Finite Element Computation of the Electromagnetic Fields Produced in the Body by Magnetic Resonance Imaging Surface Coils

1995 ◽  
pp. 257-260
Author(s):  
Olivier Le Dour ◽  
Markus Vester ◽  
Peter Henninger ◽  
Wolfgang Renz
Keyword(s):  
Magnetic Resonance Imaging ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Electromagnetic Fields ◽  
The Body ◽  
Resonance Imaging ◽  
Surface Coils ◽  
Element Computation ◽  
Finite Element Computation

scholarly journals Radio Frequency MRI coils

2020 ◽  
Vol 18 (1) ◽  
pp. 24-27
Author(s):  
Adrian Truszkiewicz ◽  
◽  
David Aebisher ◽  
Zuzanna Bober ◽  
Łukasz Ożóg ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Clinical Diagnostics ◽  
The Body ◽  
Rf Coils ◽  
Coil Design ◽  
Resonance Imaging ◽  
Surface Coils ◽  
Magnetic Resonance Imaging Mri ◽  
Mri Coils

Introduction. Magnetic Resonance Imaging (MRI) coils technology is a powerful improvement for clinical diagnostics. This includes opportunities for mathematical and physical research into coil design. Aim. Here we present the method applied to MRI coil array designs. Material and methods. Analysis of literature and self-research. Results. The coils that emit the radiofrequency pulses are designed similarly. As much as possible, they deliver the same strength of radiofrequency to all voxels within their imaging volume. Surface coils on the other hand are usually not embedded in cylindrical surfaces relatively close to the surface of the body. Conclusion. The presented here results relates to the art of magnetic resonance imaging (MRI) and RF coils design. It finds particular application of RF coils in conjunction with bore type MRI scanners.

Magnetic Resonance Imaging in the Diagnosis of Disruption of the Posterior Tibial Tendon

Foot & Ankle ◽  
1987 ◽  
Vol 8 (3) ◽  
pp. 144-147 ◽  
Author(s):  
Ian J. Alexander ◽  
Kenneth A. Johnson ◽  
Thomas H. Berquist
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Soft Tissues ◽  
Diagnostic Technique ◽  
Clinical Findings ◽  
The Body ◽  
Posterior Tibial Tendon ◽  
Resonance Imaging ◽  
Posterior Tibial ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI), a useful technique of studying soft tissues of the body, can be very effective in assessing the integrity of tendons. Usually a patient with a complete tear of the posterior tibial tendon has characteristic physical findings. In the patient presented, MRI demonstrated a complete disruption of the posterior tibial tendon, despite the absence of the commonly associated clinical findings. In view of the difficulties encountered with attempted tenography of the completely torn posterior tibial tendon, MRI provides a sensitive alternative diagnostic technique.

scholarly journals Noninvasive assessment of iron overload by magnetic resonance imaging

2020 ◽  
Vol 19 (3) ◽  
pp. 158-163
Author(s):  
E. E. Nazarova ◽  
D. A. Kupriyanov ◽  
G. A. Novichkova ◽  
G. V. Tereshchenko
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Iron Overload ◽  
Serum Ferritin ◽  
Serum Ferritin Level ◽  
Ferritin Level ◽  
Iron Concentration ◽  
The Body ◽  
Iron Accumulation ◽  
Resonance Imaging

The assessment of iron accumulation in the body is important for the diagnosis of iron overload syndrome or planning and monitoring of the chelation therapy. Excessive iron accumulation in the organs leads to their toxic damage and dysfunction. Until recently iron estimation was performed either directly by liver iron concentration and/or indirectly by measuring of serum ferritin level. However, noninvasive iron assessment by Magnetic resonance imaging (MRI) is more accurate method unlike liver biopsy or serum ferritin level test. In this article, we demonstrate the outlines of non-invasive diagnostics of iron accumulation by MRI and its specifications.

scholarly journals Magnetic Resonance Imaging Appearance of Schwannomas from Head to Toe: A Pictorial Review

2017 ◽  
Vol 7 ◽  
pp. 38 ◽  
Author(s):  
Jamie Crist ◽  
Jacob R Hodge ◽  
Matthew Frick ◽  
Fiona P Leung ◽  
Eugene Hsu ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Neurofibromatosis Type ◽  
Soft Tissue Tumors ◽  
The Body ◽  
Resonance Imaging ◽  
Pictorial Review ◽  
Benign Soft Tissue Tumors ◽  
Mri Characteristics

Schwannomas are benign soft-tissue tumors that arise from peripheral nerve sheaths throughout the body and are commonly encountered in patients with neurofibromatosis Type 2. The vast majority of schwannomas are benign, with rare cases of malignant transformation reported. In this pictorial review, we discuss the magnetic resonance imaging (MRI) appearance of schwannomas by demonstrating a collection of tumors from different parts of the body that exhibit similar MRI characteristics. We review strategies to distinguish schwannomas from malignant soft-tissue tumors while exploring the anatomic and histologic origins of these tumors to discuss how this correlates with their imaging findings. Familiarity with the MRI appearance of schwannomas can help aid in the differential diagnosis of soft-tissue masses, especially in unexpected locations.

scholarly journals Subject-Specific Finite Element Modeling of the Tibiofemoral Joint Based on CT, Magnetic Resonance Imaging and Dynamic Stereo-Radiography Data in Vivo

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Robert E. Carey ◽  
Liying Zheng ◽  
Ameet K. Aiyangar ◽  
Christopher D. Harner ◽  
Xudong Zhang
Keyword(s):  
Magnetic Resonance Imaging ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Contact Area ◽  
Resonance Imaging ◽  
Model Predictions ◽  
Subject Specific ◽  
Skeletal Kinematics ◽  
Tibiofemoral Kinematics

In this paper, we present a new methodology for subject-specific finite element modeling of the tibiofemoral joint based on in vivo computed tomography (CT), magnetic resonance imaging (MRI), and dynamic stereo-radiography (DSX) data. We implemented and compared two techniques to incorporate in vivo skeletal kinematics as boundary conditions: one used MRI-measured tibiofemoral kinematics in a nonweight-bearing supine position and allowed five degrees of freedom (excluding flexion-extension) at the joint in response to an axially applied force; the other used DSX-measured tibiofemoral kinematics in a weight-bearing standing position and permitted only axial translation in response to the same force. Verification and comparison of the model predictions employed data from a meniscus transplantation study subject with a meniscectomized and an intact knee. The model-predicted cartilage-cartilage contact areas were examined against “benchmarks” from a novel in situ contact area analysis (ISCAA) in which the intersection volume between nondeformed femoral and tibial cartilage was characterized to determine the contact. The results showed that the DSX-based model predicted contact areas in close alignment with the benchmarks, and outperformed the MRI-based model: the contact centroid predicted by the former was on average 85% closer to the benchmark location. The DSX-based FE model predictions also indicated that the (lateral) meniscectomy increased the contact area in the lateral compartment and increased the maximum contact pressure and maximum compressive stress in both compartments. We discuss the importance of accurate, task-specific skeletal kinematics in subject-specific FE modeling, along with the effects of simplifying assumptions and limitations.

Computation of electromagnetic fields for high-frequency magnetic resonance imaging applications

1996 ◽  
Vol 41 (12) ◽  
pp. 2719-2738 ◽  
Author(s):  
J M Jin ◽  
J Chen ◽  
W C Chew ◽  
H Gan ◽  
R L Magin ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Electromagnetic Fields ◽  
High Frequency ◽  
Resonance Imaging

Effect of PIN diode nonlinearity on decoupler circuits in magnetic resonance imaging surface coils

2018 ◽  
Vol 48B (3) ◽  
pp. e21398 ◽  
Author(s):  
Aasrith Ganti ◽  
Timothy Ortiz ◽  
Tracy A. Wynn ◽  
Jenshan Lin ◽  
Randy Duensing
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pin Diode ◽  
Resonance Imaging ◽  
Surface Coils

scholarly journals P.063 Stereotactic targeting of hippocampal substructures using ultra-high field magnetic resonance imaging: Feasibility study in patients with epilepsy

2018 ◽  
Vol 45 (s2) ◽  
pp. S32-S33
Author(s):  
JC Lau ◽  
J DeKraker ◽  
KW MacDougall ◽  
H Joswig ◽  
AG Parrent ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Dentate Gyrus ◽  
High Field ◽  
Longitudinal Axis ◽  
The Body ◽  
7 Tesla ◽  
Resonance Imaging ◽  
Ultra High Field

Background: The hippocampus can be divided longitudinally into the head, body, and tail; and unfolded medial-to-laterally into the subiculum, cornu ammonis (CA) sectors, and the dentate gyrus. Ultra-high field (≥ 7 Tesla; 7T) magnetic resonance imaging (MRI) enables submillimetric visualization of these hippocampal substructures which could be valuable for surgical targeting. Here, we assess the feasibility of using 7T MRI in conjunction with a novel computational unfolding method for image-based stereotactic targeting of hippocampal substructures. Methods: 53 patients with drug-resistant epilepsy were identified undergoing first-time implantation of the hippocampus. An image processing pipeline was created for computationally transforming post-operative electrode contact locations into our hippocampal coordinate system. Results: Of 178 implanted hippocampal electrodes (88 left; 49.4%), 25 (14.0%) were predominantly in the subiculum, 85 (47.8%) were in CA1, 23 (12.9%) were in CA2, 18 (10.1%) were in CA3/CA4, and 27 (15.2%) were in dentate gyrus. Along the longitudinal axis, hippocampal electrodes were most commonly implanted in the body (92; 51.7%) followed by the head (86; 48.3%). Conclusions: 7T MRI enables high-resolution anatomical imaging on the submillimeter scale in in vivo subjects. Here, we demonstrate the utility of 7T imaging for identifying the relative location of SEEG electrode implantations within hippocampal substructures for the invasive investigation of epilepsy.

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