Molecular Imaging: Basic Principles and Applications in Biomedical Research

Contents
Preface to the First Edition
Preface to the Second Edition
Preface to the Third Edition
About the Author
Acknowledgments
1. Introduction
	1.1 Biomedical Research: Elucidating Molecular Mechanisms of Disease
		1.1.1 Tumorigenesis as result of multiple mutations and interplay with microenvironment
		1.1.2 Pathogenesis in Alzheimer’s-type dementia
		1.1.3 Multiple factors causing disease: Multiplexed diagnostic tools
	1.2 Imaging in Biomedical Research
		1.2.1 Imaging as a two-stage mapping process
		1.2.2 Digital imaging
			1.2.2.1 Parameter averaging across voxel
			1.2.2.2 Contrast-to-noise ratio and spatial resolution
			1.2.2.3 Morphometry and densitometry
	1.3 Target-Specific or Molecular Imaging
		1.3.1 Definition: Molecular imaging
		1.3.2 Imaging targets
		1.3.3 Prerequisites for molecular imaging: Reporter constructs
		1.3.4 Prerequisites for molecular imaging: Imaging modalities
		1.3.5 Molecular imaging modalities
		1.3.6 Comparison of imaging modalities
	1.4 Summary
	References
Part 1: Methodologies
	2. Imaging Techniques
		2.1 X-ray Computer Tomography (X-ray CT)
			2.1.1 Interaction of X-rays with tissue
			2.1.2 Principles of X-ray CT
			2.1.3 Image representation, spatial resolution, and contrast-to-noise ratio
			2.1.4 Phase contrast X-ray imaging
			2.1.5 Small-angle-X-ray scattering (SAXS) tomography
			2.1.6 Animal CT scanners
		2.2 Magnetic Resonance Imaging
			2.2.1 Interaction of a nuclear magnetic moment with a static magnetic field
			2.2.2 Classical description of NMR: Bloch equations
			2.2.3 Relaxation
			2.2.4 The NMR experiment
			2.2.5 Measurement of relaxation rates in FT-NMR
				2.2.5.1 Measurement of the transverse relaxation rate R2
				2.2.5.2 Measurement of the longitudinal relaxation rate R1
			2.2.6 Principles of magnetic resonance imaging
				2.2.6.1 Spatial encoding
				2.2.6.2 The k-space concept
				2.2.6.3 Slice selection
				2.2.6.4 Some basic image acquisition modules
			2.2.7 Contrast in MRI, signal enhancement by contrast agents
			2.2.8 In vivo magnetic resonance spectroscopy
				2.2.8.1 Selecting the volume of interest for in vivo MRS
				2.2.8.2 Issues with MRS as molecular imaging modality
				2.2.8.3 Sensitivity enhancement by hyperpolarization of nuclear spin systems
			2.2.9 Animal MRI scanners
		2.3 Nuclear Imaging: Gamma Scintigraphy, Single Photon Emission Computerized Tomography
			2.3.1 The gamma camera: Projection images
			2.3.2 3D gamma imaging: Single photon emission computed tomography (SPECT)
			2.3.3 High-resolution animal SPECT instrumentation
		2.4 Positron Emission Tomography
			2.4.1 Physical principles of PET
			2.4.2 Image reconstruction
				2.4.2.1 Filtered backprojection
				2.4.2.2 Statistical image reconstruction
				2.4.2.3 3D reconstruction procedures
			2.4.3 High-resolution animal PET instrumentation
		2.5 Optical Imaging
			2.5.1 Photon propagation in scattering media
				2.5.1.1 The diffusion equation for light propagation in tissue
				2.5.1.2 Solutions of the diffusion equation
			2.5.2 Planar imaging/reflectance imaging
			2.5.3 Fluorescence molecular tomography
			2.5.4 Non-contact optical tomography
			2.5.5 Instrumentation for reflectance fluorescence imaging and fluorescence molecular tomography
			2.5.6 Intravital Microscopy Techniques
				2.5.6.1 Intravital confocal microscopy
				2.5.6.2 Two-photon/multiphoton microscopy
				2.5.6.3 Optical Coherence Tomography
			2.5.7 Optical Projection Tomography
			2.5.8 Raman spectroscopic imaging
		2.6 Mass Spectrometry Imaging
		2.7 Ultrasound Imaging
			2.7.1 Principles of ultrasound imaging
				2.7.1.1 Introduction, definitions
				2.7.1.2 Attenuation
				2.7.1.3 Reflection and refraction
				2.7.1.4 Scattering
			2.7.2 Axial and angular resolution, frame rate
				2.7.2.1 Spatial resolution
			2.7.3 Ultrafast ultrasound imaging
			2.7.4 Contrast enhancement in ultrasound
		2.8 Photoacoustic Imaging
			2.8.1 Generation of photoacoustic signal
			2.8.2 Photoacoustic image reconstruction
			2.8.3 Fast/real-time photoacoustic imaging
			2.8.4 Spectral photoacoustic imaging
			2.8.5 Photoacoustic imaging at microscopic resolution
		2.9 Hybrid Techniques
			2.9.1 PET/CT
			2.9.2 PET/MRI
			2.9.3 PET image reconstruction with anatomical priors
			2.9.4 FMT/CT
			2.9.5 FMT/MRI
			2.9.6 Combination of macroscopic imaging with fiber optical recordings
		2.10 Summary
		References
	3. Molecular Reporter Systems
		3.1 X-ray Contrast Agents
			3.1.1 Introduction
			3.1.2 Iodine-based contrast agents
		3.2 MRI Contrast Agents
			3.2.1 Factors determining the relaxivity of contrast agents
			3.2.2 Gadolinium-based contrast agents
			3.2.3 Magnetic nanoparticles
			3.2.4 Liposomes/micelles/microemulsions
			3.2.5 Chemical exchange saturation transfer (CEST) contrast agent
			3.2.6 Hyperpolarization by dynamic nuclear polarization (DNP)
			3.2.7 MRI reporter gene systems
		3.3 SPECT Radioisotopes
			3.3.1 Radioisotopes for gamma scintigraphy/SPECT imaging
			3.3.2 Technetium-99m
			3.3.3 Indium-111
			3.3.4 Iodine-123 and iodine-131
		3.4 PET Radioisotopes
			3.4.1 Production of radionuclides, lifetimes
			3.4.2 Carbon-11-labeled compounds
			3.4.3 Fluorine-18-labeled compounds
			3.4.4 Other PET nuclei
			3.4.5 PET reporter genes
		3.5 Optical Probes: Fluorescence and Bioluminescence Probes
			3.5.1 Principles of fluorescence
			3.5.2 Fluorescent dyes
			3.5.3 Fluorescent nanocrystals, quantum dots
			3.5.4 Genetically encoded fluorescent reporters: Fluorescent proteins
			3.5.5 Light-activatable proteins for interventions: Optogenetics
			3.5.6 Fluorescence resonance energy transfer quenching
			3.5.7 Phosphorescence, phosphorescence lifetime
			3.5.8 Bioluminescence
			3.5.9 Probes for photoacoustic imaging
		3.6 Contrast Agents for Ultrasound Imaging
			3.6.1 Microbubbles
			3.6.2 Non-microbubble-based contrast agents
		3.7 Summary
		References
	4. Design of Molecular Imaging Probes
		4.1 Design of Target-Specific Probes
			4.1.1 Low molecular weight probes
			4.1.2 Macromolecular probes: Antibodies, oligonucleotides
			4.1.3 Activatable probes (‘smart’ probes)
				4.1.3.1 Change in fluorescent properties
				4.1.3.2 ‘Caged’ bioluminescent probes
				4.1.3.3 Change in magnetic relaxation rates
		4.2 Probe Delivery, Cell Penetration
			4.2.1 Cell penetrating peptides (CPPs)
			4.2.2 Receptor-mediated endocytosis
			4.2.3 Transfection agents
		4.3 Signal Amplification
			4.3.1 Increasing the payload of reporters per target
			4.3.2 Trapping of reporters
			4.3.3 Enzymatic probe activation
		4.4 Physiological Amplification
		4.5 Summary
		References
Part 2: Applications
	5. Drug Imaging
		5.1 Drug Biodistribution and Pharmacokinetics
			5.1.1 Ex vivo techniques: Autoradiography and MS imaging
			5.1.2 In vivo studies using nuclear imaging techniques
				5.1.2.1 Labeling by radioisotopes to preserve pharmacokinetic properties
				5.1.2.2 Dose linearity
				5.1.2.3 Correction for plasma contribution
				5.1.2.4 Examples: CNS drugs
		5.2 Receptor Occupancy Studies
			5.2.1 Receptor binding in a homogeneous compartment
			5.2.2 Compartment models for estimation of tracer concentrations
			5.2.3 Indirect imaging or drug-receptor interactions
			5.2.4 Receptor occupancy studies: Examples
		5.3 Summary
		References
	6. Imaging Gene Expression
		6.1 Visualizing Transcription: Targeting mRNA using Labeled Antisense Oligonucleotides
		6.2 Direct Target Imaging Using Receptor-Specific Ligands
			6.2.1 Low molecular weight (LMW) ligands
				6.2.1.1 Peptidic probes targeting tumors
				6.2.1.2 LMW probes targeting molecules involved in neurotransmission
				6.2.1.3 Small molecule probes for studying Alzheimer’s disease
			6.2.2 Antibodies and antibody fragments
				6.2.2.1 Endovascular targets: Atherosclerosis, inflammation, tumor angiogenesis
				6.2.2.2 Tumor-specific antibody probes
				6.2.2.3 General comments regarding antibodies as targeting moieties
			6.2.3 Enzymatic drug targets
				6.2.3.1 Measuring enzyme activity
				6.2.3.2 Kinases
				6.2.3.3 Proteases
		6.3 Reporter Genes
			6.3.1 Reporter genes with intracellular gene products
			6.3.2 Reporter genes expressing membrane-associated gene products
			6.3.3 Dual/Multiple reporters
			6.3.4 Conditional or inducible reporter expression
			6.3.5 Using in vivo reporter gene assays for preclinical studies
		6.4 Summary
		References
	7. Imaging the Function of Gene Products
		7.1 Imaging of Signal Transduction Pathways/Protein–Protein Interaction
			7.1.1 Fluorescence resonance transfer
			7.1.2 Two-hybrid approach
			7.1.3 Protein fragment complementation assay (PCA)
			7.1.4 Protein splicing
		7.2 Apoptosis
			7.2.1 Targeting externalized phosphatidylserine
			7.2.2 Targeting of caspases using reporter gene assays
			7.2.3 Phenotypic marker of apoptosis
		7.3 Imaging Hypoxia Signaling
			7.3.1 Hypoxia and the HIF signaling cascade
			7.3.2 Hypoxic and non-hypoxic HIF activation — Multimodal imaging strategies
		7.4 Metabolic/Physiological Response to Receptor Activation
			7.4.1 Hemodynamic changes in central nervous system
			7.4.2 Tissue energy metabolism
				7.4.2.1 Measurement of glucose utilization
				7.4.2.2 Measurement of ATP turnover
			7.4.3 Tissue proliferation
				7.4.3.1 DNA synthesis
				7.4.3.2 Protein synthesis
				7.4.3.3 Membrane synthesis
			7.4.4 Vascular permeability changes as readout of anti-angiogenic therapy
		7.5 Summary
		References
	8. Monitoring Cell Migration
		8.1 Introduction
		8.2 Inflammatory Cells
			8.2.1 Visualization of macrophage infiltration
				8.2.1.1 Experimental models of multiple sclerosis
				8.2.1.2 Focal cerebral ischemia
				8.2.1.3 Atherosclerosis
				8.2.1.4 Solid organ transplantation
				8.2.1.5 General comments
			8.2.2 Lymphocytes
		8.3 Stem and Progenitor Cells
			8.3.1 Neurogenesis
			8.3.2 Stem cells in focal cerebral ischemia
			8.3.3 Brain tumors
			8.3.4 Myocardial infarction
		8.4 Labeled Tumor Cells/Metastasis Formation
			8.4.1 Non-invasive imaging of tumor growth, cell migration, metastasis formation
			8.4.2 Imaging tumor host interaction, modes of cell migration
			8.4.3 Imaging cellular events in cancer immunotherapy
		8.5 Summary
		References
	9. Molecular Imaging — Translational Aspects
		9.1 Molecular/Personalized Medicine — Molecular Diagnostics
		9.2 Molecular Imaging in Target Validation and Drug Discovery
		9.3 Clinical Translation: Development of a Diagnostic Imaging Agent
			9.3.1 Regulatory and economic aspects
			9.3.2 Combining development of therapeutic and diagnostic agents: Theragnostics/companion diagnostic
		9.4 Biomarkers
			9.4.1 Definition of Biomarkers
			9.4.2 Biomarker validation
			9.4.3 Individual biomarkers versus biomarker fingerprint
			9.4.4 Biomarker for drug development
		9.5 Research Challenges in (Molecular) Imaging: Understanding the Nature of the Signals
		References
Appendices
	A1 Physical Constants (see e.g. A.1)
	A2 Mathematical Formulae
		A2.1 Convolution
		A2.2 Fourier Transformation
		A2.3 Differential equations
		A2.4 Solution to coupled linear differential equations using matrix formalism
		A2.5 Green’s function
	A3 Natural Amino Acids
	A4 Nucleotides
	References
Index