All patients had preparation of the small intestine for examination: a low fiber diet for 2-3 days before the CT examination, and oral administration of an isotonic non-absorbable electrolyte solution containing polyethylene glycol or water before examination for 40-60 minutes.
All examinations were performed with a 64-slice multidetector CT scanner with the patient in supine position, by intravenous injection of iodinated contrast medium. Bowel wall enhancement was produced by intravenous injection of iodinated contrast medium with an iodine concentration 350mg/mL. The iodine flow injected per second per kilogram of body weight was maintained constant for all examinations (1.11 g I/s). The flow rate was set at 4.5–5mL/s with an automatic injector.
An important technical requirement for the CT study of the bowel is the distension of a clear lumen with appropriate separation of the intestinal walls, both for the small and large bowel, because collapsed bowel loops can hide lesions and mimic pathologic conditions.
All CT examinations were reviewed on a dedicated workstation.
We will consider various cases of ileum disease, as well as some of their complications that were detected in our center for 2 years.
1. Inflammatory diseases:
-Crohn disease (Fig. 1, 2, 3) - Crohn disease is a chronic inflammatory (idiopathic) bowel disease characterized by transmural and segmental inflammation of the bowel wall, which involves the small bowel in about 70-80% of patients (but although it can occur anywhere in the gastrointestinal tract from the mouth to the anus.). CT enterography helps detect both active and chronic involvement of the small bowel in Crohn disease and it is also useful to identify extraintestinal complications such as fistula, abscess, strictures. CT criteria of active Crohn disease include wall thickening (thickness > 3 mm),mucosal and mural hyperenhancement, mural stratification with a prominent vasa recta (comb sign), and perienteric fat stranding.
- chemotherapy induced enteritis (Fig. 4) - The enteritis may be diffuse or predominantly involve the distal ileum, they manifesting as abdominal pain, bloating, and diarrhea. CT images includes submucosal edema, bowel wall thickening and luminal narrowing. Other entities such as ischemia and radiation enteritis can have a similar appearance.
2. Infection diseases:
- tuberculosis (Fig. 5) - the clinical features of this disease are nonspecific and can be very similar to Crohn's disease. Terminal ileum and ileocecal junction are the most common sites of involvement followed by the colon and jejunum. It occurs in three forms: ulcerative (the most common), hypertrophic, and ulcerohypertrophic. Main CT findings include circumferential wall thickening of terminal ileum, extrinsic compression by enlarged lymph nodes. But this disease is very rear, therefore it can manifest itself in other organs (such as lung)
-yersiniosis (Fig. 6), actinomycosis, cytomegalovirus, Salmonella spp, typhlitis
3. Tumor:
- Benign tumors - lipoma,
- Malignancies:
- adenocarcinoma – Adenocarcinoma may manifest as annular stenosis with irregular edges, a polypoid luminal mass or mural thickening (annular). Obstruction is usually present, and leads to partial or complete obstruction. Adenocarcinomas enhance mildly after administration of IV contrast material.
- lymphoma (Fig. 7) - CT findings shows circumferential wall thickening (very thick >2 cm thickness) , luminal dilatation, lymphadenopathy. Bowel obstruction is not usually seen even though tumor is very large. The most common presentation is a thick walled infiltrating mass with aneurysmal dilatation (Fig 8).
- NET (Fig. 11, 12) - often appears as an intensely enhancing mucosal polyp, but may vary to a large intraluminal ulcerating lesion, can occasionally produce intussusception. NETs are well enhanced in the arterial phase. A desmoplastic reaction and calcification of the mesentery can be visualized.
-GIST - most GISTs are predominantly extraluminal, but may be submucosal and intraluminal. So obstruction is rare, in contrast to adenocarcinoma. The mass have heterogeneous enhancement and central areas of necrosis. GISTs also may occasionally arise from peritoneal structures such as the omentum or small bowel mesentery
-do not forget about mts - e.g. carcinomatosis (Fig. 9) - intestinal involvement in metastatic cancer is common. MTS of malignant melanoma (Fig. 10). Metastases may increase bowel wall thickness or may infiltrate the mesenteric or intraperitoneal fat and cause stranding or can cause intussusception.
4. Congenital or genetic:
-Meckel's diverticulum (Fig. 12, 13) and its complications - Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract, estimated to occur in approximately 1–2% of the population. Meckel’s diverticulum is usually asymptomatic. On CT, it is difficult to distinguish from normal small bowel. Complications result most commonly from bleeding, inflammation, and obstruction, so CT may also show some wall thickening (Rare neoplastic changes -Fig. 12), intussusception, perforation, diverticulitis, and small-bowel obstruction.
- inherited gastrointestinal polyposis syndromes: Hamartomatous polyposes (e.g. Peutz–Jeghers syndrome - large polyps can mimic primary small bowel neoplasms and can also be malignant)
5. Others:
-intestinal intussusceptions (Fig. 14) - Intussusception is defined as the invagination of a proximal bowel segment into the lumen of an adjacent distal segment (target sign). Intussusception can be obstructing or not and can develop acutely, subacutely, chronically, intermittently, or even transiently intussusception. Sometimes it recognized incidentally during imaging studies performed for other reasons.
-intestinal obstruction (Fig. 15) - is a mechanical or functional obstruction of the intestines which prevents the normal movement of the products of digestion. There is a long list of causes wich can lead to small bowel obstruction: intestinal adhesions, intussusception, tumors, hernias, strictures, inflammatory bowel disease.
-fistulas (Fig. 1, 2) - are common complications encountered in inflammatory bowel disease, post-surgical, due to abdominal malignancies or even foreign bodies.
-ectopic pancreas (Fig. 16) - is an infrequent submucosal tumor in the gastrointestinal tract. Enhancement pattern of the tumor is similar to the normal pancreas, the best visualized in the arterial phase.