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1.
AJNR Am J Neuroradiol ; 38(5): 868-874, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28302611

RESUMO

BACKGROUND AND PURPOSE: CTA can rapidly and accurately detect and localize occlusive disease in patients with ischemic stroke. We have used CTA to assess arterial stenosis and occlusion in an ischemic stroke population arriving at a tertiary stroke center within 24 hours of symptom onset in order to obtain a comprehensive picture of occlusive disease pattern, and to determine the proportion of eligible candidates for endovascular treatment. MATERIALS AND METHODS: Data from consecutive patients with acute ischemic stroke admitted to a single center between 2003 and 2012, collected in the Acute Stroke Registry and Analysis of Lausanne data base, were retrospectively analyzed. Patients with a diagnostic CTA within 24 hours of symptom onset were selected. Relevant extra- and intracranial pathology, defined as stenosis of ≥50% and occlusions, were registered and classified into 21 prespecified segments. RESULTS: Of the 2209 included patients (42.1% women; median age, 72 years), 1075 (48.7%) had pathology in and 308 (13.9%) had pathology outside the ischemic territory. In the 50,807 arterial segments available for revision, 1851 (3.6%) abnormal segments were in the ischemic (symptomatic) territory and another 408 (0.8%) were outside it (asymptomatic). In the 1211 patients with ischemic stroke imaged within 6 hours of symptom onset, 40.7% had symptomatic large, proximal occlusions potentially amenable to endovascular therapy. CONCLUSIONS: CTA in patients with acute ischemic stroke shows large individual variations of occlusion sites and degrees. Approximately half of such patients have no visible occlusive disease, and 40% imaged within 6 hours show large, proximal segment occlusions amenable to endovascular therapy. These findings show the importance of early noninvasive imaging of extra- and intracranial arteries for identifying occlusive disease, planning recanalization strategies, and designing interventional trials.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
2.
New Microbes New Infect ; 15: 65-71, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28050250

RESUMO

Bacillus cereus bacteraemia can be severe, especially among patients with haematologic malignancy. We retrospectively reviewed first episodes of true B. cereus bacteraemia (more than one positive bottle plus signs of infection) at our institution between 1997 and 2013 with the aim to compare haematologic versus nonhaematologic patients and analyse episodes with complicated outcome. Among 56 episodes of positive-blood cultures for B. cereus, 21 were considered significant. Median age was 54 years (range 23-82 years). Ten patients (48%) had a haematologic malignancy; all were neutropenic at the time of B. cereus bacteraemia. Nonhaematologic patients were either intravenous drug users (n = 3, 14%), polytraumatized (n = 3, 14%) or had multiple chronic comorbidities (n = 5, 24%). Most episodes were hospital acquired (15, 71%). Sources of bacteraemia were intravascular catheter (n = 11, 52%), digestive tract (n = 6, 29%), drug injection (n = 3, 14%) and wound (n = 1, 5%). Adequate antibiotic therapy was provided to 18 patients (86%) during a median of 17 days (range 2-253 days). The intravascular catheter was removed in eight cases (42%). Three haematologic patients had a complicated course with neurologic complications (meningoencephalitis and cerebral abscesses). Complications appeared to be associated with catheter infection (100% of complicated cases vs. 29% of noncomplicated cases). In conclusion, B. cereus bacteraemia can have a complicated course in a subset of patients, mainly those with haematologic malignancy. Catheter infection may be associated with a worse outcome with frequent neurologic complications.

3.
Neuroradiology ; 59(1): 23-29, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28028565

RESUMO

INTRODUCTION: Haemorrhagic transformation of acute ischemic stroke (AIS) and particularly parenchymal haemorrhage (PH) remains a feared complication of intravenous thrombolysis (IVT). We aimed to identify clinical and perfusion CT (PCT) variables which are independently associated with PHs. METHODS: In this observational cohort study, based on the Acute Stroke Registry Analysis of Lausanne (ASTRAL) from 2003 to December 2013, we selected patients with AIS involving the middle cerebral artery (MCA) territory who were thrombolysed within 4.5 h of symptoms' onset and who had a good quality baseline PCT at the beginning of IVT. In addition to demographic, clinical, laboratory and non-contrast CT data, volumes of salvageable tissue and ischemic core on PCT, as well as absolute CBF and CBV values within the ischemic regions were compared in patients with and without PH in multivariate analysis. RESULTS: Of the 190 included patients, 24 (12.6%) presented a PH (11 had PH1 and 13 had PH2). In multivariate analysis of the clinical and radiological variables, the lowest CBV in the core and lower body weight was both significantly associated with PH (p = 0.009 and p = 0.024, respectively). CONCLUSION: In thrombolysed MCA strokes, maximal hypoperfusion severity depicted by lowest CBV values in the core region and lower body weight are independently correlated with PH. This information, if confirmed in other case series, may add to the stratification of revascularisation decisions in patients with a perceived high PH risk.


Assuntos
Peso Corporal , Angiografia Cerebral/métodos , Hemorragia Cerebral/induzido quimicamente , Hemorragia Cerebral/diagnóstico por imagem , Circulação Cerebrovascular , Hipovolemia/induzido quimicamente , Hipovolemia/diagnóstico por imagem , Acidente Vascular Cerebral/tratamento farmacológico , Terapia Trombolítica/efeitos adversos , Tomografia Computadorizada por Raios X/métodos , Idoso , Meios de Contraste , Feminino , Humanos , Iohexol , Angiografia por Ressonância Magnética , Masculino , Sistema de Registros , Fatores de Risco , Ultrassonografia Doppler Transcraniana
4.
Eur J Neurol ; 24(1): 167-174, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27801538

RESUMO

BACKGROUND AND PURPOSE: Multimodal computed tomography (CT) based imaging (MCTI) is widely used in acute ischaemic stroke. It was postulated that the use of MCTI is associated with improved patient outcome without causing harm. METHODS: All patients with an acute ischaemic stroke and CT-based imaging within 24 h from the ASTRAL (Acute Stroke Registry and Analysis of Lausanne) registry were included. Preceding demographic, clinical, biological, radiological and follow-up data were collected. Significant predictors of MCTI use were identified retrospectively to go on to fit a multivariable analysis. Then, patients undergoing additional CT angiography (CTA) or CTA and perfusion CT (CTP) were compared with non-contrast CT only patients with regard to 3-month favourable outcome (modified Rankin Scale score ≤2), 12-month mortality, stroke mechanism, short-term renal failure, use of ancillary diagnostic tests, duration of hospitalization and 12-month stroke recurrence. RESULTS: Of the 1994 included patients, 273 had only non-contrast CT, 411 had both non-contrast CT and CTA and 1310 had all three examinations. Factors independently associated with MCTI were younger age, low pre-stroke modified Rankin Scale score, low creatinine value, known stroke onset, anterior circulation stroke, anticoagulation or antihypertensive therapy (CTA only) and higher National Institutes of Health Stroke Scale scores (CTP only). After adjustment, MCTI was associated with a 50% reduction of 12-month mortality and a lower likelihood of unknown stroke mechanism. No association was found between MCTI and 3-month outcome, contrast-induced nephropathy, hospitalization duration, number of ancillary diagnostic tests or with stroke recurrence. CONCLUSION: Our study shows an association of MCTI use with lower adjusted 12-month mortality, better identification of the stroke mechanism and no signs of harm.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Imagem Multimodal , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Sistema de Registros , Estudos Retrospectivos
5.
AJNR Am J Neuroradiol ; 37(1): 155-62, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26494693

RESUMO

BACKGROUND AND PURPOSE: The alteration of brain maturation in preterm infants contributes to neurodevelopmental disabilities during childhood. Serial imaging allows understanding of the mechanisms leading to dysmaturation in the preterm brain. The purpose of the present study was to provide reference quantitative MR imaging measures across time in preterm infants, by using ADC, fractional anisotropy, and T1 maps obtained by using the magnetization-prepared dual rapid acquisition of gradient echo technique. MATERIALS AND METHODS: We included preterm neonates born at <30 weeks of gestational age without major brain lesions on early cranial sonography and performed 3 MRIs (3T) from birth to term-equivalent age. Multiple measurements (ADC, fractional anisotropy, and T1 relaxation) were performed on each examination in 12 defined white and gray matter ROIs. RESULTS: We acquired 107 MRIs (35 early, 33 intermediary, and 39 at term-equivalent age) in 39 cerebral low-risk preterm infants. Measures of T1 relaxation time showed a gradual and significant decrease with time in a region- and hemispheric-specific manner. ADC values showed a similar decline with time, but with more variability than T1 relaxation. An increase of fractional anisotropy values was observed in WM regions and inversely a decrease in the cortex. CONCLUSIONS: The gradual change with time reflects the progressive maturation of the cerebral microstructure in white and gray matter. Our study provides reference trajectories from 25 to 40 weeks of gestation of T1 relaxation, ADC, and fractional anisotropy values in low-risk preterm infants. We speculate that deviation thereof might reflect disturbed cerebral maturation; the correlation of this disturbed maturation with neurodevelopmental outcome remains to be addressed.


Assuntos
Encéfalo/crescimento & desenvolvimento , Processamento de Imagem Assistida por Computador/métodos , Recém-Nascido Prematuro/crescimento & desenvolvimento , Imageamento por Ressonância Magnética/métodos , Anisotropia , Deficiências do Desenvolvimento/diagnóstico , Feminino , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Masculino , Valores de Referência , Estatística como Assunto
6.
Neuroimage Clin ; 8: 631-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26236628

RESUMO

OBJECTIVES: The aim of this study was to investigate pathological mechanisms underlying brain tissue alterations in mild cognitive impairment (MCI) using multi-contrast 3 T magnetic resonance imaging (MRI). METHODS: Forty-two MCI patients and 77 healthy controls (HC) underwent T1/T2* relaxometry as well as Magnetization Transfer (MT) MRI. Between-groups comparisons in MRI metrics were performed using permutation-based tests. Using MRI data, a generalized linear model (GLM) was computed to predict clinical performance and a support-vector machine (SVM) classification was used to classify MCI and HC subjects. RESULTS: Multi-parametric MRI data showed microstructural brain alterations in MCI patients vs HC that might be interpreted as: (i) a broad loss of myelin/cellular proteins and tissue microstructure in the hippocampus (p ≤ 0.01) and global white matter (p < 0.05); and (ii) iron accumulation in the pallidus nucleus (p ≤ 0.05). MRI metrics accurately predicted memory and executive performances in patients (p ≤ 0.005). SVM classification reached an accuracy of 75% to separate MCI and HC, and performed best using both volumes and T1/T2*/MT metrics. CONCLUSION: Multi-contrast MRI appears to be a promising approach to infer pathophysiological mechanisms leading to brain tissue alterations in MCI. Likewise, parametric MRI data provide powerful correlates of cognitive deficits and improve automatic disease classification based on morphometric features.


Assuntos
Disfunção Cognitiva/patologia , Globo Pálido/metabolismo , Hipocampo/patologia , Ferro/metabolismo , Imageamento por Ressonância Magnética/métodos , Substância Branca/patologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Imageamento por Ressonância Magnética/normas , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade
7.
Rev Med Suisse ; 11(461): 411-7, 2015 Feb 11.
Artigo em Francês | MEDLINE | ID: mdl-25895220

RESUMO

Giant cell arteritis (GCA) is a subacute/chronic vasculitis and represents the most common form of systemic vasculitis in people over the age of 50 years. The absence of clear and specific diagnostic criteria with the highly variable clinical presentation is a diagnostic challenge requesting a multidisciplinary approach. Yet, GCA is an emergency and the treatment must be initiated very rapidly due to the risk of blindness. This article presents a review of GCA as well as the diagnostic and therapeutic institutional guidelines of the University Hospital of Lausanne.


Assuntos
Arterite de Células Gigantes/tratamento farmacológico , Arterite de Células Gigantes/terapia , Algoritmos , Hospitais Universitários , Humanos , Guias de Prática Clínica como Assunto , Suíça
8.
Neuroradiology ; 56(8): 629-35, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24838807

RESUMO

INTRODUCTION: Intravoxel incoherent motion (IVIM) imaging is an MRI perfusion technique that uses a diffusion-weighted sequence with multiple b values and a bi-compartmental signal model to measure the so-called pseudo-diffusion of blood caused by its passage through the microvascular network. The goal of the current study was to assess the feasibility of IVIM perfusion fraction imaging in patients with acute stroke. METHODS: Images were collected in 17 patients with acute stroke. Exclusion criteria were onset of symptoms to imaging >5 days, hemorrhagic transformation, infratentorial lesions, small lesions <0.5 cm in minimal diameter and hemodynamic instability. IVIM imaging was performed at 3 T, using a standard spin-echo Stejskal-Tanner pulsed gradients diffusion-weighted sequence, using 16 b values from 0 to 900 s/mm(2). Image quality was assessed by two radiologists, and quantitative analysis was performed in regions of interest placed in the stroke area, defined by thresholding the apparent diffusion coefficient maps, as well as in the contralateral region. RESULTS: IVIM perfusion fraction maps showed an area of decreased perfusion fraction f in the region of decreased apparent diffusion coefficient. Quantitative analysis showed a statistically significant decrease in both IVIM perfusion fraction f (0.026 ± 0.019 vs. 0.056 ± 0.025, p=2.2 · 10(-6)) and diffusion coefficient D compared with the contralateral side (3.9 ± 0.79 · 10(-4) vs. 7.5 ± 0.86 · 10(-4) mm(2)/s, p=1.3 · 10(-20)). CONCLUSION: IVIM perfusion fraction imaging is feasible in acute stroke. IVIM perfusion fraction is significantly reduced in the visible infarct. Further studies should evaluate the potential for IVIM to predict clinical outcome and treatment response.


Assuntos
Imagem de Difusão por Ressonância Magnética , Angiografia por Ressonância Magnética , Acidente Vascular Cerebral/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Circulação Cerebrovascular , Pré-Escolar , Estudos de Coortes , Estudos de Viabilidade , Feminino , Humanos , Masculino , Microcirculação , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes
9.
Nuklearmedizin ; 53(4): 155-61, 2014 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-24737132

RESUMO

AIM: MRI and PET with 18F-fluoro-ethyl-tyrosine (FET) have been increasingly used to evaluate patients with gliomas. Our purpose was to assess the additive value of MR spectroscopy (MRS), diffusion imaging and dynamic FET-PET for glioma grading. PATIENTS, METHODS: 38 patients (42 ± 15 aged, F/M: 0.46) with untreated histologically proven brain gliomas were included. All underwent conventional MRI, MRS, diffusion sequences, and FET-PET within 3±4 weeks. Performances of tumour FET time-activity-curve, early-to-middle SUVmax ratio, choline / creatine ratio and ADC histogram distribution pattern for gliomas grading were assessed, as compared to histology. Combination of these parameters and respective odds were also evaluated. RESULTS: Tumour time-activity-curve reached the best accuracy (67%) when taken alone to distinguish between low and high-grade gliomas, followed by ADC histogram analysis (65%). Combination of time-activity-curve and ADC histogram analysis improved the sensitivity from 67% to 86% and the specificity from 63-67% to 100% (p < 0.008). On multivariate logistic regression analysis, negative slope of the tumour FET time-activity-curve however remains the best predictor of high-grade glioma (odds 7.6, SE 6.8, p = 0.022). CONCLUSION: Combination of dynamic FET-PET and diffusion MRI reached good performance for gliomas grading. The use of FET-PET/MR may be highly relevant in the initial assessment of primary brain tumours.


Assuntos
Neoplasias Encefálicas/patologia , Glioma/patologia , Imageamento por Ressonância Magnética/métodos , Imagem Multimodal/métodos , Tomografia por Emissão de Pósitrons/métodos , Tirosina/análogos & derivados , Adulto , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Gradação de Tumores , Variações Dependentes do Observador , Compostos Radiofarmacêuticos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
J Thromb Haemost ; 12(6): 814-21, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24628853

RESUMO

BACKGROUND: Recanalization in acute ischemic stroke with large-vessel occlusion is a potent indicator of good clinical outcome. OBJECTIVE: To identify easily available clinical and radiologic variables predicting recanalization at various occlusion sites. METHODS: All consecutive, acute stroke patients from the Acute STroke Registry and Analysis of Lausanne (2003-2011) who had a large-vessel occlusion on computed tomographic angiography (CTA) (< 12 h) were included. Recanalization status was assessed at 24 h (range: 12-48 h) with CTA, magnetic resonance angiography, or ultrasonography. Complete and partial recanalization (corresponding to the modified Treatment in Cerebral Ischemia scale 2-3) were grouped together. Patients were categorized according to occlusion site and treatment modality. RESULTS: Among 439 patients, 51% (224) showed complete or partial recanalization. In multivariate analysis, recanalization of any occlusion site was most strongly associated with endovascular treatment, including bridging therapy (odds ratio [OR] 7.1, 95% confidence interval [CI] 2.2-23.2), and less so with intravenous thrombolysis (OR 1.6, 95% CI 1.0-2.6) and recanalization treatments performed beyond guidelines (OR 2.6, 95% CI 1.2-5.7). Clot location (large vs. intermediate) and tandem pathology (the combination of intracranial occlusion and symptomatic extracranial stenosis) were other variables discriminating between recanalizers and non-recanalizers. For patients with intracranial occlusions, the variables significantly associated with recanalization after 24 h were: baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.04, 95% CI 1.02-1.1), Alberta Stroke Program Early CT Score (ASPECTS) on initial computed tomography (OR 1.2, 95% CI 1.1-1.3), and an altered level of consciousness (OR 0.2, 95% CI 0.1-0.5). CONCLUSIONS: Acute endovascular treatment is the single most important factor promoting recanalization in acute ischemic stroke. The presence of extracranial vessel stenosis or occlusion decreases recanalization rates. In patients with intracranial occlusions, higher NIHSS score and ASPECTS and normal vigilance facilitate recanalization. Clinical use of these predictors could influence recanalization strategies in individual patients.


Assuntos
Isquemia Encefálica/diagnóstico , Isquemia Encefálica/terapia , Diagnóstico por Imagem , Procedimentos Endovasculares , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/terapia , Terapia Trombolítica , Idoso , Angiografia Cerebral , Diagnóstico por Imagem/métodos , Procedimentos Endovasculares/efeitos adversos , Feminino , Humanos , Modelos Logísticos , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Seleção de Pacientes , Valor Preditivo dos Testes , Sistema de Registros , Suíça , Terapia Trombolítica/efeitos adversos , Fatores de Tempo , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Ultrassonografia de Intervenção
11.
AJNR Am J Neuroradiol ; 35(2): 256-62, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23928134

RESUMO

BACKGROUND AND PURPOSE: Intravoxel incoherent motion MRI has been proposed as an alternative method to measure brain perfusion. Our aim was to evaluate the utility of intravoxel incoherent motion perfusion parameters (the perfusion fraction, the pseudodiffusion coefficient, and the flow-related parameter) to differentiate high- and low-grade brain gliomas. MATERIALS AND METHODS: The intravoxel incoherent motion perfusion parameters were assessed in 21 brain gliomas (16 high-grade, 5 low-grade). Images were acquired by using a Stejskal-Tanner diffusion pulse sequence, with 16 values of b (0-900 s/mm(2)) in 3 orthogonal directions on 3T systems equipped with 32 multichannel receiver head coils. The intravoxel incoherent motion perfusion parameters were derived by fitting the intravoxel incoherent motion biexponential model. Regions of interest were drawn in regions of maximum intravoxel incoherent motion perfusion fraction and contralateral control regions. Statistical significance was assessed by using the Student t test. In addition, regions of interest were drawn around all whole tumors and were evaluated with the help of histograms. RESULTS: In the regions of maximum perfusion fraction, perfusion fraction was significantly higher in the high-grade group (0.127 ± 0.031) than in the low-grade group (0.084 ± 0.016, P < .001) and in the contralateral control region (0.061 ± 0.011, P < .001). No statistically significant difference was observed for the pseudodiffusion coefficient. The perfusion fraction correlated moderately with dynamic susceptibility contrast relative CBV (r = 0.59). The histograms of the perfusion fraction showed a "heavy-tailed" distribution for high-grade but not low-grade gliomas. CONCLUSIONS: The intravoxel incoherent motion perfusion fraction is helpful for differentiating high- from low-grade brain gliomas.


Assuntos
Algoritmos , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/fisiopatologia , Circulação Cerebrovascular , Glioma/diagnóstico , Glioma/fisiopatologia , Interpretação de Imagem Assistida por Computador/métodos , Angiografia por Ressonância Magnética/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Velocidade do Fluxo Sanguíneo , Criança , Pré-Escolar , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Movimento (Física) , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
12.
Forensic Sci Int ; 225(1-3): 32-41, 2013 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-22721937

RESUMO

Cases of fatal outcome after surgical intervention are autopsied to determine the cause of death and to investigate whether medical error caused or contributed to the death. For medico-legal purposes, it is imperative that autopsy findings are documented clearly. Modern imaging techniques such as multi-detector computed tomography (MDCT) and postmortem CT angiography, which is used for vascular system imaging, are useful tools for determining cause of death. The aim of this study was to determine the utility of postmortem CT angiography for the medico-legal death investigation. This study investigated 10 medico-legal cases with a fatal outcome after surgical intervention using multi-phase postmortem whole body CT angiography. A native CT scan was performed as well as three angiographic phases (arterial, venous, and dynamic) using a Virtangio(®) perfusion device and the oily contrast agent, Angiofil(®). The results of conventional autopsy were compared to those from the radiological investigations. We also investigated whether the radiological findings affected the final interpretation of cause-of-death. Causes of death were hemorrhagic shock, intracerebral hemorrhage, septic shock, and a combination of hemorrhage and blood aspiration. The diagnoses were made by conventional autopsy as well as by postmortem CT angiography. Hemorrhage played an important role in eight of ten cases. The radiological exam revealed the exact source of bleeding in seven of the eight cases, whereas conventional autopsy localized the source of bleeding only generally in five of the seven cases. In one case, neither conventional autopsy nor CT angiography identified the source of hemorrhage. We conclude that postmortem CT angiography is extremely useful for investigating deaths following surgical interventions. This technique helps document autopsy findings and allows a second examination if it is needed; specifically, it detects and visualizes the sources of hemorrhages in detail, which is often of particular interest in such cases.


Assuntos
Angiografia/métodos , Autopsia , Complicações Intraoperatórias/patologia , Tomografia Computadorizada Multidetectores , Complicações Pós-Operatórias/patologia , Adolescente , Idoso , Hemorragia Cerebral/patologia , Meios de Contraste , Exsanguinação/patologia , Feminino , Patologia Legal , Humanos , Doença Iatrogênica , Masculino , Imperícia , Pessoa de Meia-Idade , Aspiração Respiratória/patologia , Estudos Retrospectivos , Choque Hemorrágico/patologia , Choque Séptico/patologia
13.
Neuroimage ; 62(1): 87-94, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22569062

RESUMO

The objective of this study was to investigate whether it is possible to pool together diffusion spectrum imaging data from four different scanners, located at three different sites. Two of the scanners had identical configuration whereas two did not. To measure the variability, we extracted three scalar maps (ADC, FA and GFA) from the DSI and utilized a region and a tract-based analysis. Additionally, a phantom study was performed to rule out some potential factors arising from the scanner performance in case some systematic bias occurred in the subject study. This work was split into three experiments: intra-scanner reproducibility, reproducibility with twin-scanner settings and reproducibility with other configurations. Overall for the intra-scanner and twin-scanner experiments, the region-based analysis coefficient of variation (CV) was in a range of 1%-4.2% and below 3% for almost every bundle for the tract-based analysis. The uncinate fasciculus showed the worst reproducibility, especially for FA and GFA values (CV 3.7-6%). For the GFA and FA maps, an ICC value of 0.7 and above is observed in almost all the regions/tracts. Looking at the last experiment, it was found that there is a very high similarity of the outcomes from the two scanners with identical setting. However, this was not the case for the two other imagers. Given the fact that the overall variation in our study is low for the imagers with identical settings, our findings support the feasibility of cross-site pooling of DSI data from identical scanners.


Assuntos
Imagem de Difusão por Ressonância Magnética/instrumentação , Imagem de Difusão por Ressonância Magnética/métodos , Imagem de Difusão por Ressonância Magnética/estatística & dados numéricos , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Imagens de Fantasmas , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
14.
Proc Natl Acad Sci U S A ; 107(44): 19067-72, 2010 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-20956328

RESUMO

From toddler to late teenager, the macroscopic pattern of axonal projections in the human brain remains largely unchanged while undergoing dramatic functional modifications that lead to network refinement. These functional modifications are mediated by increasing myelination and changes in axonal diameter and synaptic density, as well as changes in neurochemical mediators. Here we explore the contribution of white matter maturation to the development of connectivity between ages 2 and 18 y using high b-value diffusion MRI tractography and connectivity analysis. We measured changes in connection efficacy as the inverse of the average diffusivity along a fiber tract. We observed significant refinement in specific metrics of network topology, including a significant increase in node strength and efficiency along with a decrease in clustering. Major structural modules and hubs were in place by 2 y of age, and they continued to strengthen their profile during subsequent development. Recording resting-state functional MRI from a subset of subjects, we confirmed a positive correlation between structural and functional connectivity, and in addition observed that this relationship strengthened with age. Continuously increasing integration and decreasing segregation of structural connectivity with age suggests that network refinement mediated by white matter maturation promotes increased global efficiency. In addition, the strengthening of the correlation between structural and functional connectivity with age suggests that white matter connectivity in combination with other factors, such as differential modulation of axonal diameter and myelin thickness, that are partially captured by inverse average diffusivity, play an increasingly important role in creating brain-wide coherence and synchrony.


Assuntos
Desenvolvimento do Adolescente/fisiologia , Axônios/fisiologia , Córtex Cerebral/fisiologia , Desenvolvimento Infantil/fisiologia , Bainha de Mielina/fisiologia , Sinapses/fisiologia , Adolescente , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Lactente , Imageamento por Ressonância Magnética , Masculino
15.
Neuropediatrics ; 40(2): 92-6, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19809940

RESUMO

INTRODUCTION: Cerebrovascular changes are rarely discussed in patients with hemimegalencephaly. These alterations have previously been associated with epileptical activity. CASE: We report the case of a 36-week gestation neonate presenting with total right hemimegalencephaly, as demonstrated by a magnetic resonance imaging (MRI) performed in the first days of life. Perfusion-weighted imaging displayed a clear hypervascularization of the right hemisphere. Diffusion-tensor imaging showed an arrangement of white matter fibers concentrically around the ventricle on the right hemisphere. AngioMRI showed an obvious asymmetry in the size of the middle cerebral arteries, with the right middle cerebral artery being prominent. The baby was free of clinical seizures during his first week of life. An electroencephalogram at that time displayed an asymmetric background activity, but no electrical seizures. CONCLUSION: Perfusion anomalies in hemimegalencephaly may not necessarily be related to epileptical activity, but may be related to vessel alterations.


Assuntos
Doenças Arteriais Cerebrais/diagnóstico , Doenças Arteriais Cerebrais/etiologia , Malformações do Desenvolvimento Cortical/complicações , Imagem de Difusão por Ressonância Magnética/métodos , Eletroencefalografia/métodos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Lactente , Angiografia por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Masculino
17.
Proc Natl Acad Sci U S A ; 106(6): 2035-40, 2009 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-19188601

RESUMO

In the cerebral cortex, the activity levels of neuronal populations are continuously fluctuating. When neuronal activity, as measured using functional MRI (fMRI), is temporally coherent across 2 populations, those populations are said to be functionally connected. Functional connectivity has previously been shown to correlate with structural (anatomical) connectivity patterns at an aggregate level. In the present study we investigate, with the aid of computational modeling, whether systems-level properties of functional networks--including their spatial statistics and their persistence across time--can be accounted for by properties of the underlying anatomical network. We measured resting state functional connectivity (using fMRI) and structural connectivity (using diffusion spectrum imaging tractography) in the same individuals at high resolution. Structural connectivity then provided the couplings for a model of macroscopic cortical dynamics. In both model and data, we observed (i) that strong functional connections commonly exist between regions with no direct structural connection, rendering the inference of structural connectivity from functional connectivity impractical; (ii) that indirect connections and interregional distance accounted for some of the variance in functional connectivity that was unexplained by direct structural connectivity; and (iii) that resting-state functional connectivity exhibits variability within and across both scanning sessions and model runs. These empirical and modeling results demonstrate that although resting state functional connectivity is variable and is frequently present between regions without direct structural linkage, its strength, persistence, and spatial statistics are nevertheless constrained by the large-scale anatomical structure of the human cerebral cortex.


Assuntos
Córtex Cerebral/fisiologia , Vias Neurais/fisiologia , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Imagem de Difusão por Ressonância Magnética , Humanos , Imageamento por Ressonância Magnética , Modelos Neurológicos
18.
Acta Psychiatr Scand ; 118(3): 188-99, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18636993

RESUMO

OBJECTIVE: To reveal the EEG correlates of resting hypofrontality in schizophrenia (SZ). METHOD: We analyzed the whole-head EEG topography in 14 patients compared to 14 matched controls by applying a new parameterization of the multichannel EEG. We used a combination of power measures tuned for regional surface mapping with power measures that allow evaluation of global effects. RESULTS: The SZ-related EEG abnormalities include i) a global decrease in absolute EEG power robustly manifested in the alpha and beta frequency bands, and ii) a relative increase in the alpha power over the prefrontal brain regions against its reduction over the posterior regions. In the alpha band both effects are linked to the SZ symptoms measured with Positive and Negative Symptom Scales and to chronicity. CONCLUSION: As alpha activity is related to regional deactivation, our findings support the concept of hypofrontality in SZ and expose the alpha rhythm as a sensitive indicator of it.


Assuntos
Ritmo alfa/métodos , Ritmo alfa/estatística & dados numéricos , Córtex Pré-Frontal/fisiopatologia , Esquizofrenia/fisiopatologia , Adolescente , Adulto , Mapeamento Encefálico/métodos , Dominância Cerebral , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Escalas de Graduação Psiquiátrica , Reprodutibilidade dos Testes , Descanso , Esquizofrenia/diagnóstico , Esquizofrenia/tratamento farmacológico , Psicologia do Esquizofrênico , Sensibilidade e Especificidade , Processamento de Sinais Assistido por Computador , Adulto Jovem
19.
Neonatology ; 92(1): 14-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17596732

RESUMO

We report 2 cases of non-immune hydrops fetalis (NIHF) in which autopsy findings revealed an association with right-sided congenital diaphragmatic eventration (CDE). Both patients born at 30 weeks of gestation presented with severe generalized skin oedema, pleural effusions and ascites. They both died shortly after birth of cardiorespiratory insufficiency due to lung hypoplasia and low output heart failure. The right thoracic cavity was filled with the membranous but intact right diaphragm covering the herniated visceral organs including parts of the liver, small bowel and colon surrounded by voluminous ascites. In similar fashion to the situation seen in congenital diaphragmatic hernia (CDH), the displaced visceral organs led to impaired lung growth resulting in important lung hypoplasia and obstructed venous return. Extravascular liquid accumulation was probably further aggravated by hypoproteinaemia secondary to liver dysfunction resulting from the venous congestion and cardiac failure. In summary, CDE is a rare condition resulting from impaired ingrowth of muscle fibres into the diaphragm during the first trimester. Prenatal differentiation of CDE from CDH is a real challenge. The association of CDE and NIHF has not been previously described.


Assuntos
Eventração Diafragmática/complicações , Hidropisia Fetal/etiologia , Autopsia , Baixo Débito Cardíaco/complicações , Diafragma/anormalidades , Eventração Diafragmática/diagnóstico , Feminino , Hérnia Diafragmática/complicações , Hérnias Diafragmáticas Congênitas , Humanos , Hidropisia Fetal/diagnóstico , Recém-Nascido
20.
Eur Radiol ; 17(11): 2957-63, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17492288

RESUMO

The diagnostic performance of magnetic resonance imaging (MRI) for detection of intestinal fistulas, other than perianal, in patients with known complicated inflammatory bowel conditions (CIBC) was investigated. Our study group consisted of 20 patients (12 women, mean age 43 years) with CIBC, including Crohn's disease (n=13), colonic diverticulitis (n=3), colitis after radiotherapy (n=3) and of postoperative origin (n=1). Eleven surgically proven enteral fistulas were known in ten (50%) of these patients, being of enterovesical (n=3), enterocolic (n=2), enteroenteral (n=2), rectovaginal (n=2), rectovaginovesical (n=1) and of entercutaneous (n=1) localisation. The other ten patients (50%), used as the control group, showed MR features of CIBC, although without any fistulous tract. Multiplanar T1- and T2-weighted sequences had been performed, including gadolinium-enhanced acquisition with fat saturation (1.5 T). MR findings were independently blindly and retrospectively reviewed by three radiologists for the presence and etiology of any fistula, as well as visualization and characterization of the fistulous tract. Results were compared with surgical findings (n=16) and clinical evolution (n=4). Interobserver agreement was calculated. Interobserver agreement kappa for fistula detection was 0.71. Overall sensitivity, specificity and accuracy for fistula detection were 78.6%, 75% and 77.2%, respectively. Sensitivity for fistula characterization was 80.6%, with visualization of the fistulous tract in all cases, whereby T1-weighted gadolinium-enhanced fat-saturated images were considered the most useful sequences. Gadolinium-enhanced MRI is a reliable and reproducible tool for detection of enteral fistulas secondary to inflammatory conditions.


Assuntos
Doenças Inflamatórias Intestinais/complicações , Doenças Inflamatórias Intestinais/diagnóstico , Fístula Intestinal/diagnóstico , Fístula Intestinal/patologia , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Feminino , Gadolínio/farmacologia , Humanos , Processamento de Imagem Assistida por Computador , Inflamação , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Reprodutibilidade dos Testes , Estudos Retrospectivos
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