Spectral Imaging: Dual-Energy, Multi-Energy and Photon-Counting CT (Medical Radiology)

Foreword
Contents
Part I: Technical Principles
	Material Decomposition and Post-processing: History and Basic Principles
		1	 Introduction and History
		2	 Methods of Material Decomposition
		3	 Synthetic Images from Material Decomposition and Post-Processing
			3.1	 Mixed CT Images
			3.2	 Material-Specific Images
				3.2.1	 Material Differentiation Images
				3.2.2	 Material Quantification Images
				3.2.3	 Material Negative Images
			3.3	 Virtual Monoenergetic Images
			3.4	 Electron Density and Effective Atomic Number Images
		4	 Image Quality and Quantitative Accuracy of Synthetic DECT Images
		5	 Conclusion
		References
	Dual-Energy: The Siemens Approach
		1	 General Aspects and Workflow
		2	 Dual Source-Based Dual-Energy
		3	 Twin Spiral Dual-Energy
		4	 TwinBeam Dual-Energy
		5	 Conclusions
		References
	Dual-Energy: The Philips Approach
		1	 Spectral Detection Through a Dual-Layer Detector
		2	 Spectral Material Decomposition and Reconstruction
		3	 Spectral Results
			3.1	 MonoE: Monoenergetic Images [HU]
			3.2	 VNC: Virtual Non-Contrast
			3.3	 Iodine No Water [mg/ml]
			3.4	 Calcium Suppression [HU]
			3.5	 Iodine Density [mg/ml]
			3.6	 Contrast-Enhanced Structures [HU]
			3.7	 Iodine Removed [HU]
			3.8	 Uric Acid and Uric Acid Removed Pair [HU]
				3.8.1	 Uric Acid [HU]
				3.8.2	 Uric Acid Removed [HU]
			3.9	 Z Effective
			3.10	 Electron Density [%EDW]
		References
	Dual-Energy: The GE Approach
		1	 Background
		2	 Balanced System Design
		3	 Image Reconstruction
		4	 Projection-Based Material Decomposition
		5	 Image Generation and Post-processing
			5.1	 Image Types
				5.1.1	 Monochromatic
				5.1.2	 Material Density
				5.1.3	 Material-Suppressed Iodine
				5.1.4	 Metal Artifact Reduction
			5.2	 Noise Suppression
				5.2.1	 Iterative Reconstruction
				5.2.2	 TrueFidelity™ GSI
		6	 Workflow and Clinical Processing
		7	 Spectral Applications and Future
		8	 Photon Counting: The Next Leap in Spectral Imaging
			8.1	 Photon Counting with Deep Silicon
			8.2	 X-Ray Detection Efficiency for Deep Silicon
			8.3	 X-Ray Scatter in the Detector
			8.4	 Count Rate Performance
			8.5	 Deep Silicon Summary
		References
	Dual-Energy: The Canon Approach
		1	 Introduction
		2	 The Aquilion ONE Prism and Its Technology
			2.1	 Spectral Rapid kV Switching
				2.1.1	 Deep Learning
			2.2	 Spectral Deep Learning Reconstruction
		3	 Spectral Performance
			3.1	 Spatial Resolution and CNR Performance
			3.2	 Wide Volume Detector
			3.3	 Virtual Monochromatic Images
			3.4	 Spectral Iodine Maps
			3.5	 Workflow
		References
	Basic Principles and Clinical Applications of Photon-Counting CT
		1	 Principles of Photon-Counting CT
			1.1	 Properties of Current Solid-State Scintillation Detectors
			1.2	 Properties of Photon-Counting Detectors
			1.3	 Challenges for Photon-Counting Detectors
		2	 Material Decomposition for Photon-Counting CT
		3	 Pre-clinical Evaluation of Photon-Counting CT
		References
	Contrast Media for Modern Computed Tomography
		1	 Introduction
		2	 Iodinated Contrast Media: Current Standard in Safety and Tolerability
			2.1	 Structure and Physicochemistry
			2.2	 Tolerability and Safety
			2.3	 LOCM, the Reference Standard
		3	 The Technology Is a Determining Factor for the Efficiency of Contrast Media
		4	 Pharmacokinetics of Iodinated Contrast Media and Their Relevance for Modern CT
			4.1	 Volume of Distribution and Excretion
			4.2	 Basic Mechanisms of Contrasting Inside the Body
		5	 Contrast Media in  Dual-Energy CT
		6	 Clinical Applications of Dual-Energy Material Decomposition
			6.1	 Oncology Applications
			6.2	 Cardiovascular Applications
			6.3	 Pulmonary Applications
		7	 Summary and Outlook
		References
Part II: Clinical Applications
	Neuroradiological Imaging
		1	 Introduction
		2	 Technical Background and Workflow Considerations
			2.1	 Background
			2.2	 Training Considerations for Technologists and Radiologists
			2.3	 Patient Selection and Scan Acquisition
			2.4	 Protocol and Dose Optimization
			2.5	 Image Reconstruction and Storage
			2.6	 Considerations for Image Interpretation
		3	 Clinical Applications
			3.1	 Introduction to Clinical Applications
			3.2	 Differentiation Between Contrast Staining and Intracranial Hemorrhage
			3.3	 Further Material and Tissue Differentiation
			3.4	 Image Quality, Radiation Dose, and Artifact Reduction
			3.5	 Other Applications of DECT in Emergency Neuroradiology
		4	 Photon Counting
		5	 Outlook and Conclusion
		References
	Head and Neck Imaging
		1	 Head and Neck Oncology
			1.1	 Delineation and Visibility of Tumors
				1.1.1	 Invasion of Cartilage
			1.2	 Lymph Node Imaging
		2	 Salivary Glands
		3	 Inflammation
		4	 Metal Artifact Reduction
		5	 Thyroid and Parathyroid Lesions
		6	 Angiography of the Head and Neck
		7	 Future Directions: Assessment of Therapy Response and Prediction of Recurrence
		References
	Clinical Applications in Cardiac Imaging
		1	 History of Cardiac Imaging
		2	 Benefits and Applications of Cardiac CT Imaging
		3	 Functional Applications for Cardiac CT
		4	 Advantages of Spectral Imaging
			4.1	 Optimizing Image Quality
			4.2	 Artifact Reduction
			4.3	 Reducing Contrast Media
			4.4	 Virtual Reconstructions to Lower Radiation Dose
		5	 Coronary Arteries
			5.1	 Improvement of Imaging Quality and Artifact Reduction
			5.2	 General Improvements of Image Quality
			5.3	 Reducing Calcium Blooming Artifacts
			5.4	 Improved Visualization of Coronary Artery Stents
			5.5	 Improved Plaque Imaging
			5.6	 Calcium Scoring
		6	 Myocardial Characterization
			6.1	 Myocardial Fibrosis
			6.2	 Iron Overload
			6.3	 Perfusion Imaging
			6.4	 Scar Imaging
		7	 Cardiac Valves
		8	 Cardiac Masses
		9	 Outlook Cardiac CT
			9.1	 Artificial Intelligence and Radiomics
			9.2	 Photon-Counting CT
			9.3	 Conclusion
		References
	Dual-Energy CT Angiography
		1	 Dual-Energy CT Angiography
			1.1	 Image Contrast
			1.2	 Contrast Agent
			1.3	 Virtual Unenhanced
				1.3.1	 Bones
			1.4	 Plaques
			1.5	 Clinical Applications
				1.5.1	 Pulmonary Angiography
				1.5.2	 Carotid Angiography
				1.5.3	 Aortic Angiography
				1.5.4	 Abdominal Angiography
				1.5.5	 Peripheral Angiography
				1.5.6	 Venous System
		References
	Thoracic Imaging: Ventilation/Perfusion
		1	 Perfusion Dual-Energy CT
			1.1	 Imaging Protocol
			1.2	 Clinical Applications
				1.2.1	 Pulmonary Vascular Diseases (Pulmonary Embolism and Pulmonary Hypertension)
				1.2.2	 Diffuse Parenchymal/Airway Disease
				1.2.3	 Lung Cancer
		2	 Ventilation Dual-Energy CT
			2.1	 Technical Aspects
				2.1.1	 Noble Gas Contrast Agents
				2.1.2	 Imaging Protocol
				2.1.3	 Postprocessing
			2.2	 Clinical Applications
				2.2.1	 Chronic Obstructive Pulmonary Disease
				2.2.2	 Asthma
				2.2.3	 Other Ventilation Related Diseases: Asthma-COPD Overlap Syndrome, Bronchiolitis Obliterans
		3	 Comprehensive Assessment of Morphology, Pulmonary Ventilation, Perfusion, and Relationship of Ventilation and Perfusion Using Dual-Energy CT
			3.1	 Concept
			3.2	 Clinical Application: Pulmonary Embolism, COPD
		4	 Perspective and Conclusion
		References
	Thoracic Oncology
		1	 Artifact Reduction and Improved Image Quality
			1.1	 Metal Artifacts
			1.2	 Beam-Hardening Artifacts Due to Contrast Media
		2	 Imaging Pulmonary Nodules
			2.1	 Introduction
			2.2	 Detection of Pulmonary Nodules
			2.3	 Classification of Pulmonary Nodules
				2.3.1	 Solid Pulmonary Nodules
				2.3.2	 Ground-Glass Pulmonary Nodules
				2.3.3	 Calcified Pulmonary Nodules
		3	 Imaging Lung Cancer
			3.1	 Introduction
			3.2	 Detecting Lung Cancer
			3.3	 Differentiate Lung Cancer and Inflammation
			3.4	 Characterization of Lung Cancer
				3.4.1	 Virtual Biopsy with DECT
				3.4.2	 PCDCT and Molecular Imaging
			3.5	 Staging Lung Cancer
				3.5.1	 Lymph Node Metastasis
				3.5.2	 Bone Metastasis
		4	 Therapy Evaluation of Lung Cancer
			4.1	 Introduction
			4.2	 Therapy Response with DECT
				4.2.1	 Evaluation of RFA Therapy with DECT
				4.2.2	 Evaluation of Anti-angiogenic Therapy with DECT
				4.2.3	 Correlation of DECT and PET-CT in Therapy Evaluation
				4.2.4	 Predicting Recurrence with DECT
		References
	Gastrointestinal Imaging: Oncology (Liver, Pancreas, Bowel Cancer, and Treatment Response)
		1	 Introduction
		2	 Clinical Applications of Dual-Energy CT for Oncologic Imaging of the Liver
			2.1	 Imaging Protocols
			2.2	 Challenges in Imaging the Liver
			2.3	 Liver Lesion Detection and Delineation
			2.4	 Liver Lesion Characterization
			2.5	 Response Assessment of Hepatocellular Carcinoma
		3	 Dual-Energy Imaging Applications for Pancreatic Imaging
			3.1	 Imaging Protocols
			3.2	 Imaging of Pancreatic Lesions
			3.3	 Imaging of Pancreatic Cancer
		4	 Oncologic Imaging of the Gastrointestinal System with Dual-Energy CT
			4.1	 Imaging Protocols
			4.2	 Upper GI Tract
			4.3	 Lower Intestinal Tract
				4.3.1	 Dual-Energy Colonography
		5	 Oncologic Applications of DECT in the Abdomen outside of Parenchymal Organs
		6	 The Role of Dual-Energy CT for Assessing Oncologic Treatment Response
			6.1	 Assessment of Treatment Response After Locoregional Therapy
			6.2	 Assessment of Treatment Response After Antiangiogenic Treatment
		References
	Gastrointestinal Imaging: Liver Fat and Iron Quantification
		1	 Clinical Background
		2	 Physical Background
		3	 Scan Protocol and Contrast Injection
		4	 Post-processing
		5	 Diagnostic Evaluation and Scientific Evidence
			5.1	 Liver Fat
			5.2	 Liver Iron
		6	 Conclusion
		References
	Bowel Imaging
		1	 Clinical Background
		2	 Physical Background
		3	 Scan Protocol Considerations
		4	 Postprocessing
		5	 Diagnostic Evaluation and Scientific Evidence
			5.1	 Chronic Inflammatory Conditions
			5.2	 Acute Infectious Conditions
			5.3	 Vascular Bowel Conditions
			5.4	 CT Colonography
			5.5	 Contrast Materials
		6	 Conclusion
		References
	Role of Dual-Energy Computed Tomography (DECT) in Acute Abdomen
		1	 Introduction
		2	 Role of DECT in Non-traumatic Acute Abdomen
		3	 Bowel Ischemia
		4	 Bowel Perforation
		5	 Diverticulitis
		6	 Ruptured Abdominal Aortic Aneurysm
		7	 Gastrointestinal (GI) Hemorrhage
		8	 Gangrenous Cholecystitis
		9	 Gangrenous Appendicitis
		10	 Pancreatitis
		11	 Urinary Tract Calculi
		12	 Ovarian Torsion
		13	 DECT in the Acute Traumatic Abdomen
			13.1	 Blunt Abdominal Trauma
			13.2	 Pneumoperitoneum
			13.3	 Hemoperitoneum
		14	 Active Extravasation on DECT
		15	 Visceral Injuries on DECT
		16	 Splenic Injuries
		17	 Hepatic Injuries
		18	 Pancreatic Injuries
		19	 Urinary Tract Injuries
		20	 Diaphragmatic Injuries
		21	 Bowel and Mesenteric Injuries
		22	 Vascular Injuries
		23	 Bone Injuries
		24	 Penetrating Abdominal Trauma
		25	 Conclusions
		References
	Spectral Computed Tomography Imaging of the Adrenal Glands
		1	 Introduction
		2	 Lipid-Rich Adenoma and Virtual Non-contrast Imaging
		3	 Lipid-Poor Adenoma, Washout Analysis, and Chemical Shift MRI
		4	 Quantification of Iodine
		5	 Summary
		References
	Urogenital Imaging: Kidneys (Lesion Characterization)
		1	 Virtual Monoenergetic/Monochromatic Imaging (VMI)
		2	 Material Specific Imaging
		3	 Virtual Unenhanced Imaging (VUE)
		4	 Iodine Imaging
		5	 Radiation Dose Consideration
		6	 Conclusion
		References
	Urogenital Imaging: Kidneys: Urinary Stones
		1	 Introduction: Clinical Workup in Suspected Urolithiasis
		2	 Dual-Energy CT in Suspected Urolithiasis: Protocol Decisions
			2.1	 Protocol Recommendations
		3	 DECT-Concepts to Determine Stone Composition
			3.1	 In Vitro Capabilities for Stone Composition
			3.2	 In Vivo Capabilities for Stone Composition
		4	 Advanced Concepts
			4.1	 Stone Composition
			4.2	 Other Applications
			4.3	 Future Developments
		5	 Conclusion
		References
	Skeletal Imaging: Bones
		1	 Metal Artifact Reduction Techniques
			1.1	 Introduction
			1.2	 Technical Background
			1.3	 Literature Overview
		2	 Bone Marrow Assessment
			2.1	 Introduction
			2.2	 Technical Background
			2.3	 Applications in Clinical Routine
				2.3.1	 Spine
				2.3.2	 Appendicular Skeleton
		3	 Bone Mineral Density Analysis
			3.1	 Introduction
			3.2	 Technical Background
			3.3	 Initial Experience in Literature
		4	 Future Innovations
		5	 Conclusion
		References
	Gout
		1	 Pathogenesis and Clinical Presentation
		2	 Diagnostic Options
		3	 Dual-Energy CT
			3.1	 Physics: Two-Material Decomposition
			3.2	 Clinical Indications for DECT
			3.3	 Scan Protocols
			3.4	 Contrast Media
			3.5	 Image Reconstruction
			3.6	 Image Interpretation
			3.7	 Report: What Information to Include
			3.8	 Issues Regarding Tophus Density and Radiation Exposure
			3.9	 DECT for Follow-Up
		4	 Case Discussions
			4.1	 Case 1: Patient with Acute Wrist Arthritis
			4.2	 Case 2: Chronic Pain of the Feet
			4.3	 Case 3: Pain of the First MTP Joint
			4.4	 Case 4: Patient with Knee Pain
			4.5	 Case 5: Patient with Rheumatoid Arthritis
		5	 Summary
		References
	Dual-Energy CT in Radiation Oncology
		1	 Introduction: Dual-Energy CT in Radiotherapy: From First Idea to Clinical Application
		2	 Dual-Energy CT Techniques in Radiation Oncology
			2.1	 Spectral Separation
			2.2	 Temporal Coherence
			2.3	 Spatio-Temporal Resolution
			2.4	 Cross-Scattering
			2.5	 Imaging Dose
			2.6	 Field of View
			2.7	 Respiratory
		3	 Tumor and Organ Segmentation
		4	 Treatment Planning and Dose Calculation
			4.1	 Photon Therapy
			4.2	 Proton Therapy
		5	 Potential of Photon-Counting CT in Radiation Oncology
		6	 Conclusion
		References
	The Future of Spectral CT: Radiomics and Beyond
		1	 Introduction
		2	 Future Advancements in Scanning Techniques and Image Reconstruction
			2.1	 Automated Voltage and Current Optimization Techniques
			2.2	 Automated Patient Positioning and Scan Length Optimization
			2.3	 A Novel Image Quality Metric: The Detectability Index
			2.4	 Advancements in Contrast Media Applications
				2.4.1	 Patient-Optimized Contrast Media Protocols
				2.4.2	 Patient-Optimized Contrast Media Timing
			2.5	 Reconstruction Techniques
		3	 The Hidden Potential of Underutilized Data
			3.1	 Radiomics
			3.2	 Machine Learning for Diagnosis
			3.3	 Opportunistic Screening
			3.4	 Distributed Learning
		4	 Limitations of Radiomics and Artificial Intelligence
		5	 Outlook
		References
	Photon-Counting CT: Initial Clinical Experience
		1	 Introduction
		2	 Technical Specifications
		3	 Cardiovascular Imaging
		4	 Abdominal Imaging
		5	 Lung Imaging
		6	 Skeletal Imaging
		7	 Conclusions
		References