Molecular Imaging Basic Principles and Applications in Biomedical Research Third Edition b2530 International Strategic Relations and China’s National Security: World at the Crossroads TTTThhhhiiiissss ppppaaaaggggeeee iiiinnnntttteeeennnnttttiiiioooonnnnaaaallllllllyyyy lllleeeefffftttt bbbbllllaaaannnnkkkk b2530_FM.indd 6 01-Sep-16 11:03:06 AM Molecular Imaging Basic Principles and Applications in Biomedical Research Third Edition ••• Markus Rudin University of Zürich and ETH Zürich, Switzerland World Scientific NEW JERSEY • LONDON • SINGAPORE • BEIJING • SHANGHAI • HONG KONG • TAIPEI • CHENNAI • TOKYO Published by World Scientific Publishing Europe Ltd. 57 Shelton Street, Covent Garden, London WC2H 9HE Head office: 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 Library of Congress Cataloging-in-Publication Data Names: Rudin, M. (Markus), 1953– author. Title: Molecular imaging : basic principles and applications in biomedical research / by Markus Rudin (University of Zürich and ETH Zürich, Switzerland). Description: 3rd edition. | New Jersey : World Scientific, [2019] | Includes bibliographical references. Identifiers: LCCN 2019008599 | ISBN 9781786346841 (hardcover) | ISBN 9781786346858 (ebook) | ISBN 9781786346865 (ebook other) Subjects: LCSH: Molecular probes. | Diagnostic imaging. | Imaging systems in medicine. Classification: LCC QP519.9.M64 R83 2019 | DDC 616.07/54--dc23 LC record available at https://lccn.loc.gov/2019008599 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Copyright © 2020 by World Scientific Publishing Europe Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. For any available supplementary material, please visit https://www.worldscientific.com/worldscibooks/10.1142/Q0204#t=suppl Desk Editors: Herbert Moses/Jennifer Brough/Shi Ying Koe Typeset by Stallion Press Email: [email protected] Printed in Singapore Herbert Moses - Q0204 - Molecular Imaging.indd 1 09-03-20 1:48:37 PM March9,2020 12:42 MolecularImaging:BasicPrinciples…(3rdEdition)9inx6in b3482-fm pagev Preface to the First Edition Many scientists consider molecular imaging not a new discipline. In fact, a PubMed search using the term ‘in vivo molecular imaging 1970’yieldedfourhits.Nuclearimagingapproachessuchaspositron emission tomography (PET) and single-photon emission computer tomography have used molecular imaging concepts since decades to visualizethebiodistributionoflabeledcompoundsincludinganalyses ofreceptoroccupancy.Insuchstudies,imagecontrastisnotgoverned by the anatomical features of the sample but rather by the local con- centrationoftheradiolabeledreportercompound,i.e.,byamolecular property. Otherscientistswillclaimmolecularimaginganewscientificarea merging concepts of molecular biology with non-invasive imaging technologies,enablingstudiesofbiologicalprocessesinanon-invasive manner. Such concepts go beyond mere labeling of reporter ligands. Theyinvolvethedevelopmentofabatteryofreporterassaysthatare used to address specific biological questions: is the expression of a receptor modified under specific pathological conditions? Does the receptor exert its biological activity; does it activate its associated signalingcascade?Canthesemolecularmarkersbeusedasearlyindi- cators of a pathological transformation? The last years experienced rapid growth in the field of molecular imaging. Many of the assay systems originally developed for study- ing biochemical systems in homogeneous solutions or isolated cells have been successfully translated to the in vivo situation allowing the testing of a biomedical hypothesis in the context of the intact organism.Molecularortarget-specificimagingpotentiallyprovidesa v March9,2020 12:42 MolecularImaging:BasicPrinciples…(3rdEdition)9inx6in b3482-fm pagevi vi PrefacetotheFirstEdition holistic view on a biological system in contrast to the reductionistic approaches of classical molecular biology and biochemistry. Despite the rapid progress that has been achieved in the last couple of years the field is still in its infancy and major developments are required. This relates to the imaging technologies, which should provide high sensitivity, high temporal and spatial resolutions, and most impor- tantly quantitative data, as well as to the design of reporter systems. Highly specific probe constructs should provide the desired infor- mation with little interference by non-specific background signals. The development of multiplexed probes that allow the monitoring of several biological processes simultaneously would be of outmost relevance. There are considerable expectations associated with molecular imaging techniques. First, the study of molecular events in the intact organismwillenhanceourbasicmolecularbiologicalknowledge.For instance, specific receptor systems or signal transduction pathways can be studied in their biological context. Secondly, tissue functional or structural aberrations are always preceded by molecular events such as abnormal cellular signaling. It is reasonable to assume that molecularmarkersmightserveasearlyindicatorsofadiseaseprocess, long before a patho-morphological or -physiological transformation oftissueoccurs.Itmayfurthermoreimprovethespecificityofdiagno- sisandmayhelptoselectthepatientpopulationthatismostlikelyto respond to a specific therapy. Thirdly, modern pharmaceutical drugs are designed to interact with a well characterized molecular target. As clinical drug development is becoming increasingly expensive (in 2005,thedevelopmentofadrugtoreachthemarketwillcostapprox- imately 800–1000 Mio USD), early information on clinical efficacy is of crucial importance. Molecular imaging might provide a direct proof that a therapeutic concept is valid also in man; e.g., the target enzymeisinfactinhibitedbythedrugcandidateorinhibitionofaspe- cific receptor shuts down the associated molecular signaling cascade. Forthesereasons,molecularimagingwillsoonbecomeanindispens- able tool in biomedical research in particular for drug discovery and development. This book is aimed to give the reader an introduction into this fascinatinganddynamicallyevolvingfield.Itdiscussesbasicaspectsof March9,2020 12:42 MolecularImaging:BasicPrinciples…(3rdEdition)9inx6in b3482-fm pagevii PrefacetotheFirstEdition vii molecularimagingtechnologyandprobedesign,whichareillustrated withnumerousselectedexamplesfromtheliterature.Itdoes,however, not provide a comprehensive review of the current activities in the field. This was never intended as such a book would probably never befinished:newexcitingapplicationsarebeingreportedalmostona daily basis. Thefirstpartofthebookdiscussestechnologicalaspectsofmolec- ular imaging. In Chapter 2, the various imaging modalities such as X-ray computer tomography (CT), magnetic resonance imag- ing (MRI), single photon emission computer tomography (SPECT), PET, fluorescence and bioluminescence imaging, as well as ultra- sound imaging are discussed in some detail. Chapter 3 describes the various reporter systems that are being used for the various imaging approaches, from short-lived radionuclides to microbubbles suited for ultrasound studies. The design of reporter constructs for molecular imaging applications is the topic of Chapter 4. Impor- tant aspects to consider are target-specificity, delivery of the probe to the target site, and signal amplification. Most molecular targets are expressed at low concentration (nano- to femtomolar), hence strategies to enhance the signals produced by the reporter system are essential. The second part deals with applications of molecular imaging in biomedicalresearch.Knowledgeofthedrugbiodistributionandphar- macokinetics (PK) is highly relevant for drug development as many drugcandidatesfailduetoinadequatePKproperties.Chapter5deals with drug imaging using PET techniques. In Chapter 6, methods to visualize the expression of the drug targets are being discussed. Lev- els of transcription products can be probed using labeled antisense molecules, and receptor imaging relies on the availability of small molecular probes or labeled antibodies. Enzymatic drug targets are attractiveforimagingastheenzymeactivitycanbeexploitedtoacti- vate or trap a reporter substrate thus yielding high degrees of signal amplificationandminimalinterferencebybackgroundsignals.Adif- ferentapproachtovisualizegeneexpressionistheuseofthereporter genes, which allows unique questions to be addressed. Drug–target interaction will initiate a series of downstream processes. Measure- ment of these effector readouts are the topic of Chapter 7, which March9,2020 12:42 MolecularImaging:BasicPrinciples…(3rdEdition)9inx6in b3482-fm pageviii viii PrefacetotheFirstEdition discusses methods to visualize protein–protein interactions or apop- totic activity as an example. Further downstream, a ligand–receptor interactionwillinitiateaphysiologicalresponsethatcanbevisualized using conventional imaging approaches such as the measurement of glucose utilization, energy turnover, tissue perfusion, or second mes- senger turnover. The final Chapter 8 describes techniques for moni- toring of cell trafficking. Myeloid and lymphoid cells are important mediatorsofinflammationandvisualizationoftheinfiltrationofthese cellsintoinflamedtissuearesensitiveindicatorsofthediseaseprocess. Novel therapeutic approaches in degenerative diseases try to exploit the pluripotency of stem cells for tissue repair. Obviously, such ther- apy concepts will benefit from the ability to monitor the fate of such cells under in vivo conditions. While many of the techniques and applications described will undergofurtherdevelopmentintheupcomingyears,mostofthebasic conceptsoutlinedinthisbookwillremainvalidandwillbeapplicable alsototheseadvancedprocedures.Inthisregard,thebookisdesigned asatextbooksummarizingthebasicprinciplesandpotentialapplica- tions of molecular imaging in biomedical research. March9,2020 12:42 MolecularImaging:BasicPrinciples…(3rdEdition)9inx6in b3482-fm pageix Preface to the Second Edition The field of molecular imaging has rapidly evolved since the appear- anceofthefirsteditionofthisbook;aquicksearchinPubMedusing thesearchitem‘invivomolecularimaging’revealedthatthenumber ofarticlesonthesubjecthasmorethantripledbetweentheyears2005 and 2010 from 588 to 2164 following an exponential growth curve. This illustrates the importance of molecular imaging approaches in biomedical research as a basic research tool, for enhancing the sen- sitivity and specificity of diagnostic assays, and for facilitating the development of novel therapeutic interventions. Significant progress has been made with regard to the development of advanced imaging technologies, novel reporter principles, and in particular with regard to applications of the approach in addressing important biological questions. It is beyond the scope of this book to cover the field com- prehensively.Thesecondversionincludesnoveldevelopmentsifthey add new aspects to the overall topic. I have focused on including aspectsregardingmolecularimagingmethodologythatareofgeneral conceptual interest and have included novel applications for illustra- tion purposes. Concerningimagingtechnologies,apartfromimportantimprove- ments of already established tools, the major thrive was toward the development of hybrid imaging solutions combining two or multiple modalities, commonly the combination of a structural with a molec- ular imaging technique. Representative examples and the combina- tionofthehighlysensitivetechniquespositronemissiontomography (PET) or fluorescence tomography (FMT) with the high resolution modalitiesX-raycomputertomography(CT)andmagneticresonance ix