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INTRODUCTION: Type 2 Diabetes (T2D) is associated with fractures, despite preserved Bone Mineral Density (BMD). This study aimed to evaluate the relationship between BMD and trabecular bone score (TBS) with the reallocation of fat within muscle in individuals with eutrophy, obesity, and T2D. METHODS: The subjects were divided into three groups: eutrophic controls paired by age and sex with the T2D group (n = 23), controls diagnosed with obesity paired by age, sex, and body mass index with the T2D group (n = 27), and the T2D group (n = 29). BMD and body fat percentage were determined using dual-energy X-Ray absorptiometry. TBS was determined using TBS iNsight software. Intra and extramyocellular lipids in the soleus were measured using proton magnetic resonance spectroscopy. RESULTS: TBS was lower in the T2D group than in the other two groups. Glycated hemoglobin (A1c) was negatively associated with TBS. Body fat percentage was negatively associated with TBS and Total Hip (TH) BMD. TH BMD was positively associated with intramuscular lipids. A trend of negative association was observed between intramuscular lipids and TBS. CONCLUSION: This study showed for the first time that the reallocation of lipids within muscle has a negative association with TBS. Moreover, these results are consistent with previous studies showing a negative association between a parameter related to insulin resistance (intramuscular lipids) and TBS.
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Absorciometría de Fotón , Tejido Adiposo , Densidad Ósea , Hueso Esponjoso , Diabetes Mellitus Tipo 2 , Músculo Esquelético , Humanos , Diabetes Mellitus Tipo 2/fisiopatología , Diabetes Mellitus Tipo 2/metabolismo , Masculino , Femenino , Persona de Mediana Edad , Densidad Ósea/fisiología , Hueso Esponjoso/diagnóstico por imagen , Estudios de Casos y Controles , Tejido Adiposo/diagnóstico por imagen , Adulto , Obesidad/fisiopatología , Obesidad/metabolismo , Hemoglobina Glucada/análisis , Índice de Masa Corporal , Anciano , Control Glucémico , Valores de ReferenciaRESUMEN
Accurately studying structural connectivity requires precise tract segmentation strategies. The U-Net network has been widely recognized for its exceptional capacity in image segmentation tasks and provides remarkable results in large tract segmentation when high-quality diffusion-weighted imaging (DWI) data are used. However, short tracts, which are associated with various neurological diseases, pose specific challenges, particularly when high-quality DWI data acquisition within clinical settings is concerned. Here, we aimed to evaluate the U-Net network ability to segment short tracts by using DWI data acquired in different experimental conditions. To this end, we conducted three types of training experiments involving 350 healthy subjects and 11 white matter tracts, including the anterior, posterior, and hippocampal commissure, fornix, and uncinated fasciculus. In the first experiment, the model was exclusively trained with high-quality data of the Human Connectome Project (HCP) dataset. The second experiment focused on images of healthy subjects acquired from a local hospital dataset, representing a typical clinical routine acquisition. In the third experiment, a hybrid training approach was employed, combining data of the HCP and local hospital datasets. Then, the best model was also tested in unseen DWIs of 10 epilepsy patients of the local hospital and 10 healthy subjects acquired on a scanner from another company. The outcomes of the third experiment demonstrated a notable enhancement in performance when contrasted with the preceding trials. Specifically, the short tracts within the local hospital dataset achieved Dice scores ranging between 0.60 and 0.65. Similar intervals were obtained with HCP data in the first experiment, and a substantial improvement compared to the scores between 0.37 and 0.50 obtained with the local hospital dataset at the same experiment. This improvement persisted when the method was applied to diverse scenarios, including different scanner acquisitions and epilepsy patients. These results indicate that combining datasets from different sources, coupled with resolution standardization strengthens the neural network ability to generalize predictions across a spectrum of datasets. Nevertheless, short tract segmentation performance is intricately linked to the training composition, to validation, and to testing data. Moreover, curved tracts have intricate structural nature, which adds complexities to their segmenting. Although the network training approach tested herein has provided promising results, caution must be taken when extrapolating its application to datasets acquired under distinct experimental conditions, even in the case of higher-quality data or analysis of long or short tracts.
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Conectoma , Epilepsia , Procesamiento de Imagen Asistido por Computador , Sustancia Blanca , Humanos , Masculino , Femenino , Procesamiento de Imagen Asistido por Computador/métodos , Adulto , Epilepsia/diagnóstico por imagen , Sustancia Blanca/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Imagen de Difusión Tensora/métodos , Imagen por Resonancia Magnética/métodos , AlgoritmosRESUMEN
PURPOSE: Individuals with isolated GH deficiency (IGHD) due to a mutation in the GHRH receptor gene have a normal life expectancy and above 50 years of age, similar total cognitive performance, with better attention and executive function than controls. Our objectives were to evaluate their brain morphometry and brain aging using MRI. METHODS: Thirteen IGHD and 14 controls matched by age, sex, and education, were enrolled. Quantitative volumetric data and cortical thickness were obtained by automatic segmentation using Freesurfer software. The volume of each brain region was normalized by the intracranial volume. The difference between the predicted brain age estimated by MRI using a trained neuronal network, and the chronological age, was obtained. p < 0.005 was considered significant and 0.005 < p < 0.05 as a suggestive evidence of difference. RESULTS: In IGHD, most absolute values of cortical thickness and regional brain volumes were similar to controls, but normalized volumes were greater in the white matter in the frontal pole and in the insula bilaterally, and in the gray matter, in the right insula and in left Caudate (p < 0.005 for all comparisons) We also noticed suggestive evidence of a larger volume in IGHD in left thalamus (p = 0.006), right thalamus (p = 0.025), right caudate (p = 0.046) and right putamen (p = 0.013). Predicted brain ages were similar between groups. CONCLUSION: IGHD is primarily associated with similar absolute brain measurements, and a set of larger normalized volumes, and does not appear to alter the process of brain aging.
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OBJECTIVE: Dual-energy X-ray absorptiometry (DXA)-derived bone mineral density (BMD) often fails to predict fragility fractures. Quantitative textural analysis using magnetic resonance imaging (MRI) may potentially yield useful radiomic features to predict fractures. We aimed to investigate the correlation between BMD and texture attributes (TAs) extracted from MRI scans and the interobserver reproducibility of the analysis. METHODS: Forty-nine volunteers underwent lumbar spine 1.5-T MRI and DXA. Three-dimensional (3-D) gray-level co-occurrence matrices were measured from routine sagittal T2 fast spin-echo images using the IBEX software. Twenty-two TAs were extracted from 3-D segmented L3 vertebrae. The estimated concordance coefficient was calculated using linear regression analysis. A Pearson correlation coefficient analysis was performed to evaluate the correlation between BMD and the TAs. Interobserver reproducibility was assessed with the concordance coefficient described by Lin. RESULTS: The results revealed a fair-to-moderate significant correlation between BMD and 13 TAs (r=−0.20 to 0.39; p<0.05). Eight TAs (autocorrelation, energy, homogeneity 1, homogeneity 1.1, maximum probability, sum average, sum variance, and inverse difference normalized) negatively correlated with BMD (r=−0.20 to −0.38; p<0.05), whereas five TAs (dissimilarity, difference entropy, entropy, sum entropy, and information measure corr 1) positively correlated with BMD (r=0.29-0.39; p<0.05). The interobserver agreement was almost perfect for all significant TAs (95% confidence interval, 0.92-1.00; p<0.05). CONCLUSION: Specific TAs could be reliably extracted from routine MRI and correlated with BMD. Our results encourage future evaluation of the potential usefulness of quantitative texture measurements from MRI scans for predicting fragility fractures.
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Humanos , Densidad Ósea , Vértebras Lumbares/diagnóstico por imagen , Imagen por Resonancia Magnética , Absorciometría de Fotón , Reproducibilidad de los ResultadosRESUMEN
ABSTRACT In elderly individuals, low educational level may represent a risk factor for the development of dementia and a proxy of cognitive reserve. Objective: This study examined the cognitive and neuroanatomic correlates of high versus low educational levels in cognitively healthy community-dwelling older adults in Brazil. Methods: Fifty-three older adults (mean age: 68±5.3 years) were divided into a "low education" group [LE; 1-4 years of education (N=33)] and "high education" group [HE; >11 years of education (N=20)]. Both groups completed a comprehensive neuropsychological battery and underwent in vivo structural MRI close to the time of testing. Results: Higher educational level increased the chance of having better scores on neuropsychological tests, including verbal and visual delayed recall of information, verbal learning, category fluency, global cognition, and vocabulary. Better scores on these tests were observed in the HE group relative to the LE group. Despite this, there were no group differences between MRI measures. Conclusion: Older adults with higher educational levels showed better scores on neuropsychological measures of cognition, highlighting the need for education-adjusted norms in developing countries. Given the absence of differences in structural anatomy between the groups, these findings appear to be best explained by theories of cognitive reserve.
RESUMO Sabe-se que baixos níveis de educação são comuns em países em desenvolvimento. Em indivíduos idosos, em particular, baixos níveis de educação podem representar um fator de risco para o desenvolvimento de demência. Objetivo: Este estudo examina os correlatos cognitivos e neuroanatômicos de escolaridade alta versus baixa, em idosos cognitivamente saudáveis,vivendo em comunidade no Brasil. Métodos: Cinquenta e três idosos (média de idade: 68±5,3) foram divididos em um grupo de "baixa escolaridade" [LE; 1-4 anos de escolaridade (N=33)] e um grupo de "alta escolaridade" [HE; >11 anos de escolaridade (N=20)]. Ambos os grupos completaram uma bateria neuropsicológica abrangente e foram submetidos à RM estrutural in vivo próximo à testagem. Resultados: O nível educacional aumentou a chance de se obter melhores pontuações em testes neuropsicológicos, incluindo evocação verbal e visual da informação, aprendizagem verbal, fluência de categoria, cognição global e vocabulário. Escores mais altos foram encontrados no grupo HE, em detrimento do LE. Apesar disso, não houve diferenças entre os grupos nas medidas de ressonância magnética in vivo. Conclusão: Idosos com maiores níveis de escolaridade apresentaram melhores pontuações nas medidas neuropsicológicas da cognição, destacando a necessidade de normas ajustadas à educação nos países em desenvolvimento. Não havendo diferenças na anatomia estrutural entre os grupos, os achados parecem ser melhor explicados pelas teorias da "reserva cognitiva".
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Humanos , Espectroscopía de Resonancia Magnética , Escolaridad , Reserva Cognitiva , Envejecimiento Cognitivo , Pruebas NeuropsicológicasRESUMEN
OBJECTIVES: Approximately one-third of candidates for epilepsy surgery have no visible abnormalities on conventional magnetic resonance imaging. This is extremely discouraging, as these patients have a less favorable prognosis. We aimed to evaluate the utility of quantitative magnetic resonance imaging in patients with drug-resistant neocortical focal epilepsy and negative imaging. METHODS: A prospective study including 46 patients evaluated through individualized postprocessing of five quantitative measures: cortical thickness, white and gray matter junction signal, relaxation rate, magnetization transfer ratio, and mean diffusivity. Scalp video-electroencephalography was used to suggest the epileptogenic zone. A volumetric fluid-attenuated inversion recovery sequence was performed to aid visual inspection. A critical assessment of follow-up was also conducted throughout the study. RESULTS: In the subgroup classified as having an epileptogenic zone, individualized postprocessing detected abnormalities within the region of electroclinical origin in 9.7% to 31.0% of patients. Abnormalities outside the epileptogenic zone were more frequent, up to 51.7%. In five patients initially included with negative imaging, an epileptogenic structural abnormality was identified when a new visual magnetic resonance imaging inspection was guided by information gleaned from postprocessing. In three patients, epileptogenic lesions were detected after visual evaluation with volumetric fluid-attenuated sequence guided by video electroencephalography. CONCLUSION: Although quantitative magnetic resonance imaging analyses may suggest hidden structural lesions, caution is warranted because of the apparent low specificity of these findings for the epileptogenic zone. Conversely, these methods can be used to prevent visible lesions from being ignored, even in referral centers. In parallel, we need to highlight the positive contribution of the volumetric fluid-attenuated sequence.
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Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Adulto Joven , Imagen por Resonancia Magnética/métodos , Epilepsia Refractaria/diagnóstico por imagen , Mapeo Encefálico , Estudios Prospectivos , Diagnóstico por Computador/métodos , Electroencefalografía/métodos , Imagen MultimodalRESUMEN
Abstract Introduction Multiple Sclerosis (MS) is a neurodegenerative disease characterized by inflammatory demyelination in the central nervous system. Quantitative Magnetic Resonance Imaging (qMRI) enables a detailed characterization of brain tissue, but generates a large number of numerical results. In this study, we elucidated the main qMRI techniques and the brain regions that allow the identification of MS patients from neuroimaging data and pattern recognition techniques. Methods The data came from the combination of computational tools of image processing and neuroimaging acquired in a 3 Tesla scanner using different techniques: Diffusion, T2 Relaxometry, Magnetization Transfer Ratio (MTR) and Structural Morphometry. Data from 126 brain regions of 203 healthy individuals and 124 MS patients were separated into two groups and processed in a data-mining program using the k-nearest-neighbor (KNN) algorithm. Results The most relevant anatomical structures in the classification procedure were: corpus callosum, precuneus, left cerebellum and fusiform. Among the quantitative techniques the most relevant was the MTR, being indicated for longitudinal studies of this disease. KNN with 5 neighbors and pre-selected attributes had a better performance with an area under the ROC curve (97.3%) and accuracy (95.7%). A restricted classification considering only brain regions previously reported in the literature as affected by MS brought slightly lower scores, area: 97.1% and accuracy: 93.2%. Conclusion The use of standard recognition techniques from quantitative neuroimaging techniques has confirmed that the white matter of the brain is the most affected tissue by MS following a global pattern with greater involvement of the left hemisphere.
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Abstract Introduction: Diffusion tensor imaging (DTI) is an important medical imaging modality that has been useful to the study of microstructural changes in neurological diseases. However, the image noise level is a major practical limitation, in which one simple solution could be the average signal from a sequential acquisition. Nevertheless, this approach is time-consuming and is not often applied in the clinical routine. In this study, we aim to evaluate the anisotropic anomalous diffusion (AAD) filter in order to improve the general image quality of DTI. Methods A group of 20 healthy subjects with DTI data acquired (3T MR scanner) with different numbers of averages (N=1,2,4,6,8, and 16), where they were submitted to 2-D AAD and conventional anisotropic diffusion filters. The Relative Mean Error (RME), Structural Similarity Index (SSIM), Coefficient of Variation (CV) and tractography reconstruction were evaluated on Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC) maps. Results The results point to an improvement of up to 30% of CV, RME, and SSIM for the AAD filter, while up to 14% was found for the conventional AD filter (p<0.05). The tractography revealed a better estimative in fiber counting, where the AAD filter resulted in less FA variability. Furthermore, the AAD filter showed a quality improvement similar to a higher average approach, i.e. achieving an image quality equivalent to what was seen in two additional acquisitions. Conclusions In general, the AAD filter showed robustness in noise attenuation and global image quality improvement even in DTI images with high noise level.
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Abstract Introduction The interpretation of brain tumors and abscesses MR spectra is complex and subjective. In clinical practice, different experimental conditions such as field strength or echo time (TE) reveal different metabolite information. Our study aims to show in which scenarios magnetic resonance spectroscopy can differentiate among brain tumors, normal tissue and abscesses using classification algorithms. Methods Pairwise classification between abscesses, brain tumor classes, and healthy subjects tissue spectra was performed, also the multiclass classification between meningiomas, grade I-II-III gliomas, and glioblastomas and metastases, in 1.5T short TE (n = 195), 1.5T long TE (n = 231) and 3.0T long TE (n = 59) point resolved spectroscopy setups, using LCModel metabolite concentration as input to classifiers. Results Areas under the curve of the Receiver Operating Characteristic above 0.9 were obtained for the classification between abscesses and all classes except glioblastomas, reaching 0.947 when classifying against metastases, grade I-II gliomas and glioblastomas (0.980), meningiomas and glioblastomas (0.956), grade I-II gliomas and metastases (0.989), meningiomas and metastases (0.990), and between healthy tissue and all other classes in both conditions except for anaplastic astrocytomas in short TE 1.5T setup. When the multiclass classification agrees with radiological diagnosis the accuracy reaches 96.8% for short TE and 98.9% for long TE. Conclusions The results in the three conditions were similar, highlighting comparable quality, robust quantification and good regularization and flexibility in either algorithm. Multiclass classification provides useful information to the radiologist. These findings show the potential of the development of decision support systems as well as tools for the accompaniment of treatments.
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PURPOSE:Small size needles have been regularly used for intradiscal injection of innocuous/potential therapeutic compounds in experimental conditions, but also in clinic procedures, such as discography. Our aim was to investigate if a 30-gauge needle could trigger observable changes on intact intervertebral discs. We compared these effects to those induced by a large size needle (21-gauge), a well-known intervertebral disc degenerative model based on needle puncture.METHODS:Coccygeal intervertebral discs (Co8-9) of adult male Wistar rats were punctured with a 21-gauge needle, while the coccygeal levels Co7-8 and Co9-10 remained intact. The 30-gauge needle was used to inject a safe volume of saline (2 µl) on both intact (Co9-10) and punctured (Co8-9) discs. MRI and histological score were performed at 2, 15 and 42 days after procedure.RESULTS: MRI analyses revealed significant reduction on signal intensity of 21-gauge punctured discs. Intact discs which received a saline injection through a 30-gauge needle also revealed significant alterations in the MRI signal when compared with control discs. No histological changes were observed in the intact saline injected discs at any time analyzed.CONCLUSION: Since significant intervertebral image changes were observed with a 30-gauge needle, cautious interpretation of the pharmacological inoculation findings is required.
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Animales , Masculino , Degeneración del Disco Intervertebral/patología , Disco Intervertebral/patología , Agujas/efectos adversos , Punciones/efectos adversos , Punciones/instrumentación , Modelos Animales de Enfermedad , Diseño de Equipo , Degeneración del Disco Intervertebral/etiología , Disco Intervertebral/lesiones , Imagen por Resonancia Magnética , Ratas Wistar , Región Sacrococcígea , Factores de TiempoRESUMEN
Objective: To present a detailed explanation on the processing of magnetic susceptibility weighted imaging (SWI), demonstrating the effects of echo time and sensitive mask on the differentiation between calcification and hemosiderin. Materials and Methods: Computed tomography and magnetic resonance (magnitude and phase) images of six patients (age range 41– 54 years; four men) were retrospectively selected. The SWI images processing was performed using the Matlab’s own routine. Results: Four out of the six patients showed calcifications at computed tomography images and their SWI images demonstrated hyperintense signal at the calcification regions. The other patients did not show any calcifications at computed tomography, and SWI revealed the presence of hemosiderin deposits with hypointense signal. Conclusion: The selection of echo time and of the mask may change all the information on SWI images, and compromise the diagnostic reliability. Amongst the possible masks, the authors highlight that the sigmoid mask allows for contrasting calcifications and hemosiderin on a single SWI image. .
Objetivo: Expor em detalhes o processamento da imagem ponderada em suscetibilidade magnética (susceptibility weighted imaging – SWI), destacando o efeito da escolha do tempo de eco e da máscara sensível à diferenciação de calcificação e hemossiderina simultaneamente. Materiais e Métodos: Imagens de tomografia computadorizada e por ressonância magnética (magnitude e fase) foram selecionadas, retrospectivamente, de seis pacientes (idades entre 41 e 54 anos; quatro homens). O processamento das imagens SWI foi realizado em rotina própria no programa Matlab. Resultados: Dos seis pacientes estudados, quatro apresentaram calcificações nas imagens de tomografia computadorizada. Nestes, as imagens SWI mostraram sinal hiperintenso para as regiões de calcificações. Os outros dois pacientes não apresentaram calcificações nas imagens de tomografia computadorizada e apresentaram depósito de hemossiderina com sinal hipointenso na imagem SWI. Conclusão: A escolha do tempo de eco e da máscara pode alterar toda a informação da imagem SWI e comprometer a confiabilidade diagnóstica. Dentre as possíveis máscaras, destacamos que a máscara sigmoide permite contrastar calcificação e hemossiderina em uma única imagem SWI. .
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Animales , Ratones , Empalme Alternativo/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteína de Unión al Tracto de Polipirimidina/genética , Tropomiosina/genética , Secuencia de Bases , Sitios de Unión , Cartilla de ADN , Exones , Vectores Genéticos , Ligandos , Sistemas de Lectura Abierta , Reacción en Cadena de la Polimerasa , Proteína de Unión al Tracto de Polipirimidina/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Represoras/metabolismo , TransfecciónRESUMEN
INTRODUCTION: The intrinsically high sensitivity of Magnetic Resonance Spectroscopy (MRS) causes considerable variability in metabolite quantification. In this study, we evaluated the variability of MRS in two research centers using the same model of magnetic resonance image scanner. METHODS: Two metabolic phantoms were created to simulate magnetic resonance spectra from in vivo hippocampus. The phantoms were filled with the same basic solution containing the following metabolites: N-acetyl-aspartate, creatine, choline, glutamate, glutamine and inositol. Spectra were acquired over 15 months on 26 acquisition dates, resulting in a total of 130 spectra per center. RESULTS: The phantoms did not undergo any physical changes during the 15-month period. Temporal analysis from both centers showed mean metabolic variations of 3.7% in acquisitions on the same day and of 8.7% over the 15-month period. CONCLUSION: The low deviations demonstrated here, combined with the high specificity of Magnetic Resonance Spectroscopy, confirm that it is feasible to use this technique in multicenter studies in neuroscience research.
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OBJECTIVE: To understand the relationships between brain structures and function (behavior and cognition) in healthy aging. METHOD: The study group was composed of 56 healthy elderly subjects who underwent neuropsychological assessment and quantitative magnetic resonance imaging. Cluster analysis classified the cohort into two groups, one (cluster 1) in which the magnetic resonance imaging metrics were more preserved (mean age: 66.4 years) and another (cluster 2) with less preserved markers of healthy brain tissue (mean age: 75.4 years). RESULTS: The subjects in cluster 2 (older group) had worse indices of interference in the Stroop test compared with the subjects in cluster 1 (younger group). Therefore, a simple test such as the Stroop test could differentiate groups of younger and older subjects based on magnetic resonance imaging metrics. CONCLUSION: These results are in agreement with the inhibitory control hypotheses regarding cognitive aging and may also be important in the interpretation of studies with other clinical groups, such as patients with dementia and mild cognitive impairment. .
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Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Envejecimiento/fisiología , Encéfalo/anatomía & histología , Encéfalo/fisiología , Cognición/fisiología , Imagen por Resonancia Magnética/métodos , Pruebas Neuropsicológicas , Factores de Edad , Mapeo Encefálico , Conducta/fisiología , Estudios de Casos y Controles , Análisis por Conglomerados , Demencia/fisiopatología , Estudios Prospectivos , Factores Socioeconómicos , Estadísticas no ParamétricasRESUMEN
Este artigo busca compilar e organizar as informações atualmente disponíveis e sugerir algumas medidas de segurança para a realização do exame de ressonância magnética (IRM), na ausência de alternativa diagnóstica. Até o momento, não há estudos com a fnalidade de criar uma normativa de consenso, que envolvam todos os interessados no tema. Estudos recentes indicam que é possível realizar com segurança exames de IRM em portadores de sistemas artificiais de estimulação cardíaca (SAEC), desde que algumas ações preventivas sejam observadas previamente. São abordadas propostas para alcançar um consenso em relação ao exame de IRM no portador de SAEC. Os dispositivos mais novos oferecidos ao mercado já incorporam tecnologia para aumentar a segurança dos pacientes submetidos a IRM.