CT and MRI findings of small bowel diverticula and potential complications.

Transcription

1 CT and MRI findings of small bowel diverticula and potential complications. Poster No.: C-0498 Congress: ECR 2011 Type: Educational Exhibit Authors: R. Reinhard, J. Bradshaw, B. M. Wiarda ; Amsterdam/NL, Alkmaar/NL Keywords: Diverticula, Acute, Diagnostic procedure, MR, CT, Small bowel, Gastrointestinal tract, Abdomen DOI: /ecr2011/C-0498 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 31

2 Learning objectives To demonstrate specific characteristics and complications of small bowel diverticula on abdominal CT and MRI. To illustrate a differential diagnosis of complicated small bowel diverticula. Background Small bowel diverticula are relatively common. Different imaging techniques can be used to demonstrate small bowel diverticula. Ultrasound can be used as a screening modality, but CT is mostly used if complications are expected. However particularly in young or pregnant patients, MRI should always be considered as an alternative to prevent ionizing radiation. As complications can be severe, awareness of imaging features and potential complications are essential to ensure correct diagnosis and proper treatment. In this exhibit we review the pathogenesis, prevalence, imaging characteristics and potential complications of small bowel diverticula with an emphasis on CT and MRI. The differential diagnosis is mentioned as well, including a few cases. Imaging findings OR Procedure details Introduction Small bowel diverticula can be congenital or acquired. True diverticula, like Meckel's diverticulum, are congenital and composed of all layers of the intestinal wall. False diverticula are acquired and consist of mucosal and submucosal layers herniating through a muscular defect [1]. A current hypothesis for acquired diverticula focuses on a pulsion phenomenon with local increases in intraluminal pressure. This results in herniation of mucosa and submucosa through the weakest mesenteric site of the bowel wall alongside the penetrating vessels. Others believe that smooth muscle abnormalities create localized weakness in the wall [1]. Most patients with small bowel diverticula are asymptomatic, except when the diverticula become complicated. Different imaging modalities can be used if complications are expected. Page 2 of 31

3 Duodenal diverticula Duodenal diverticula are more common than jejuno-ileal diverticula. Most duodenal diverticula are acquired [2]. The most common location is the medial border of the descending duodenum [3]. More than 90 % of patients are asymptomatic. Diverticula are often multiple and they usually appear as smooth outpouchings of the duodenum. If the diverticulum is filled with air, fluid or a combination, it can be seen at abdominal radiographs (Fig. 1 on page 5), barium studies, CT (Fig. 2 on page 5) or MRI (Fig. 3 & 4). A fluid-filled diverticulum can mimic a cystic neoplasm in the head of the pancreas [3,4]. In patients with diverticula who undergo endoscopic retrograde cholangiopancreatography (ERCP), it can be difficult to cannulate the bile ducts if they drain into the diverticulum [5]. Complicated duodenal diverticula CT is the primary mode of imaging if complications of duodenal diverticula are expected. However, in young or pregnant patients MRI should be considered instead of CT to prevent ionizing radiation. The reported complications include haemorrhage, duodenal diverticulitis and perforation. Because duodenal diverticula are mainly retroperitoneal structures, perforation can occur without peritonism and without free intraperitoneal air. It often leads to retroperitoneal abscess formation [2,6]. Jejuno-ileal diverticula Most small bowel diverticula are false diverticula, occurring along the mesenteric border of the small bowel. They are more common in jejunum than in ileum [7]. Incidence of jejuno-ileal diverticula on small bowel studies by enteroclysis is comparable to autopsy data, showing an incidence of %, respectively % [8,9]. Having a few diverticula is more common than pan-jejuno-ileal diverticulosis [10]. Because it is an acquired condition, jejuno-ileal diverticula are more common in older patients, often above the age of sixty [11]. On barium studies jejuno-ileal diverticula can be well identified, especially if double contrast is used [1,11]. However, they may not be recognized when hidden in the mesenteric fat or if the neck of the diverticulum is large. Jejuno-ileal diverticulosis is an infrequent diagnosis on CT. It can be hard to differentiate the diverticula from small bowel loops. CT tends to underestimate the degree of diverticulosis, compared with barium studies. It is easier to recognize the diverticula with MR enteroclysis (Fig. 4 on page 7). Complicated jejuno-ileal diverticula Page 3 of 31

4 Symptoms of jejuno-ileal diverticula can include vague abdominal pain. Stasis within the diverticula can cause bacterial overgrowth with resulting diarrhea and malabsorption [11]. Jejuno-ileal diverticula are nearly four times more likely to develop complications, compared to duodenal diverticula. Complications requiring surgical intervention occur in 8-30 % of patients. Most common acute complications are haemorrhage, intestinal obstruction, diverticulitis (Fig. 5-13) and perforation [7]. Jejuno-ileal diverticulitis occurs in about 2-6 % of cases and has a mortality rate as high as 24 % [12,13]. Patients with jejuno-ileal diverticulitis usually present with a localized or diffuse peritonitis. The clinical presentation may mimic acute appendicitis [14]. CT shows mesenteric inflammatory changes, with or without signs of abscess or perforation. Diagnosis can also be made on MRI (Fig. 10,11). In case of complications surgical intervention is usually the treatment of choice [7]. Meckel's diverticulum Meckel's diverticulum is a true diverticulum, composed of all layers of the ileal wall. It is the most common congenital anomaly of the gastrointestinal tract and occurs in 2 % of the population. The cause is failure of the omphalomesenteric duct to regress. The length of the diverticulum ranges from 1 to 10 cm and is generally located within cm of the ileocecal valve. About 50 % contain heterotopic mucosa, mostly gastric type (Fig. 20 on page 23) and less frequently pancreatic [15-17]. Complicated Meckel's diverticulum Main complications include haemorrhage, inflammation and obstruction. Meckel's diverticulitis on CT will show a blind-ending pouch in the lower quadrants or periumbilical region, with an enhancing thickened wall and surrounding inflammation (Fig ). Visualization of a normal appendix can be helpful in narrowing the differential diagnosis. Occasionally an enterolith can be seen in the diverticulum, probably due to stasis (Fig ). A rare but serious complication is perforation, usually secondary to inflammatory diverticulitis, gangrene or peptic ulceration. CT is most sensitive in detecting free intraperitoneal air. In children with gastrointestinal haemorrhage and suspected Meckel's diverticulum the modality of choice is scintigraphy, using 99mTc-Na-pertechnetate (Fig. 18 on page 21). Intestinal obstruction is one of the main complications in adults. CT is a good imaging modality to evaluate these patients (Fig. 21 on page 24). However MRI should always be considered as an alternative, particularly in young or pregnant patients (Fig. 19,20). Different causes of obstruction can be found, including intussusception, inverted Meckel's diverticulum (Fig. 22,23) causing luminal obstruction, volvulus of the diverticulum or Page 4 of 31

5 extension of the diverticulum into a hernia sac. It is often difficult to indicate a Meckel's diverticulum as cause of obstruction. However identification of an enterolith can be helpful. These usually show peripheral calcification and a radiolucent centre [15,16]. Differential diagnosis The differential diagnosis of Meckel's diverticulitis includes appendicitis (Fig. 24 on page 27), colonic diverticulitis, focal Crohn's disease (Fig. 12,13), (perforated) neoplasm, foreign body perforation, medication-induced ulceration and in female patients pelvic inflammatory disease [15,18,19]. Images for this section: Fig. 1: Case 1. Axial CECT confirms the diagnosis of a large duodenal diverticulum (arrow). Page 5 of 31

6 Fig. 2: Case 1. Duodenal diverticulum. Abdominal radiograph shows a round structure in the right upper quadrant with an air-fluid level (arrow). Page 6 of 31

7 Fig. 3: Case 1. Coronal True FISP fatsat: Large duodenal diverticulum (arrow). Page 7 of 31

8 Fig. 4: Case 2. MR enteroclysis: coronal HASTE image shows incidental finding of several large jejunal diverticula (arrows). Page 8 of 31

9 Fig. 5: Case year-old woman with left abdominal pain. Axial CECT reveals an ovoid inflammatory process (arrows), in close relation with the jejunum. Operation and PA showed an inflamed jejunal diverticulum. Page 9 of 31

10 Fig. 6: Case 3. Coronal CECT reveals an ovoid inflammatory process with a calcification (arrow), in close relation with the jejunum. There are no signs of perforation. Operation and PA showed an inflamed jejunal diverticulum. Page 10 of 31

11 Fig. 7: Case 3. Resected inflamed jejunal diverticulum. Page 11 of 31

12 Fig. 8: Case 4. Axial CECT shows several ileal diverticula (arrows) without signs of complication. Page 12 of 31

13 Fig. 9: Case 4. After 6 days CT scan was repeated because of progressive pain. Axial CECT shows ileal diverticula with wall thickening and adjacent mesenteric infiltration (arrow); ileal diverticulitis. Page 13 of 31

14 Fig. 10: Case 4. Ileal diverticulitis. Axial HASTE image shows same findings as CT: ileal diverticula, wall thickening and adjacent inflammatory changes (arrow). Page 14 of 31

15 Fig. 11: Case 4. Ileal diverticulitis. Axial DWI demonstrates several diverticula with restricted diffusion (arrow). Corresponding ADC maps shows low signal (not shown). Page 15 of 31

16 Fig. 12: Case 5. Crohn's disease with inflamed ileal diverticula. 67 year-old woman with abdominal pain and weight loss. Coronal CECT shows several ileal diverticula (arrow), wall thickening of the terminal ileum (arrowhead) and surrounding inflammatory changes. Ileo-cecal resection was performed and Crohn's disease was confirmed. Page 16 of 31

17 Fig. 13: Case 5. Crohn's disease with inflamed ileal diverticula. 67 year-old woman with abdominal pain and weight loss. Axial CECT shows several thickened ileal diverticula (arrow), wall thickening of the terminal ileum (arrowhead) and surrounding inflammatory changes. Ileo-cecal resection was performed and Crohn's disease was confirmed. Page 17 of 31

18 Fig. 14: Case 6. Meckel's diverticulitis. 62-year-old man with abdominal pain and peritonism. Axial CECT demonstrates a dilated Meckels's diverticulum with two enteroliths and surrounding infiltration (arrow). Laparotomy and pathology confirmed Meckel's diverticulitis. Page 18 of 31

19 Fig. 15: Case 6. Meckel's diverticulitis. 62-year-old man with abdominal pain and peritonism. Coronal CECT demonstrates a dilated Meckels's diverticulum and surrounding infiltration (arrow). The ileum shows reactive wall thickening (arrowhead). Laparotomy and pathology confirmed Meckel's diverticulitis. Page 19 of 31

20 Fig. 16: Case 7. Meckel's diverticulitis. 45-year-old man with left abdominal pain. Coronal CECT reveals an inflamed Meckel's diverticulum with an enterolith (arrow). Surgery and pathology confirmed Meckel's diverticulitis. Page 20 of 31

21 Fig. 17: Case 7. Meckel's diverticulitis. 45-year-old man with left abdominal pain. Axial CECT reveals an inflamed Meckel's diverticulum with an enterolith (arrow). Surgery and pathology confirmed Meckel's diverticulitis. Page 21 of 31

22 Fig. 18: Case 8. Meckel's diverticulum. 12-year-old girl with lower abdominal pain since 2 years. Coronal Dynamic technetium pertechnetate image shows activity in stomach and right lower quadrant (arrow), due to heterotopic gastric mucosa in Meckel's diverticulum. Page 22 of 31

23 Fig. 19: Case 8. Meckel's diverticulum. Axial True FISP fatsat image shows a blind ending structure in close relation to the ileum (arrow). There are no signs of intussusception. Page 23 of 31

24 Fig. 20: Case 8. PA specimen of Meckel's diverticulum, which contained heterotopic gastric mucosa. Page 24 of 31

25 Fig. 21: Case 9. Inverted Meckel's diverticulum with intussusception. 59 year-old male with complaints of nausea and vomiting. Axial CECT shows an ileo-ileal intussusception (arrow). Page 25 of 31

26 Fig. 22: Case 9. Coronal True FISP fatsat shows a tubular blind-ending intraluminal structure in the distal ileum (arrows); ileo-ileal intussusception due to inverted Meckel's diverticulum. Page 26 of 31

27 Fig. 23: Case 9. PA specimen of partially resected ileum shows Meckel's diverticulum (arrow). Page 27 of 31

28 Fig. 24: Case 10. Differential diagnosis; acute appendicitis. 34-year-old man with left lower quadrant pain. Axial HASTE images demonstrates an extremely long appendix which crosses the midline (arrows). The distal part of the appendix is thickened and the adjacent mesenteric fat shows extensive inflammation (arrowhead). Surgery confirmed a very long appendix with inflammation of the distal part. Page 28 of 31

29 Conclusion Awareness of imaging features of small bowel diverticula is essential. CT is often used if complications are expected. However MRI is a good alternative, especially in young or pregnant patients. Personal Information Thank you for your interest in this exhibit. If you have any questions or comment, please contact me via ; r.reinhard@vumc.nl. Rinze Reinhard Radiologist / Fellow Abdominal Radiology VU Medical Center Amsterdam, the Netherlands References 1. Liu CY, Chang WH, Lin SC, Chu CH, Wang TE, Shih SC. Analysis of clinical manifestations of symptomatic acquired jejunoileal diverticular disease. World J Gastroenterol 2005; 11(35): Martínez-Cecilia D, Arjona-Sánchez A, Gómez-Álvarez M et al. Conservative management of perforated duodenal diverticulum: a case report and review of the literature. World J Gastroenterol 2008; 14(12): Levine MS, Megibow AJ. Other malignant tumors of the stomach and duodenum. In: Gore RM, Levine MS, editors. Textbook of gastrointestinal radiology. Philadelphia: Saunders Elsevier, 2008: Macari M, Faust M, Liang H, Pachter HL. CT of jejunal diverticulitis: imaging findings, differential diagnosis and clinical management. Clin Radiol 2007; 62: Page 29 of 31

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