SECTION 1: COMMON SYMPTOMS AND SIGNS: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 4 Imaging Anatomy and Overview 10 Abdominal Pain 16 Nausea and Vomiting 20 Diarrhea 24 Constipation 28 Gastrointestinal (GI) Bleeding 34 Jaundice 40 Abdominal Trauma 44 Abdominal Abscesses and Fistulas 46 Iatrogenic Injury: Feeding Tubes 48 Imaging of Bariatric Surgery 54 Imaging of Pregnant Patients 54 Postoperative and Postprocedure Bowel Imaging SECTION 2: DISORDERS AFFECTING MULTIPLE ORGANS: IMAGING APPROACH INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 60 HIV/AIDS 64 IgG4-Related Disease 66 Vasculitis 68 Eosinophilic Gastroenteritis and Esophagitis 69 Scleroderma and Related Disorders 70 Cystic Fibrosis TRAUMA AND FOREIGN BODIES 72 Foreign Bodies 76 Barotrauma NEOPLASMS 78 Leukemia and Lymphoma 80 Gastrointestinal Stromal Tumors (GIST) 82 Neuroendocrine Tumors SECTION 3: ABDOMINAL WALL, MESENTERY, AND PERITONEAL CAVITY: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 90 Abdominal Wall, Mesentery, and Peritoneal Cavity: Imaging Approach and Differential Diagnosis Michael P. Federle, MD, FACR INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 94 Peritonitis 96 Ascites 98 Omental Infarction 99 Inguinal Hernia 100 Femoral Hernia 101 Ventral Hernia 102 Umbilical Hernia 103 Obturator Hernia 104 Spigelian Hernia 105 Lumbar Hernia 106 Paraduodenal Hernia 108 Transmesenteric Hernia 110 Bochdalek Hernia 111 Morgagni Hernia 112 Mesenteritis BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 114 Lymphangioma (Mesenteric Cyst) 116 Desmoid MALIGNANT NEOPLASMS 118 Peritoneal Metastases and Lymphoma 120 Abdominal Mesothelioma 121 Pseudomyxoma Peritonei SECTION 4: ESOPHAGUS: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 124 Esophagus: Imaging Approach and Differential Diagnosis INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 128 Reflux Esophagitis 129 Barrett Esophagus 130 Caustic Esophagitis 131 Drug-Induced Esophagitis 132 Radiation Esophagitis 133 Esophageal Webs 134 Schatzki Ring 135 Cricopharyngeal Achalasia 136 Achalasia 138 Esophageal Motility Disturbances 140 Zenker Diverticulum 141 Pulsion Diverticulum 142 Traction Diverticulum TRAUMA 143 Esophageal Perforation 144 Boerhaave Syndrome TREATMENT RELATED 146 Esophagectomy: Ivor Lewis and Other Procedures 150 Fundoplication and Other Antireflux Procedures BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 154 Intramural Mesenchymal Esophageal Tumors 155 Fibrovascular Polyp MALIGNANT NEOPLASMS 156 Esophageal Carcinoma 157 Esophageal Metastases and Lymphoma SECTION 5: STOMACH AND DUODENUM: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 160 Stomach and Duodenum: Imaging Approach and Differential Diagnosis Michael P. Federle, MD, FACR EMBRYOLOGY AND ANOMALIES 166 Gastric Diverticulum 167 Duodenal Diverticulum INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 168 Gastritis and Duodenitis 172 Duodenal Ulcer 173 Gastric Ulcer 174 Zollinger-Ellison Syndrome 175 Ménétrier Disease 176 Gastroparesis 177 Gastric Bezoar 178 Hiatal Hernia 180 Gastric Volvulus TREATMENT RELATED 182 Partial Gastrectomy: Bilroth Procedures BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 184 Gastric Polyps 186 Intramural Mesenchymal Gastric Tumors MALIGNANT NEOPLASMS 188 Gastric Carcinoma 190 Gastric Metastases and Lymphoma SECTION 6: SMALL INTESTINE: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 194 Small Intestine: Imaging Approach and Differential Diagnosis EMBRYOLOGY AND ANOMALIES 198 Malrotation 199 Duplication Cyst 200 Meckel Diverticulum INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 202 Small Bowel Diverticula 203 Mesenteric Adenitis and Enteritis 204 Opportunistic Intestinal Infections 206 Gallstone Ileus 208 Celiac Sprue Disease 210 Intestinal Lymphangiectasia 212 Crohn''s Disease 216 Intestinal (Angioneurotic) Angioedema 217 Small Bowel NSAID Stricture 218 Pneumatosis of the Intestine 220 Bowel Ischemia 224 Intussusception TREATMENT RELATED 226 Radiation Enteritis and Colitis 228 Small Intestine Transplantation BENIGN NEOPLASMS 232 Hamartomatous Polyposis Syndromes MALIGNANT NEOPLASMS 234 Small Bowel Carcinoma 235 Intestinal Metastases and Lymphoma SECTION 7: COLON: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 238 Colon: Imaging Approach and Differential Diagnosis INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 242 Infectious Colitis 246 Stercoral Colitis 246 Neutropenic Enterocolitis (Typhlitis) 248 Ulcerative Colitis 250 Toxic Megacolon 252 Ischemic Colitis 254 Appendicitis 256 Colonic Diverticulosis and Diverticulitis 258 Epiploic Appendagitis 260 Sigmoid Volvulus 261 Cecal Volvulus 262 Colonic Ileus and Ogilvie Syndrome 264 Colorectal Trauma BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 266 Colonic Polyps MALIGNANT NEOPLASMS 268 Colon Carcinoma 272 Rectal Carcinoma 274 Familial Polyposis and Gardner Syndrome 278 Appendiceal Tumors 279 Colonic Metastases and Lymphoma SECTION 8: SPLEEN: IMAGING APPROACH AND DIFFERENTIAL DIGANOSIS 282 Spleen: Imaging Approach and Differential Diagnosis 286 Accessory Spleen 288 Asplenia and Polysplenia 292 Splenic Infection and Abscess 294 Splenomegaly and Hypersplenism 296 Splenic Infarction 300 Splenic Trauma 304 Splenosis 306 Splenic Cyst 308 Primary Splenic Tumors 312 Splenic Metastases and Lymphoma SECTION 9: LIVER: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 316 Liver: Imaging Approach and Differential Diagnosis EMRYOLOGY AND ANOMALIES 320 Congenital Hepatic Fibrosis 321 Polycystic Liver Disease INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 322 Hepatic Pyogenic Abscess 324 Hepatic Mycobacterial and Fungal Infections 325 Hepatic Amebic Abscess 326 Hepatic Hydatid Cyst 327 Hepatic Schistosomiasis 328 Viral Hepatitis 329 Autoimmune Hepatitis 330 Alcoholic Liver Disease 332 Steatosis and Steatohepatitis 334 Hepatic Injury From Toxins 336 Cirrhosis 340 Nodular Regenerative Hyperplasia 344 Regenerative and Dysplastic Nodules VASCULAR DISORDERS 348 Arterioportal Shunt 349 Passive Hepatic Congestion 350 Portal Vein Occlusion 354 Budd-Chiari Syndrome 358 Sinusoidal Obstruction Syndrome 359 Peliosis Hepatis 360 Hepatic Infarction 362 Hereditary Hemorrhagic Telangiectasia TREATMENT RELATED 364 Transjugular Intrahepatic Portosystemic Shunt (TIPS) 366 Hepatic Transplantation BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 376 Hepatic Cyst 378 Hepatic Cavernous Hemangioma 380 Focal Nodular Hyperplasia 382 Hepatic Adenoma 390 Biliary Hamartomas 391 Hepatic Angiomyolipoma and Lipoma 392 Hepatic Inflammatory Pseudotumor MALIGNANT NEOPLASMS 394 Hepatocellular Carcinoma 400 Peripheral (Intrahepatic) Cholangiocarcinoma 402 Epithelioid Hemangioendothelioma 404 Biliary Cystadenocarcinoma 406 Fibrolamellar Carcinoma 407 Hepatic Angiosarcoma 408 Hepatic Metastases and Lymphoma SECTION 10: BILIARY SYSTEM: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 414 Biliary System: Imaging Approach and Differential Diagnosis EMBRYOLOGY AND ANOMALIES 420 Congenital Abnormalities of the Gallbladder Siva P. Raman, MD 422 Caroli Disease 424 Choledochal Cyst INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 426 Ascending Cholangitis 428 Primary Sclerosing Cholangitis 430 Recurrent Pyogenic Cholangitis 432 Gallstones and Choledocholithiasis 436 Gallbladder Hydrops and Empyema 437 Emphysematous Cholecystitis 438 Acute Calculous Cholecystitis 440 Acalculous Cholecystitis 442 Xanthogranulomatous Cholecystitis 443 Mirizzi Syndrome 444 Hyperplastic Cholecystoses 445 Porcelain Gallbladder TREATMENT RELATED 446 Chemotherapy-Induced Cholangitis 448 Postoperative Biliary Tract BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 448 Gallbladder Polyps 449 Biliary Papillomatosis MALIGNANT NEOPLASMS 450 Gallbladder Carcinoma 452 Cholangiocarcinoma 454 Ampullary Carcinoma 455 Biliary Metastases and Lymphoma 456 Biliary IPMN SECTION 11: PANCREAS: IMAGING APPROACH AND DIFFERENTIAL DIAGNOSIS 460 Pancreas: Imaging Approach and Differential Diagnosis EMBRYOLOGY AND ANOMALIES 466 Agenesis of Dorsal Pancreas Siva P. Raman, MD 467 Annular Pancreas 468 Pancreas Divisum 469 Ectopic Pancreatic Tissue INFECTIOUS, INFLAMMATORY, AND DEGENERATIVE 470 Acute Pancreatitis and Complications 474 Chronic Pancreatitis 478 Groove Pancreatitis 480 Autoimmune (IgG4) Pancreatitis TREATMENT RELATED 482 Postoperative Pancreas 484 Pancreatic Transplantation.