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1.
Allergol Immunopathol (Madr) ; 51(3): 28-35, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37169557

RESUMO

BACKGROUND: L-Asparaginase (L-asp), the unconjugated form of polyethylene glycol-conjugated L-asparaginase (PEG-asp), regulates T cell stimulation, antibody production, and lysosomal protease activity to mediate PEG-asp-related anaphylaxis. This study aimed to investigate the relation of L-asp activity and anti-L-asp antibody with anaphylaxis risk and non-anaphylaxis adverse reaction risk in childhood acute lymphoblastic leukemia (ALL) patients who underwent PEG-asp contained therapy. METHODS: In total, 170 childhood ALL patients underwent PEG-asp-contained treatment and their L-asp activity and anti-L-asp antibody were detected on the 7th day after treatment initiation. RESULTS: There were 27 (15.9%) patients who had PEG-asp-related adverse reaction: 17 (10.0%) patients experienced PEG-asp-related anaphylaxis and 14 (8.2%) patients experienced PEG- asp-related non-anaphylaxis adverse reaction. Moreover, L-asp activity was negatively related to anti-L-asp antibody in childhood ALL patients (P<0.001). Elevated L-asp activity was associated with the absence of PEG-asp-related anaphylaxis (P<0.001), PEG-asp-related non-anaphylaxis adverse reaction (P=0.004), and PEG-asp-related adverse reaction (P<0.001). However, the anti- L-asp antibody displayed opposite trend similar to L-asp activity. Receiver operating characteristic (ROC) curve analyses exhibited L-asp activity and anti-L-asp antibody exhibited superior predictive values in estimating PEG-asp-related anaphylaxis risk with area under curve (AUC) of 0.955 and 0.905, respectively compared to PEG-asp-related non-anaphylaxis adverse reaction risk with AUC of 0.730 and 0.675, respectively. Besides, patients with de novo disease, higher risk stratification, and allergic history showed trends linked with PEG-asp-related anaphylaxis risk. CONCLUSION: The monitoring of L-asp activity and anti-L-asp antibody maybe useful for early estimation and prevention of PEG-asp-related anaphylaxis in childhood ALL management.


Assuntos
Anafilaxia , Asparaginase , Leucemia-Linfoma Linfoblástico de Células Precursoras , Humanos , Anafilaxia/induzido quimicamente , Asparaginase/efeitos adversos , Asparaginase/uso terapêutico , Biomarcadores , Polietilenoglicóis/efeitos adversos , Polietilenoglicóis/uso terapêutico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/induzido quimicamente , Criança
2.
Allergol. immunopatol ; 51(3): 28-35, 01 mayo 2023. tab
Artigo em Inglês | IBECS | ID: ibc-219810

RESUMO

Background: L-Asparaginase (L-asp), the unconjugated form of polyethylene glycol-conjugated L-asparaginase (PEG-asp), regulates T cell stimulation, antibody production, and lysosomal protease activity to mediate PEG-asp-related anaphylaxis. This study aimed to investigate the relation of L-asp activity and anti-L-asp antibody with anaphylaxis risk and non-anaphylaxis adverse reaction risk in childhood acute lymphoblastic leukemia (ALL) patients who underwent PEG-asp contained therapy. Methods: In total, 170 childhood ALL patients underwent PEG-asp-contained treatment and their L-asp activity and anti-L-asp antibody were detected on the 7th day after treatment initiation. Results: There were 27 (15.9%) patients who had PEG-asp-related adverse reaction: 17 (10.0%) patients experienced PEG-asp-related anaphylaxis and 14 (8.2%) patients experienced PEG- asp-related non-anaphylaxis adverse reaction. Moreover, L-asp activity was negatively related to anti-L-asp antibody in childhood ALL patients (P<0.001). Elevated L-asp activity was associated with the absence of PEG-asp-related anaphylaxis (P<0.001), PEG-asp-related non-anaphylaxis adverse reaction (P=0.004), and PEG-asp-related adverse reaction (P<0.001). However, the anti- L-asp antibody displayed opposite trend similar to L-asp activity. Receiver operating characteristic (ROC) curve analyses exhibited L-asp activity and anti-L-asp antibody exhibited superior predictive values in estimating PEG-asp-related anaphylaxis risk with area under curve (AUC) of 0.955 and 0.905, respectively compared to PEG-asp-related non-anaphylaxis adverse reaction risk with AUC of 0.730 and 0.675, respectively. Besides, patients with de novo disease, higher risk stratification, and allergic history showed trends linked with PEG-asp-related anaphylaxis risk. Conclusion: The monitoring of L-asp activity and anti-L-asp antibody maybe useful for early estimation and prevention of PEG-asp-related anaphylaxis in childhood ALL management (AU)


Assuntos
Humanos , Masculino , Feminino , Pré-Escolar , Anafilaxia/prevenção & controle , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Asparaginase/metabolismo , Asparaginase/antagonistas & inibidores , Autoanticorpos
3.
Sensors (Basel) ; 22(19)2022 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-36236760

RESUMO

A coarse-to-fine multi-view stereo network with Transformer (MVS-T) is proposed to solve the problems of sparse point clouds and low accuracy in reconstructing 3D scenes from low-resolution multi-view images. The network uses a coarse-to-fine strategy to estimate the depth of the image progressively and reconstruct the 3D point cloud. First, pyramids of image features are constructed to transfer the semantic and spatial information among features at different scales. Then, the Transformer module is employed to aggregate the image's global context information and capture the internal correlation of the feature map. Finally, the image depth is inferred by constructing a cost volume and iterating through the various stages. For 3D reconstruction of low-resolution images, experiment results show that the 3D point cloud obtained by the network is more accurate and complete, which outperforms other advanced algorithms in terms of objective metrics and subjective visualization.

4.
Comput Math Methods Med ; 2022: 8289548, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35785141

RESUMO

Background: Chinese Materia Medica and Jiangsu New Medical College record that Radix Veratri root is Liliaceae Veratrum taliense Loses. f. and the root of Veratrum stenophyllum Diels. According to traditional Chinese medicine (TCM) example, Radix Veratri is a Liliaceae plant Veratrum taliense. Another literature pointed out that the aliases of Veratrum taliense and Veratrum angustifolia are both Radix Veratri, and their effects are basically the same. The main active ingredient of Veratrum is veratramine, of which veratramine and Jervine are higher in content, reaching 24.60% and 21.28% of the total alkaloids, respectively. Veratrum alkaloids are both toxic and effective ingredients. In addition to its good clinical efficacy, attention should also be paid to its pharmacokinetic characteristics in vivo. It is particularly important to study the pharmacokinetic characteristics of veratramine and Jervine in vivo. Objective: The goal of this study was to develop a simple and effective method for measuring veratramine and Jervine in rat plasma at the same time. This method was used to study the pharmacokinetic characteristics of veratramine and Jervine in the alcohol extract of Radix Veratri in rats, to provide a reasonable basis for the clinical use of Radix Veratri. Methods: Eighteen SD rats were randomly assigned into three groups, half male and half female, and were given 0.04 g/kg, 0.08g/kg, and 0.16 g/kg Radix Veratri alcohol extract, respectively. Blood samples were collected at different time points and were analyzed by LC-MS/MS after protein precipitation. Bullatine was set as the internal standard; the plasma samples were extracted with ethyl acetate. After the sample was processed, acetonitrile-10 mM ammonium acetate, whose pH was adjusted to 8.8 with ammonia water, was taken as the mobile phase. Veratramine quantitative ion pair was 410.1⟶295.1m/z, Jervine quantitative ion pair was 426.2⟶114.1m/z, and Bullatine B (IS) quantitative ion pair was 438.2⟶420.1m/z. In the positive ion mode, the multireaction monitoring (MRM) mode was used to determine the blood concentration of veratramine and Jervine. DAS 3.3.0 was used to calculate the relevant pharmacokinetic parameters. Results: Veratramine had a good linear relationship in the concentration range of 0.0745~18.2 ng/mL, and that of Jervine was 1.11~108 ng/mL. The correlation coefficient r of three consecutive batches of the standard curve was greater than 0.995. Veratramine's lower quantification limit was 0.745 ng/mL, Jervine's was 1.11 ng/mL, and precision and accuracy were both less than 15%. The accuracy of veratramine was between 88.96% and 101.85%, and the accuracy of Jervine was between 92.96% and 104.50%. This method was adopted for the pharmacokinetic study of alcohol extracts of Radix Veratri. The results showed that only C max of veratramine female rats did not show linear kinetic characteristics in the dose range of Radix Veratri alcohol extract from 0.04 g/kg to 0.16 g/kg. For AUC0-t and C max of veratramine and Jervine, it could not determine whether the Radix Veratri alcohol extract showed linear kinetic characteristics within the dosage range of 0.04 g/kg~0.16 g/kg. Veratramine and Jervine showed obvious gender differences in the absorption and elimination stages. The absorption rate of veratramine and Jervine by male mice was about 10 times higher than that of female mice, and the elimination rate of male mice is about 20 times lower than that of female mice. It was suggested that the clinical application of the steroidal alkaloids veratramine and Jervine in Radix Veratri required rational use of drugs based on gender. Conclusion: An LC-MS/MS analysis method suitable for the pharmacokinetic study of veratramine and Jervine in Radix Veratri in SD rats was established to provide a basis for in vivo pharmacokinetic studies. The pharmacokinetic characteristics of veratramine and Jervine in the alcohol extract of Radix Veratri were significantly different in female and male rats. During the clinical use of Radix Veratri, it should pay close attention to the obvious gender differences that may occur after the medication.


Assuntos
Alcaloides , Veratrum , Animais , Cromatografia Líquida , Feminino , Humanos , Masculino , Camundongos , Extratos Vegetais , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem , Veratrum/química , Alcaloides de Veratrum/química , Alcaloides de Veratrum/farmacocinética
5.
Sensors (Basel) ; 22(6)2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35336291

RESUMO

Infrared image simulation is challenging because it is complex to model. To estimate the corresponding infrared image directly from the visible light image, we propose a three-level refined light-weight generative adversarial network with cascaded guidance (V2T-GAN), which can improve the accuracy of the infrared simulation image. V2T-GAN is guided by cascading auxiliary tasks and auxiliary information: the first-level adversarial network uses semantic segmentation as an auxiliary task, focusing on the structural information of the infrared image; the second-level adversarial network uses the grayscale inverted visible image as the auxiliary task to supplement the texture details of the infrared image; the third-level network obtains a sharp and accurate edge by adding auxiliary information of the edge image and a displacement network. Experiments on the public dataset Multispectral Pedestrian Dataset demonstrate that the structure and texture features of the infrared simulation image obtained by V2T-GAN are correct, and outperform the state-of-the-art methods in objective metrics and subjective visualization effects.

6.
Ann Transl Med ; 10(23): 1276, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36618816

RESUMO

Background: Natural killer/T cell lymphoma (NKTCL) is a rare and aggressive tumor of non-Hodgkin's lymphoma. The role of micro ribonucleic acid (RNA) (miR)-363 in NKTCL has not yet been elucidated. The present study aimed to investigate the potential role of miR-363 in NKTCL. Methods: The expression of the top five differentially expressed microRNAs (miRNAs) as well as sirtuin 6 (SIRT6) in NK normal cells and its tumor cell lines were explored. The clinical tissues of NKTCL patients were collected and analyzed for expression of miR-363 and SIRT6. In addition, human NK/T-cell lymphoma cells (SNK-6) were transfected into different groups to detect cell proliferation and apoptosis abilities through cell counting kit 8 (CCK-8) experiment and flow cytometry analysis. Western blot assay was employed to examine protein expression. NKTCL nude mice models were constructed by subcutaneous injection of stably transfected SNK-6 cells to validate the mechanism of miR-363 in NKTCL via SIRT6 in vivo. Results: MiR-363 was down-regulated in NKTCL tissues and cell lines. Overexpression of miR-363 inhibited cell proliferation and promoted cell apoptosis. In contrast, SIRT6 was up-regulated in NKTCL and proved to be a downstream target of miR-363. SIRT6 could activate the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. Also, miR-363 mimic could suppress the proliferation and induce the apoptosis of NKTCL via the SIRT6/PI3K/AKT axis both in vitro and in vivo. Conclusions: MiR-363 suppresses the SIRT6/PI3K/AKT pathway to restrain cell proliferation and accelerate cell apoptosis during NKTCL progression.

7.
Front Plant Sci ; 12: 645899, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34177976

RESUMO

Counting the number of wheat ears in images under natural light is an important way to evaluate the crop yield, thus, it is of great significance to modern intelligent agriculture. However, the distribution of wheat ears is dense, so the occlusion and overlap problem appears in almost every wheat image. It is difficult for traditional image processing methods to solve occlusion problem due to the deficiency of high-level semantic features, while existing deep learning based counting methods did not solve the occlusion efficiently. This article proposes an improved EfficientDet-D0 object detection model for wheat ear counting, and focuses on solving occlusion. First, the transfer learning method is employed in the pre-training of the model backbone network to extract the high-level semantic features of wheat ears. Secondly, an image augmentation method Random-Cutout is proposed, in which some rectangles are selected and erased according to the number and size of the wheat ears in the images to simulate occlusion in real wheat images. Finally, convolutional block attention module (CBAM) is adopted into the EfficientDet-D0 model after the backbone, which makes the model refine the features, pay more attention to the wheat ears and suppress other useless background information. Extensive experiments are done by feeding the features to detection layer, showing that the counting accuracy of the improved EfficientDet-D0 model reaches 94%, which is about 2% higher than the original model, and false detection rate is 5.8%, which is the lowest among comparative methods.

8.
J Xray Sci Technol ; 28(6): 1171-1186, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32925164

RESUMO

Currently, cardiac computed tomography angiography (CTA) is widely applied to coronary artery disease diagnosis. Automatic segmentation of coronary artery has played an important role in coronary artery disease diagnosis. In this study, we propose and test a fully automatic coronary artery segmentation method that does not require any human-computer interaction. The proposed method uses a growing strategy and contains three main parts namely, (1) the initial seed detection that automatically detects the root points of the left and right coronary arteries where the ascending aorta meets the coronary arteries, (2) the growing strategy that searches for the neighborhood blocks to decide the existence of coronary arteries with an improved convolutional neural network, and (3) the iterative termination condition that decides whether the growing iteration finishes. The proposed framework is validated using a dataset containing 32 cardiac CTA volumes from different patients for training and testing. Experimental results show that the proposed method obtained a Dice loss ranged from 0.70 to 0.83, which indicates that the new method outperforms the traditional methods such as level set.


Assuntos
Algoritmos , Angiografia por Tomografia Computadorizada/métodos , Vasos Coronários/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Doença da Artéria Coronariana/diagnóstico por imagem , Humanos , Redes Neurais de Computação
9.
RSC Adv ; 10(24): 14262-14273, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-35498465

RESUMO

Edible fungus residue as an efficient and low-cost precursor was used to produce Edible Fungus residue Activated Carbon (EFAC) using the zinc chloride activation method at a 1 : 2 impregnation ratio and 600 °C activation for 3 hours. The activation process does not need gases like nitrogen and is suitable for mass production. Fungal biodegradation facilitates efficient chemical activation, which might have generated abundant pores on the activated carbon sample. Using BET, X-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR characterization, reveals that EFAC exhibits a large specific surface area (1070 m2 g-1), and large pore volume (0.68 cm3 g-1), with its surface displaying a honeycomb-like structure. The EFAC adsorbs methylene blue (MB) and aniline in water, with maximum adsorptions of 662.25 and 27.10 mg g-1, respectively. Various adsorption conditions, such as the EFAC dosage, pH, contact time and initial concentration were investigated. The adsorption is characterized by the pseudo-second-order kinetic and Langmuir isotherm models, with thermodynamics studies indicating that the adsorption is endothermic and spontaneous. Furthermore, the EFAC exhibited good regeneration performance by a 90% ethanol solution. The EFAC is a low-cost and environmentally friendly adsorbent for removing organic contaminants in wastewater.

10.
RSC Adv ; 9(34): 19365-19374, 2019 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-35519370

RESUMO

Studies have reported that scorpion toxins have excellent anti-cancer effects; however, the anti-inflammatory activity of scorpion peptides has rarely been studied. Here, a series of Mesobuthus martensii Karsch peptides (MMKPs) were isolated and the amino acid sequence was identified. The MMKPs mitigated TNF-α-mediated inflammation in human umbilical vein endothelial cells (HUVECs). The results showed that MMKP-1 (His-Glu-Gly-His) treatment (43.0 µM) significantly attenuated the reactive oxygen species (ROS) generation and mitochondrial membrane potential collapse in HUVECs. Moreover, MMKP-1 down-regulated the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expressions and blocked the NF-κB pathway to alleviate the damage caused by TNF-α. Of note, our study provides a good reference for the anti-inflammation research on scorpion oligopeptides.

11.
Biosens Bioelectron ; 74: 843-8, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26233640

RESUMO

An ultrasensitive label-free immunosensor was developed for the detection of squamous cell carcinoma antigen (SCCA) based on CdS sensitized Fe-TiO2 nanocomposites with high visible-light photoelectrochemical (PEC) activity. In this protocol, ascorbic acid was used as an efficient electron donor for scavenging photogenerated holes. The Fe-doped TiO2 improved the absorption of TiO2 in the visible light region and promoted the photocurrent production distinctly. Especially, 0.1% Fe-TiO2 showed the highest photocurrent, which was 7.4 times that of pure TiO2. Carboxyl functionalized CdS nanoparticles (CdS NPs) were bonded onto Fe-TiO2 composite through interactions between carboxyl groups and TiO2, which further enhanced the PEC signal strength by approximately 2.9 fold compared with 0.1% Fe-TiO2. The specific binding between SCCA and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of SCCA concentration in the range of 0.001-75 ng mL(-1) with a detection limit of 0.22 pg mL(-1). The developed CdS enhanced Fe-TiO2 PEC immunosensor exhibited high sensitivity, good reproducibility, and low cost, which may have potential applications in clinical diagnosis of cancers, aptasensors, photocatalysis, and other related fields.


Assuntos
Antígenos de Neoplasias/isolamento & purificação , Técnicas Biossensoriais , Nanopartículas/química , Serpinas/isolamento & purificação , Titânio/química , Antígenos de Neoplasias/química , Compostos de Cádmio/química , Técnicas Eletroquímicas , Humanos , Limite de Detecção , Nanocompostos/química , Processos Fotoquímicos , Pontos Quânticos , Serpinas/química , Sulfatos/química
12.
Zhong Yao Cai ; 34(10): 1565-9, 2011 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-22372147

RESUMO

OBJECTIVE: To research the effects of Na-FA on gastrointestinal movement and gastriculcer in mice. METHODS: Using charcoal powder as an indicator, the effects of FA-Na on bowel movement of mice was evaluated by determining the propulsive percent-age of charcoal powder in normal mice, inhibition of small intestinal propulsion model induced by Compound Diphenoxylate and spleen asthenia and diarrhea model caused by Rheum officinale Baill; The acute gastric ulcer model was induced by intragastric alcohol given orally, the protective effect of FA-Na given ahead on gastric injury was evaluated, the ulcer index and the inhibition ratio of ulcer was calculated. RESULTS: FA-Na (intragastric administration) had inhibit effect on normal mice and diarrhea model caused by Rheum officinale, significantly synergetic effect on gastrointestinal asynersis induced by Compound Diphenoxylate, and protective effect on mice gastric mucosal injury cause by dehydrated alcohol. Compared with the positive control drug Ranitidine, the ulcer index and ulcer inhibition ratio large doses of FA-Na had no significant difference. CONCLUSION: The acute toxicity of FA-Na is very low, it has the effects of antidiarrheal and anti-gastric ulcer.


Assuntos
Antiulcerosos/farmacologia , Benzopiranos/farmacologia , Quelantes/farmacologia , Gastroenteropatias/tratamento farmacológico , Motilidade Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/efeitos dos fármacos , Administração Oral , Animais , Antiulcerosos/uso terapêutico , Antidiarreicos/farmacologia , Antidiarreicos/uso terapêutico , Benzopiranos/uso terapêutico , Peso Corporal , Carbono/química , Quelantes/uso terapêutico , Diarreia/induzido quimicamente , Diarreia/tratamento farmacológico , Difenoxilato , Modelos Animais de Doenças , Feminino , Mucosa Gástrica/efeitos dos fármacos , Mucosa Gástrica/lesões , Gastroenteropatias/induzido quimicamente , Substâncias Húmicas , Masculino , Camundongos , Ranitidina/farmacologia , Ranitidina/uso terapêutico , Úlcera Gástrica/induzido quimicamente , Úlcera Gástrica/tratamento farmacológico , Úlcera Gástrica/prevenção & controle
13.
Magn Reson Imaging ; 29(2): 230-42, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21129881

RESUMO

Signal variation in diffusion-weighted images (DWIs) is influenced both by thermal noise and by spatially and temporally varying artifacts, such as rigid-body motion and cardiac pulsation. Motion artifacts are particularly prevalent when scanning difficult patient populations, such as human infants. Although some motion during data acquisition can be corrected using image coregistration procedures, frequently individual DWIs are corrupted beyond repair by sudden, large amplitude motion either within or outside of the imaging plane. We propose a novel approach to identify and reject outlier images automatically using local binary patterns (LBP) and 2D partial least square (2D-PLS) to estimate diffusion tensors robustly. This method uses an enhanced LBP algorithm to extract texture features from a local texture feature of the image matrix from the DWI data. Because the images have been transformed to local texture matrices, we are able to extract discriminating information that identifies outliers in the data set by extending a traditional one-dimensional PLS algorithm to a two-dimension operator. The class-membership matrix in this 2D-PLS algorithm is adapted to process samples that are image matrix, and the membership matrix thus represents varying degrees of importance of local information within the images. We also derive the analytic form of the generalized inverse of the class-membership matrix. We show that this method can effectively extract local features from brain images obtained from a large sample of human infants to identify images that are outliers in their textural features, permitting their exclusion from further processing when estimating tensors using the DWIs. This technique is shown to be superior in performance when compared with visual inspection and other common methods to address motion-related artifacts in DWI data. This technique is applicable to correct motion artifact in other magnetic resonance imaging (MRI) techniques (e.g., the bootstrapping estimation) that use univariate or multivariate regression methods to fit MRI data to a pre-specified model.


Assuntos
Artefatos , Encéfalo/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Interpretação de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão/métodos , Diagnóstico Pré-Natal/métodos , Efeitos Tardios da Exposição Pré-Natal/patologia , Algoritmos , Simulação por Computador , Feminino , Humanos , Aumento da Imagem/métodos , Lactente , Análise dos Mínimos Quadrados , Masculino , Modelos Biológicos , Modelos Estatísticos , Movimento (Física) , Gravidez , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
14.
Magn Reson Imaging ; 27(3): 311-23, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18835122

RESUMO

In the processing and analysis of diffusion tensor imaging (DTI) data, certain predefined morphological features of diffusion tensors are often represented as simplified scalar indices, termed diffusion anisotropy indices (DAIs). When comparing tensor morphologies across differing voxels of an image, or across corresponding voxels in different images, DAIs are mathematically and statistically more tractable than are the full tensors, which are probabilistic ellipsoids consisting of three orthogonal vectors that each has a direction and an associated scalar magnitude. We have developed a new DAI, the "ellipsoidal area ratio" (EAR), to represent the degree of anisotropy in the morphological features of a diffusion tensor. The EAR is a normalized geometrical measure of surface curvature in the 3D diffusion ellipsoid. Monte Carlo simulations and applications to the study of in vivo human data demonstrate that, at low noise levels, EAR provides a similar contrast-to-noise ratio (CNR) but a higher signal-to-noise ratio (SNR) than does fractional anisotropy (FA), which is currently the most popular anisotropy index in active use. Moreover, at the high noise levels encountered most commonly in real-world DTI datasets, EAR compared with FA is consistently much more robust to perturbations from noise and it provides a higher CNR, features useful for the analysis of DTI data that are inherently noise sensitive.


Assuntos
Algoritmos , Encéfalo/anatomia & histologia , Imagem de Difusão por Ressonância Magnética/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Anisotropia , Humanos , Aumento da Imagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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