Clinical and Biomedical Engineering in the Human Nose: A Computational Fluid Dynamics Approach

Preface
Acknowledgements
Contents
Contributors
List of Figures
List of Tables
1 Clinical and Biomedical Engineering in the Human Nose
	1.1 Introduction
	1.2 Historical Perspectives
	1.3 CFD for Clinical Practice in the Human Nose
	1.4 CFD Workflow for Clinical Applications
	1.5 Summary
	References
2 Anatomy and Physiology  of the Human Nose
	2.1 Functions and Organisation of the Respiratory System
		2.1.1 Secondary Functions of the Conducting Zone
	2.2 Nasal Cavity Anatomy
	2.3 Nasal Anatomy
		2.3.1 The External Nose
		2.3.2 Nasal Valves
		2.3.3 The Nasal Cavity
		2.3.4 The Paranasal Sinuses
		2.3.5 Maxillary Sinuses
		2.3.6 Ethmoid Sinuses
		2.3.7 Sphenoid Sinuses
		2.3.8 Frontal Sinuses
		2.3.9 The Ostiomeatal Complex
	2.4 Function and Physiology of the Nose
		2.4.1 The Nasal Cycle
		2.4.2 Filtration
		2.4.3 Thermoregulation and Humidification
		2.4.4 Olfaction
	2.5 Histology
		2.5.1 Nasal Mucosal Surface
	2.6 Summary
	References
3 Sinonasal Anatomic Variants, Diseases and their Management
	3.1 Nasal Cavity Variants
		3.1.1 Gender Difference
		3.1.2 Age Variation
		3.1.3 Ethnic Climatic Variation
	3.2 Pneumatization of the Paranasal Sinuses
	3.3 Ethmoid Cell Variations
	3.4 Common Disorders of the Nose, Sinuses and Their Treatment
		3.4.1 Sinonasal Symptoms
		3.4.2 Assessment of the Nasal Cavity
	3.5 Common Disorders of the Nasal Cavity
		3.5.1 Septal Deviation
		3.5.2 Concha Bullosa
		3.5.3 Allergic Rhinitis
		3.5.4 Non-allergic Rhinitis
		3.5.5 Nasal Valve Collapse
		3.5.6 Septal Perforation
		3.5.7 Chronic Rhinosinusitis
	References
4 Surgery of the Nasal Cavity
	4.1 Introduction
	4.2 Pre-operative Assessment of Nasal Function
		4.2.1 Patient-Reported Outcome Measures (PROMs)
		4.2.2 Objective Measures of NAO
	4.3 General Approach to Nasal Surgery
		4.3.1 Preoperative Approach
		4.3.2 Peri-Operative Approach
	4.4 Septoplasty and Rhinoplasty
		4.4.1 Septoplasty
		4.4.2 Endoscopic Septoplasty
		4.4.3 Open Septorhinoplasty
	4.5 Management of the Inferior Turbinate
	4.6 Management of the Middle Turbinate
	4.7 Functional Endoscopic Sinus Surgery
	4.8 FESS in Detail
	4.9 Scope of CFD in Virtual Surgery
	4.10 Validity of CFD in Modelling the Nasal Cavity
	4.11 Nasal Airflow
	4.12 Virtual Septoplasty
	4.13 Virtual Inferior Turbinoplasty
	4.14 Virtual Sinus Surgery
	4.15 Virtual Surgery Software
	4.16 Limitations
	4.17 Summary
	References
5 Computational Reconstruction of the Human Nasal Airway
	5.1 Introduction
	5.2 Acquisition of Imaging Data
		5.2.1 Computed Tomography
		5.2.2 Magnetic Resonance
	5.3 Image Enhancement
		5.3.1 Metal Artifact Reduction (MAR)
		5.3.2 Edge-Preserving Smoothing
	5.4 Image Segmentation
		5.4.1 Threshold-Based Segmentation
		5.4.2 Edge-Based Segmentation
		5.4.3 Hybrid Techniques
		5.4.4 Energy Minimization
		5.4.5 Deep Learning
	5.5 Nasal Cavity Reconstructions, NASAL-Geom
	5.6 Controversies, Challenges and Future Directions in Reconstruction
	References
6 Computational Meshing for CFD Simulations
	6.1 Introduction
	6.2 Mesh Types
		6.2.1 Unstructured Meshes
		6.2.2 Structured Meshes
		6.2.3 Structured Versus Unstructured Meshes
		6.2.4 Polyhedral Meshing
	6.3 Parallel Mesh Generation of Hierarchical Cartesian Meshes
		6.3.1 Description of the Parallel Meshing Algorithm
		6.3.2 Meshing Example and Parallel Performance
	6.4 Quality of Meshes
		6.4.1 Skewness and Aspect Ratio
		6.4.2 Mesh Independence
	6.5 Advanced Application: Lattice-Boltzmann Methods in Complex Geometries
		6.5.1 The Boltzmann Equation
		6.5.2 Computational Lattice-Boltzmann Methods
		6.5.3 Summary and Conclusions on Using Lattice-Bolztmann Methods
	6.6 Advanced Application: Highly Resolved Simulations
		6.6.1 Mesh Resolution Required for Fully-Resolved Simulations
		6.6.2 Examples of Simulation Results
		6.6.3 Recapitulation: Using Highly-Resolved Meshes
	6.7 Summary and Conclusion
	References
7 Fundamentals of Fluid Dynamics
	7.1 Introduction
		7.1.1 CFD Fundamentals
		7.1.2 CFD Solver Basics
	7.2 Fluid Dynamics and Governing Equations
		7.2.1 Conservation of Mass
		7.2.2 Newton's Second Law
		7.2.3 Conservation of Energy
		7.2.4 Transport
		7.2.5 Derivation of the Navier–Stokes and Continuity Equations
	7.3 Turbulent Flow
		7.3.1 Flow Regimes—Laminar and Turbulent Flow
		7.3.2 Features of Turbulent Flow
		7.3.3 Introduction to Turbulence Modelling
		7.3.4 Near-Wall Modelling
	7.4 Flow and Time—Steady or Unsteady?
		7.4.1 Steady Simulations
		7.4.2 Unsteady Simulations
		7.4.3 Temporal Considerations in Respiratory Simulations
	7.5 Practical Respiratory Airflow Modelling
		7.5.1 Simulation Resolution
		7.5.2 Turbulence Modelling
		7.5.3 Comparison to Experimental Results
		7.5.4 Boundary Conditions
	References
8 Clinical Implications of Nasal Airflow Simulations
	8.1 Introduction
		8.1.1 Importance of Nasal Airflow
	8.2 Interpreting CFD Simulation Results
		8.2.1 Physical Accuracy
		8.2.2 Physiological Accuracy
		8.2.3 Clinical Relevance
	8.3 Correlating CFD with Objective Clinical Tests
		8.3.1 CFD versus Rhinomanometry
		8.3.2 CFD versus Acoustic Rhinometry
	8.4 Some Open Problems in Comparing CFD to Objective Clinical Tests
	8.5 Correlating CFD with Subjective Measures of Nasal Airflow
		8.5.1 Subjective Measures of Nasal Airflow
		8.5.2 Nasal Resistance
		8.5.3 Airflow Partitioning
		8.5.4 Mucosal Cooling
		8.5.5 Intranasal Airflow Distribution
		8.5.6 Other CFD Variables
	8.6 CFD Results in the Normal Nose
		8.6.1 Normal Nasal Anatomical Variability
		8.6.2 Normal Nasal Airflow Description
		8.6.3 CFD Results in the Normal Sinuses
		8.6.4 Nitric Oxide and Sinuses
	8.7 Summary
	References
9 Clinical CFD Applications 1
	9.1 Airflow and Conditioning in the Nasal Cavity
		9.1.1 Introduction
		9.1.2 Airflow and Conditioning in the Paranasal Sinuses
		9.1.3 Summary
	9.2 Fluid and Particle Dynamics from Sniffing
		9.2.1 What Is Sniffing?
		9.2.2 Modelling
		9.2.3 Sniffing Airflow Behaviour
		9.2.4 Particle Deposition
		9.2.5 Summary
	9.3 Nasal Obstruction and Empty Nose Syndrome: What Are Our Noses Sensing?
		9.3.1 Introduction
		9.3.2 Image-Based Computational Fluid Dynamics (CFD) Simulations
		9.3.3 Menthol Lateralization Detection (LDT) Thresholds
		9.3.4 Clinical Studies of Empty Nose Syndrome Patients
		9.3.5 Conclusion Remarks and Future Directions
	9.4 Nasal Nitric Oxide (nNO) Dynamics and the Ostiomeatal Complex: Fertile Ground for CFD?
		9.4.1 Background
		9.4.2 Normal NO Physiology
		9.4.3 nNO: Clinical Studies
		9.4.4 Studies of NO Dynamics in the Upper Airway
		9.4.5 Conclusions
	References
10 Clinical CFD Applications 2
	10.1 Whole-Lung Modelling
		10.1.1 Introduction
		10.1.2 Existing Whole-Lung Modeling Strategies
		10.1.3 The Future of Whole-Lung Modeling
	10.2 Modeling the Effect of Airway Motion Using Dynamic Imaging
		10.2.1 Introduction and Clinical Significance
		10.2.2 3D Cine Imaging
		10.2.3 Extracting Airway Motion from Cine Images
		10.2.4 Dynamic CFD Simulations
		10.2.5 Outputs from Moving Airway CFD Simulations
		10.2.6 Clinical Implications of Moving CFD Simulations
	10.3 Automatic Reconstruction of the Nasal Geometry from CT Scans
		10.3.1 Introduction
		10.3.2 How Does a CNN Work and How Can a CNN Be Trained to Segment CT Images?
	References
11 CFD Applications for Drug Delivery
	11.1 Introduction
	11.2 CFD Modeling of Nasally Administered Drug Delivery in Regulatory Science Research
		11.2.1 Generic Drug Regulatory Research Program
		11.2.2 General Model Development for CFD and PBPK Modeling of Nasal Drug Products
		11.2.3 Application-Specific CFD Modeling of Nasal Drug Products
		11.2.4 Conclusion
	11.3 Improving Olfactory Targeting for Nose-to-Brain Drug Delivery
		11.3.1 Introduction
		11.3.2 Methods
		11.3.3 Discussion
	11.4 Nasal Spray Atomization
		11.4.1 Nasal Spray Drug Delivery
		11.4.2 Experimental Visualisation
		11.4.3 Spray Droplet Characteristics
		11.4.4 Spray Models
		11.4.5 Summary
	11.5 Nasal Saline Irrigation Using a Neti-Pot
		11.5.1 Introduction
		11.5.2 Method
		11.5.3 Results
		11.5.4 Sinus Penetration
		11.5.5 Discussion
		11.5.6 Conclusion
	11.6 Nasal Saline Irrigation from a Squeeze Bottle
		11.6.1 Nasal Saline Irrigation
		11.6.2 Model Setup
		11.6.3 Comparisons
		11.6.4 Summary
	References
12 Future Topics, Challenges
	12.1 Whole Respiratory Models
	12.2 Dynamic Meshing
	12.3 Machine Learning and Big Data
	12.4 Advanced Physiology
	References
Appendix A List of Useful Computational Software
A.1 Dicom Viewers
A.2 Open Source Medical Imaging and Segmentation
A.3 Commercial Medical Imaging and Segmentation
A.4 Open Source Computer Aided Design Software
A.5 Commercial Computer Aided Design Software
A.6 Open Source CFD Packages
A.7 Commercial CFD Packages
A.8 Third Party Post-Processing Software
Index