Table Of ContentMETHODS IN ENZYMOLOGY
EDITORS-IN-CHIEF
John N. Abelson Melvin I. Simon
DIVISIONOFBIOLOGY
CALIFORNIAINSTITUTEOFTECHNOLOGY
PASADENA,CALIFORNIA
FOUNDINGEDITORS
Sidney P. Colowick and Nathan O. Kaplan
Preface
As these volumes were being completed, American Paul C. Lauterbur and
Briton Sir Peter Mansfield won the 2003 Nobel Prize for medicine for
discoveriesleadingtothedevelopmentofMRI.
The Washington Post story on October 6, 2003 announced the accolade,
noting: ‘‘Magnetic resonance imaging, or MRI, has become a routine method
for medical diagnosis and treatment. It is used to examine almost all organs
withoutneedforsurgery,butisespeciallyvaluablefordetailedexaminationof
thebrain and spinal cord.’’ Unfortunately,the articleoverlooked thegrowing
usefulnessofthistechniqueinbasicresearch.
MRI, along with other imaging methods, has made it possible to glance
inside the living system. For patients, this may obviate the need for surgery;
for researchers, it becomes a noninvasive method that enables the model
systemstocontinue‘‘doingwhattheydo’’withoutbeingdisturbed.Thevalue
and potential of these techniques is enormous, and that is why these once
clinicalmethodsarefindingtheirwaytothelaboratory.
Authors have been selected based on research contributions in the area
about which they have written and based on their ability to describe their
methodologicalcontributionsinaclearandreproducibleway.Theyhavebeen
encouragedtomakeuseofgraphicsandcomparisonstoothermethods,andto
providetricksandapproachesthatmakeitpossibletoadaptmethodstoother
systems.
The editor wants to express appreciation to the contributors for providing
theircontributionsinatimelyfashion,tothesenioreditorsforguidance,andto
thestaffatAcademicPressforhelpfulinput.
P. Michael Conn
xiii
Contributors to Volume 385
Articlenumbersareinparenthesesandfollowingthenamesofcontributors.
Affiliationslistedarecurrent.
David L. Alexoff (12), Department of Stuart Clare (8), Centre for Functional
Chemistry, Brookhaven National La- Magnetic Resonance, Department of
boratory,Upton,NewYork11973 ClinicalNeurology,JohnRadcliffeHos-
pital,UniversityofOxford,Headington,
Robert S. Balaban (15), Laboratory of OxfordOX39DU,UnitedKingdom
Cardiac Energetics, National Heart,
Lung, and Blood Institute, National Christian A. Combs (15), Light Micro-
InstitutesofHealth,Bethesda,Maryland scopy Facility, National Heart, Lung,
20892 and Blood Institute, National Institutes
ofHealth,Bethesda,Maryland20892
Nicolau Beckmann (14), Novartis Insti-
tuteforBiomedicalResearch,Analytical AndrE´ Constantiensco (9), Laboratoire
and Imaging Sciences Unit, CH-4002 de Biomecanique, Centre Hospitalier
Basel,Switzerland Universitaire Hautepierre, Strasbourg,
France
MarkusBeu(13),ClinicofNuclearMed-
Bruce M. Damon (2), Department of
icine, University Hospital Du¨sseldorf,
Radiology and Radiological Sciences,
Du¨sseldorf40225,Germany
Vanderbilt University Institute of Ima-
Kevin J. Black (6), Departments of Psy- gingScience,Nashville,Tennessee37232
chiatry,Neurology,andRadiology,Wa- Carmen S. Dence (16), Department of
shingtonUniversitySchoolofMedicine,
Radiology,WashingtonUniversitySchool
St.Louis,Missouri63110-1093
ofMedicine,St.Louis,Missouri,63110
Britton Chance (20), Eldridge Reeves Doris J. Doudet (10), Department of
JohnsonUniversity,Philadelphia,Penn- Medicine/Neurology, Pacific Parkinson
sylvania19104 Research Center, University of British
Columbia,Vancouver,BritishColombia
DelphineL.Chen(17),WashingtonUni-
V6T2B5,Canada
versity School of Medicine, St. Louis,
Missouri63110 David J. Dubowitz (7), Department of
Radiology, Center for Functional Mag-
PhilippeChoquet(9),LaboratoiredeBio- netic Resonance Imaging, University of
mecanique,CentreHospitalierUniversi- California,SanDiego,LaJolla,Califor-
taireHautepierre,Strasbourg,France nia92093-0677
Bradley T. Christian (11), Department Guillaume Duhamel (9), Laboratoire
ofNuclearMedicineandPositronEmis- Mixte, Universite Joseph Fourier, Neu-
sion Topography, Kettering Medical roimagerie Fonctionelle et Metabolique,
Center,Kettering,Ohio454229 Grenoble,France
ix
x contributors to volume 385
M. R. Gerasimov (18), Department of D. W.J.Klomp(3), DepartmentofRadi-
Chemistry,BrookhavenNationalLabo- ology,MedicalFacultyoftheUniversity
ratory,Upton,NewYork11973 of Nijmegen. Nijmegan 6500 HB, The
Netherlands
JohnC.Gore(2),DepartmentofRadiol-
ogy and Radiological Sciences, Vander- Jonathan M. Koller (6), Department of
bilt University Institute of Imaging Psychiatry,WashingtonUniversitySchool
Science,Nashville,Tennessee37232 of Medicine, St. Louis, Missouri 63110-
Emmaunelle Grillon (9), Laboratoire 1093
Mixte, Universite Joseph Fourier, Neu-
RakeshKumar(1),DepartmentofNucle-
roimagerie Fonctionelle et Metabolique,
arMedicine,AllIndiaInstituteofMed-
Grenoble,France
icalSciences,NewDelhi110029,India*
Robert J. Gropler (16), Department of
RolfLarisch(13),ClinicofNuclearMed-
Radiology,WashingtonUniversitySchool
icine, University Hospital Du¨sseldorf,
ofMedicine,St.Louis,Missouri,63110
Du¨sseldorf40225,Germany
A.Heerschap(3),DepartmentofRadiol-
Jean-LouisLeviel(9),LaboratoireMixte,
ogy,MedicalFacultyoftheUniversityof
Universite Joseph Fourier, Neuro-
Nijmegen, Nijmegan 6500 HB, The
imagerie Fonctionelle et Metabolique,
Netherlands
Grenoble,France
PilarHerrero(16),DepartmentofRadi-
ology,WashingtonUniversitySchoolof JeanLogan(12),DepartmentofChemis-
try, Brookhaven National Laboratory,
Medicine,St.Louis,Missouri,63110
Upton,NewYork11973
JamesHolden(10),DepartmentofMedi-
cal Physics, University of Wisconsin, KathrynE.Luker(19),MallinckrodtIn-
stituteofRadiology,WashingtonUniver-
Madison,Wisconsin53706
sity School of Medicine, St. Louis,
Jean-NoE¨l Hyacinthe (9), Laboratoire Missouri63110
Mixte, Universite Joseph Fourier, Neu-
roimagerie Fonctionelle et Metabolique, Robert H. Mach (16), Department of
Grenoble,France Radiology,WashingtonUniversitySchool
ofMedicine,St.Louis,Missouri,63110
N.R.Jagannathan(4),DepartmentHead
ofNuclearMagneticResonance,AllIn- Evan D. Morris (11), Indiana University
diaInstituteofMedicalSciences,Ansari School of Medicine, Department of
Nagar,NewDelhi110029,India Radiology,Indianapolis,Indiana46202
Suman Jana (1), Nuclear Medicine Divi- Hans-Wilhelm MU¨ller (13), Clinic of
sion, Albert Einstein College of Medi- Nuclear Medicine, University Hospital
cine,Bronx,NewYork10461 Du¨sseldorf,Du¨sseldorf40225,Germany
M.Khubchandani(4),DepartmentofNu- Raymond F. Muzic, Jr. (11), University
clearMagneticResonance,AllIndiaIn- Hospitals of Cleveland, Case Western
stituteofMedicalSciences,AnsariNagar, Reserve University, Cleveland, Ohio
NewDelhi110029,India 44106
*CurrentAffiliation:DepartmentofRadiology,DivisionofNuclearMedicine,Hospitalofthe
UniversityofPennsylvania,Philadelphia,Pennsylvania19104-4283
contributors to volume385 xi
Kiyoshi Nakahara (5), Department of Abraham Z. Snyder (6), Departments of
Physiology, The University of Tokyo Radiology and Neurology, Washington
School of Medicine, Tokyo 113-0033, UniversitySchoolofMedicine,St.Louis,
Japan Missouri63110-1093
SusanneNikolaus(13),ClinicofNuclear M. G. Sommers (3), Department of Radi-
Medicine, University Hospital Du¨ssel- ology,MedicalFacultyoftheUniversity
dorf,Du¨sseldorf40225,Germany of Nijmegen, Nijmegan 6500 HB, The
Joel S. Perlmutter (6), Departments of Netherlands
Neurology, Radiology, Anatomy and
PaulVaska(12),DepartmentofChemis-
Neurobiology,andthePrograminPhy-
try, Brookhaven National Laboratory,
sical Therapy, Washington University
Upton,NewYork11973
SchoolofMedicine,St.Louis,Missouri
63110-1093
A.A.Veltien(3),DepartmentofRadiol-
DavidPiwnica-Worms(19),Mallinckrodt ogy,MedicalFacultyoftheUniversityof
InstituteofRadiology,WashingtonUni- Nijmegen, Nijmegan 6500 HB, The
versity School of Medicine, St. Louis, Netherlands
Missouri63110
HenningVosberg(13),ClinicofNuclear
W.K.J.Renema(3),DepartmentofRadi-
Medicine, University Hospital Du¨ssel-
ology,MedicalFacultyoftheUniversity
dorf,Du¨sseldorf40225,Germany
of Nijmegen, Nijmegan 6500 HB, The
Netherlands Michael J. Welch (16), Department of
Jean-ChristopheRichard(17),Washing- Radiology,WashingtonUniversitySchool
ton University School of Medicine, ofMedicine,St.Louis,Missouri,63110
St.Louis,Missouri63110
Karmen K. Yoder (11), Indiana Univer-
MarkusRudin(14),NovartisInstitutefor sity School of Medicine, Department of
Biomedical Research, Analytical and Radiology,Indianapolis,Indiana46202
Imaging Sciences Unit, CH-4002 Basel,
Switzerland H. J. A. in ‘t Zandt (3), Department of
Daniel P. Schuster (17), Washington Radiology, Medical Faculty of the Uni-
versityofNijmegen,Nijmegan6500HB,
UniversitySchoolofMedicine,St.Louis,
TheNetherlands
Missouri63110
Sally W. Schwarz (16), Department of AnneZiegler(9),CenterHospitalierUni-
Radiology,WashingtonUniversitySchool versitaire,NeuroimagerieFonctionelleet
ofMedicine,St.Louis,Missouri,63110 Metabolique,Grenoble,France
[1] PET inresearch andclinicalimaging 3
[1] Positron Emission Tomography: An Advanced
Nuclear Medicine Imaging Technique from
Research to Clinical Practice
By Rakesh Kumar and Suman Jana
Introduction
Positron emission tomography (PET) is an advanced diagnostic
imagingtechnique,whichcannotonlydetectandlocalize,butalsoquantify
physiological and biochemical processes in the body noninvasively. The
ability of PET to study various biological processes opens up new pos-
sibilities for both fundamental research and day-to-day clinical use. PET
imaging utilizes (cid:1)-emitting radionuclides such as 11C, 13N, 15O, and 18F,
which can replace their respective stable nuclei in biologically active
molecules. These radionuclides decay by positron emission. After being
emitted from the nucleus, a positron will combine with a nearby electron
through a process known as annihilation. Annihilation converts the
mass of both particles into energy in the form of two antiparallel 511-keV
(cid:2) rays. The PET detectors are arranged in a ring in order to detect
these (cid:2) rays.
At present, 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) is the most
commonly used positron-emitting radiopharmaceutical used for PET
imaging. 18F-FDG is a radioactive analog of glucose and is able to detect
altered glucose metabolism in pathological processes. Like glucose,
FDG is transported into cells by means of a glucose transporter protein
and begins to follow the glycolytic pathway. FDG is subsequently
phosphorylated by an enzyme known as hexokinase to form FDG-
6-phosphate.1,2 However, FDG-6-phosphate cannot continue through gly-
colysis because it is not a substrate for glucose-6-phosphate isomerase.
As a result, FDG-6-phosphate is trapped biochemically within the cell.
This process of metabolic trapping constitutes the basis of PET imaging
of the biodistribution of FDG. Because there can be a manyfold increase
or decrease in the glucose metabolism of diseased tissue as compared to
normal tissue, it is easy to detect such differences in metabolism using
PET.ThisChapterdiscussesgeneralaspectsofPET,includingdrugevalu-
ation, biological functions evaluation, clinical applications, and future
directionsof PET imaging.
1K.M.McGowanetal.,Pharmacol.Ther.66,465(1995).
2R.L.Wahl,J.Nucl.Med.37,1038(1996).
Copyright2004,ElsevierInc.
Allrightsreserved.
METHODSINENZYMOLOGY,VOL.385 0076-6879/04$35.00
4 imaging in animal and human models [1]
Tracers
Position emission tomography uses radioisotopes of naturally occur-
ring elements, such as 11C, 13N, and 15O, in order to perform in vivo im-
aging of biologically active molecules. Although there is no radioisotope
of H that can be used for PET, many molecules can replace a hydrogen
orhydroxylgroupwith18Fwithoutchangingitsbiologicalproperties.Flu-
orine-18canalsobeusedasasubstituteinfluorine-containingcompounds
such as5-fluorouresil (5-FU), asdemonstrated by Mintun et al.3
Most PET tracers utilize a radioisotope that has a short half-life and
can be produced by a cyclotron (see Table I for a list of important
tracers). However, there are some radiotracers, such as copper-62, that
can be manufactured in a nuclear generator. Radiopharmaceuticals are
produced after the radioisotope has been generated and substituted into
the compound of interest. Because of the short half-lives of most PET
tracers, sequentialscanning on thesame day is not usually possible.
Drug Evaluation
The development of new drugs presents many questions that must
be addressed: is the drug sufficiently delivered to target of interest? How
is normal tissue affected? At what dose is toxicity produced? How much
drug is eliminated from both target tissue and normal tissue in relation
to time? Does the drug affect target tissue in the predicted way? All of
these questions can be answered by labeling the drug of interest with an
appropriate radionuclide forPET imaging.
In addition, mathematical kinetic modeling is necessary for all aspects
of drug pharmacology and to measure physiological functions, such as
TABLEI
Positron-EmitterRadiotracers
Radioisotope Half-life(min)
Carbon-11 20.4
Fluorine-18 109.8
Nitrogen-13 10
Oxygen-15 2.03
Copper-62 9.7
Rubidium-82 1.25
Yttrium-86 14.7
3M.A.Mintunetal.,Radiology169,45(1988).
[1] PET inresearch andclinicalimaging 5
tissue perfusion, metabolic rate, and elimination. Dynamic data can be
collected in a specific biological organ or tissue by defining the region of
interest and recording the radioactivity over time. Input functions can be
calculated by measuring tracer concentration in arterial blood. By com-
paringtheinputfunctionsandtimeactivitycurvesovertheorganortissue
of interest with theoretical models, it is possible to calculate the me-
tabolism of the applied drugs. When these drugs are not metabolized in
the tissue, the calculation of drug concentration is very simple. However,
most drugs will undergo some degree of metabolism to produce me-
tabolites. If these metabolites do not include the original radionuclide,
there is no problem regarding the calculation of drug metabolism. How-
ever, if these metabolites also contain a radionuclide it can be difficult for
PET to distinguish signals from the parent radiopharmaceutical and those
from its metabolite. Blasberg et al.4 and Salem et al.5 have suggested a
number of mathematical calculations in order to determine the parent
contribution from total measuredradiotracer activity.
Pharmacokinetic studies of new pharmaceuticals are greatly simplified
by labeling these compounds with a PET tracer. It is possible to measure
the time-dependent, in vivo biodistribution of a new drug labeled with
PET tracer in one experiment, which can be subsequently compared to
many animal experiments. Furthermore, the various effects of a drug on
different biological processes, such as blood flow, tissue metabolism, and
receptoractivation,canalsobedemonstratedinvivothroughPETimaging.
Biological Function Evaluation
Theoretically, any biological function can be studied in vivo using an
appropriately labeled PET tracer molecule. However, at present, PET
tracers, which are utilized most commonly, are small molecules, which
canbe labeledby well-defined methods.Anotherimportant consideration
isthattheconcentrationofanyPETtracermoleculeshouldbesignificantly
higher at the target sites than in the background. This allows biological
functiontobemeasuredbydeterminingtracerconcentrationoveraspeci-
fied time interval and by drawing a region of interest over the specified
target tissue or organ region. Physiological processes such as oxygen con-
sumption, blood flow, and tissue metabolism can also be demonstrated
invivousingPET tracers.
In the body, binding of an activating molecule (agonist) to a biochem-
ical structure (receptor) can activate many biological functions. The same
4R.G.Blasbergetal.,CancerRes.60,624(2000).
5A.Salemetal.,Lancet355,2125(2000).
6 imaging in animal and human models [1]
process canbeblocked byanantagonist,whichmayhaveahigheraffinity
for receptors as compared to the agonist.Receptors can be visualized and
quantified by labeling receptor-binding substances (ligands) with PET
tracers. Most receptors have several biochemically similar subtypes and
are composed of multiple subunits. Identification of these subtypes and
subunits requires specific ligands. The details of in vivo research of recep-
tors and their clinical applications in the diagnosis of neurodegenerative
and heart diseases arediscussed later.
Clinical Applications
Theresolutionofcomputedtomography(CT)andmagneticresonance
imaging (MRI) is excellent for the visualization of both normal and dis-
eased tissues. However,all disease processesstartwithmolecular and cel-
lularabnormalities.Mostdiseaseprocessestakealongtimetoprogressto
astagewheretheycanbedetectedbythesestructuralimagingtechniques.
Infact,manydiseasesmayalreadybeinadvancedstagesbythetimethey
aredetectedbyMRIorCT.However,theprincipleofPETistodetectthe
alteredmetabolismofdiseaseprocessesandnotthealteredanatomy,such
as CT and MRI. PET, as a functional molecular imaging technique, can
alsoprovidehighlyaccuratequantitativeresultsandthereforecanbeused
forvarious researchand clinical applications.
Kumaretal.6discussedtheroleof18F-FDGPETinthemanagementof
cancerpatients.Forthesepatients,PEThasbecomeimportantindiagnosis,
staging, monitoring the response to treatment, and detecting recurrence.
However, PET has also played an important role for both diagnostic and
therapeutic purposes in patients with neurological and cardiological
infections and inflammations, vasculitis, and other autoimmunediseases.7
PET in Oncology
18F-FDGisthemostwidelyusedradiotracerinoncology.Becauseglu-
cosemetabolismisincreasedmanyfoldinmalignanttumorsascomparedto
normalcells,PEThashighsensitivityandahighnegativepredictivevalue.
It has a well-established role in initial staging, monitoring response to the
therapy, and management of many types of cancer, including lung cancer,
colon cancer, lymphoma, melanoma, esophageal cancer, head and neck
cancer, and breast cancer (TableII).
6R.Kumaretal.,Ind.J.Cancer.40,87(2003).
7M.Schirmeretal.,Expr.Gerontol.38,463(2003).
