Imaging in Nephrology

This book is a wide-ranging guide to current and emerging applications of ultrasonography within nephrology that aims to provide readers with a sound understanding of the rationale for and the use of ultrasound techniques in various disease settings, including, for example, complications following renal transplantation, arteriovenous fistulas, renal artery stenosis, nonstenotic renal artery pathology, renal vein pathology, aortic disease, and acute renal failure. Particular emphasis is placed on newer applications, such as those involving elastosonography, contrast-enhanced ultrasonography, and color Doppler imaging. There is no doubt that ultrasound techniques can improve the standard of care in nephrology, from vascular access planning to management of uremic complications. Nevertheless, many nephrologists continue to delegate the performance of ultrasonography to radiologists or other colleagues, which is especially regrettable given the advent of affordable, portable ultrasound scanners. This book will be of value for all clinicians interested in the role of ultrasound techniques in nephrology and will be especially useful for nephrologists seeking to incorporate ultrasonography into their practice. Foreword Foreword Contents About the Editors Part I: General Principles 1: Doppler Signal and Doppler Waveform Analysis 1.1 Doppler Effect in Ultrasound 1.1.1 Doppler Effect 1.1.2 Doppler Effect: From Theory to Clinical Applications 1.2 Doppler Ultrasound Technology Systems 1.2.1 Continuous-Wave Doppler (CW) 1.2.2 Pulsed-Wave Doppler (PW) 1.2.3 Duplex Scanner 1.2.4 Color Doppler (CD) and Power Doppler (PD) Technology 1.3 Hemodynamic Principles 1.4 Doppler Signal Semeiotics 1.4.1 Interpretation of the Spectral Curve 1.4.1.1 The Arterial Flow 1.4.1.2 The Venous Flow 1.4.2 Parameters of the Spectral Curve 1.4.2.1 Quantitative Parameters 1.4.2.2 Semiquantitative Parameters 1.4.3 Alterations of the Spectral Curve 1.4.3.1 Effects of Stenosis and Dilatations 1.4.3.2 Alterations of Peripheral Blood Stream 1.4.3.3 Arterial Wall Elasticity References 2: Grayscale Ultrasound Artifacts 2.1 Introduction 2.2 Artifacts Related to Structures and Beam Interaction 2.2.1 Rear Reinforcement (Enhancement Artifact) 2.2.2 Shadowing Artifacts 2.2.3 Side Acoustic Shadows 2.2.4 Comet-Tail Artifact 2.2.5 Ring-Down Artifact 2.2.6 Reverberation 2.2.7 Rain Effect 2.2.8 Mirror Image Artifact 2.2.9 Lateral Displacement of the Image Artifact 2.2.10 Image Splitting or Refraction Artifact 2.2.11 Speed Error Artifact 2.2.12 The Partial-Volume Effect (Artifacts Caused by the Layer Thickness) 2.2.13 Side-Lobe Artifact 2.2.14 The Speckle Artifact 2.3 Artifacts Related to Apparatus and to the Beam Properties and Processing 2.3.1 Range-Ambiguity Artifact 2.3.2 Artifacts from Incorrect Adjustment of Gain 2.3.3 Artifacts Produced by the Ultrasound Malfunction 2.3.4 Artifacts from Incorrect Image Processing 2.3.5 Artifacts Produced by the Adaptive Filtering (Artifacts from Poor Resolution) 2.3.6 The Dragging Artifact (Cigar Effect) 2.3.7 Hyperbolic Artifacts References 3: Color Doppler and CEUS Artifacts 3.1 Introduction 3.2 Doppler Imaging Artifacts 3.2.1 Aliasing Artifact 3.2.2 Twinkling Artifact 3.2.3 Edge Artifact 3.2.4 Flash Artifact 3.2.5 Pseudoflow Artifact (Ureteral Jet Phenomenon Included) 3.3 Contrast-Enhanced Doppler Imaging Artifacts 3.3.1 (Color) Blooming Artifact 3.3.2 Jail-Bar Artifact 3.3.3 Systolic Peak Velocity Increase 3.3.4 High-Intensity Spikes 3.4 Contrast-Enhanced, Grayscale Sonography Artifacts 3.4.1 Slice-Thickness Artifact or Partial-Volume Artifact 3.4.2 Background Signal and Pseudoenhancement 3.4.3 Overenhancement 3.4.4 Underenhancement References 4: AKI and CIN: Real or Hype? 4.1 Introduction 4.2 Limitations of Previous Studies on CIN 4.3 Definition of CIN and PC-AKI 4.4 Risk Factors 4.5 Management of At-Risk Patients 4.6 Conclusion References 5: NSF: Real or Hype? 5.1 Introduction 5.2 MR Contrast Agents 5.2.1 Chemistry 5.2.2 Stability 5.2.3 Transmetallation 5.2.4 Pharmacokinetics 5.3 Adverse Reactions 5.3.1 Acute Adverse Reactions 5.3.2 Very Late Adverse Reaction 5.4 Discussion 5.5 Conclusion References 6: Gadolinium Retention in Brain and Body: Clinical and Preclinical Evidence 6.1 Introduction to Clinical GBCA Use in MRI and Gadolinium Retention in General 6.1.1 Clinical Use of Contrast-Enhanced MRI 6.1.2 Definitions and Terminologies 6.1.3 Safety and Efficacy of GBCAs: The Role of Gadolinium Retention 6.2 Gadolinium Retention in the Brain 6.2.1 Clinical Studies 6.2.2 Preclinical Results on Brain Retention (i.e., Animal Studies) 6.3 Gadolinium Retention in Bone 6.3.1 Clinical Studies 6.3.2 Preclinical Results on Bone Retention (i.e., Animal Studies) 6.4 Gadolinium Retention in the Skin 6.4.1 Clinical Studies 6.4.2 Preclinical Results on Skin Retention (i.e., Animal Studies) 6.5 Gadolinium Retention in Splanchnic Organs 6.5.1 Clinical Studies 6.5.2 Preclinical Results from Splanchnic Organs (i.e., Animal Studies) 6.6 Clinical Consequences of Gadolinium Retention 6.7 Concluding Remarks References Part II: Native Kidney 7: Acute Kidney Injury: Color Doppler US 7.1 Introduction 7.2 Prerenal AKI 7.3 Renal AKI 7.4 Postrenal AKI References 8: Chronic Kidney Disease: Color Doppler US 8.1 Introduction 8.2 Ultrasound Evaluation 8.3 Pathological Modifications References 9: The Diabetic Kidney 9.1 Introduction 9.2 Pathophysiology and Natural History 9.3 Ultrasound Imaging References 10: Renal Vessels 10.1 Normal Anatomy 10.1.1 Renal Arteries 10.1.2 Renal Veins 10.2 Ultrasound Examination 10.2.1 Technique 10.3 Computed Tomography: Technique and Indications 10.4 MRI: Technique and Indications 10.5 Renal Angiography: Indications and Technique 10.6 Renal Artery Stenosis 10.6.1 Introduction 10.6.2 Renal Artery Stenosis: Ultrasound 10.6.3 Direct (Proximal) Criteria 10.6.4 Indirect (Distal) Criteria 10.7 Prognostic Value of Doppler Measurements 10.8 Technological Improvements Over the Years 10.9 Follow-Up After Revascularization 10.10 Atherosclerotic Stenosis 10.10.1 CT 10.10.2 MRI 10.10.3 Nuclear Medicine 10.10.4 Angiography 10.11 Fibromuscular Dysplasia 10.11.1 Fibromuscular Dysplasia 10.11.1.1 CT 10.11.1.2 Angiography 10.12 Renal Artery Aneurysm 10.12.1 Endovascular Embolization of Renal Artery Aneurysm 10.13 Arteriovenous Malformations 10.14 Renal Artery Dissection 10.15 Acute Renal Artery Occlusion: Renal Artery Thrombosis 10.16 Vasculitis 10.17 Renal Vein Thrombosis 10.18 Spontaneous Splenorenal Shunt 10.19 Renal Varix 10.20 Nutcracker Syndrome 10.21 Miscellaneous References 11: Renal Traumas in Nephrologic Patients 11.1 Introduction 11.2 Clinical Evaluation 11.3 Type and Classification of Renal Trauma 11.4 Imaging 11.5 Second-Level Imaging with Contrast 11.6 Conclusions References 12: The Elderly Kidney 12.1 Introduction 12.2 Structural Changes 12.3 Functional Changes 12.4 Ultrasound and Color Doppler Evaluation of Kidney in Elderly 12.4.1 Ultrasound 12.4.2 Color Doppler 12.5 Renal Disorders in the Elderly 12.5.1 Chronic Kidney Disease (CKD) 12.5.1.1 US/Color Doppler 12.5.2 Occult Renal Insufficiency (ORI) 12.5.3 Diabetic Nephropathy 12.5.3.1 US/Color Doppler 12.5.4 Acute Renal Failure 12.5.4.1 US/Color Doppler 12.5.5 Vasculitis 12.5.5.1 US/Color Doppler 12.5.6 Acute Obstructive Uropathy 12.5.6.1 US/Color Doppler References 13: Intraparenchymal Renal Resistive Index: The Basic of Interpretation and Common Misconceptions 13.1 Introduction 13.2 Examination Technique 13.3 Renal Resistive Index Main Determinants 13.4 Cardiovascular System and Resistive Renal Index 13.5 Renal Resistive Index in Acute Kidney Injury 13.6 Renal Resistive Index in Chronic Kidney Disease 13.7 Renal Resistive Index in Transplanted Kidney 13.8 Renal Resistive Index and Splenic Resistive Index 13.9 Renal Resistive Index Heritability 13.10 Conclusions References 14: Contrast-Enhanced Ultrasound (CEUS) in Nephrology 14.1 Introduction 14.2 The Chemical Structure of Echo Amplifiers 14.3 Tolerance and Side Effects 14.4 Clinical Applications of CEUS Imaging in Nephrology 14.4.1 Study Methods 14.4.2 Normal Kidney 14.4.3 Pseudo-Lesions 14.4.4 Differential Diagnosis Between Solid Lesions and Cysts 14.4.5 Lesions with Dubious Enhancement at CT 14.4.6 Traumatic Pathology 14.4.7 Phlogistic Pathology 14.4.8 Study of Patients Submitted to Ablative Therapies 14.4.9 Renal Ischemia 14.4.10 Renal Artery Stenosis 14.4.11 Vesicoureteral Reflux 14.4.12 Transplanted Kidney References 15: Functional MR Imaging in Native Kidney Dysfunction 15.1 Functional MRI Tools 15.2 Dynamic Contrast-Enhanced MRI (DCE-MRI) 15.2.1 Clinical Applications 15.3 Arterial Spin Labeling (ASL) 15.3.1 Clinical Applications 15.4 Diffusion-Weighted MRI (DW-MRI) 15.4.1 Clinical Applications 15.5 Blood Oxygen Level-Dependent (BOLD) 15.5.1 Clinical Applications 15.6 Limitations and Future Directions References Part III: Transplanted Kidney 16: Transplanted Kidney 16.1 Introduction 16.2 Methods for the Study of Renal Transplant 16.2.1 Computed Tomography 16.2.2 MR Imaging 16.2.3 Nuclear Medicine 16.3 Ultrasound Evaluation of Normal Renal Transplant 16.4 Parenchymal Complications 16.4.1 Immediate Graft Parenchymal Complications 16.4.1.1 Hyper-Acute Rejection 16.4.1.2 Acute Tubular Necrosis (ATN) 16.4.2 Early Graft Parenchymal Complications 16.4.2.1 Acute Rejection 16.4.2.2 Drug Toxicity 16.4.2.3 Acute Graft Pyelonephritis (AGPN) 16.4.2.4 Viral Infections: BK and Cytomegalovirus Nephropathy 16.4.3 Late Graft Parenchymal Complications 16.4.3.1 Recurrent Primary Disease and “De Novo” Renal Disease 16.4.3.2 Chronic Renal Rejection 16.4.3.3 Neoplasm (Posttransplant Lymphoproliferative Disorder) 16.5 Vascular Complications 16.6 Transplanted Renal Artery Stenosis (TRAS) 16.6.1 Epidemiology 16.6.2 Clinical Manifestations and Pathogenesis 16.6.3 Diagnosis 16.6.4 Color Doppler Ultrasound (CDUS) 16.6.4.1 New Renal Ultrasound-Based Imaging: Contrast-Enhanced Ultrasound (CEUS) 16.6.5 Nuclear Medicine Imaging (NMI) 16.6.6 CT and MRI Angiography 16.6.7 Arteriography 16.7 Renal Artery Thrombosis (RAT) 16.7.1 Epidemiology 16.7.2 Clinical Manifestations and Pathogenesis 16.7.3 Diagnosis 16.8 Renal Vein Thrombosis (TTRV) 16.8.1 Epidemiology, Clinical Manifestations, and Pathogenesis 16.8.2 Diagnosis 16.8.2.1 Ultrasound-Based Diagnosis (CDUS and CEUS) 16.8.2.2 Arteriography 16.9 Arteriovenous Fistulas and Pseudoaneurysms 16.9.1 Epidemiology, Clinical Manifestations, and Pathogenesis 16.9.2 Diagnosis 16.9.2.1 Ultrasound-Based Diagnosis (CDUS and CEUS) 16.9.2.2 Arteriography 16.10 Rare Vascular Complications 16.10.1 Diagnosis 16.10.1.1 Ultrasound-Based Diagnosis (CDUS and CEUS) 16.10.1.2 CT and MRI Angiography 16.11 Conclusions References 17: Sonographic Evaluation of Surgical Complications of Kidney Transplantation 17.1 Introduction 17.2 Sonographic Evaluation of Surgical Complications of Kidney Transplantation 17.2.1 Focal Renal Parenchymal Lesions 17.2.2 Perinephric Fluid Collections 17.2.2.1 Urinoma or Urinary Leak 17.2.2.2 Hematoma 17.2.2.3 Lymphoceles 17.2.2.4 Perinephric Abscesses 17.2.3 Vascular Complications 17.2.3.1 Renal Artery Stenosis (RAS) 17.2.3.2 Renal Artery Thrombosis 17.2.3.3 Renal Vein Thrombosis 17.2.3.4 Arteriovenous Fistulas and Pseudoaneurysms 17.2.4 Complications of the Collecting System and Ureter 17.2.4.1 Ureteral Obstruction References 18: Functional MR Imaging in Transplanted Kidney Dysfunction 18.1 Blood-Oxygen Level-Dependent MRI 18.2 Arterial Spin Labeling (ASL) 18.3 Diffusion-Weighted and Diffusion Tensor Imaging 18.4 MR Angiography 18.5 MR Nephro/Urography References Part IV: Inteventional Procedures and New Trends 19: Elastography of the Kidney 19.1 Introduction 19.2 Elastography Techniques 19.2.1 US Elastography 19.2.2 MR Elastography 19.3 Technical Impact on Renal Sampling 19.4 Normal Values and Reproducibility 19.5 Elastography and Renal Function 19.6 Elastography and Histopathological Changes 19.6.1 Preclinical Studies 19.6.2 Clinical Studies on Native Kidneys 19.6.3 Clinical Studies on Transplanted Kidneys 19.7 Factors of Variation Influencing Elasticity Measurement in the Kidney References 20: Renal Biopsy 20.1 Introduction 20.2 Indications for Renal Biopsy 20.3 Contraindications for Renal Biopsy 20.4 Equipment 20.5 Preparation of the Patient 20.6 Position of the Patient 20.7 Ultrasound Survey 20.7.1 Prebiopsy Ultrasound Study 20.7.2 Procedure of Renal Biopsy 20.7.3 Performing the Biopsy in the Prone Position 20.7.4 Performing the Biopsy in the Supine Anterolateral Position (SALP) 20.8 Percutaneous Renal Transplant Biopsy 20.9 Monitoring 20.10 Complications 20.11 Conclusion References 21: Peritoneal Dialysis Catheter 21.1 Introduction 21.2 Catheter-Related Infections 21.3 Peritoneal Catheter Malfunction 21.4 Leakage and Defects of the Peritoneal Wall 21.5 Peritoneal Adherences 21.6 Prevention of Inferior Epigastric Artery Lesion 21.7 Catheter Placement 21.8 Peritoneal Thickening 21.9 Intraperitoneal Cyst or Abscess Formation 21.10 Intestinal Perforation 21.11 Encapsulating Peritoneal Sclerosis 21.12 Conclusions and Outlook References 22: Ultrasound-Guided Central Venous Catheter Placement for Hemodialysis 22.1 Introduction 22.2 Type of Ultrasound Scanner 22.2.1 Type and Position of Ultrasound Probe 22.2.2 Ultrasound Setting 22.3 Ultrasound Scan and Anatomy 22.4 Preoperative Evaluation of the Patient 22.5 Ultrasonography Techniques 22.6 Materials 22.7 Procedure 22.8 Indications: Anatomical Sites Compared 22.9 Early Complications 22.9.1 Arterial Puncture, Hematoma, Hemorrhage 22.9.2 Pneumothorax 22.9.3 Hemothorax 22.9.4 Air Embolism 22.9.5 Cardiac Arrhythmias 22.9.6 CVC Malposition 22.10 Conclusion References Part V: Non-renal Imaging in Nephrologic Patients 23: Parathyroid 23.1 Introduction 23.2 Anatomical Characteristics of Parathyroid Glands 23.3 Echographic Evaluation of the Cervical Region 23.4 Parathyroid Scintigraphy 23.5 Computed Tomography (CT) and Nuclear Magnetic Resonance (NMR) References 24: The Role of Doppler Ultrasound in Preoperative Vascular Mapping and Postoperative Follow-Up of Arteriovenous Fistula for Hemodialysis 24.1 Introduction 24.2 The Doppler Ultrasound in the Presurgical Phase: “Preoperative Vascular Mapping” 24.2.1 Technical Requirements and Examination Technique 24.2.2 Preoperative Arterial Mapping: Morphological Parameters 24.2.3 Preoperative Arterial Mapping: Functional Parameters 24.2.4 Preoperative Venous Mapping: Morphological Parameters 24.2.5 Preoperative Venous Mapping: Functional Parameters 24.3 The Doppler Ultrasound in the Postsurgical Phase: “Maturation and Surveillance of AVF” 24.3.1 Role of DUS in the Assessment of AVF Maturation 24.3.2 Calculation of AVF Flow Volume 24.3.3 Role of DUS in the Surveillance of AVF (Follow-Up and Detection of Complications) 24.4 Morphological Assessment (B-Mode) 24.5 Color Doppler Examination 24.6 Doppler Ultrasound Assessment 24.7 Diagnosis of Stenosis 24.8 Conclusions References 25: Carotid Artery Evaluation 25.1 Carotid Arteries: Normal Anatomy 25.2 Imaging Techniques 25.2.1 Ultrasound 25.2.1.1 US Technological Innovations 25.2.2 Computed Tomography Angiography 25.2.3 Magnetic Resonance 25.3 Atherosclerotic Stenosis 25.3.1 Doppler Ultrasound Evaluation for Carotid Stenosis 25.3.1.1 Plaque Characterization 25.3.1.2 Grading ICA Stenosis 25.3.1.3 Waveform Analysis 25.3.2 CTA in Carotid Stenosis 25.3.3 MRI in Carotid Stenosis and Occlusion 25.3.4 Carotid Angiography and Stenosis Treatment 25.4 Carotid Aneurysm and Pseudoaneurysm 25.5 Carotid Artery Dissection 25.6 Carotid Vasculitis 25.7 Fibromuscular Dysplasia References 26: Echocardiography in Nephrology 26.1 Introduction 26.2 Role of Echocardiography 26.3 Echocardiography: Principles of Cardiac Ultrasonography 26.4 Echocardiography Views 26.4.1 Parasternal Long- and Short-Axis View 26.4.2 Apical Views 26.4.3 Subcostal and Suprasternal Views 26.5 Principles of the Doppler Echocardiography 26.6 Contrast Echocardiography 26.7 Echocardiography in CKD 26.7.1 CKD-Related Cardiomyopathy 26.7.2 Left Ventricular Systolic and Diastolic Dysfunction 26.7.3 Right Heart Dysfunction and Pulmonary Hypertension 26.7.4 Pericardial Disease References 27: Basic Lung Ultrasonography for the Nephrologist 27.1 Introduction 27.2 Lung Ultrasound in Kidney Disease: Current Knowledge and Future Perspectives 27.2.1 Detection of Volume Overload 27.2.2 Prognosis 27.2.3 Methodology 27.3 Conclusions References