RF Coil Design for MRI Applications in Inhomogeneous Main Magnetic Fields

Yılmaz, Ayşen
Eyueboglu, B. M.
Conventional Magnetic Resonance Imaging (MRI) techniques require homogeneous main magnetic fields. However, MRI applications that are executed in inhomogenous main magnetic fields have been developed in recent years. In this study, RF coil geometries are designed for MRI applications in inhomogeneous magnetic fields. Method of moments is used to obtain the current density distribution on a predefined surface that can produce a desired magnetic field, which is perpendicular to the given inhomogenous main magnetic field. The basis functions are represented by Fourier series and a conductor pattern that can provide the calculated current density distribution is obtained using stream functions. The error percentages between the calculated and the desired magnetic fields are calculated and regularization techniques are used in order to obtain realizable conductor patterns. Taking the error and realizability of the conductor patterns into consideration, the optimum conductor patterns on cylindrical, cubic and planar surfaces are determined.


Magnetic Resonance Imaging in Inhomogeneous Magnetic Fields with Noisy Signal
Arpinar, V. E.; Eyüboğlu, Behçet Murat (2008-11-27)
In this study, an image reconstruction algorithm for a Magnetic Resonance Imaging (MRI) system with inhomogeneous magnetic fields is proposed. The proposed reconstruction algorithm uses spatial distributions of main magnetic field, Radio Frequency (RF) and gradient fields as inputs, together with the pulse sequence and the noisy Magnetic Resonance (MR) signal. To calculate the noise signal, noise model for MRI with homogeneous fields is extended for inhomogeneous magnetic fields. Using this embedded noise m...
Electrical impedance tomography using the magnetic field generated by injected currents
Birgul, O; Ider, YZ (1996-11-03)
In 2D EIT imaging, the internal distribution of the injected currents generate a magnetic field in the imaging region which can be measured by magnetic resonance imaging techniques. This magnetic field is perpendicular to the imaging region on the imaging region and it can be used in reconstructing the conductivity distribution inside the imaging region. For this purpose, internal current distribution is found using the finite element method. The magnetic fields due to this current is found using Biot-Savar...
Magnetic Resonance Signal Analysis in Inhomogenous Magnetic Fields
Arpinar, V. E.; Eyüboğlu, Behçet Murat (2009-09-12)
Nuclear Magnetic Resonance (NMR) systems with inhomogenous main magnetic fields have been satisfactorily used to explore material properties. So that, imaging of biological tissues using Magnetic Resonance Imaging (MRI) systems with inhomogenous main magnetic fields could be explored. In this work, magnetic resonance (MR) signal deviation due to inhomogeneity in the main magnetic field of a MRI system is investigated. This analysis gives the understanding of the effect of inhomogeneity in magnetic field to ...
Magnetic Resonance - Electrical Impedance Tomography (MR-EIT) Research at METU
Eyüboğlu, Behçet Murat (2006-09-01)
Following development of magnetic resonance current density imaging (MRCDI), magnetic resonance - electrical impedance tomography (MR-EIT) has emerged as a promising approach to produce high resolution conductivity images. Electric current applied to a conductor results in a potential field and a magnetic flux density distribution. Using a magnetic resonance imaging (MRI) system, the magnetic flux density distribution can be reconstructed as in MRCDI. The flux density is related to the current density distr...
Magnetic Resonance Electrical Impedance Tomography For Anisotropic Conductivity Imaging
Degirmenci, E.; Eyüboğlu, Behçet Murat (2008-11-27)
Magnetic Resonance Electrical Impedance Tomography (MREIT) brings high resolution imaging of true conductivity distribution to reality. MREIT images are reconstructed based on measurements of current density distribution and a surface potential value, induced by an externally applied current flow. Since biological tissues may be anisotropic, isotropic conductivity assumption, as it is adopted in most of MREIT reconstruction algorithms, introduces reconstruction inaccuracy. In this study, a novel algorithm i...
Citation Formats
A. Yılmaz and B. M. Eyueboglu, “RF Coil Design for MRI Applications in Inhomogeneous Main Magnetic Fields,” Seoul, Korea, 2006, vol. 14, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/53006.