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In JoVE (1)
Other Publications (9)
- Annals of Biomedical Engineering
- Journal of Biomechanical Engineering
- Journal of Magnetic Resonance Imaging : JMRI
- Magnetic Resonance Imaging
- Stroke; a Journal of Cerebral Circulation
- Journal of Magnetic Resonance Imaging : JMRI
- Journal of Neuroimmunology
- Journal of Neuroscience Methods
- International Journal of Biomedical Imaging
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Articles by Yutong Liu in JoVE
JoVE Bioengineering
Bioimaging مسجلة لرصد المواد النانوية للتشخيص والعلاج
1Department of Radiology, University of Nebraska Medical Center, 2Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center
الأساليب المستخدمة لتقييم Bioimaging biodistribution خلية من جزيئات قابلة للتطبيق لرصد العلاجية والتشخيصية للمركبات nanoformulated. الأساليب المذكورة هنا هي حساسة ومحددة عندما المقررة coregistration النسيجية. المنهجيات توفير مسارا متعدية من القوارض إلى تطبيقات الإنسان.
Other articles by Yutong Liu on PubMed
Alteration in Fluid Mechanics in Porcine Femoral Arteries with Atheroma Development
Although the relationship between the local wall shear stresses (WSS) and atheroma development has been previously studied, the effect of variable regional wall distensibility with early atherosclerotic lesions and its effect on local hemodynamics have not been well investigated. We induced early atherosclerotic lesion development in one femoral artery in a Yucatan miniswine model with the contralateral artery serving as control. Eight weeks following atheroma formation, hemodynamic and intravascular ultrasound image data were obtained. Using the measured regional arterial distension as the moving boundary condition, unsteady laminar incompressible computational analysis was performed on the reconstructed arterial segments. With the development of early atherosclerotic lesions, there was increased wall distensibility and an increase in the computed normalized wall shear stress amplitude (NWSA). Alterations in the local fluid mechanics and mass transport at these sites may need to be considered in our understanding of the continued growth of these lesions.
The Effects of Different Mesh Generation Methods on Computational Fluid Dynamic Analysis and Power Loss Assessment in Total Cavopulmonary Connection
The flow field and energetic efficiency of total cavopulmonary connection (TCPC) models have been studied by both in vitro experiment and computational fluid dynamics (CFD). All the previous CFD studies have employed the structured mesh generation method to create the TCPC simulation model. In this study, a realistic TCPC model with complete anatomical features was numerically simulated using both structured and unstructured mesh generation methods. The flow fields and energy losses were compared in these two meshes. Two different energy loss calculation methods, the control volume and viscous dissipation methods, were investigated. The energy losses were also compared to the in vitro experimental results. The results demonstrated that: (1) the flow fields in the structured model were qualitatively similar to the unstructured model; (2) more vortices were present in the structured model than in the unstructured model; (3) both models had the least energy loss when flow was equally distributed to the left and right pulmonary arteries, while high losses occurred for extreme pulmonary arterial flow splits; (4) the energy loss results calculated using the same method were significantly different for different meshes; and (5) the energy loss results calculated using different methods were significantly different for the same mesh.
Dynamic Susceptibility Contrast Perfusion Imaging of Cerebral Ischemia in Nonhuman Primates: Comparison of Gd-DTPA and NMS60
To study a new gadolinium (Gd) contrast agent-NMS60-for MR perfusion-weighted imaging (PWI) of brain tissue.
A Nonlinear Mesh-warping Technique for Correcting Brain Deformation After Stroke
This article presents a warping technique for correcting brain tissue distortion on magnetic resonance imaging (MRI) scans due to stroke lesion growth and for mapping MRI scans to histological sections. Meshes are imposed upon the images for feature specification, and these features are exactly matched in the different images to be mapped, while the other voxels are matched by interpolation. This technique was tested on serial MR images and histological sections that were acquired in a nonhuman primate model of stroke. This technique was able to deliver satisfactory warping results. It is simple and robust and can be utilized in many applications for comparison of multimodality medical images and histological sections.
Serial Diffusion Tensor MRI After Transient and Permanent Cerebral Ischemia in Nonhuman Primates
We measured the temporal evolution of the T2 and diffusion tensor imaging parameters after transient and permanent cerebral middle cerebral artery occlusion (MCAo) in macaques, and compared it to standard histological analysis at the study end point.
MRI of Spontaneous Fluctuations After Acute Cerebral Ischemia in Nonhuman Primates
To study the spontaneous low-frequency blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal fluctuations during hyperacute focal cerebral ischemia.
Ingress of Blood-borne Macrophages Across the Blood-brain Barrier in Murine HIV-1 Encephalitis
Blood-borne macrophage ingress into brain in HIV-1 associated neurocognitive disorders governs the tempo of disease. We used superparamagnetic iron-oxide particles loaded into murine bone marrow-derived macrophages (BMM) injected intravenously into HIV-1 encephalitis mice to quantitatively assess BMM entry into diseased brain regions. Magnetic resonance imaging tests were validated by histological coregistration and enhanced image processing. The demonstration of robust BMM migration into areas of focal encephalitis provide 'proof of concept' for the use of MRI to monitor macrophage ingress into brain.
A Semi-automatic Image Segmentation Method for Extraction of Brain Volume from in Vivo Mouse Head Magnetic Resonance Imaging Using Constraint Level Sets
In vivo magnetic resonance imaging (MRI) of mouse brain has been widely used to non-invasively monitor disease progression and/or therapeutic effects in murine models of human neurodegenerative disease. Segmentation of MRI to differentiate brain from non-brain tissue (usually referred to as brain extraction) is required for many MRI data processing and analysis methods, including coregistration, statistical parametric analysis, and mapping to brain atlas and histology. This paper presents a semi-automatic brain extraction technique based on a level set method with the incorporation of user-defined constraints. The constraints are derived from the prior knowledge of brain anatomy by defining brain boundary on orthogonal planes of the MRI. Constraints are incorporated in the level set method by spatially varying the weighting factors of the internal and external forces and modifying the image gradient (edge) map. Both two-dimensional multislice and three-dimensional versions of the brain extraction technique were developed and applied to MRI data with minimal brain/non-brain contrast T(1)-weighted (T(1)-wt) FLASH and maximized contrast T(2)-weighted (T(2)-wt) RARE. Results were evaluated by calculating the overlap measure (OM) between the automatically segmented and manually traced brain volumes. Results demonstrate that this technique accurately extracts the brain volume (mean OM=94%) and consistently outperformed the region growing method applied to the T(2)-wt RARE MRI (mean OM=81%). This method not only successfully extracts the mouse brain in low and high contrast MRI, but can also be used to segment other organs and tissues.
Landmark Optimization Using Local Curvature for Point-based Nonlinear Rodent Brain Image Registration
Purpose. To develop a technique to automate landmark selection for point-based interpolating transformations for nonlinear medical image registration. Materials and Methods. Interpolating transformations were calculated from homologous point landmarks on the source (image to be transformed) and target (reference image). Point landmarks are placed at regular intervals on contours of anatomical features, and their positions are optimized along the contour surface by a function composed of curvature similarity and displacements of the homologous landmarks. The method was evaluated in two cases (n = 5 each). In one, MRI was registered to histological sections; in the second, geometric distortions in EPI MRI were corrected. Normalized mutual information and target registration error were calculated to compare the registration accuracy of the automatically and manually generated landmarks. Results. Statistical analyses demonstrated significant improvement (P < 0.05) in registration accuracy by landmark optimization in most data sets and trends towards improvement (P < 0.1) in others as compared to manual landmark selection.
