SPECT Imaging of the Brain

201 Pages·1997·8.893 MB·English

by  James Patterson, David J. Wyper (auth.), Roderick Duncan (eds.)

SPECT IMAGING OF THE BRAIN
The colour section (pages 179-188) has been made possible by an
unrestricted educational grant from Janssen-Cilag Ltd .
• JANSSEN-CILAG
Ltd
Developments in Nuclear Medicine
VOLUME 29
Series Editor. Peter H. Cox
The titles published in this series are listed at the end of this volume.
SPECT Imaging of the Brain
edited by
RODERICK DUNCAN
Department of Neurology, Institute ofN eurological Sciences,
Southern General Hospital, Glasgow, Scotland
"
SPRINGER SCIENCE+BUSINESS MEDIA, B.V.
L1 brary of Congress Cata 1o g1 ng-1 n-Pub11 cat1 on Data
SPECT imaging of the brain I edited by R. Duncan.
p. cm. -- (Developments in nuclear medicine : v. 29)
Inel udes index.
ISBN 978-94-010-6271-8 ISBN 978-94-011-5398-0 (eBook)
DOI 10.1007/978-94-011-5398-0
1. Brain--Tomography. 1. Duncan, R. II. Series.
[DNLM: 1. Brain Diseases--radionuclide imaging. 2. Mental
Disorders--radionuclide imaging. 3. Tomography, Emission-Comp.uted,
Single-Photon. Wl DE99BKF v. 291996 I WL 348 S7411996]
RC386.6.T65S67 1996
616.8'047572--dc20
DNLM/DLC
for Li brary of Congress 96-28961
A cataIogue record for this book is available from the British Library
ISBN 978-94-010-6271-8
Copyright
© 19rrT by Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1997
Softcover reprint of the hardcover 1s t edition 1997
An rights reserved. No part of this publication may be reproduced, stored in a retrieval system,
or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise, without priOT permission from the publishers, Springer Science+Business Media, B.V.
Typeset by Speedlith Photo Litho Ltd., Stretford, Manchester, UK.
Table of contents
List of Contributors VB
Introduction ix
1. Basics of SPECT
by J. Patterson and DJ. Wyper
2. SPECT imaging in focal epilepsy
by R. Duncan 43
3. SPECT in head injury
by J.T. Lindsay Wilson and P. Mathew 69
4. SPECT in cerebrovascular disorders
by D.G. Grosset and I. Bone 95
5. SPECT in dementia, schizophrenia and other psychiatric disorders
by M. Turner and DJ. Wyper 131
6. The use of SPECT in the analysis of brain tumours
by G.S. Cruickshank 161
Colour section 179
Index 189
v
List of contributors
IAN BONE
Department of Neurology
Institute of Neurological Sciences
Southern General Hospital
Govan Road
Glasgow G51 4TF
Scotland
GARTH S. CRUICKSHANK
Department of Neurosurgery
Institute of Neurological Sciences
Southern General Hospital
Govan Road
Glasgow G51 4TF
Scotland
RODERICK DUNCAN
Department of Neurology
Institute of Neurological Sciences
Southern General Hospital
Govan Road
Glasgow G51 4TF
Scotland
DONALD G. GROSSET
Department of Neurology
Institute of Neurological Sciences
Southern General Hospital
Govan Road
Glasgow G51 4TF
Scotland
PETER MATHEW
Department of Neurosurgery
Institute of Neurological Sciences
Southern General Hospital
Govan Road
Glasgow G51 4TF
Scotland
vii
Vlll List of contributors
JAMES PATTERSON
Department of Clinical Physics
Institute of Neurological Sciences
Southern General Hospital, NHS Trust
Govan Road
Glasgow G51 4TF
Scotland
MARTIN TURNER
Larkfield Centre
Garngaber Avenue
Lenzie G66 3UG
Scotland
J.T. LINDSAY WILSON
Department of Psychology
University of Stirling
Stirling FK9 4LA
Scotland
DAVIDJ. WYPER
Department of Clinical Physics
Institute of Neurological Sciences
Southern General Hospital, NHS Trust
Govan Road
Glasgow G51 4TF
Scotland
Introduction
In the developed world, images of brain structure are available as an everyday
diagnostic aid, and the characteristic appearances of most pathological conditions
can be looked up in a textbook. Functional brain imaging is to this day less widely
used, partly because most pressing diagnostic questions can be answered by refer
ence to the patient's cerebral anatomy, partly for reasons of technical limitations
of functional techniques. PET as a technique is sufficiently resource-demanding
and complex to inhibit its use as an everyday diagnostic technique. SPECT lacked
suitable tracers for many years, and early systems had poor spatial resolution.
However, rotating gamma camera technology has advanced to the point where
images of the brain of reasonable quality can be obtained at most large hospitals,
and practical tracers, particularly of regional cerebral blood flow, are easily avail
able. As research advances, clinical applications are emerging. A recent report of
the Therapeutics and Technology Assessment Subcommittee of the American
Academy of Neurology! details a number of currently recognised clinical appli
cations, some of which are dealt with in this book. Given this recognition, it is
increasingly important that clinicians (particularly neuroclinicians, psychiatrists
and specialists in cerebrovascular disease), nuclear medicine specialists and
physicists acquire an idea of the major applications of the technique, and the
research background on which these applications are based.
This book does not pretend to cover all applications of SPECT. It confines itself
rather to major pathological areas, i.e. epilepsy, cerebrovascular disease, cerebral
malignancy, head injury and psychiatric illness, aiming to give the reader an
overview of clinical and research applications in each. Where practical guidance
is appropriate (e.g. ictal SPECT in epilepsy), this is also given. The book starts
with a technical chapter aimed particularly at clinicians; a basic understanding of
how a technique works allows an appreciation of its strengths and weaknesses,
and thereby a better understanding of the results.
References
1. Assessment of brain SPECT. Report of the Therapeutics and Technology Assessment Sub
committee of the American Academy of Neurology. Neurology, 1996;46:278-285.
1. Basics of SPECT
JAMES PATIERSON and DAVID J. WYPER
Introduction
To make the best use of any technique, it is important to have a clear idea of the
strengths, weaknesses and limitations of the data it produces. This requires an
understanding of the technical and scientific bases of the technique. It is assumed
that specialists in nuclear medicine will already have this understanding, and this
chapter is largely directed toward clinicians intending to use SPECT for clinical
or research purposes.
The development of emission tomography is a good example of the fusion of
a number of scientific and medical disciplines to produce an effective imaging
technique. Each image is the end result of the physical production of a radio
nuclide, the labelling of that nuclide to a chemical tracer, the administration of
the resulting ligand to a patient, the detection of the emitted radioactivity using
a scanner and the reconstruction of the information from the scanner's detectors
to reproduce the distribution of the radionuclide in graphic form. There are two
different techniques of emission tomography: positron emission tomography
(PET), is based on radionuclides which decay by positron emission, while single
photon emission computed tomography (SPECT, or sometimes SPET) is based
on radionuclides which emit gamma rays or X-rays. While PET has some inherent
technical advantages over SPECT, economic reality dictates that SPECT is usually
the only technique available in routine clinical practice. Recent innovations in
the design of multi-head SPECT systems, which allow them to detect positron
emitting radionuclides, have diminished the sharp distinction between the two
techniques.
Radioactivity
There are more than 100 atomic elements, each made up of a positively charged
nucleus surrounded by a negatively charged 'cloud' of electrons. The fundamental
factor which distinguishes one element from another is the number of protons
within the nucleus: this is referred to as the atomic number (Z). The number of
protons in an atom is balanced by the number of negatively charged electrons,
making the atom electrically neutral. If an electron is removed or added, the atom
is said to be ionized and will have a resulting charge. The number of electrons in
a non-ionized atom determines its chemical behaviour.
2 Patterson and Wyper
The nucleus also contains neutrons, which are uncharged particles with approxi
mately the same mass as protons. The number of protons plus the number of
neutrons makes up the atomic weight (A). A particular nucleus with a specific
number of protons and neutrons is known as a nuclide and is denoted by the
;X,
symbol where X is the chemical symbol of the element. There are many
more nuclides (approximately 17(0) than elements since each element can have
different numbers of neutrons. The different nuclides of an element are referred
to as isotopes: isotopes of anyone element must have the same number of protons,
and hence the same atomic number, but have different numbers of neutrons,
hence different atomic masses, e.g. I!C, I~C, I~C, I;C. Isotopes can also differ in
their nuclear energy states (the same numbers of protons and neutrons are in a
different configuration within the nucleus). They are then classed as isomers, e.g.
~ TC, ~ Tc. Most of the nuclei found in nature are stable and retain the same
structure indefinitely. The vast majority of known nuclei, however, are unstable
and undergo a transformation to a more stable form. This process of radioactive
decay alters the mass and! or energy of the nucleus and occurs over a period ranging
from a fraction of a second to millions of years. About 1400 radioactive nuclides
are known, each of which has a unique and unalterable decay time (see below).
The change from an unstable to a stable configuration is accompanied by the
emission from the nucleus of nuclear particles or electromagnetic radiation.
Alpha particles, beta particles and gamma rays are the major forms of radioactive
emission from the nucleus. Secondary processes within the electron shells result
in the emission of X-rays and electrons. Although X-rays are physically indis
tinguishable from gamma rays they are given this name to differentiate their
origin.
An alpha particle consists of two protons and two neutrons bound together. It
therefore has an electrical charge of plus two. Beta particles come in two forms
({3-and {3+) and result from the transformation of a neutron to a proton and vice
versa. The {3-emission has a single negative charge and is equivalent to emission
of an electron whereas the {3+ emission has a single positive charge and is
equivalent to a positively charged electron, or positron. After emission, positrons
themselves take part in a secondary process which has great significance to
imaging. As a positron slows down and encounters an electron the two particles
undergo an annihilation reaction where the mass of both particles disappears and
is replaced by two gamma rays of equal energy (511 keY) travelling in opposite
directions. Detection of these two coincident photons at 1800 to each other forms
the basis of positron emission tomography.
Smaller amounts of energy can be emitted as gamma rays, a form of electro
magnetic energy and part of the electromagnetic spectrum (Figure 1.1). Unlike
light rays and radio waves, gamma rays and X-rays have enough energy to
remove an electron from one of the electron shells in an atom and are referred to
as ionizing radiation. A gamma ray emitted by 99mTc, for example, is 100000
times more powerful than a photon in the visible part of the spectrum.