Electromagnetic Analysis and Design in Magnetic Resonance Imaging

by Jin; Jianming

• ISBN13: 9780849396939
• ISBN10: 084939693X
• Format: Hardcover
• Copyright: 1998-09-29
• Publisher: CRC Press

Summary

This book presents a comprehensive treatment of electromagnetic analysis and design of three critical devices for an MRI system - the magnet, gradient coils, and radiofrequency (RF) coils. Electromagnetic Analysis and Design in Magnetic Resonance Imaging is unique in its detailed examination of the analysis and design of the hardware for an MRI system. It takes an engineering perspective to serve the many scientists and engineers in this rapidly expanding field.Chapters present:o an introduction to MRIo basic concepts of electromagnetics, including Helmholtz and Maxwell coils, inductance calculation, and magnetic fields produced by special cylindrical and spherical surface currentso principles for the analysis and design of gradient coils, including discrete wires and the target field methodo analysis of RF coils based on the equivalent lumped-circuit model as well as an analysis based on the integral equation formulationo survey of special purpose RF coilso analytical and numerical methods for the analysis of electromagnetic fields in biological objectsWith the continued, active development of MRI instrumentation, Electromagnetic Analysis and Design in Magnetic Resonance Imaging presents an excellent, logically organized text - an indispensable resource for engineers, physicists, and graduate students working in the field of MRI.

Table of Contents

Preface	v	(2)
About the Author	vii	(2)
Acknowledgments	ix	(2)
Contents	xi
1 Introduction to Magnetic Resonance Imaging	1	(38)
1.1 Introduction	1	(2)
1.2 Physical Principles of Nuclear Magnetic Resonance	3	(18)
1.2.1 Property of Spin	3	(2)
1.2.2 Behavior of Nuclei in an External Magnetic Field	5	(3)
1.2.3 Bulk Magnetization	8	(2)
1.2.4 Effects of a Radiofrequency Pulse	10	(6)
1.2.5 Phenomenological Relaxation--the Bloch Equations	16	(2)
1.2.6 Physical Origins of Relaxation	18	(3)
1.3 Hardware of Magnetic Resonance Imaging	21	(6)
1.3.1 The Main Magnet	21	(2)
1.3.2 The Gradient Coils	23	(1)
1.3.3 The Transmitter	24	(1)
1.3.4 The RF Coils	25	(1)
1.3.5 The Receiver	26	(1)
1.4 Basic Pulse Sequences and Imaging Methods	27	(9)
1.4.1 RF Pulse Sequences	27	(5)
1.4.2 Basic Imaging Methods	32	(4)
References	36	(3)
2 Basic Electromagnetic Theory	39	(40)
2.1 Introduction	39	(1)
2.2 Brief Review of Vector Analysis	39	(2)
2.3 Magnetostatic Fields in Free Space	41	(6)
2.4 Helmholtz and Maxwell Coils	47	(3)
2.5 Boundary Conditions for Magnetostatic Fields	50	(2)
2.6 Magnetostatic Fields in Source-Free Regions	52	(2)
2.7 Magnetostatic Fields Produced by Cylindrical and Spherical Surface Currents	54	(3)
2.8 Inductance Calculation	57	(4)
2.9 Time-Varying Electromagnetic Fields	61	(2)
2.10 Time-Harmonic Fields	63	(1)
2.A Divergence, Curl, Gradient, and Laplacian Operations	64	(1)
2.B Associated Legendre Polynomials	65	(3)
2.C Magnetic Field Produced by a Spherical Surface Current	68	(3)
2.D Computer Program for Inductance Calculation	71	(3)
Problems	74	(2)
References	76	(3)
3 Analysis and Design of Gradient Coils	79	(58)
3.1 Introduction	79	(1)
3.2 Effect of Coil's Inductance	80	(3)
3.3 Figure of Merit	83	(1)
3.4 Gradient Coils Made of Discrete Wires	83	(10)
3.4.1 Longitudinal Gradient	83	(4)
3.4.2 Transverse Gradients	87	(6)
3.5 Magnetic Field Produced by a Cylindrical Surface Current	93	(5)
3.6 Target Field Method	98	(10)
3.7 Shielded Gradient Coils	108	(5)
3.8 Minimization of Inductance and Power Dissipation	113	(5)
3.9 Planar Gradient Coils	118	(8)
3.9.1 Magnetic Field Produced by a Planar Surface Current	118	(3)
3.9.2 Target Field Method	121	(1)
3.9.3 Shielded Planar Coils	122	(1)
3.9.4 Minimization of Inductance and Power Dissipation	123	(3)
3.A Modified Bessel Functions	126	(4)
3.B Alternative Derivation of Equation (3.66)	130	(1)
Problems	131	(2)
References	133	(4)
4 Analysis and Design of RF Coils	137	(74)
4.1 Introduction	137	(2)
4.2 Concepts of Resonance and Reciprocity	139	(5)
4.3 Equivalent Circuit Analysis	144	(20)
4.3.1 A Simple Example	144	(2)
4.3.2 Highpass Birdcage Coil	146	(3)
4.3.3 Lowpass Birdcage Coil	149	(6)
4.3.4 Hybrid Birdcage Coil	155	(2)
4.3.5 Open Coils	157	(7)
4.4 Analysis of RF Shields	164	(11)
4.4.1 Analysis Using Image Method	165	(5)
4.4.2 Improving Field Homogeneity Using End-Caps	170	(2)
4.4.3 Design of RF Shield	172	(3)
4.5 Field Inhomogeneity of Birdcage Coils	175	(6)
4.6 Method of Moments Analysis	181	(10)
4.6.1 Unshielded Coil	181	(4)
4.6.2 Shielded Coil	185	(1)
4.6.3 Numerical Simulation	186	(5)
4.7 Miscellaneous Topics	191	(11)
4.7.1 Brief History of Birdcage Coils	191	(3)
4.7.2 Quadrature Coils	194	(1)
4.7.3 Double-Tuned Coils	195	(2)
4.7.4 Surface Coils	197	(1)
4.7.5 Phased Arrays	198	(1)
4.7.6 Unicoil Concept and Design	198	(4)
Problems	202	(3)
References	205	(6)
5 RF Fields in Biological Objects	211	(62)
5.1 Introduction	211	(2)
5.2 Analytical Methods	213	(6)
5.2.1 Two-Dimensional Example	213	(3)
5.2.2 Three-Dimensional Example	216	(3)
5.3 Two-Dimensional Numerical Analysis	219	(21)
5.3.1 Finite Difference Method	219	(5)
5.3.2 Finite Element Method	224	(2)
5.3.3 Numerical Simulations	226	(14)
5.4 Three-Dimensional Numerical Analysis	240	(15)
5.4.1 Finite-Difference Time-Domain Method	240	(4)
5.4.2 Method of Moments	244	(7)
5.4.3 Numerical Simulations	251	(4)
5.A Bessel Functions	255	(8)
5.B Spherical Bessel Functions	263	(3)
Problems	266	(1)
References	267	(6)
A About the Software	273	(6)
A.1 Introduction	273	(1)
A.2 RF Coil Analysis	274	(1)
A.3 RF Field Analysis	275	(4)
Index	279