RESUMO
OBJECTIVE: Several studies have found an increase in hippocampal volume following electroconvulsive therapy (ECT), but the effect on cortical thickness has been less investigated. We aimed to examine the effects of ECT on cortical thickness and their associations with clinical outcome. METHOD: Using 3 Tesla MRI scanner, we obtained T1-weighted brain images of 18 severely depressed patients at three time points: before, right after and 6 months after a series of ECT. The thickness of 68 cortical regions was extracted using Free Surfer, and Linear Mixed Model was used to analyze the longitudinal changes. RESULTS: We found significant increases in cortical thickness of 26 regions right after a series of ECT, mainly within the frontal, temporal and insular cortex. The thickness returned to the baseline values at 6-month follow-up. We detected no significant decreases in cortical thickness. The increase in the thickness of the right lateral orbitofrontal cortex was associated with a greater antidepressant effect, r = 0.75, P = 0.0005. None of the cortical regions showed any associations with cognitive side effects. CONCLUSION: The increases in cortical thickness induced by ECT are transient. Further multimodal MRI studies should examine the neural correlates of these increases and their relationship with the antidepressant effect.
Assuntos
Córtex Cerebral/patologia , Transtorno Depressivo/patologia , Transtorno Depressivo/terapia , Eletroconvulsoterapia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Córtex Cerebral/diagnóstico por imagem , Transtorno Depressivo/diagnóstico por imagem , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
BACKGROUND AND PURPOSE: The integrity of the blood-brain barrier (BBB) has been questioned in migraine, but BBB permeability has never been investigated during spontaneous migraine attacks. In the present study, BBB permeability during spontaneous attacks of migraine without aura was investigated compared to an interictal state. METHODS: Seventy-four patients suffering from migraine without aura were recruited to participate in this cross-sectional dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) study. The patients were instructed to report at the hospital for DCE-MRI scan during and outside of a spontaneous migraine attack. The primary end-point was a difference in the BBB permeability (ml/100 g/min) between the attack and the headache-free days. The permeability was assessed in five different regions of interest (ROIs) located in the anterior, middle and posterior cerebral area, brain stem, posterior pons and whole brain. The paired samples t test was used to compare Ki (permeability) values between the attack and headache-free days. RESULTS: Nineteen patients completed the study. Median time from onset of migraine attack to scan was 6.5 h (range 4.0-15.5 h). No change in the mean BBB permeability (ml/100 g/min) was found between the attack and the headache-free days in any of the measured ROIs. No relationship between the pain side or intensity and BBB permeability was found in 15 patients with unilateral pain during the examined attack. CONCLUSIONS: It was demonstrated that the BBB permeability during spontaneous migraine attacks without aura was unchanged.
Assuntos
Barreira Hematoencefálica/diagnóstico por imagem , Enxaqueca sem Aura/diagnóstico por imagem , Adulto , Barreira Hematoencefálica/fisiopatologia , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Enxaqueca sem Aura/fisiopatologia , Medição da Dor , Permeabilidade , Cintilografia , Adulto JovemRESUMO
BACKGROUND: Cerebrospinal fluid (CSF) biomarkers have been suggested to predict multiple sclerosis (MS) after clinically isolated syndromes, but studies investigating long-term prognosis are needed. OBJECTIVE: To assess the predictive ability of CSF biomarkers with regard to MS development and long-term disability after optic neuritis (ON). METHODS: Eighty-six patients with ON as a first demyelinating event were included retrospectively. Magnetic resonance imaging (MRI), CSF leukocytes, immunoglobulin G index and oligoclonal bands were registered. CSF levels of chitinase-3-like-1, osteopontin, neurofilament light-chain, myelin basic protein, CCL2, CXCL10, CXCL13 and matrix metalloproteinase-9 were measured by enzyme-linked immunosorbent assay. Patients were followed up after 13.6 (range 9.6-19.4) years and 81.4% were examined, including Expanded Disability Status Scale and MS functional composite evaluation. 18.6% were interviewed by phone. Cox regression, multiple regression and Spearman correlation analyses were used. RESULTS: Forty-six (53.5%) developed clinically definite MS (CDMS) during follow-up. In a multivariate model MRI (p=0.0001), chitinase 3-like 1 (p=0.0033) and age (p=0.0194) combined predicted CDMS best. Neurofilament light-chain predicted long-term disability by the multiple sclerosis severity scale (p=0.0111) and nine-hole-peg-test (p=0.0202). Chitinase-3-like-1 predicted long-term cognitive impairment by the paced auditory serial addition test (p=0.0150). CONCLUSION: Neurofilament light-chain and chitinase-3-like-1 were significant predictors of long-term physical and cognitive disability. Furthermore, chitinase-3-like-1 predicted CDMS development. Thus, these molecules hold promise as clinically valuable biomarkers after ON as a first demyelinating event.
Assuntos
Adipocinas/líquido cefalorraquidiano , Progressão da Doença , Lectinas/líquido cefalorraquidiano , Esclerose Múltipla/líquido cefalorraquidiano , Proteínas de Neurofilamentos/líquido cefalorraquidiano , Neurite Óptica/líquido cefalorraquidiano , Adolescente , Adulto , Biomarcadores/líquido cefalorraquidiano , Proteína 1 Semelhante à Quitinase-3 , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Índice de Gravidade de Doença , Adulto JovemRESUMO
BACKGROUND: Imaging studies of patients with Tourette's syndrome (TS) across different cohorts have shown alterations in gray and white matter in areas associated with the cortico-striato-thalamic-cortical (CSTC) pathways; however, no consistent findings have subsequently established a clear indication of the pathophysiology of TS. METHODS: This study was designed to investigate changes in gray and white matter in medication-free children with TS in the CSTC areas. With MRI, 24 children with TS and 18 healthy controls were analyzed using three complementary methods. RESULTS AND CONCLUSION: Analyses revealed no differences between controls and patients with TS in gray or white matter. Possible discrepancies between cohorts and methods may play a role in the different findings in other studies. Further studies investigating well-defined cohorts with TS analyzing both gray and white matter in the same cohort may add additional information to the pathophysiology of TS.
Assuntos
Encéfalo/patologia , Imageamento por Ressonância Magnética , Síndrome de Tourette/patologia , Mapeamento Encefálico , Estudos de Casos e Controles , Criança , Corpo Caloso/patologia , Imagem de Tensor de Difusão , Feminino , Humanos , MasculinoRESUMO
Physical exercise increases peripheral insulin sensitivity, but regional differences are poorly elucidated in humans. We investigated the effect of aerobic exercise training on insulin-stimulated glucose uptake in five individual femoral muscle groups and four different adipose tissue regions, using dynamic (femoral region) and static (abdominal region) 2-deoxy-2-[¹8F]fluoro-d-glucose (FDG) PET/CT methodology during steady-state insulin infusion (40 mU·m⻲·min⻹). Body composition was measured by dual X-ray absorptiometry and MRI. Sixty-one healthy, sedentary [V(O2max) 36(5) ml·kg⻹·min⻹; mean(SD)], moderately overweight [BMI 28.1(1.8) kg/m²], young [age: 30(6) yr] men were randomized to sedentary living (CON; n = 17 completers) or moderate (MOD; 300 kcal/day, n = 18) or high (HIGH; 600 kcal/day, n = 18) dose physical exercise for 11 wk. At baseline, insulin-stimulated glucose uptake was highest in femoral skeletal muscle followed by intraperitoneal visceral adipose tissue (VAT), retroperitoneal VAT, abdominal (anterior + posterior) subcutaneous adipose tissue (SAT), and femoral SAT (P < 0.0001 between tissues). Metabolic rate of glucose increased similarly (~30%) in the two exercise groups in femoral skeletal muscle (MOD 24[9, 39] µmol·kg⻹·min⻹, P = 0.004; HIGH 22[9, 35] µmol·kg⻹·min⻹, P = 0.003) (mean[95% CI]) and in five individual femoral muscle groups but not in femoral SAT. Standardized uptake value of FDG decreased ~24% in anterior abdominal SAT and ~20% in posterior abdominal SAT compared with CON but not in either intra- or retroperitoneal VAT. Total adipose tissue mass decreased in both exercise groups, and the decrease was distributed equally among subcutaneous and intra-abdominal depots. In conclusion, aerobic exercise training increases insulin-stimulated glucose uptake in skeletal muscle but not in adipose tissue, which demonstrates some interregional differences.
Assuntos
Tecido Adiposo Branco/metabolismo , Exercício Físico , Transportador de Glucose Tipo 4/metabolismo , Glucose/metabolismo , Resistência à Insulina , Músculo Esquelético/metabolismo , Sobrepeso/terapia , Tecido Adiposo Branco/diagnóstico por imagem , Tecido Adiposo Branco/efeitos dos fármacos , Adiposidade , Adulto , Transporte Biológico/efeitos dos fármacos , Índice de Massa Corporal , Meios de Contraste/metabolismo , Fluordesoxiglucose F18/metabolismo , Técnica Clamp de Glucose , Transportador de Glucose Tipo 4/biossíntese , Humanos , Hipoglicemiantes/metabolismo , Hipoglicemiantes/farmacologia , Insulina/metabolismo , Insulina/farmacologia , Estudos Longitudinais , Masculino , Imagem Multimodal , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/efeitos dos fármacos , Sobrepeso/metabolismo , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Regulação para Cima , Adulto JovemRESUMO
The diagnosis of MS is based on the revised McDonald criteria and is multidisciplinary. Both clinical and paraclinical measures are included. High-field magnetic resonance imaging (MRI) is becoming increasingly available and it is therefore necessary to clarify possible advantages of high-field MRI in MS. The aim of this paper was to review MRI studies in MS where a direct comparison of MRI at high field with MRI at 1-1.5 tesla (T) had been performed. The studies evaluated were found by searching Pubmed with relevant terms including MeSH terms. The reviewed studies all found the conspicuity of lesions to be better at high field. Of the seven studies, six found more and bigger lesions at high-field MRI. In the present paper, the relevant MRI sequences are evaluated in detail. The detection of more lesions at high-field strength did not seem to lead to earlier diagnosis of clinically definite multiple sclerosis. Further larger studies of patients with clinically isolated syndromes are needed to settle the question of a diagnostic consequence of high-field imaging in MS. We suggest that the next revision of the McDonald diagnostic criteria include a recommendation of field strength.
Assuntos
Encéfalo/patologia , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/normas , Esclerose Múltipla/diagnóstico , Diagnóstico Diferencial , Diagnóstico Precoce , Humanos , Processamento de Imagem Assistida por Computador , PubMed/estatística & dados numéricosRESUMO
Study Objectives: Obstructive sleep apnea (OSA) is associated with increased risk of stroke but the underlying mechanism is poorly understood. We suspect that the normal cerebrovascular response to hypoxia is disturbed in patients with OSA. Methods: Global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and lactate concentration during hypoxia were measured in patients with OSA and matched controls. Twenty-eight patients (82.1% males, mean age 52.3 ± 10.0 years) with moderate-to-severe OSA assessed by partial polysomnography were examined and compared with 19 controls (73.7% males, mean age 51.8 ± 10.1 years). Patients and controls underwent magnetic resonance imaging (MRI) during 35 min of normoxia followed by 35 min inhaling hypoxic air (10%-12% O2). After 3 months of continuous positive airway pressure (CPAP) treatment, 22 patients were rescanned. Results: During hypoxia, CBF significantly increased with decreasing arterial blood oxygen concentration (4.53 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001) in the control group, but was unchanged (0.89 mL (blood)/100 g/min per -1 mmol(O2)/L, p = 0.289) in the patient group before CPAP treatment. The CBF response to hypoxia was significantly weaker in patients than in controls (p = 0.003). After 3 months of CPAP treatment the CBF response normalized, showing a significant increase during hypoxia (5.15 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001). There was no difference in CMRO2 or cerebral lactate concentration between patients and controls, and no effect of CPAP treatment. Conclusions: Patients with OSA exhibit reduced CBF in response to hypoxia. CPAP treatment normalized these patterns.
Assuntos
Circulação Cerebrovascular/fisiologia , Hipóxia/sangue , Ácido Láctico/sangue , Oxigênio/sangue , Apneia Obstrutiva do Sono/sangue , Adulto , Biomarcadores/sangue , Pressão Positiva Contínua nas Vias Aéreas/métodos , Feminino , Humanos , Hipóxia/diagnóstico por imagem , Hipóxia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Polissonografia/métodos , Apneia Obstrutiva do Sono/diagnóstico por imagem , Apneia Obstrutiva do Sono/fisiopatologiaRESUMO
Infants with low birth weight are at increased risk of perinatal brain injury. Disruption of normal cortical development may have consequences for later motor, behavioural and cognitive development. The aim of this study was to measure cerebral cortical thickness, area and volume with an automated MRI technique in 15-year-old adolescents who had low birth weight. Cerebral MRI for morphometric analysis was performed on 50 very low birth weight (VLBW, birth weight =1500 g), 49 term small for gestational age births (SGA, birth weight <10th percentile at term) and 58 control adolescents. A novel method of cortical surface models yielded measurements of cortical thickness and area for each subject's entire brain and computed cross-subject statistics based on cortical anatomy. The cortical surface models demonstrated regional thinning of the parietal, temporal and occipital lobes in the VLBW group, whereas regional thickening was demonstrated in the frontal and occipital lobes. The areas of change were greatest in those with the shortest gestational age at birth and lowest birth weight. Cortical surface area and cortical volume were lower in the VLBW than in the Control group. Within the VLBW group, there was an association between surface area and estimation of the intelligence quotient IQ (IQ(est)) and between cortical volume and IQ(est). Furthermore, cortical grey matter as a proportion of brain volume was significantly lower in the VLBW, but not in the SGA group compared with Controls. This observed reorganization of the developing brain offers a unique opportunity to investigate any relationship between changes in cortical anatomy and cognitive and social impairments, and the increase in psychiatric disorders that have been found in VLBW children and adolescents.
Assuntos
Córtex Cerebral/patologia , Recém-Nascido de Baixo Peso , Adolescente , Peso ao Nascer , Mapeamento Encefálico/métodos , Cefalometria/métodos , Córtex Cerebral/crescimento & desenvolvimento , Feminino , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Recém-Nascido de muito Baixo Peso , Inteligência , Imageamento por Ressonância Magnética/métodos , MasculinoRESUMO
OBJECTIVES: The purpose of the study was to investigate the effects of beta1-blockade on left ventricular (LV) size and function for patients with chronic heart failure. BACKGROUND: Large-scale trials have shown that a marked decrease in mortality can be obtained by treatment of chronic heart failure with beta-adrenergic blocking agents. Possible mechanisms behind this effect remain yet to be fully elucidated, and previous studies have presented insignificant results regarding suspected LV antiremodeling effects. METHODS: In this randomized, placebo-controlled and double-blind substudy to the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF), 41 patients were examined with magnetic resonance imaging three times in a six-month period, assessing LV dimensions and function. RESULTS: Decreases in both LV end-diastolic volume index (150 ml/m2 at baseline to 126 ml/m2 after six months, p = 0.007) and LV end-systolic volume index (107 ml/m2 to 81 ml/m2, p = 0.001) were found, whereas LV ejection fraction increased in the metoprolol CR/XL group (29% to 37%, p = 0.005). No significant changes were seen in the placebo group regarding these variables. Left ventricular stroke volume index remained unchanged, whereas LV mass index decreased in both groups (175 g/m2 to 160 g/m2 in the placebo group [p = 0.005] and 179 g/m2 to 164 g/m2 in the metoprolol CR/XL group [p = 0.011). CONCLUSIONS: This study is the first randomized study to demonstrate that the beta1-blocker metoprolol CR/XL has antiremodeling effects on the LV in patients with chronic heart failure and consequently provides an explanation for the highly significant decrease in mortality from worsening heart failure found in the MERIT-HF trial.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Metoprolol/farmacologia , Função Ventricular Esquerda/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos , Antagonistas Adrenérgicos beta/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Método Duplo-Cego , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Imageamento por Ressonância Magnética , Masculino , Metoprolol/uso terapêutico , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
This paper presents a novel method for registration of single and multi-slice cardiac perfusion MRI. Utilising off-line computer intensive analyses of variance and clustering in an annotated training set, the presented method is capable of providing registration without any manual interaction in less than a second per frame. Changes in image intensity during the bolus passage are modelled by a slice-coupled active appearance model, which is augmented with a cluster analysis of the training set. Landmark correspondences are optimised using the MDL framework due to Davies et al. Image search is verified and stabilised using perfusion specific prior models of pose and shape estimated from training data. Qualitative and quantitative validation of the method is carried out using 2000 clinical quality, short-axis, perfusion MR slice images, acquired from 10 freely breathing patients with acute myocardial infarction. Despite evident perfusion deficits and varying image quality in the limited training set, a leave-one-out cross-validation of the method showed a mean point to curve distance of 1.25+/-0.36 pixels for the left and right ventricle combined. We conclude that this learning-based method holds great promise for the automation of cardiac perfusion investigations, due to its accuracy, robustness and generalisation ability.
Assuntos
Circulação Coronária/fisiologia , Doença das Coronárias/diagnóstico , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Artefatos , Meios de Contraste/farmacocinética , Doença das Coronárias/fisiopatologia , HumanosRESUMO
BACKGROUND AND PURPOSE: There is growing evidence that white matter hyperintensities (WMH) should not be considered as benign age-dependent changes on MR images but indicate pathological changes with clinical consequences. Previous studies comparing subjects with WMH to normal controls have reported global reductions in cerebral blood flow (CBF) and cerebral vascular reactivity. In this study, we examined localized hemodynamic status to compare WMH to normal appearing white matter (NAWM). METHODS: A group of 21 normal 85-year-old subjects were studied using dynamic contrast-enhanced MRI together with administration of acetazolamide. From a combination of anatomic images with different signal weighting, regions of interest were generated corresponding to gray and white matter and WMH. Localized measurements of CBF and cerebral blood volume (CBV) and mean transit time were obtained directly within WMH and NAWM. RESULTS: When comparing WMH to NAWM, measurements showed significantly lower CBF (P=0.004) and longer mean transit time (P< 0.001) in WMH but no significant difference in CBV (P=0.846). The increases in CBF and CBV induced by acetazolamide were significantly smaller in WMH than in NAWM (P=0.026, P<0.001). CONCLUSION: These results show that a change in the hemodynamic status is present within the WMH, making these areas more likely to be exposed to transient ischemia inducing myelin rarefaction. In the future, MRI may be used to examine the effect of therapeutic strategies designed to prevent or normalize vascular changes.
Assuntos
Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Circulação Cerebrovascular/fisiologia , Hemodinâmica/fisiologia , Imageamento por Ressonância Magnética/métodos , Acetazolamida/administração & dosagem , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Estudos de Coortes , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Modelos Cardiovasculares , Valor Preditivo dos Testes , Valores de ReferênciaRESUMO
OBJECTIVE: To study the association of brain magnetic resonance imaging (MRI) findings and HLA findings to clarify the relationship between monosymptomatic optic neuritis (ON) and ON as part of clinically definite multiple sclerosis (CDMS). DESIGN: Population-based cohort of patients with ON referred prospectively during 6 years by neurologists and ophthalmologists within 4 weeks of onset of ON. SETTING: Referral center in the general community of greater Copenhagen (Denmark) (population, 1.5 million). PATIENTS: A consecutive sample of 199 patients aged 12 to 59 years with ON (133 with idiopathic ON, 66 with ON + CDMS), ethnically matched with 192 healthy volunteers. MAIN OUTCOME MEASURES: Relation between the HLA-DR15, -DR17, -DQA-1B, and -DQB-1B polymorphisms as defined by restriction fragment length polymorphism analysis, and presence of plaques on T2-weighted brain MRI. RESULTS: The frequency of HLA-DR15 was significantly increased in patients with ON + CDMS (52%) and ON (47%) compared with control subjects (31%). The frequency of HLA-DR17 was almost equal in the ON + CDMS (18%), ON (23%), and control (23%) groups. The frequencies of HLA-DQA-1B (55% in ON + CDMS, 58% in ON) and HLA-DQB-1B (49% in ON + CDMS, 59% in ON) were significantly increased compared with control subjects (41%, HLA-DQA-1B; 37%, HLA-DQB-1B). Brain MRI was abnormal in 48 of 56 examined patients with ON + CDMS and in 64 of 120 examined patients with ON (P < .001). In contrast, the frequencies of HLA alleles did not differ between patients with and without demyelinating lesions. However, patients with ON and normal MRI findings did not show association with HLA-DR15. CONCLUSIONS: The frequencies of alleles were similar in patients with ON and ON + CDMS, confirming that they are not 2 immunogenetically distinct disease entities. The heterogeneity within the group of patients with ON suggests that the HLA-DR15 molecule is involved in susceptibility to initial demyelinating lesion formation.
Assuntos
Antígenos HLA-DQ/análise , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico , Esclerose Múltipla/imunologia , Neurite Óptica/diagnóstico , Neurite Óptica/imunologia , Doença Aguda , Adolescente , Adulto , Alelos , Criança , Feminino , Antígenos HLA-DQ/genética , Antígenos HLA-DR/análise , Humanos , Imunofenotipagem , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
BACKGROUND: A range of neurohumoral substances have been suggested as diagnostic markers in heart failure. It is, however, undetermined which marker has the greatest diagnostic potential, and whether additional information is gained by a comprehensive neurohumoral evaluation. AIMS: The purpose of the study was to compare the value of epinephrine, norepinephrine, renin activity, aldosterone (ALDO), atrial (ANP) and brain (BNP) natriuretic peptides, arginine-vasopressin and endothelin (ENDO) as markers for left ventricular (LV) dimensions and ejection fraction (LVEF) in patients with systolic heart failure. METHODS: Forty-eight patients with symptomatic heart failure were examined with blood samples and magnetic resonance imaging along with 20 age and gender-matched normal controls. RESULTS: In multiple regression analyses, BNP was the strongest independent marker for LV end-diastolic (r=0.71, P<0.0001), and end-systolic (r=0.75, P<0.0001) volumes, myocardial mass (r=0.69, P<0.0001), and LVEF (r=-0.78, P<0.0001). ANP was a supplementary independent marker for LV end-diastolic (r=0.76, P<0.0001) and end-systolic (r=0.78, P<0.0001) (ANP and BNP combined) volumes, ENDO for myocardial mass [r=0.71, P<0.0001 (ENDO/BNP)], and ALDO for LVEF [r=-0.81, P<0.0001 (ALDO/BNP)]. CONCLUSION: BNP is the strongest marker for LV dimensions and LVEF in patients with systolic heart failure. However, a comprehensive neurohumoral evaluation may add some information to the diagnosis.
Assuntos
Neurotransmissores/sangue , Volume Sistólico/fisiologia , Disfunção Ventricular Esquerda/sangue , Disfunção Ventricular Esquerda/complicações , Idoso , Aldosterona/sangue , Arginina Vasopressina/sangue , Fator Natriurético Atrial/sangue , Biomarcadores/sangue , Pressão Sanguínea/fisiologia , Endotelina-1/sangue , Epinefrina/sangue , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/complicações , Frequência Cardíaca/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico/sangue , Norepinefrina/sangue , Análise de Regressão , Renina/sangueRESUMO
Measurement of water self-diffusion in the brain in 25 patients with multiple sclerosis was performed by magnetic resonance imaging. Quantitative diffusion measurements were obtained using single spin-echo pulse sequences with pulsed magnetic field gradients of different magnitude. Twenty-two of these patients also underwent measurement of the transverse relaxation time (T2). Only one plaque was evaluated in each patient. Based on prior knowledge, 12 plaques were classified as being 3 mo or less in age, and 7 plaques were classified as being more than 3 mo old. In all 25 plaques, water self-diffusion was found to be higher than in apparently normal white matter. Furthermore, water self-diffusion was found to be higher in acute plaques compared with chronic plaques. Finally, a slight tendency toward a relationship between the diffusion capability and T2 was found. We believe that an increased diffusion capability signifies an increase of the extracellular water space, which probably is related to the degree of demyelination. Thus, measurement of water self-diffusion in multiple sclerosis plaques may contribute to the study of pathogenesis of demyelination.
Assuntos
Encéfalo/patologia , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico , Adulto , Doenças Desmielinizantes/patologia , Espaço Extracelular/metabolismo , Feminino , Humanos , Masculino , Esclerose Múltipla/patologiaRESUMO
The precision (reproducibility) of relaxation times derived from magnetic resonance images of patients with multiple sclerosis (MS) were investigated. Measurements of 10 MS patients were performed at 1.5 T on two occasions within 1 wk. T1 and T2 was measured using a partial saturation inversion recovery sequence (6 points) and a Carr-Purcell-Meiboom-Gill phase alternating-phase shift multiple spin-echo sequence with 32 echoes. Regions of interest (ROI) were placed both in apparently normal white matter and plaques. The precision (+/- 1.96 SD) and the confidence intervals for T1 and T2 for white matter and plaques were calculated. The precision of T1 for white matter and plaques was respectively +/- 94 msec and +/- 208 msec. The precision of T2 for white matter and plaques was respectively +/- 18 msec and +/- 26 msec. For all measurements the coefficient of variation was about 9%. Judging from our own study and others as well, a precision better than 10% for T1 and T2 would seem unrealistic at present.
Assuntos
Encéfalo/patologia , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico , Adulto , Humanos , Pessoa de Meia-Idade , Reprodutibilidade dos TestesRESUMO
The fully relaxed water signal was used as an internal standard in a STEAM experiment to calculate the concentrations of the metabolites: N-acetyl aspartate (NAA), creatine + phosphocreatine (Cr + PCr), and choline (Cho) containing compounds in four different parts of the brain in two age groups of healthy volunteers (20-30 yr, n = 8) and (60-80 yr, n = 8). Furthermore, T1 and T2 relaxation time of the metabolites and signal ratios: NAA/Cho, NAA/Cr + PCr, and Cho/Cr + PCr at TE = 272 msec were calculated. The experiments were carried out using a Siemens Helicon SP 63/84 wholebody MR-scanner at 1.5 T. In the younger age group, the concentration of NAA was significantly higher in the occipital part than in the other three parts of the brain. No significant regional variation was found for any other metabolite concentration. There was a significantly higher concentration of NAA in the occipital part of the brain in the younger age group compared to the older one. No significant regional or age dependent variation was found concerning the T1 and T2 relaxation times.
Assuntos
Envelhecimento/metabolismo , Ácido Aspártico/análogos & derivados , Encéfalo/metabolismo , Colina/análise , Creatina/análise , Espectroscopia de Ressonância Magnética , Fosfocreatina/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Ácido Aspártico/análise , Humanos , Pessoa de Meia-IdadeRESUMO
The reliability of absolute quantification of average metabolite concentrations in the human brain in vivo by 1H-MRS using the fully relaxed water signal as an internal standard was tested in a number of in vitro as well as in vivo measurements. The experiments were carried out on a SIEMENS HELICON SP 63/84 wholebody MR-scanner operating at 1.5 T using a STEAM sequence. In vitro studies indicate a very high correlation between metabolite signals (area under peaks) and concentration, R = 0.99 as well as between metabolite signals and the volume of the selected voxel, R = 1.00. The error in quantification of N-acetyl aspartate (NAA) concentration was about 1-2 mM (6-12%). Also in vivo a good linearity between water signal and selected voxel size was seen. The same was true for the studied metabolites, N-acetyl aspartate (NAA), creatine/phosphocreatine (Cr/PCr), and choline (Cho). Calculated average concentrations of NAA, Cr/PCr, and Cho in the occipital lobe of the brain in five healthy volunteers were (mean +/- 1 SD) 11.6 +/- 1.3 mM, 7.6 +/- 1.4 mM, and 1.7 +/- 0.5 mM. The results indicate that the method presented offers reasonable estimation of metabolite concentrations in the brain in vivo and therefore is useful in clinical research.
Assuntos
Água Corporal/metabolismo , Encéfalo/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Estudos de Avaliação como Assunto , Humanos , Hidrogênio , Técnicas In Vitro , Espectroscopia de Ressonância Magnética/instrumentação , Matemática , Modelos Estruturais , Valores de Referência , Fatores de TempoRESUMO
The purpose of this study was to optimize an inversion-recovery (IR) turbo fast low-angle shot (FLASH) for multislice imaging by evaluating the accuracy of calculated the relaxation-rate (R1) for different inversion times (TI). This is important for tracer kinetic modeling because it requires a system responding linearly to input. R1 are linearly related to changes in the concentration of gadolinium (Gd)-diethylenetriaminepentaacetic acid (DTPA), and R1 is a parameter that can be derived from the magnetic resonance (MR) signal. The accuracy of calculated R1 using an IR turbo fast low-angle shot was evaluated in phantoms and for increasing TIs using spectroscopically measured R1 values as reference. Signal curves, obtained in vivo after a bolus injection of Gd-DTPA, were used in an analytical computer program to study the effect of different TI-values on accurate calculation of R1. Results show that TIeff should be <200 ms to measure the bolus-passage of Gd-DTPA in blood accurately, whereas the myocardial response can be measured correctly for TIeff < 870 ms at 1.5 T. The initial slope of the myocardial signal enhancement curve becomes steeper for larger TI values, whereas the calculated R1 curves were similar, indicating that these curves, rather than signal curves, are more suitable even for qualitative perfusion evaluation. It is concluded that the results can be incorporated in a multislice IR turbo fast low-angle shot using the first slice (with a short TI) for assessment of both the arterial input function and the tissue response and the second slice in another position for assessment of the tissue response alone.
Assuntos
Gadolínio DTPA , Coração/anatomia & histologia , Imageamento por Ressonância Magnética/métodos , Meios de Contraste , Eletrocardiografia , Humanos , Imagens de FantasmasRESUMO
Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles of the involved RF pulses are taken into account. A small flow-independent off-set may be present in the data. The off-set is explained by the model. Based on the correspondence between the phantom and the in vivo models, it is shown that the lowest flow values that could be measured in the phantom correspond to perfusion values lower than the cortical perfusion in the brain. Thus, the experimental accuracy and the computational methods for quantitative perfusion measurements in vivo can be validated by a tube-flow phantom.
Assuntos
Imagem Ecoplanar , Modelos Teóricos , Perfusão , Imagem Ecoplanar/métodos , Humanos , Imagens de FantasmasRESUMO
Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized that it is caused by a relatively greater increase of oxygen consumption compared to rCBF (regional cerebral blood flow) increase. We studied the rCBF changes during visual stimulation in four sedated children, aged 4-71 months, and four alert adults, with an arterial water spin labeling technique (FAIR) and BOLD fMRI in a 1.5T MR scanner. In the children, FAIR signal decreased by a mean of 0.96% (range 0.77-1.05) of the baseline periods of the non-selective images, while BOLD signal decreased by 2.03% (range 1.99-2.93). In the adults, FAIR and BOLD signal increased by 0.88% (range 0.8-0.99) and 2.63% (range 1.99-2.93), respectively. Thus, in the children, an rCBF increase could not be detected by perfusion MRI, but indications of a FAIR signal decrease were found. An rCBF decrease in the primary visual cortex during stimulation has not been reported previously, but it is a possible explanation for the negative BOLD response. Future studies will have to address if this response pattern is a consequence of age or sleep/sedation.