1 Carcinoma of the Esophagus and Gastroesophageal Junction.- Technique of Examination.- Normal Anatomy.- Morphology and Staging.- Posttherapeutic Evaluation.- References.- 2 Gastric Carcinoma.- Pathologic Considerations.- Spread of Gastric Cancer and Its Staging.- CT Diagnosis.- >Conclusions Regarding CT Assessment of Surgical Resectability.- References.- 3 Gastrointestinal Lymphoma, Leiomyoma, and Leiomyosarcoma.- Gastrointestinal Lymphoma.- Leiomyomas and Leiomyosarcomas.- References.- 4 Inflammatory Bowel Disease and Related Conditions.- Thickening of the Bowel Wall.- Small Bowel.- Colon.- Differential Diagnosis of Crohn's Disease and Ulcerative Colitis.- References.- 5 Subperitoneal Spread of Intra-Abdominal Disease.- CT Demonstration of Normal Anatomy.- CT Demonstration of Pathology.- Conclusion.- References.- 6 Mesenteric Disease.- Anatomy.- Scanning Techniques.- Benign Conditions.- Malignant Conditions.- Acquired Immune Deficiency Syndrome (AIDS).- References.- 7 Intraperitoneal Fluid Collections.- Anatomic Considerations.- Ascites.- Intra-Abdominal Abscess.- Intraperitoneal Hemorrhage.- Pseudomyxoma Peritonei.- Miscellaneous Fluid Collections.- References.- 8 Acute Appendicitis.- Anatomic Considerations.- Computed Tomography Findings.- References.- 9 Diverticulitis.- Radiologic Diagnosis.- CT Findings: Colonic and Pericolic Changes.- Abscess and Peritonitis.- Fistula Formation.- Correlation of CT Findings and Contrast Enema.- Differential Diagnosis.- Clinical Utility.- References.- 10 Colorectal Carcinoma.- Technique of Examination.- Normal Anatomy.- Primary Diagnosis.- Staging.- Recurrent Carcinoma.- Radiotherapy.- References.