-type antiferromagnetic order. The observed magnitude of the ordered magnetic moment at T = 1.5 K is found to be only 0.20(1)[Formula: see text] / Co. Already in comparably small magnetic fields of [Formula: see text] T, we observe a metamagnetic transition that can be attributed to spin-rearrangements of CsCo2Se2, with the moments fully ferromagnetically saturated in a magnetic field of [Formula: see text] T. We discuss the entire experimentally deduced magnetic phase diagram for CsCo2Se2 with respect to its unconventionally weak magnetic coupling. Our study characterizes CsCo2Se2, which is chemically and electronically posed closely to the A x Fe2-y Se2 superconductors, as a host of versatile magnetic interactions.

10.
J Am Chem Soc ; 136(35): 12422-30, 2014 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-25133552

RESUMO

We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12-46 nm and with excellent size distribution as small as 7-8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and passivating Ga-oxide layer (2-3 nm). The mechanism of Ga nanoparticles formation is elucidated using nuclear magnetic resonance spectroscopy and with molecular dynamics simulations. Size-dependent crystallization and melting of Ga nanoparticles in the temperature range of 98-298 K are studied with X-ray powder diffraction, specific heat measurements, transmission electron microscopy, and X-ray absorption spectroscopy. The results point to delta (δ)-Ga polymorph as a single low-temperature phase, while phase transition is characterized by the large hysteresis and by the large undercooling of crystallization and melting points down to 140-145 and 240-250 K, respectively. We have observed size-tunable plasmon resonance in the ultraviolet and visible spectral regions. We also report stable operation of Ga nanoparticles as anode material for Li-ion batteries with storage capacities of 600 mAh g(-1), 50% higher than those achieved for bulk Ga under identical testing conditions.

11.
J Phys Condens Matter ; 25(7): 075804, 2013 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-23343638

RESUMO

The thermoelectric properties between 10 and 300 K and the growth of single crystals of n-type and p-type GeBi(4)Te(7), GeSb(4)Te(7) and Ge(Bi(1-x)Sb(x))(4)Te(7) solid solution are reported. Single crystals were grown by the modified Bridgman method, and p-type behavior was achieved by the substitution of Bi by Sb in GeBi(4)Te(7). The thermopower in the Ge(Bi(1-x)Sb(x))(4)Te(7) solid solution ranges from -117 to +160 µV K(-1). The crossover from n-type to p-type is continuous with increasing Sb content and is observed at x ≈0.15. The highest thermoelectric efficiencies among the tested n-type and p-type samples are Z(n)T = 0.11 and Z(p)T = 0.20, respectively. For an optimal n-p couple in this alloy system the composite figure of merit is Z(np)T = 0.17 at room temperature.


Assuntos
Cristalização/métodos , Germânio/química , Semicondutores , Condutividade Elétrica , Transferência de Energia , Teste de Materiais , Temperatura
12.
J Neuroimaging ; 20(2): 198-200, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18826442

RESUMO

An isolated CNS relapse is rarely seen in acute myeloid leukemia. However, it has a potentially fatal clinical outcome. We herein present the case of a 39-year-old man, who presented to our emergency room with horizontal diplopic images, vertigo, bilateral deafness, and progressing somnolence. Cerebral imaging revealed cerebral and cerebellar edema and a diffuse leukoencephalopathy. With the one-year-old history of an initially successfully treated FAB-M0 acute myeloid leukemia (AML) in mind, a lumbar puncture was carried out that showed a vast number of myeloid blasts in the morphologic analysis of the cerebrospinal fluid. In conjunction with normal findings in the peripheral blood-count with differential and the bone marrow examination a diagnosis of an isolated CNS relapse of the AML was made. Cytarabine chemotherapy was initiated and the symptoms resolved rapidly. To our surprise, cerebral imaging in the course of the treatment not only showed a resolution of the brain edema but also of the leukoencephalopathy, pointing to a direct infiltration of brain parenchyma by leukemic blasts. The case highlights the relevance of the CNS as a pharmacologic "sanctuary" for tumor cells in patients that on prior treatments have not received intrathecal chemotherapy or chemotherapeutics that cross the blood-brain barrier.


Assuntos
Edema Encefálico/diagnóstico , Edema Encefálico/etiologia , Leucemia Mieloide Aguda/complicações , Leucemia Mieloide Aguda/diagnóstico , Leucoencefalopatias/diagnóstico , Leucoencefalopatias/etiologia , Imageamento por Ressonância Magnética , Adulto , Humanos , Masculino , Recidiva
13.
Med Image Comput Comput Assist Interv ; 11(Pt 1): 576-84, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18979793

RESUMO

We present a method for fast and automatic labeling of anatomical structures in MR FastView localizer images, which can be useful for automatic MR examination planning. FastView is a modern MR protocol, that provides larger planning fields of view than previously available with isotropic 3D resolution by scanning during continuous movement of the patient table. Hence, full 3D information is obtained within short acquisition time. Anatomical labeling is done by registering the images to a statistical atlas created from training image data beforehand. The statistical atlas consists of a statistical model of deformation and a statistical model of grey value appearance. It is generated by non-rigid registration and principal component analysis of the resulting deformation fields and registered images. Labeling of an unseen FastView image is done by non-rigid registration of the image to the statistical atlas and propagating the labels from the atlas to the image. In our implementation, the statistical models of deformation and appearance are both implemented on the GPU (graphics processing unit), which permits computing the atlas based labeling using GPU hardware acceleration. The running times of about 10 to 30 seconds are of the same magnitude as the image acquisition itself, which allows for practical usage in clinical MR routine.


Assuntos
Documentação/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Modelos Biológicos , Reconhecimento Automatizado de Padrão/métodos , Técnica de Subtração , Algoritmos , Inteligência Artificial , Simulação por Computador , Humanos , Aumento da Imagem/métodos , Modelos Estatísticos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Interface Usuário-Computador
14.
J Neurosurg ; 109(2): 215-21, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18671632

RESUMO

OBJECT: The use of dural grafts is frequently unavoidable when tension-free dural closure cannot be achieved following neurosurgical procedures or trauma. Biodegradable collagen matrices serve as a scaffold for the regrowth of natural tissue and require no suturing. The aim of this study was to investigate the efficacy and safety of dural repair with a collagen matrix using different fixation techniques. METHODS: A total of 221 patients (98 male and 123 female; mean age 55.6 +/- 17.8 years) undergoing cranial (86.4%) or spinal (13.6%) procedures with the use of a collagen matrix dural graft were included in this retrospective study. The indications for use, fixation techniques, and associated complications were recorded. RESULTS: There were no complications of the dural graft in spinal use. Five (2.6%) of 191 patients undergoing cranial procedures developed infections, 3 of which (1.6%) were deep infections requiring surgical revision. There was no statistically significant relationship between the operative field status before surgery and the occurrence of a postoperative wound infection (p = 0.684). In the 191 patients undergoing a cranial procedure, cerebrospinal fluid (CSF) collection occurred in 5 patients (2.6%) and a CSF fistula in 5 (2.6%), 3 of whom (1.6%) required surgical revision. No patient who underwent an operation with preexisting CSF leakage had postoperative CSF leakage. Postoperative infection significantly increased the risk for postoperative CSF leakage. The collagen matrix was used without additional fixation in 124 patients (56.1%), with single fixation in 55 (24.9%), and with multiple fixations in 42 (19%). There were no systemic allergic reactions or local skin changes. Follow-up imaging in 112 patients (50.7%) revealed no evidence of any adverse reaction to the collagen graft. CONCLUSIONS: The collagen matrix is an effective and safe cranial and spinal dural substitute that can be used even in cases of an existing local infection. Postoperative deep infection increases the risk for CSF leakage.


Assuntos
Materiais Biocompatíveis , Colágeno , Dura-Máter/cirurgia , Procedimentos Neurocirúrgicos/métodos , Procedimentos de Cirurgia Plástica/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Craniotomia , Dura-Máter/patologia , Feminino , Humanos , Hipersensibilidade/etiologia , Lactente , Fixadores Internos , Masculino , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos/efeitos adversos , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Procedimentos de Cirurgia Plástica/efeitos adversos , Estudos Retrospectivos , Coluna Vertebral , Derrame Subdural/etiologia , Derrame Subdural/prevenção & controle , Infecção da Ferida Cirúrgica/etiologia , Infecção da Ferida Cirúrgica/prevenção & controle
15.
AJNR Am J Neuroradiol ; 26(10): 2446-54, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16286384

RESUMO

BACKGROUND AND PURPOSE: Primary central nervous system lymphomas (PCNSLs) are usually high-grade and are rarely low-grade non-Hodgkin lymphomas (NHLs). On MR imaging, PCNSLs typically present as contrast-enhancing lesions in contact with the subarachnoid space without evidence of necrosis. We evaluated the radiologic morphology and clinical characteristics of low-grade PCNSLs, hypothesizing that they may differ from high-grade PCNSLs. METHODS: Records were reviewed from 332 patients screened for inclusion in 3 multicenter prospective trials. MR imaging scans were obtained from all patients and were centrally reviewed by 2 consultant neuroradiologists. RESULTS: Ten patients (3%) with low-grade PCNSLs (7 men and 3 women; median age, 59 years; age range, 19-61 years) were identified. Four patients had one lesion, 2 patients 2 lesions, and 4 patients had multiple lesions. The following radiologic features infrequently seen in high-grade PCNSLs were found in a substantial proportion of patients: location in deep structures or spine (n = 6); lack of periventricular location (n = 5); hyperintensity on T2-weighted images (n = 10); moderate or absent contrast enhancement (n = 6); and heterogeneous contrast enhancement (n = 5). In 8 patients, >2 of these features were present in at least one lesion, and, thus, the radiologic appearance was assessed atypical of high-grade PCNSLs. The atypical radiologic appearance in combination with atypical or mild symptoms resulted in a false or delayed diagnosis. CONCLUSION: Low-grade PCNSLs may have a variable and atypical radiologic morphology compared with high-grade PCNSLs with the risk of false or delayed diagnosis.


Assuntos
Neoplasias do Sistema Nervoso Central/diagnóstico por imagem , Imunocompetência , Linfoma não Hodgkin/diagnóstico por imagem , Adulto , Neoplasias do Sistema Nervoso Central/patologia , Meios de Contraste/administração & dosagem , Feminino , Humanos , Linfoma não Hodgkin/classificação , Linfoma não Hodgkin/patologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Intensificação de Imagem Radiográfica , Interpretação de Imagem Radiográfica Assistida por Computador , Análise de Sobrevida
16.
AJNR Am J Neuroradiol ; 26(2): 360-2, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15709136

RESUMO

We report our observations on MR imaging quality and functionality of a recently introduced intracranial pressure monitoring device. The device was tested at two different field strengths in a pig brain specimen to investigate MR imaging artifacts, probe function during and after MR data acquisition, and device-related temperature changes in the brain tissue. Image reading was not impaired, and probe function, although reduced, was not fully interrupted during data acquisition.


Assuntos
Técnicas de Diagnóstico Neurológico/instrumentação , Pressão Intracraniana , Imageamento por Ressonância Magnética , Animais , Falha de Equipamento , Suínos
17.
Br J Haematol ; 128(5): 616-24, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15725082

RESUMO

Primary central nervous system lymphomas (PCNSL) are usually diffuse large B-cell non-Hodgkin's lymphomas (NHL). Here we characterize the clinical presentation, course and outcome of patients with low-grade PCNSL. Records of 332 patients screened for inclusion in three multicentre prospective trials were reviewed. Ten patients (3%) with a median age of 59 years and a median Karnofsky performance status of 70% were identified. Seven patients had B-cell and three had T-cell lymphoma. The median growth fraction was 4%. The radiological morphology was unusual for PCNSL in eight patients. Three patients underwent complete tumour resection, combined with chemotherapy in one patient and with chemotherapy plus local radiotherapy in another. Four patients received chemotherapy and three received chemotherapy plus whole-brain irradiation, resulting in four complete remissions, two no-change situations and one progressive disease. Patients had an overall survival (OAS) of 2-58+ months with a 2-year OAS of 67%. Low-grade PCNSL may differ from classical high-grade PCNSL in its clinical features and radiological morphology. The clinical course may be variable and frequently more indolent than in classical PCNSL.


Assuntos
Neoplasias do Sistema Nervoso Central/patologia , Linfoma/patologia , Adulto , Neoplasias do Sistema Nervoso Central/mortalidade , Neoplasias do Sistema Nervoso Central/terapia , Terapia Combinada , Feminino , Humanos , Linfoma/mortalidade , Linfoma/terapia , Linfoma de Células B/mortalidade , Linfoma de Células B/patologia , Linfoma de Células B/terapia , Linfoma de Células T/mortalidade , Linfoma de Células T/patologia , Linfoma de Células T/terapia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Taxa de Sobrevida
18.
J Psychiatr Res ; 39(2): 129-35, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15589560

RESUMO

INTRODUCTION: It has been proposed that the often found hyperintensities on MRI representing vascular changes might be correlated with a worse outcome of cognitive malfunction in depression. The purpose of this study was to evaluate neuropsychological status in the acute depressed state and following remission and to investigate the potential relationship between MRI hyperintensities and neuropsychological functioning through the treatment course in a group of middle-aged depressed patients. MATERIALS AND METHODS: Twenty-seven depressed patients were assessed by a series of neuropsychological tests at the beginning of the depressive episode and again after an euthymic phase of 6 months following treatment. Thirty healthy controls were tested at comparable intervals. In all patients and controls a MRI was performed to identify hyperintensities representing a possible correlation with test performance during treatment course. RESULTS: At the onset of a depressive episode patients performed significantly worse than the controls in all tests. After sustained remission the patient group still performed significantly worse in verbal memory and verbal fluency compared to controls. There were no significant correlations between number of presence of vascular risk factors, or presence of hyperintensities on MRI, and cognitive abilities at either time point. DISCUSSION: These findings favor the hypothesis that some neuropsychological deficits might persist following treatment for depression, even in middle-aged patients. We found, however, that any residual cognitive deficit is not associated with MRI-hyperintensities in this age-group.


Assuntos
Encéfalo/patologia , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Depressão/complicações , Depressão/psicologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade
19.
AJNR Am J Neuroradiol ; 25(5): 784-6, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15140720

RESUMO

A rare case of multiple cerebral aneurysms and factor VII deficiency is presented. The authors hypothesize a possible combined genetic defect similar to that of other conditions with clotting disorders. Different treatment options are discussed for factor VII deficiency in particular and multiple cerebral aneurysms in general. The authors advise treatment of all detected aneurysms in case of a subarachnoid hemorrhage rather than only treatment of the ruptured aneurysms in order to immediately start the so-called triple-H therapy.


Assuntos
Deficiência do Fator VII/complicações , Aneurisma Intracraniano/complicações , Adulto , Feminino , Humanos
20.
Anticancer Res ; 24(2C): 1143-7, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15154639

RESUMO

BACKGROUND: Despite progress in diagnosis and therapy, the prognosis of patients with glioblastoma remains poor. Recently it has been found that the antibacterial agent taurolidine has a direct and selective antineoplastic effect on brain tumor cells by the induction of programmed cell death. This paper reports on intravenous taurolidine treatment in two patients with a progressive glioblastoma despite conventional therapy. PATIENTS AND METHODS: Two male patients with histopathologically diagnosed glioblastoma were included. The tumors were progressive despite conventional therapy. Intravenous taurolidine treatment was initiated. RESULTS: The neurological condition and quality of life improved in both patients such that they could be discharged for further outpatient treatment. Follow-up demonstrated partial remission of the tumor in both patients. However, both patients died about 4 months following the start of taurolidine treatment, from pneumonia and acute thrombembolism, respectively. CONCLUSION: Both patients achieved a transient, marked improvement in quality of life and partial tumor remission. There was a clear response to the taurolidine treatment.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Glioblastoma/tratamento farmacológico , Taurina/análogos & derivados , Taurina/uso terapêutico , Tiadiazinas/uso terapêutico , Adulto , Idoso , Humanos , Injeções Intravenosas , Masculino
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