DT-MRI muscle

INTRODUCTION: Structural evidence of exercise-induced muscle disruption has traditionally involved histological analysis of muscle tissue obtained by needle biopsy, however, there are multiple limitations with this technique. Recently, diffusion tensor magnetic resonance imaging (DT-MRI) has been successfully demonstrated to noninvasively assess skeletal muscle abnormalities induced by traumatic injury. METHODS: To determine the potential for DT-MRI to detect musculoskeletal changes after a bout of eccentric exercise, 10 healthy men performed 300 eccentric actions on an isokinetic dynamometer...

Fiber curvature is a functionally significant muscle structural property, but its estimation from diffusion-tensor magnetic resonance imaging fiber tracking data may be confounded by noise. The purpose of this study was to investigate the use of polynomial fitting of fiber tracts for improving the accuracy and precision of fiber curvature (κ) measurements. Simulated image data sets were created in order to provide data with known values for κ and pennation angle (θ). Simulations were designed to test the effects of increasing inherent fiber curvature (3...

PURPOSE: To investigate the water diffusion tensor properties of ex vivo tissue in the fibroid uterus, including the influence of degeneration, and the relevance of the principal eigenvector orientation to the underlying tissue structure. MATERIALS AND METHODS: Following hysterectomy, high-resolution structural T(2) -weighted and diffusion tensor magnetic resonance imaging (DT-MRI) were performed on nine uteri at 7 T. Mean diffusivity (MD), fractional anisotropy (FA), and principal eigenvector orientation were measured in myometrium and in myxoid and dense tissue in fibroids...

Muscle architecture is an important parameter affecting the muscle function. Most of the previous studies on in-vivo muscle architecture have used in 2D ultrasound. The importance of the third dimension has not been much explored due to lack of appropriate methods. DT-MRI has been used to study muscle architecture in 3D, however, due to long scan times of about 15 min DT-MRI has not been suitable to study active muscle contractions. The purpose of this study was to develop and validate methods to determine in-vivo muscle fascicle orientations in 3D using ultrasound...

We have previously shown in rabbit that the pacemaker of the heart (the sinus node) is widespread and matches the wide distribution of the leading pacemaker site within the right atrium. There is, however, uncertainty about the precise location of the pacemaker in human heart, and its spatial relationships with the surrounding right atrial muscle. Therefore, the aim of the current study was to investigate the distribution of the sinus node tissue in a series of healthy human hearts and, for one of the hearts to construct a computer three-dimensional anatomical model of the sinus node, including the likely orientation of myocytes...

In this paper, we introduce a new approach for tensor field segmentation based on the definition of mixtures of Gaussians on tensors as a statistical model. Working over the well-known Geodesic Active Regions segmentation framework, this scheme presents several interesting advantages. First, it yields a more flexible model than the use of a single Gaussian distribution, which enables the method to better adapt to the complexity of the data. Second, it can work directly on tensor-valued images or, through a parallel scheme that processes independently the intensity and the local structure tensor, on scalar textured images...

Evaluation of structural parameters following a myocardial infarction (MI) is important to assess left ventricular function and remodeling. In this study, we assessed the capability of 3D diffusion tensor magnetic resonance imaging (DT-MRI) to assess tissue degeneration shortly after an MI using a porcine model of infarction. Two days after an induced infarction, hearts were explanted and immediately scanned by a 3T MRI scanner with a diffusion tensor imaging protocol. 3D fiber tracks and clustering models were generated from the diffusion-weighted imaging data...

OBJECTIVE: The aim of our study was to determine the optimal b value for 1.5-T diffusion tensor (DT) MRI and fiber tractography of in vivo human skeletal muscle. SUBJECTS AND METHODS: Five healthy volunteers were included in this prospective study. DT MRI of the proximal calf was performed with 15 directions of diffusion sensitization and parallel imaging with an acceleration factor of 2. Each single-shot spin-echo echo-planar imaging sequence was performed in each volunteer with eight b values ranging from 125 s/mm(2) to 1,000 s/mm(2)...

PURPOSE: To determine the feasibility of using diffusion tensor MRI (DT-MRI) -based muscle fiber tracking to create biomechanical models of the quadriceps mechanism in healthy subjects and those with chronic lateral patellar dislocation (LPD). MATERIALS AND METHODS: Four healthy (average 14.5 years old; BMI 21.8) and four chronic LPD (average 17.3 years old; BMI 22.4) females underwent DT and axial T1W MRI of the thighs. The anatomical and physiologic cross-sectional areas (ACSA and PCSA, respectively) and pennation angle were calculated of the vastus lateralis oblique (VLO) and vastus medialis oblique (VMO) muscles...

Diffusion tensor (DT)-MRI studies of skeletal muscle provide information about muscle architecture, microstructure, and damage. However, the effects of noise, the diffusion weighting (b)-value, and partial volume artifacts on the estimation of the diffusion tensor (D) are unknown. This study investigated these issues using Monte Carlo simulations of 3 x 9 voxel regions of interest (ROIs) containing muscle, adipose tissue, and intermediate degrees of muscle volume fractions (f(M)). A total of 1000 simulations were performed for each of eight b-values and 11 SNR levels...

OBJECTIVES: To compare diffusion tensor-magnetic resonance imaging (DT-MRI) of human calf muscles at 1.5 T and 3.0 T, and to measure a number of quantitative parameters to characterize diffusion anisotropy in organized muscle tissue using similar imaging parameters. METHODS AND MATERIALS: After Institutional Review Board approval and informed consent, five healthy volunteers were studied. Imaging was performed on both 1.5 T and 3.0 T MR systems using the similar imaging protocol...

The goal of this study was to assess the changes of water diffusion during contraction and elongation of calf muscles using diffusion tensor (DT) MRI in normal volunteers. Twenty volunteers (mean age, 29+/-4 years) underwent DT MRI examination of the right calf. Echo planar imaging sequence was performed at rest, during dorsal flexion and during plantar flexion. The three eigenvalues (lambda1, lambda2, and lambda3), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the diffusion tensor were calculated for medial gastrocnemius (mGM) and tibialis anterior (TA)...

Diffusion-tensor magnetic resonance imaging (DT-MRI) offers great potential for understanding structure-function relationships in human skeletal muscles. The purposes of this study were to demonstrate the feasibility of using in vivo human DT-MRI fiber tracking data for making pennation angle measurements and to test the hypothesis that heterogeneity in the orientation of the tibialis anterior (TA) muscle's aponeurosis would lead to heterogeneity in pennation angle. Eight healthy subjects (5 male) were studied...

Diffusion-tensor (DT) MRI fiber tracking may potentially be used for in vivo structural analysis. The purpose of this study was to assess quantitatively the ability of a DT-MRI fiber-tracking algorithm to measure the fiber orientation (pennation) in skeletal muscle in vivo. In five adult Sprague-Dawley rats, the pennation angle (theta) was measured in the rat lateral gastrocnemius with DT-MRI (theta(DT-MRI)) and by direct anatomical inspection (DAI) (theta(DAI)). The mean theta(DT-MRI) was not significantly different from the mean theta(DAI)...

This paper presents processing and visualization techniques for Diffusion Tensor Magnetic Resonance Imaging (DT-MRI). In DT-MRI, each voxel is assigned a tensor that describes local water diffusion. The geometric nature of diffusion tensors enables us to quantitatively characterize the local structure in tissues such as bone, muscle, and white matter of the brain. This makes DT-MRI an interesting modality for image analysis. In this paper we present a novel analytical solution to the Stejskal-Tanner diffusion equation system whereby a dual tensor basis, derived from the diffusion sensitizing gradient configuration, eliminates the need to solve this equation for each voxel...