Virtual Colonoscopy (eBook)

Copyright Page 4
Foreword 5
Preface to the Second Edition 6
Preface to the First Edition 7
Contents 9
Chapter 1 11
Why We Do CTC: Screening for Colorectal Cancer 11
1.1 Introduction: What Is Screening? 11
1.2 Types of Screening: Some Defi nitions 11
1.3 Why Screen for Colorectal Neoplasm? 12
1.4 Screening Tests 14
1.4.1 The “Ideal” Screening Test 14
1.4.2 Problems with Screening 14
1.5 Screening Tests for Colorectal Neoplasm 15
1.5.1 Risk Stratification for CRN 15
1.5.2 Fecal Occult Blood Testing 15
1.5.3 Flexible Sigmoidoscopy 16
1.5.4 Colonoscopy 16
1.5.5 Barium Enema 17
1.6 CT Colonography as a Screening Test for CRN 17
1.6.1 Accuracy 17
1.6.1.1 The Problem of Flat, Depressed and Serrated Lesions 18
1.6.2 Acceptability and Participation Rates 19
1.6.3 Availability of CTC 19
1.6.4 Cost-Effectiveness of CTC Screening 19
1.6.5 Risks and Side-Effects of CTC 20
1.6.5.1 Risks of Preparation 20
1.6.5.2 Radiation Exposure 20
1.6.5.3 Colorectal Perforation 20
1.6.6 CTC as Triage in FOBT Positive Subjects 20
1.7 CT Colonography Screening: Technique 20
1.7.1 Preparation 20
1.7.1.1 Diet 20
1.7.1.2 Purgation 20
1.7.1.3 Fecal and Fluid Tagging 20
1.7.2 Colonic Distension 20
1.7.3 The Use of Intravenous Contrast Agents 21
1.7.4 Scanning Parameters and Radiation Dose 21
1.7.5 Reading the CTC Examination 21
1.7.6 Effect of Computer Aided Polyp Detection on Screening CTC 21
1.7.7 CT Colonography Reporting 21
1.7.7.1 Reporting of Polyps at CTC 22
1.7.7.2 Extracolonic Pathology 22
1.8 Future Developments 23
References 23
Chapter 2 26
The Performance of CTC 26
2.1 Introduction 26
2.2 CT Colonography 27
2.3 Our Experience 28
2.3.1 Patient Acceptance 28
2.3.2 Polyp Detection 29
2.3.3 Referral to Optical Colonoscopy 31
2.3.4 Interpretation 32
2.3.5 CAD 32
2.3.6 Polyp Measurements 34
2.3.7 The Issue of Radiation 34
2.4 Conclusion 35
References 35
Chapter 3 38
Starting CT Colonography in Your Department 38
3.1 Introduction 38
3.2 Technical Requirements 38
3.3 CT Colonography Protocols 40
3.4 Reading and Training 40
3.5 Reading Conditions 42
3.6 Patient Information, Referral and Follow Up 43
3.7 Cost and Financial Implications 43
3.8 Quality Assurance 43
References 43
Chapter 4 45
The Eligible Patient: Indications and Contraindications 45
4.1 History 45
4.2 Indications 46
4.2.1 Screening CT Colonography 46
4.2.2 Diagnostic CT Colonography 49
4.2.3 Preoperative Assessment 49
4.2.4 Preoperative Colorectal Cancer Surveillance 50
4.2.5 Incomplete Optical Colonoscopy 50
4.2.6 Inflammatory Bowel Disease Surveillance 51
4.3 Contraindications 51
4.3.1 Absolute Contraindications 52
4.3.2 Relative Contraindications 52
4.4 Current Reimbursable Indications 53
4.5 Future Indications 53
4.6 Summary 53
References 53
Chapter 5 56
Patient Preparation for CT Colonography 56
5.1 Introduction 56
5.2 Colonic Preparation 57
5.2.1 Polyethylene Glycol 57
5.2.2 Sodium Phosphate 59
5.2.3 Magnesium Citrate 60
5.3 Colonic Distension 60
5.3.1 Room Air 62
5.3.2 Carbon Dioxide 62
5.4 Anti-Spasmodic Agents 63
5.4.1 Glucagon 63
5.4.2 Hyoscine n-Butylbromide 64
References 64
Chapter 6 67
The Prerequisite: Faecal Tagging 67
6.1 Introduction 67
6.2 What Is Fecal Tagging? 68
6.3 Rationale: Why We Do It! 68
6.3.1 Improving Diagnosis 68
6.3.2 Improving Patient Compliance 68
6.4 How to Do Fecal Tagging! 69
6.4.1 Basic Principles 69
6.4.2 What Product to Use? 70
6.4.3 Implementation in Clinical Practice 70
6.4.3.1 Instruction Folder 70
6.4.3.2 Indications 71
6.4.3.2.1 After Incomplete Colonoscopy 71
6.4.3.2.2 The Symptomatic Patient 71
6.4.3.2.3 The Asymptomatic Patient 71
6.4.3.2.4 The Frail and Elderly Patient 72
6.5 Imaging Findings 72
6.5.1 Reading the Data Sets 72
6.5.2 Stool Tagging 72
6.5.2.1 Tagged Stool 72
6.5.2.2 Non-Tagged Stool 73
6.5.2.2.1 Non-Tagged Stool < 6 mm
6.5.2.2.2 Non-Tagged Stool > 6 mm
6.5.3 Fluid Tagging 73
6.5.4 Miscellaneous Findings 74
6.5.4.1 Mucous Filaments 74
6.5.4.2 Foam 74
6.6 The Future: Laxative-Free CT Colonography 77
6.6.1 Principles 77
6.6.2 Results 77
6.7 Conclusion 78
References 78
Chapter 7 80
How to Get the Colon Distended? 80
7.1 Introduction 80
7.2 Patient Preparation 81
7.3 Colonic Insufflation Methods 83
7.3.1 Manual Insufflation 83
7.3.2 Automated Insufflation 84
7.4 Carbon Dioxide or Air? 85
7.5 Choice of Rectal Catheter 86
7.6 Single vs. Multidetector Row Scanners 86
7.7 Patient Positioning 86
7.8 Intravenous Spasmolytics 87
7.9 Perforation Risk 88
7.10 Recommended Technique 89
7.11 Conclusion 89
References 90
Chapter 8 92
Right Parameters 92
8.1 Introduction 92
8.2 Scanning Parameters: Collimation and Image Reconstruction Thickness 93
8.3 The Issue of Dose Exposure 94
8.3.1 Optimization of Low-Dose Protocol 95
8.3.1.1 mAs and kVp 95
8.3.1.2 Pitch 97
8.3.1.3 Automatic Dose Modulation Systems 97
8.3.2 Other Considerations 98
References 99
Chapter 9 101
How to Interpret CTC Data: Evaluation of the Different Lesion Morphologics 101
9.1 Introduction 101
9.2 Current Maindtream Image Display Techniques 102
9.2.1 2D Multiplanar Reformation 102
9.2.2 3D Endoscopic Fly-Through 103
9.2.3 3D Transparency View (Edge-Enhanced View) 104
9.2.4 Future Advances of Image Display Techniques 104
9.3 Four Basic Steps to Detect/Characterize Focal Lesions 104
9.4 Infl uence of Stool and Fluid Tagging on Image Interpretation 106
9.5 Major Categories of Colorectal Lesion Morphologies 107
9.5.1 Focal Polypoid Lesions (r/o Stool) 107
9.5.2 Pedunculated Lesions 108
9.5.3 Sessile/Flat Lesions (r/o Thick or Confl uent Folds) 108
9.5.4 Advanced Mural Lesions (r/o Collapse) 110
9.6 Standardization of Reporting of Clinically Signifi cant Colorectal Findings and Quality Assurance 112
References 113
Chapter 10 115
How to Avoid Pitfalls in Imaging: Causes and Solutions to Overcome False-Negatives and False-Positives 115
10.1 Introduction 115
10.2 False-Negative Diagnosis 116
10.2.1 Failure to Detect the Lesion 116
10.2.1.1 Preparation-Related False-Negative Diagnosis 116
10.2.1.2 Technical Artifacts 116
10.2.1.3 Normal Anatomy: Blind Spots and Areas of Danger 117
10.2.1.4 Diverticular Disease 120
10.2.1.5 Sessile Polyps 121
10.2.1.6 Small Lesions and Small Flat Lesions 121
10.2.2 Failure to Characterize the Lesions 122
10.2.2.1 Annular Structuring Lesions 122
10.2.2.2 Larger Flat Lesions 122
10.2.2.3 Small Sessile Polyps 124
10.2.2.4 Sessile Cancers 125
10.2.2.5 Pedunculated Lesions 125
10.3 False-Positive Diagnosis 127
10.3.1 Preparation-Related False-Positive Findings 127
10.3.2 Technical Artifacts Causing False-Positive Findings 127
10.3.2.1 Breathing Artifacts 127
10.3.2.2 Spasm 130
10.3.3 Pitfalls Related to Normal Anatomy and Non-Tumoral Lesions 130
10.3.3.1 Ileocecal Valve 130
10.3.3.2 Extrinsic Impression 130
10.3.3.3 Complex or Thickened Folds 130
10.3.3.4 Submucosal Non-Tumoral Lesions 132
10.3.3.5 Appendiceal Orifi ce 135
10.3.3.6 Scar After Polypectomy 135
10.3.3.7 Spasm of the Internal Sphincter 136
10.3.3.8 Intermittently Prolapsing Rectal Mucosa 136
10.3.3.9 Diverticular Disease 136
10.3.3.9.1 The Diverticular Fecalith 136
10.3.3.9.2 Inverted Diverticulum 138
10.3.3.9.3 C Polyp-Simulating Mucosal Prolapse Syndrome 138
References 139
Chapter 11 142
3D Imaging: Invaluable for the Correct Diagnosis? 142
11.1 Introduction 142
11.2 2D and 3D Reading Are Complementary 142
11.3 Cathartic and Electronic Cleansing 144
11.4 3D Image Rendering 145
11.5 3D Display Methods 145
11.5.1 Conventional 3D Display 145
11.5.2 Alternative Enhanced 3D Display Methods 146
11.6 Primary 2D and Primary 3D Methods: Difference in Accuracy? 149
11.6.1 High-Prevalence Population 150
11.6.1.1 3D Methods 150
11.6.1.2 2D Methods 150
11.6.1.3 2D vs. 3D Method 150
11.6.2 Low-Prevalence Population 151
11.6.2.1 3D Methods 151
11.6.2.2 2D Methods 151
11.6.2.3 2D vs. 3D Technique 151
11.6.3 Discussion on Accuracy 152
11.7 Review Time 152
11.8 Conclusion and Future Development 153
References 154
Chapter 12 156
The Challenge: Detection of Early-Stage Superficial Colorectal Lesions 156
12.1 Introduction 156
12.2 Current Diagnosis of Early-Stage Colorectal Carcinomas 157
12.3 Introduction of CT Colonography in National Cancer Center, Japan 158
12.4 CTC Diagnosis of Early-Stage Superficial Colorectal Lesions 159
12.5 Potential of Computer-Assisted Detection for Superficial Lesions in CTC 160
12.6 Future Prospects of CTC Diagnosis for Early-Stage Colorectal Cancer 164
12.7 Conclusion 165
12.8 Topics 165
12.8.1 Superficial Tumor 165
12.8.2 Endoscopic Submucosal Dissection (ESD) 166
References 166
Chapter 13 167
Extracolonic Findings 167
13.1 Introduction 167
13.2 Definitions of Extracolonic Findings 168
13.3 Prevalence of the Extracolonic Findings 168
13.4 Monetary 173
References 174
Chapter 14 176
The Future: Computer-Aided Detection 176
14.1 Introduction 176
14.2 Why CAD? 177
14.3 CAD Techniques for Detection of Polyps 178
14.4 Performance in the Detection of Polyps 180
14.4.1 Performance of CAD 180
14.4.2 Improvement of Radiologists’ Detection Performance 181
14.5 CAD Pitfalls 181
14.5.1 CAD False-Negatives 181
14.5.2 CAD False-Positives 182
14.6 Current and Future Challenges 184
14.6.1 Detection and Extraction of Colorectal Masses 184
14.6.2 Use of Correspondence Between Supine and Prone Views 184
14.6.3 Effect of Fecal Tagging and Digital Bowel Cleansing 185
14.6.4 CAD for Rapid Interpretation: First Reader Paradigm 187
14.7 Conclusion 187
References 188
Chapter 15 191
Quality and Consistency in Reporting CT Colonography 191
15.1 Introduction 191
15.2 Patient Cohort 191
15.3 Patient Preparation 192
15.4 Spasmolytics and Insufflation Method 192
15.5 CT Parameters 192
15.6 Examination Interpretation 192
15.6.1 Interpretation Factors 192
15.6.2 Use of Computer-aided Detection 193
15.6.3 Readers’ Experience 193
15.6.4 Confi dence Scales 193
15.7 Lesion Size 193
15.7.1 CTC Measurement 193
15.7.2 Size Categories 193
15.7.3 Endoscopic Measurement 194
15.8 Lesion Location 194
15.8.1 CTC Location Reporting 194
15.8.2 Endoscopic Location Reporting 195
15.9 Lesion Morphology 195
15.10 Lesion Histology 195
15.11 Defi nition of “Gold Standard” 195
15.12 Diagnostic Performance 196
15.12.1 By-Patient Performance 196
15.12.2 By-Polyp Performance 196
15.13 Conclusion 196
References 196
Chapter 16 198
Virtual Colonoscopy: Beyond Polyp Detection 198
16.1 Introduction 198
16.2 Diverticular Disease 199
16.3 Infl ammatory Bowel Disease 201
16.3.1 Ulcerative Colitis 203
16.3.2 Crohn’s Disease 205
16.4 Colorectal Carcinoma 206
16.5 Colorectal Lymphoma 210
16.6 Surveillance Post-Surgery or Post-Intervention 212
References 215
Chapter 17 217
Pictorial Overview of Normal Antomy, Mimics of Disese, and Neoplasia Using CT Colonography 217
17.1 Introduction 217
17.2 Intrinsic Features of the Normal Colon 218
17.2.1 Hemorrhoids 218
17.2.2 Diverticulosis 219
17.2.3 Folds 220
17.2.4 Collapse and Contraction 221
17.2.5 Ileocecal Valve 221
17.2.6 Inverted Appendiceal Stump and Appendiceal Intussusception 224
17.3 Benign Findings 224
17.3.1 Lipomas 224
17.3.2 Diverticulitis 225
17.3.3 Pneumatosis Cystoides Coli 226
17.4 Intracolonic and Extracolonic Processes Mimicking Disease 226
17.4.1 Stool 226
17.4.2 Fluid 227
17.4.3 Extrinsic Compression 227
17.4.4 Technical Artifacts 228
17.5 Colonic Neoplasia in CT Colonography 228
17.5.1 Polyps 230 228
17.5.2 Carcinomas 235
17.6 Conclusion 236
References 239 237
Subject Index 238
List of Contributors 243
Medical Radiology 247
Diagnostic Imaging 247
Medical Radiology 249
Radiation Oncology 249