MRI in Practice

by Catherine Westbrook (Senior Lecturer and MRI Field Leader at Anglia Polytechnic University, Cambridge); Carolyn Kaut Roth (Fellow SMRT (Section for Magnetic Resonance Technologists); Director Technologist Continuing Education and MRI Internship Progr

• ISBN13: 9781405127875
• ISBN10: 1405127872
• Edition: 3rd
• Format: Paperback
• Copyright: 2005-06-01
• Publisher: Wiley-Blackwell

Summary

Since the first edition of MRI in Practice was published in 1993, the book has become the standard text for radiographers, technologists, radiology residents, radiologists and even sales representatives on the subject of magnetic resonance imaging. This text is essential reading on postgraduate courses. Furthermore, MRI in Practice has come to be known as the number one reference book and study guide in the areas of MR instrumentation, principles, pulse sequences, image acquisition, and imaging parameters for the advanced level examination for MRI offered by the American Registry for Radiologic Technologists (ARRT) in the USA. The book explains in clear terms the theory that underpins magnetic resonance so that the capabilities and operation of MRI systems can be fully appreciated and maximized. This third edition captures recent advances, and coverage includes: parallel imaging techniques, functional imaging techniques and new sequences such as balanced gradient echo. Building on the success of the first two editions, the authors have now re-conceptualized the design of the book. The third edition contains a wealth of additional illustrations and chapter enhancements draw on the depth of the authors' experience in delivering MRI education and training. To promote accessibility of difficult concepts, extended analogies have been developed to relate the complexities of MRI physics to everyday phenomena. Learning points are clearly articulated, and frequent summaries are included to assist the reader in digesting the information.

Author Biography

Catherine Westbrook is a Senior Lecturer and MRI Field Leader at Anglia Polytechnic University, Cambridge, UK and external examiner, lecturer and advisor on several other postgraduate courses in MRI around the world. In the past, Cathy has been President of the British Association of MR Radiographers, Honorary Secretary of the British Institute of Radiology and Chairperson of the Consortium for the Accreditation of Clinical MR Education.

Carolyn Kaut Roth is the Director of MRI Internship Programs & Continuing Education for Technologists at the University of Pennsylvania Health Systems, Philadelphia, Pennsylvania, USA. In the past, Carolyn has served as President of the Section for Magnetic Resonance Technologists (SMRT), and is currently a Fellow of SMRT. She has lectured around the world and has published numerous books, articles and papers on the topic of MRI. Carolyn is also the CEO of Imaging Education Associates (IEA), a company that develops and produces computer-based education modules and educational curricula for radiographers & educators.

John Talbot is a Senior Lecturer at Anglia Polytechnic University, Cambridge UK and a leader in the development and production of e-learning materials. As well as lecturing MRI around the world, John is a gifted illustrator and his vision has been central to the re-shaping of the figures in the book.

Table of Contents

Foreword	x
Preface to the third edition	xi
Acknowledgments	xii
Basic principles	1	(20)
Introduction	1	(1)
Atomic structure	1	(2)
Motion in the atom	3	(1)
MR active nuclei	4	(1)
The hydrogen nucleus	4	(1)
Alignment	5	(3)
Precession	8	(1)
The Larmor equation	9	(1)
Resonance	10	(5)
The MR signal	15	(1)
The free induction decay signal (FID)	15	(1)
Relaxation	16	(1)
T1 recovery	16	(1)
T2 decay	16	(3)
Pulse timing parameters	19	(1)
Questions	20	(1)
Image weighting and contrast	21	(40)
Introduction	21	(1)
Image contrast	21	(1)
Contrast mechanisms	22	(1)
Relaxation in different tissues	23	(3)
T1 contrast	26	(1)
T2 contrast	27	(1)
Proton density contrast	27	(2)
Weighting	29	(8)
T2* decay	37	(1)
Pulse sequences	37	(23)
Questions	60	(1)
Encoding and image formation	61	(43)
Encoding	61	(20)
Introduction	61	(1)
Gradients	62	(2)
Slice selection	64	(4)
Frequency encoding	68	(3)
Phase encoding	71	(5)
Sampling	76	(5)
Data collection and image formation	81	(23)
Introduction	81	(1)
K space description	81	(2)
K space filling	83	(4)
Fast Fourier transform (FFT)	87	(4)
Important facts about K space	91	(6)
K space traversal and gradients	97	(2)
Options that fill K space	99	(2)
Types of acquisition	101	(2)
Questions	103	(1)
Parameters and trade-offs	104	(39)
Introduction	104	(1)
Signal to noise ratio (SNR)	105	(20)
Contrast to noise ratio (CNR)	125	(3)
Spatial resolution	128	(7)
Scan time	135	(2)
Trade-offs	137	(1)
Decision making	137	(2)
Volume imaging	139	(3)
Questions	142	(1)
Pulse sequences	143	(59)
Introduction	143	(2)
Spin echo pulse sequences	145	(23)
Conventional spin echo	145	(1)
Fast or turbo spin echo	146	(10)
Inversion recovery	156	(6)
Fast inversion recovery	162	(1)
STIR (short tau inversion recovery)	162	(3)
FLAIR (fluid attenuated inversion recovery)	165	(3)
Gradient echo pulse sequences	168	(30)
Conventional gradient echo	168	(2)
The steady state and echo formation	170	(3)
Coherent gradient echo	173	(3)
Incoherent gradient echo (spoiled)	176	(3)
Steady state free precession (SSFP)	179	(5)
Balanced gradient echo	184	(5)
Fast gradient echo	189	(2)
Echo planar imaging (EPI)	191	(7)
Parallel imaging techniques	198	(4)
Questions	201	(1)
Flow phenomena	202	(27)
Introduction	202	(1)
The mechanisms of flow	202	(2)
Flow phenomena	204	(9)
Time of flight phenomenon	204	(3)
Entry slice phenomenon	207	(5)
Intra-voxel dephasing	212	(1)
Flow phenomena compensation	213	(16)
Introduction	213	(1)
Even echo rephasing	214	(1)
Gradient moment rephasing (nulling)	214	(3)
Spatial pre-saturation	217	(11)
Questions	228	(1)
Artefacts and their compensation	229	(34)
Introduction	229	(1)
Phase mismapping	229	(9)
Aliasing or wrap around	238	(8)
Chemical shift artefact	246	(3)
Chemical misregistration	249	(2)
Truncation artefact	251	(1)
Magnetic susceptibility artefact	251	(4)
Cross excitation and cross talk	255	(2)
Zipper artefact	257	(1)
Shading artefact	258	(1)
Moires artefact	259	(1)
Magic angle	260	(2)
Questions	262	(1)
Vascular and cardiac imaging	263	(38)
Introduction	263	(1)
Conventional MRI vascular imaging techniques	263	(6)
Magnetic resonance angiography (MRA)	269	(16)
Perfusion and diffusion imaging	285	(1)
Cardiac gating	286	(6)
Peripheral gating	292	(2)
Pseudo-gating	294	(1)
Multi-phase cardiac imaging	294	(1)
Cine	295	(3)
SPAMM	298	(2)
Questions	300	(1)
Instrumentation and equipment	301	(28)
Introduction	301	(1)
Magnetism	302	(4)
Permanent magnets	306	(1)
Electromagnets	306	(3)
Superconducting electromagnets	309	(4)
Fringe fields	313	(1)
Shim coils	313	(1)
Gradient coils	314	(7)
Radio frequency coils	321	(5)
The pulse control unit	326	(1)
Patient transportation system	326	(1)
Operator interface	327	(1)
Questions	328	(1)
MRI safety	329	(23)
Introduction	329	(1)
The main magnetic field	330	(5)
Projectiles	335	(1)
Medical emergencies	336	(1)
Implants and prostheses	337	(5)
Pacemakers	342	(1)
Gradient magnetic fields	342	(2)
Radio frequency fields	344	(2)
Claustrophobia	346	(1)
Quenching	346	(1)
Safety education	347	(1)
Patient monitoring	347	(1)
Monitors and devices in MRI	348	(2)
Site planning	350	(1)
Questions	351	(1)
Contrast agents in MRI	352	(20)
Introduction	352	(1)
Review of weighting	353	(1)
Mechanism of action	354	(1)
Dipole-dipole interactions	355	(1)
Magnetic susceptibility	356	(2)
Relaxivity	358	(1)
Gadolinium safety	359	(2)
Iron oxide safety	361	(1)
Current applications of contrast agents	362	(9)
Conclusion	371	(1)
Questions	371	(1)
Functional imaging techniques	372	(17)
Introduction	372	(1)
Diffusion weighted imaging (DWI)	373	(4)
Perfusion imaging	377	(3)
Functional imaging (fMRI)	380	(2)
Interventional MRI	382	(1)
MR spectroscopy (MRS)	383	(3)
Whole body imaging	386	(1)
MR microscopy (MRM)	387	(1)
Questions	388	(1)
Answers to questions	389	(4)
Glossary	393	(10)
Index	403