MRI of the Gastrointestinal Tract (eBook)

Medical Radiology Diagnostic Imaging 1
Title Page 2
Copyright Page 3
Foreword 4
Preface 6
Contents 7
Part I: Technique 9
Chapter 1 10
MRI of the Gastrointestinal Tract: Coils, Sequences, Techniques 10
1.1 Introduction 11
1.2 Coils 11
1.2.1 Requirements 11
1.2.2 MultiCoil Receive Arrays 11
1.2.3 Endoluminal Coils 12
1.3 Sequences 12
1.3.1 Requirements 12
1.3.2 Echoplanar (EPI) 13
1.3.3 RARE (TSE, FSE) 13
1.3.4 Single Shot RARE (TSE, FSE)/Single Shot Half-Fourier RARE (HASTE, SSFSE) 15
1.3.5 Balanced SSFP (True-FISP, FIESTA, Balanced FFE) 16
1.3.6 Spoiled Gradient Echo (FLASH, SPGR, T1FFE) 17
1.3.7 Breath-Hold Interpolated 3D T1W (VIBE, LAVA, FAME, THRIVE) 18
1.3.8 Hydrographic Projection Imaging 19
1.3.9 Fat Suppression 20
1.3.10 Dynamic Acquisition 21
1.3.11 Diff usion-Weighted Imaging 22
1.3.12 Perfusion Imaging 23
1.4 Techniques 23
1.4.1 Requirements 23
1.4.2 Pharynx and Esophagus 24
1.4.3 Stomach 24
1.4.4 Small Bowel 24
1.4.5 Colon 24
1.4.6 Rectum and Anus 24
References 25
Chapter 2 27
MRI of the Gastrointestinal Tract at High-Field Strength 27
2.1 Principal Problem of High-Field MRI 27
2.1.1 Tissue Relaxation Rates 28
2.1.2 Susceptibility 28
2.1.3 Contrast Agents 29
2.1.4 Chemical Shift Artifacts 29
2.1.5 B1-inhomogeneity Artifacts 30
2.1.6 SAR Limitations 30
2.1.7 SSFP Banding Artifacts 31
2.2 Changes to Accomodate These Problems 34
2.2.1 Improvement Using Parallel and Fast Imaging Techniques 34
2.2.2 Solving the Banding Artifact at 3 T 36
References 36
Chapter 3 38
Contrast Media for MRI of the Gastrointestinal Tract 38
3.1 Introduction 38
3.2 Contrast Agents, General Concepts 39
3.2.1 Historical Overview 39
3.2.2 Contrast Resolution 40
3.2.3 Magnetic Properties and Relaxation 41
3.2.4 T1 and T2 Agents 41
3.2.5 General Requirements for Contrast Agents 41
3.2.6 Relaxivity 42
3.2.7 Future Aspects 43
3.3 Bowel Contrast Agents 43
3.3.1 Positive Agents: Bright Lumen 43
3.3.1.1 Mechanism of Action 44
3.3.1.2 Positive Bowel Agents 44
3.3.2 Negative Agents: Dark Lumen 44
3.3.2.1 Mechanism of Action 44
3.3.2.2 Negative Bowel Agents 45
3.3.3 Biphasic Agents: MR Hydrography 45
3.3.3.1 Osmosis 46
3.3.3.2 Water Balance 46
3.3.3.3 Osmolarity: A Decisive Parameter for Bowel Distension 46
3.3.3.4 Biphasic Agents and Additives 47
3.4 Application of Bowel Agents 48
3.5 Gadolinium-Based Agentsfor Intravenous Use 49
3.5.1 Mechanism of Action 49
3.5.2 Classifi cation of Gadolinium Agents 49
3.5.3 Stability and Transmetallation 51
3.6 Conclusions 51
References 52
Chapter 4 55
Dynamic Contrast-Enhanced and Diffusion-Weighted MRI of the Gastrointestinal Tract 55
4.1 Introduction 55
4.2 Dynamic Contrast-Enhanced MRI (DCE-MRI) 56
4.2.1 Technical Parameters 56
4.2.2 Kinetic Modeling 57
4.2.2.1 Experiments Using T1-Weighted Sequences 57
4.2.2.2 Experiments Using T2*-Weighted Sequences 59
4.2.3 Histopathological Validation 59
4.2.4 Measurement Reproducibility 60
4.2.5 Clinical Studies 60
4.3 Diffusion-Weighted MRI (DW-MRI) 60
4.3.1 Technical Parameters 61
4.4 Image Analysis 62
4.5 Diffusion Tensor Imaging 62
4.6 Reproducibility and Histological Validation 63
4.7 Clinical Studies 64
4.7.1 Challenges for Bowel Imaging 64
Acknowledgments 65
References 65
Part II: Clinical Application 68
Chapter 5 69
MRI of the Esophagus and Stomach 69
5.1 Introduction 69
5.2 Techniques 71
5.2.1 Patient Preparation 71
5.2.2 Conventional MRI 71
5.2.3 High-Resolution MRI 71
5.2.3.1 External Surface Coil 71
5.2.3.2 Endoluminal: Endoscopic and Expandable surface coils 72
5.3 Normal Anatomy on MRI 73
5.3.1 Wall Layers 73
5.3.2 Surrounding Structures 74
5.4 Clinical Application: Staging Malignant Disease 74
5.4.1 T Staging 74
5.4.1.1Conventional MRI 74
5.4.1.2 High-Resolution MRI 75
T Staging Using an External Surface Coil 75
Assessment of Resectability 77
T Staging Using an Endoluminal Surface Coil 77
5.4.2 N Staging 78
5.4.3 Metastatic Disease 79
5.5 Conclusion 80
References 80
Chapter 6 83
MRI of Upper GI Tract Motility 83
6.1 Introduction 83
6.2 Physiology of Deglutition 84
6.3 MR-Fluoroscopy: Technique and Protocols 85
6.3.1 Background 85
6.3.2 Oral Contrast Agent 86
6.3.3 Oro-Pharyngeal Motility 86
6.3.4 Esophageal Motility 87
6.4 MR Patterns 89
6.4.1 Normal Findings 89
6.4.2 Abnormal Findings 89
6.4.2.1 Oro-Pharyngeal Motility 89
6.4.2.2 Esophageal Motility 89
6.5 MR Evaluation of Gastric Motility 90
6.6 Discussion 91
6.6.1 Advantages and Drawbacks 91
6.7 Conclusion 92
References 92
Chapter 7 94
MRI of the Duodenum 94
7.1 Introduction 94
7.2 Examination Technique 95
7.2.1 General Considerations 95
7.2.2 Sequences (see Table 7.1) 95
7.3 Magnetic Resonance Imaging Findings 97
7.3.1 General Considerations 97
7.3.2 Lesions of Duodenal Origin 97
7.3.2.1 Diverticula 97
7.3.2.2 Duodenal Duplication 97
7.3.2.3 Duodenal Lipoma 98
7.3.2.4 Duodenal Hematoma 99
7.3.2.5 Duodenal Stromal Tumors 99
7.3.2.6 Duodenal Adenocarcinoma 100
7.3.2.7 Duodenal Lymphoma 102
7.3.2.8 Duodenal Carcinoids 103
7.3.2.9 Duodenal Metastases 103
7.3.3 Lesions of Ampullary Origin 104
7.3.3.1 Choledococele 104
7.3.3.2 Ampullary Tumors 104
7.3.4 Lesions of Pancreatic Origin 106
7.3.4.1 Annular Pancreas 106
7.3.4.2 Paraduodenal Pancreatitis 106
7.3.5 MRI Compared to CT 108
References 115
Chapter 8 117
MRI of the Small Bowel: Enterography 117
8.1 Introduction 117
8.2 Contrast Media Used for MR Enterography 118
8.2.1 Positive Oral Contrast Agents 118
8.2.2 Negative Oral Contrast Agents 119
8.2.3 Biphasic Oral Contrast Agents 119
8.2.4 Intravenous Contrast Agents 120
8.2.5 Anti-Spasmolytic Agents 120
8.3 Technique 120
Patient position 120
Patient acceptance of MR enterography 120
8.3.1 Sequences 121
8.3.1.1 Half-Fourier Single Shot RARE (HASTE) 121
8.3.1.2 Balanced Steady-State Free Precession 121
8.3.1.3 T1-Weighted Sequences 121
8.3.1.4 Diff usion-Weighted Imaging (DWI) 121
8.3.1.5 Cine Imaging 122
8.4 Results 123
8.4.1 Crohn’s Disease 123
8.4.1.1 Bowel Wall Thickening 123
8.4.1.2 High Signal Intensity of the Bowel Wall on T2-Weighted Images 124
8.4.1.3 Enhancement After Intravenous Contrast Administration 124
8.4.1.4 Bowel Wall Stratification 124
8.4.1.5 Ulcerations 124
8.4.1.6 Comb Sign 125
8.4.1.7 Lymph Nodes 125
8.4.1.8 Fistula and Abscess 125
8.4.1.9 Stenosis 126
8.4.1.10 Creeping Fat 126
8.4.1.11 CD Disease Activity Assessment 126
8.4.1.12 CD Disease Severity Assessment 127
8.4.1.13 Place of MR Enterography in CD Patients 127
8.4.2 Celiac Disease 129
8.4.3 Benign Small Bowel Neoplasms 129
8.4.4 Malignant Small Bowel Neoplasms 130
8.4.5 Miscellaneous 131
8.5 Future Prospects of MR Enterography 132
References 132
Chapter 9 135
MRI of the Small Bowel: Enteroclysis 135
9.1 Introduction 136
9.2 MR Enteroclysis Technique 136
9.2.1 Duodenal Intubation 136
9.2.2 Intraluminal Contrast Agents 136
9.2.3 Patient’s Position 137
9.2.4 Pulse Sequences 137
9.3 Normal Appearences 140
9.4 Interpretation of Imaging Findings 141
9.4.1 Crohn’s Disease 141
9.4.2 Small Bowel Neoplasms 145
9.4.3 Intestinal Obstruction 146
9.4.4 Malabsorption Disorders 146
9.5 Limitations and Disadvantagesof MR Enteroclysis 147
9.6 Conclusions 147
List of Abbreviations 147
References 147
Chapter 10 149
MRI of the Small Bowel: Clinical Role 149
10.1 Introduction 149
10.2 Small Bowel Imaging:What is the Question? 150
10.3 Choice of Small Bowel Imaging Technique: General Considerations 150
10.3.1 The Radiation Issue 150
10.3.2 Invasive Investigations: Bowel Preparation and Tubes 150
10.3.3 Acute vs. Elective Evaluation 151
10.3.4 Capacity and Hardware 152
10.3.5 Disease Stage 152
10.3.6 Extra Enteric Assessment 152
10.4 Small Bowel Assessment: Head-to-Head Comparison – General Considerations 152
10.4.1 MR Enterography or Enteroclysis? 152
10.4.2 Radiology or Endoscopy? 155
10.5 Indications for Small Bowel Imaging 155
10.5.1 Inflammatory Bowel Disease: Crohn’s disease 155
10.5.2 Autoimmune Disease: Celiac Disease and Scleroderma/Progressive Systemic Sclerosis 159
10.5.3 Polyposis Syndromes: Familial Adenomatous Polyposis and Peutz–Jeghers Syndrome 160
10.5.4 Malignancy 162
10.5.5 Evaluation of Occult GI Bleeding 163
10.5.6 Other Small Bowel Diseases 165
10.5.6.1 Adhesions 165
10.5.6.2 Radiation Enteritis 165
10.5.6.3 Endometriosis 167
10.6 Conclusion 167
References 168
Chapter 11 172
MRI of the Colon (MR Colonography): Technique 172
11.1 Introduction 172
11.2 Basics for the Scan: Hardware 173
11.2.1 Main Magnet 173
11.2.2 Gradient System 173
11.2.3 HF-System 173
11.3 Patient Preparation and Prerequisites 174
11.3.1 Bowel Preparation 174
11.3.1.1 Bowel Cleansing 174
11.3.1.2 Fecal Tagging 175
11.3.2 Bowel Distention 176
11.3.2.1 Water-Based Distension 176
Tap Water 176
Water-Based Barium Solutions 176
Water/Gadolinium Mixture 176
11.3.2.2 Other Distension Media 176
CO2 176
Air 177
Other 177
11.3.2.3 Impact of Spasmolytic Agents 177
Glucagon 177
Butylscopolamine 177
11.3.3 Image Contrast 178
11.3.3.1 Bright Lumen MRC 178
11.3.3.2 Dark Lumen MRC 178
11.4 The Scan: Performance of MRC 179
11.5 After the Scan: Postprocessing and Image Analysis 180
11.6 Particularities of MR of the Colon at 3 T 181
References 182
Chapter 12 184
MRI of the Colon (Colonography): Results 184
12.1 Introduction 185
12.2 When to Perform MR of the Large Bowel 185
12.3 Detection of Precursors of Colorectal Cancer 185
12.3.1 Intermediate and Large Polyps 186
12.3.2 Image Interpretation 186
12.3.3 High-Prevalence Population 187
12.3.3.1 Bright Lumen Strategy 187
12.3.3.2 Dark Lumen Strategy 189
12.3.3.3 Fecal Tagging 191
12.3.4 Low Prevalence Population 193
12.3.4.1 Screening MR Colonography 193
12.4 Colorectal Cancer (CRC) 193
12.4.1 Clinical Staging 193
12.5 Infl ammatory Bowel Disease (IBD) 193
12.5.1 MRI of the Colon in Inflammatory Bowel Disease (IBD) 193
12.5.2 MR Colonography in IBD 194
12.6 Diverticular Disease and Acute Colonic Diverticulitis 197
12.7 Incomplete Colonoscopy 198
12.8 Patient Acceptance in MR Colonography 199
12.8.1 Bowel Preparation 199
12.8.2 Colonic Distension 200
12.9 Conclusion 200
References 201
Chapter 13 204
MRI of the Rectum 204
13.1 Introduction/Clinical Background 204
13.2 Standard MR Protocol for Rectal Cancer Staging 207
13.3 MR Anatomy of the Rectum and Mesorectum 208
13.3.1 Rectum 208
13.3.2 Mesorectum 209
13.3.3 Peritoneum 210
13.3.4 Blood Supply 210
13.4 Risk Assessment with MR Imaging 210
13.4.1 T-Stage 211
13.4.2 CRM 211
13.4.3 Lymph Nodes 213
13.4.3.1 Extramesorectal Lymph Nodes 214
13.5 Restaging Rectal Cancer 215
13.5.1 The yT-Stage 216
13.5.2 Tumor Regression from the Mesorectal Fascia 217
13.5.3 The yN Stage 219
13.6 Other Imaging Modalities 219
13.6.1 Endorectal Ultrasound (EUS) 219
13.6.2 CT 220 219
13.6.3 PET-CT 220
13.7 Future Perspectives 220
13.8 Conclusions and Recommendations for Rectal Cancer Management 221
13.9 Anorectal Fistulas 221
13.10 Endometriosis 223
13.10.1 MRI of “Deep Endometriosis” 224
List of Abbreviations 225
References 225
Chapter 14 227
MRI of Bowel Motility 227
14.1 Introduction 227
14.1.1 Physiology 227
14.1.2 Current Measuring Techniques 229
14.1.2.1 Scintigraphy 229
14.1.2.2 Manometry 230
14.1.2.3 Impedance Measurement 230
14.1.3 Magnetic Resonance Imaging 231
14.2 Technique 231
14.2.1 Preparation 231
14.2.2 Imaging 233
14.2.3 Data Analysis 235
14.3 In Vivo Results of Peristaltic Motion Using Dynamic MRI 238
14.3.1 Displaying Normal Motility with MRI 239
14.3.2 Postoperative Ileus and Its Recovery Phase 239
14.3.3 Impact of Drugs on Small Bowel Motility 239
14.3.4 Motility Changes in Infl ammatory Bowel Diseases 240
14.3.5 Future MR Motility Imaging Applications 242
14.4 Motility Measurement: Which Technique for What Task? 243
14.4.1 Ultrasound 243
14.4.2 Scintigraphy 243
14.4.3 Manometry 243
14.4.4 MR Motility Imaging 243
14.5 Conclusion 244
References 244
Chapter 15 246
MRI of the Peritoneum 246
15.1 Introduction 246
15.2 Technical Considerations and Protocols for Peritoneal MRI 247
15.2.1 Intraluminal Contrast Material 247
15.2.2 Intravenous Contrast Agents 248
15.2.3 Antiperistaltic Agents 248
15.2.4 MRI Protocol 248
15.2.5 MR Image Interpretation 249
15.3 Peritoneal Anatomy 250
15.4 Benign Diseases of the Peritoneum 253
15.4.1 Mesenteric Paniculitis 253
15.4.2 Mesenteric Adenitis 254
15.4.3 Peritonitis 254
15.4.4 Tuberculous Peritonitis 254
15.4.5 Sclerosing Encapsulating Peritonitis 255
15.5 Malignant Diseases of the Peritoneum 256
15.5.1 Mechanisms of Peritoneal Tumor Spread 256
15.5.1.1 Intraperitoneal Tumor Dissemination 256
15.5.1.2 Direct Spread of Tumors Along Peritoneum Pathways 257
15.5.1.3 Hematogenous Tumor Dissemination to the Peritoneum 258
15.5.2 Ovarian Cancer 258
15.4.3 Gastrointestinal Cancers 260
15.5.4 Pseudomyxoma Peritonei 260
15.5.5 Mesothelioma 262
15.5.6 Primary Peritoneal Cancer 263
15.6 Conclusion 264
References 264
Chapter 16 267
MRI of Adhesions and Small Bowel Obstruction 267
16.1 Introduction 267
16.2 MR Imaging Protocols 268
16.2.1 Functional Cine MRI 268
16.2.1.1 Method 268
16.2.1.2 Imaging Criteria 269
16.3 Bowel Obstruction 271
16.3.1 General Considerations 271
16.3.2 Extrinsic Causes 272
16.3.2.1 Intraabdominal Adhesions 272
16.3.2.2 Hernia 272
16.3.2.3 Extrinsic Masses 274
Peritoneal Carcinomatosis 274
Lymphoma 274
Appendicitis and Diverticulitis 275
16.3.3 Intrinsic Causes 275
16.3.3.1 Adenocarcinoma 275
16.3.3.2 Crohn’s Disease 275
16.3.3.3 Radiation Enteropathy 275
16.3.3.4 Intramural Intestinal Hemorrhage 276
16.3.3.5 Intussusception 276
16.3.4 Intraluminal Causes 276
16.3.4.1 Bezoars 276
16.3.4.2 Other Intraluminal Causes 276
16.3.5 Developmental Causes 276
16.3.5.1 Malrotation 276
16.4 Conclusion 277
References 277
Chapter 17 279
MRI of Acute Conditions of the Gastrointestinal Tract 279
17.1 Introduction 279
17.2 Imaging Protocols 280
17.3 Specifi c Acute Conditions of the Gastrointestinal Tract 283
17.3.1 Acute Infl ammatory Conditions of the Gastrointestinal Tract 283
17.3.1.1 Acute Appendicitis 283
Imaging Features of the Normal Appendix 284
Imaging Features of Acute Appendicitis 284
Alternative Diagnoses 287
17.3.1.2 Infl ammatory Bowel Disease 289
17.3.1.3 Primary Epiploic Appendagitis 294
17.3.1.4 Colonic Diverticulitis 296
17.3.1.5 Peptic Ulcer Disease 297
17.3.1.6 Ectopic Pancreas 300
17.3.2 Acute Neoplastic Conditions of the Gastrointestinal Tract 300
17.3.3 Ischemia and Obstruction of the Gastrointestinal Tract 301
17.3.4 Infection of the Gastrointestinal Tract 304
17.4 Conclusion 305
References 307
Chapter 18 310
MRI of the Pelvic Floor 310
18.1 Introduction 310
18.2 Technical Considerations 311
18.2.1 Patient Positioning 311
18.2.2 Patient Preparation 311
18.2.3 Imaging Technique 312
18.2.4 Image Analysis 313
18.2.5 Normal Findings 313
18.3 Spectrum of Abnormal Findings 314
18.3.1 Rectocele 314
18.3.2 Enterocele 316
18.3.3 Intussusception and Rectal Prolapse 317
18.3.3.1 Intussusception 317
18.3.3.2 External Rectal Prolapse 318
18.3.2 Pelvic Organ Prolapse 318
18.3.2.1 Cystocele 318
18.3.2.2 Utero-Vaginal Prolapse 319
18.3.3 Pelvic Floor Relaxation (Pelvic Floor Descent), Descending Perineal Syndrome 319
18.3.4 Dyssynergic Defecation 319
18.4 Conclusion 321
References 321
Chapter 19 323
MRI of the Anus 323
19.1 MRI of Fistula-In-Ano 323
19.1.1 Anal Anatomy and the Etiology of Fistula-In-Ano 324
19.1.2 Classifi cation of Fistula-In-Ano 325
19.1.3 Clinical Assessment and Treatment of Fistula-In-Ano 326
19.1.4 MR Imaging of Fistula-In-Ano 327
19.1.5 MRI Technique 328
19.1.6 Image Interpretation 329
19.1.7 Effect of Preoperative MRI on Surgery and Clinical Outcome 333
19.1.8 Differential Diagnosis of Perianal Sepsis 334
19.1.9 Which Patients Should Be Imaged? 335
19.2 MR Imaging to Investigate Anal Incontinence 336
19.2.1 Anal Incontinence 336
19.2.2 MRI Findings in Anal Incontinence 336
19.3 MR Imaging of Anal Malignancy 337
References 339
Subject Index 341
List of Contributors 346
Medical Radiology 350
Medical Radiology 352