Can We Use In Vivo MRI and FEA to Determine Peak Cap Stress in Carotid Plaques? MRI Simulations Provide Answers

2013 ◽  
Author(s):  
Harm A. Nieuwstadt ◽  
Jolanda W. Wentzel ◽  
Aad van der Lugt ◽  
Anton F. W. van der Steen ◽  
Marcel Breeuwer ◽  
...  
Keyword(s):  
Plaque Rupture ◽  
Important Determinant ◽  
Peak Stress ◽  
Necrotic Core ◽  
Rupture Risk ◽  
Resonance Imaging ◽  
Element Analysis ◽  
Fibrous Cap ◽  
Magnetic Resonance Imaging Mri

Vulnerable plaques are characterized by a large lipid-rich necrotic core (LRNC) separated by a thin fibrous cap (FC) from the lumen. Plaque rupture occurs when the peak stress in the FC exceeds its strength. Carotid in vivo magnetic resonance imaging (MRI) data can be segmented to obtain the plaque geometry noninvasively. An increasing number of studies use MR imaging for biomechanical finite element analysis (FEA) to compute peak cap stresses [1, 2]. Previous studies have shown that the thickness of the FC is an important determinant of peak cap stress: the thinner the FC, the higher the stress, the higher the plaque rupture risk [3].

Plaque Deformation in Atherosclerotic Porcine Arteries

2012 ◽  
Author(s):  
L. Speelman ◽  
M. Goffi ◽  
A. C. Akyildiz ◽  
H. Nieuwstadt ◽  
K. Van der Heiden ◽  
...  
Keyword(s):  
Arterial Wall ◽  
Important Determinant ◽  
Ex Vivo ◽  
Accurate Determination ◽  
Numerical Approach ◽  
Atherosclerotic Plaques ◽  
Resonance Imaging ◽  
Fibrous Cap ◽  
Magnetic Resonance Imaging Mri

Atherosclerosis is the main cause of cardiovascular disease and is characterized by plaque formation, with lipid accumulation in the arterial wall, covered by a fibrous cap. Rupture of such a cap is the main underlying cause of sudden coronary deaths and strokes. Cap rupture occurs when the mechanical stress in the cap exceeds local cap strength. Accurate determination of cap stresses might therefore play an important role in the prediction of cap rupture. An important determinant of plaque deformation and cap stress is the mechanical behaviour of the diseased plaque components, of which little is known. The aim of this study is to determine material properties of atherosclerotic plaques using a mixed experimental-numerical approach. Plaque deformation as measured ex-vivo with magnetic resonance imaging (MRI) will be matched with computed deformations based on the measured plaque geometry.

scholarly journals Nanoanalytical analysis of bisphosphonate-driven alterations of microcalcifications using a 3D hydrogel system and in vivo mouse model

2021 ◽  
Vol 118 (14) ◽  
pp. e1811725118
Author(s):  
Jessica L. Ruiz ◽  
Joshua D. Hutcheson ◽  
Luis Cardoso ◽  
Amirala Bakhshian Nik ◽  
Alexandra Condado de Abreu ◽  
...  
Keyword(s):  
Vascular Calcification ◽  
Cardiovascular Events ◽  
Plaque Rupture ◽  
Three Dimensional ◽  
Element Analysis ◽  
Fibrous Cap ◽  
3D Collagen ◽  
Atherosclerotic Plaque Rupture

Vascular calcification predicts atherosclerotic plaque rupture and cardiovascular events. Retrospective studies of women taking bisphosphonates (BiPs), a proposed therapy for vascular calcification, showed that BiPs paradoxically increased morbidity in patients with prior acute cardiovascular events but decreased mortality in event-free patients. Calcifying extracellular vesicles (EVs), released by cells within atherosclerotic plaques, aggregate and nucleate calcification. We hypothesized that BiPs block EV aggregation and modify existing mineral growth, potentially altering microcalcification morphology and the risk of plaque rupture. Three-dimensional (3D) collagen hydrogels incubated with calcifying EVs were used to mimic fibrous cap calcification in vitro, while an ApoE−/− mouse was used as a model of atherosclerosis in vivo. EV aggregation and formation of stress-inducing microcalcifications was imaged via scanning electron microscopy (SEM) and atomic force microscopy (AFM). In both models, BiP (ibandronate) treatment resulted in time-dependent changes in microcalcification size and mineral morphology, dependent on whether BiP treatment was initiated before or after the expected onset of microcalcification formation. Following BiP treatment at any time, microcalcifications formed in vitro were predicted to have an associated threefold decrease in fibrous cap tensile stress compared to untreated controls, estimated using finite element analysis (FEA). These findings support our hypothesis that BiPs alter EV-driven calcification. The study also confirmed that our 3D hydrogel is a viable platform to study EV-mediated mineral nucleation and evaluate potential therapies for cardiovascular calcification.

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.

scholarly journals Perspectives on the Role of Magnetic Resonance Imaging (MRI) for Noninvasive Evaluation of Diabetic Kidney Disease

2021 ◽  
Vol 10 (11) ◽  
pp. 2461
Author(s):  
José María Mora-Gutiérrez ◽  
María A. Fernández-Seara ◽  
Rebeca Echeverria-Chasco ◽  
Nuria Garcia-Fernandez
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Kidney Disease ◽  
Diabetic Kidney Disease ◽  
Imaging Biomarkers ◽  
Major Advance ◽  
Resonance Imaging ◽  
Diabetic Kidney ◽  
Magnetic Resonance Imaging Mri

Renal magnetic resonance imaging (MRI) techniques are currently in vogue, as they provide in vivo information on renal volume, function, metabolism, perfusion, oxygenation, and microstructural alterations, without the need for exogenous contrast media. New imaging biomarkers can be identified using these tools, which represent a major advance in the understanding and study of the different pathologies affecting the kidney. Diabetic kidney disease (DKD) is one of the most important diseases worldwide due to its high prevalence and impact on public health. However, its multifactorial etiology poses a challenge for both basic and clinical research. Therefore, the use of novel renal MRI techniques is an attractive step forward in the comprehension of DKD, both in its pathogenesis and in its detection and surveillance in the clinical practice. This review article outlines the most promising MRI techniques in the study of DKD, with the purpose of stimulating their clinical translation as possible tools for the diagnosis, follow-up, and monitoring of the clinical impacts of new DKD treatments.

scholarly journals In vivo intervertebral disc deformation: intratissue strain patterns within adjacent discs during flexion–extension

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert L. Wilson ◽  
Leah Bowen ◽  
Woong Kim ◽  
Luyao Cai ◽  
Stephanie Ellyse Schneider ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Biomechanical Analysis ◽  
Resonance Imaging ◽  
Tissue Architecture ◽  
Mechanical Responses ◽  
Flexion Extension ◽  
Adjacent Disc ◽  
Shear Strains ◽  
Magnetic Resonance Imaging Mri

AbstractThe biomechanical function of the intervertebral disc (IVD) is a critical indicator of tissue health and pathology. The mechanical responses (displacements, strain) of the IVD to physiologic movement can be spatially complex and depend on tissue architecture, consisting of distinct compositional regions and integrity; however, IVD biomechanics are predominately uncharacterized in vivo. Here, we measured voxel-level displacement and strain patterns in adjacent IVDs in vivo by coupling magnetic resonance imaging (MRI) with cyclic motion of the cervical spine. Across adjacent disc segments, cervical flexion–extension of 10° resulted in first principal and maximum shear strains approaching 10%. Intratissue spatial analysis of the cervical IVDs, not possible with conventional techniques, revealed elevated maximum shear strains located in the posterior disc (nucleus pulposus) regions. IVD structure, based on relaxometric patterns of T2 and T1ρ images, did not correlate spatially with functional metrics of strain. Our approach enables a comprehensive IVD biomechanical analysis of voxel-level, intratissue strain patterns in adjacent discs in vivo, which are largely independent of MRI relaxometry. The spatial mapping of IVD biomechanics in vivo provides a functional assessment of adjacent IVDs in subjects, and provides foundational biomarkers for elastography, differentiation of disease state, and evaluation of treatment efficacy.

In Vivo MR Studies of Dynamic Changes in the Interosseous Membrane of the Forearm During Rotation

1999 ◽  
Vol 24 (2) ◽  
pp. 245-248 ◽  
Author(s):  
T. NAKAMURA ◽  
Y. YABE ◽  
Y. HORIUCHI
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Interosseous Membrane ◽  
Resonance Imaging ◽  
Forearm Rotation ◽  
Dynamic Changes ◽  
Magnetic Resonance Imaging Mri ◽  
Membranous Part ◽  
The Right

In vivo dynamic changes in the interosseous membrane (IOM) during forearm rotation were studied using magnetic resonance imaging (MRI). The right forearms of 20 healthy volunteers were examined in five different rotational positions. Axial slices were obtained at the proximal quarter, the middle and the distal quarter of the forearm. The changes in shape of the IOM during rotation were observed in an axial MR plane. For each image, we measured the interosseous distance and the length of the interosseous membrane. Images of the tendinous and membranous parts of the IOM could be differentiated by thickness. There were minimal dynamic changes in the tendinous part on the MRI while the membranous part showed numerous changes during rotation. The interosseous distance and the length of the interosseous membrane were maximum from a neutral to a slightly supinated position. The tendinous part is considered to be taut during rotation to provide stability between the radius and the ulna, but the membranous part which is soft, thin and elastic, allows smooth rotation.

Finite Element Analysis of Brain Injury due to Head Impact

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1355-1361
Author(s):  
Chang Min Suh ◽  
Sung Ho Kim ◽  
Werner Goldsmith
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Brain Injury ◽  
Head Impact ◽  
Stress And Strain ◽  
Resonance Imaging ◽  
Element Analysis ◽  
External Impact ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

Traumatic Brain Injury (TBI) due to head impact by external impactor was analyzed using Finite Element Method (FEM). Two-dimensiona modeling was performed according to Magnetic Resonance Imaging (MRI) data of Mongolian subject. Pressure variation in a cranium due to external impact was analyzed in order to simulate Nahum et al.'s cadaver test.6 And, analyzed results were compared with Nahum et al.'s experimental data.6 As results, stress and strain behaviors of the brain during impact were accorded with experimental data qualitatively even though there were some differences in quantitative values. In addition, they were accorded with other references about brain injury as well.

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