scholarly journals Optimization of Nonlinear Hyperelastic Coefficients for Foot Tissues Using a Magnetic Resonance Imaging Deformation Experiment

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Marc Petre ◽  
Ahmet Erdemir ◽  
Vassilis P. Panoskaltsis ◽  
Thomas A. Spirka ◽  
Peter R. Cavanagh
Keyword(s):  
Magnetic Resonance Imaging ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Internal Stress ◽  
Material Properties ◽  
Accurate Prediction ◽  
Finite Element Models ◽  
Resonance Imaging ◽  
Fat Pad

Accurate prediction of plantar shear stress and internal stress in the soft tissue layers of the foot using finite element models would provide valuable insight into the mechanical etiology of neuropathic foot ulcers. Accurate prediction of the internal stress distribution using finite element models requires that realistic descriptions of the material properties of the soft tissues are incorporated into the model. Our investigation focused on the creation of a novel three-dimensional (3D) finite element model of the forefoot with multiple soft tissue layers (skin, fat pad, and muscle) and the development of an inverse finite element procedure that would allow for the optimization of the nonlinear elastic coefficients used to define the material properties of the skin muscle and fat pad tissue layers of the forefoot based on a Ogden hyperelastic constitutive model. Optimization was achieved by comparing deformations predicted by finite element models to those measured during an experiment in which magnetic resonance imaging (MRI) images were acquired while the plantar surface forefoot was compressed. The optimization procedure was performed for both a model incorporating all three soft tissue layers and one in which all soft tissue layers were modeled as a single layer. The results indicated that the inclusion of multiple tissue layers affected the deformation and stresses predicted by the model. Sensitivity analysis performed on the optimized coefficients indicated that small changes in the coefficient values (±10%) can have rather large impacts on the predicted nominal strain (differences up to 14%) in a given tissue layer.

Finite Element Modeling of Knee Joint Contact Pressures and Comparison to Magnetic Resonance Imaging of the Loaded Knee

2003 ◽  
Author(s):  
Jiang Yao ◽  
Art D. Salo ◽  
Monica Barbu-McInnis ◽  
Amy L. Lerner
Keyword(s):  
Magnetic Resonance Imaging ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Knee Joint ◽  
Material Properties ◽  
Three Dimensional ◽  
Resonance Imaging ◽  
Three Dimensional Model ◽  
Model Predictions

A finite element model of the knee joint could be helpful in providing insight on mechanisms of injury, effects of treatment, and the role of mechanical factors in degenerative conditions. However, preparation of such a model involves many geometric simplifications and input of material properties, some of which are poorly understood. Therefore, a method to compare model predictions to actual behaviors under controlled conditions could provide confidence in the model before exploration of other loading scenarios. Our laboratory has developed a method to apply axial loads to the in vivo human knee during magnetic resonance imaging, resembling weightbearing conditions. Image processing algorithms may then be used to assess the three-dimensional kinematics of the tibia and femur during loading. A three-dimensional model of the tibio-menisco-femoral contact has been generated and the image-based kinematic boundary conditions were applied to investigate the distribution of stresses and strains in the articular cartilage and menisci throughout the loading period. In this study, our goal is to investigate the contact patterns during long term loading of up to twenty minutes in the healthy knee. Specifically, we assess the use of both elastic and poroelastic material properties in the cartilage, and compare model predictions to known loading conditions and images of tissue deformations.

The Role of Magnetic Resonance Imaging for Diagnosing Soft Tissue Lesions Associated with Anterior Cruciate Ligament Injuries

2018 ◽  
Vol 69 (9) ◽  
pp. 2498-2500
Author(s):  
Bogdan Sendrea ◽  
Antoine Edu ◽  
George Viscopoleanu
Keyword(s):  
Magnetic Resonance Imaging ◽  
Anterior Cruciate Ligament ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Traumatic Event ◽  
Cruciate Ligament ◽  
Soft Tissue Injuries ◽  
Resonance Imaging ◽  
Soft Tissue Lesions ◽  
Anterior Cruciate

Magnetic resonance imaging has become the gold standard for soft tissue lesions evaluation especially after a traumatic event where there is need for diagnostic confirmation. The objective of the current paper was to evaluate the ability of magnetic resonance imaging in diagnosing soft tissue lesions in patients who underwent anterior cruciate ligament reconstruction compared with arthroscopic findings. Through the ability to diagnose soft tissue injuries, particularly meniscal lesions, magnetic resonance imaging should be considered as fundamental in guiding therapeutic management in patients with anterior cruciate ligament lesions.

Imaging of soft tissue tumors

2020 ◽  
Vol 16 ◽  
Author(s):  
Shinji Tsukamoto ◽  
Andreas F. Mavrogenis ◽  
Yasuhito Tanaka ◽  
Costantino Errani
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Tumor Size ◽  
Critical Role ◽  
Evaluation Criteria ◽  
Soft Tissue Tumors ◽  
Resonance Imaging ◽  
Benign Soft Tissue Tumors ◽  
Response To Chemotherapy

: Differentiation of malignant from benign soft tissue tumors is challenging with imaging alone, including that by magnetic resonance imaging and computed tomography. However, the accuracy of this differentiation has increased owing to the development of novel imaging technology. Detailed patient history and physical examination remain essential for differentiation between benign and malignant soft tissue tumors. Moreover, measurement only of tumor size based on Response Evaluation Criteria In Solid Tumors criteria is insufficient for the evaluation of response to chemotherapy or radiotherapy. Change in metabolic activity measured by 18F-fluorodeoxyglucose positron emission tomography or dynamic contrast enhanced-derived quantitative endpoints can more accurately evaluate treatment response compared to change in tumor size. Magnetic resonance imaging can accurately evaluate essential factors in surgical planning such as vascular or bone invasion and “tail sign”. Thus, imaging plays a critical role in the diagnosis and treatment of soft tissue tumors.

scholarly journals Non-invasive diagnostics in fossils - Magnetic Resonance Imaging of pathological belemnites

2005 ◽  
Vol 2 (2) ◽  
pp. 133-140 ◽  
Author(s):  
D. Mietchen ◽  
H. Keupp ◽  
B. Manz ◽  
F. Volke
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Clinical Diagnostics ◽  
Resonance Imaging ◽  
Non Invasive ◽  
Physiological Processes ◽  
Magnetic Resonance Imaging Mri ◽  
Invasive Diagnostics

Abstract. For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical diagnostics because it allows non-invasive studies of anatomical structures and physiological processes in vivo and to differentiate between healthy and pathological states, particularly of soft tissue. Here, we demonstrate that MRI can likewise be applied to fossilized biological samples and help in elucidating paleopathological and paleoecological questions: Five anomalous guards of Jurassic and Cretaceous belemnites are presented along with putative paleopathological diagnoses directly derived from 3D MR images with microscopic resolution. Syn vivo deformities of both the mineralized internal rostrum and the surrounding former soft tissue can be traced back in part to traumatic events of predator-prey-interactions, and partly to parasitism. Besides, evidence is presented that the frequently observed anomalous apical collar might be indicative of an inflammatory disease. These findings highlight the potential of Magnetic Resonance techniques for further paleontological applications.

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