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DOI: 10.1148/rg.274065164
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RadioGraphics 2007;27:1039-1054
© RSNA, 2007

EDUCATION EXHIBIT

Spectrum of Normal and Abnormal CT Appearances of the Ileocecal Valve and Cecum with Endoscopic and Surgical Correlation1

Alvin C. Silva, MD, Sean D. Beaty, MD, Amy K. Hara, MD, Joel G. Fletcher, MD, Jeff L. Fidler, MD, Christine O. Menias, MD, and C. Daniel Johnson, MD

1 From the Department of Diagnostic Radiology, Mayo Clinic, 13400 E Shea Blvd, Scottsdale, AZ 85259 (A.C.S., S.D.B., A.K.H., C.D.J.); Department of Radiology, Mayo Clinic, Rochester, Minn (J.G.F., J.L.F.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.O.M.). Recipient of a Certificate of Merit award for an education exhibit at the 2005 RSNA Annual Meeting. Received September 5, 2006; revision requested October 30 and received February 23, 2007; accepted March 1. J.G.F. developed a Continuing Medical Education course for E-Z-EM, is supported in part by Siemens Medical Systems, and has a licensing agreement with GE Healthcare; J.L.F. is a medical advisor for GE Medical Systems; C.D.J. has licensing agreements with GE Medical Systems and E-Z-EM; and A.J.H. has a licensing agreement with GE Medical Systems. All remaining authors have no financial relationships to disclose. Address correspondence to A.C.S. (e-mail: silva.alvin{at}mayo.edu).


   Abstract
Top
 Abstract
Introduction
 Normal Anatomy
 Polyps and Masses
 Appendix
 Conclusions
 References
 
Because of advances in imaging technology, evaluation of the gastrointestinal tract is increasingly being performed with cross-sectional imaging (eg, computed tomographic [CT] colonography, CT enterography). However, the diagnosis of disease involving the ileocecal valve (ICV), cecum, and appendix with CT can be challenging. The normal ICV can have many different appearances, depending on cecal distention and mobility, whether the valve is open or closed, and inherent variable morphologic characteristics. In addition, flat cecal lesions are difficult to detect, and larger masses are sometimes mistaken for the ICV or residual stool. Familiarity with the typical appearances of the normal anatomy and various pathologic conditions of the gastrointestinal tract on two- and three-dimensional cross-sectional images is useful in making the correct diagnosis.

© RSNA, 2007


   Introduction
Top
 Abstract
 Introduction
Normal Anatomy
 Polyps and Masses
 Appendix
 Conclusions
 References
 
The advent of multidetector computed tomography (CT) and faster, higher-capacity workstations now allows direct, rapid interrogation of volumetric data sets in multiple planes with various postprocessing algorithms. Because of these technologic advances, evaluation of the gastrointestinal tract is steadily changing from fluoroscopic or conventional radiographic assessment to cross-sectional imaging (eg, CT colonography, CT enterography).

As a result, the radiologist must become facile at identifying the normal anatomy and pathologic conditions of the gastrointestinal tract in various two-dimensional (2D) imaging planes and on three-dimensional (3D) images on the basis of their endoluminal morphologic characteristics.

In this article, we review the various 2D and 3D CT appearances of the normal ileocecal valve (ICV) and cecum. In addition, we demonstrate the appearances of various pathologic conditions affecting the ICV and cecum (polyps, lipomas, primary malignancy, lymphoma, cecal diverticulitis, ischemic colitis, Crohn colitis, neutropenic colitis, cecal obstruction) and the appendix (mucocele, appendiceal stump), correlating these CT appearances with endoscopic or surgical findings.


   Normal Anatomy
Top
 Abstract
 Introduction
 Normal Anatomy
Polyps and Masses
 Appendix
 Conclusions
 References
 
The distal ileum terminates by opening into the medial and posterior aspect of the large intestine at the junction of the cecum and ascending colon. The ICV, also known as the colic valve or valvula coli, regulates this opening (Fig 1) (1). The valve is composed of two segments—an upper lip and a lower lip—that are formed by intrusion of the circular muscle layer of the ileum into the lumen of the large intestine. A narrow membranous ridge continues at the ends of the aperture medially and laterally where the lips meet, representing the frenula of the valve. The ICV modulates the flow of luminal contents from the ileum into the colon, minimizing rapid anterograde passage of chyme into the colon as well as the retrograde flow of contents from the colon. However, the circular ICV muscle is poorly developed; consequently, the valve has minimal sphincteric action, a fact that explains the common observation of barium reflux into the terminal ileum during a barium enema examination. The valve is positioned within a cecal fold, usually along the medial aspect of the cecum.


Figure 1
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  		Figure 1.  Drawings illustrate the anatomic structures of the terminal ileum, ICV, cecum, and appendix. m. = muscle. (Reprinted with permission from the Mayo Foundation for Medical Education and Research, Rochester, Minn.)

 
At endoscopy, the ICV may be classified into three main categories on the basis of its morphologic appearance: labial, papillary, or lipomatous (2–4). The labial type has a slitlike opening (Fig 2), the papillary type is dome shaped (Fig 3), and the lipomatous type has a substantial deposit of fat within its lips (Fig 4). Most nonlipomatous valves will demonstrate streaks of fat within the valve lips. Each ICV subtype may vary in appearance when the patient is prone rather than supine or when the valve is open rather than closed. Normal ICVs of all types exhibit a smooth surface on 2D and 3D images, with the lips of the valve generally symmetric with respect to the valve orifice.


Figure 2A
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  		Figure 2a.  Labial ICV. Three-dimensional CT colonographic (a) and endoscopic (b) images depict a labial ICV with a flat, slitlike opening (arrows). Note the small amount of fluid flowing from the valve on the endoscopic image.

 

Figure 2B
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  		Figure 2b.  Labial ICV. Three-dimensional CT colonographic (a) and endoscopic (b) images depict a labial ICV with a flat, slitlike opening (arrows). Note the small amount of fluid flowing from the valve on the endoscopic image.

 

Figure 3A
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  		Figure 3a.  Papillary ICV. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a papillary type ICV (arrows) with the characteristic dome shape protruding into the lumen of the right colon.

 

Figure 3B
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  		Figure 3b.  Papillary ICV. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a papillary type ICV (arrows) with the characteristic dome shape protruding into the lumen of the right colon.

 

Figure 3C
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  		Figure 3c.  Papillary ICV. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a papillary type ICV (arrows) with the characteristic dome shape protruding into the lumen of the right colon.

 

Figure 4A
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  		Figure 4a.  Lipomatous ICV. Endoscopic (a) and axial 2D CT colonographic (b) images depict a prominent lipomatous ICV (arrow). Note the substantial deposit of yellow fat on the endoscopic image and the fat attenuation on the CT colonographic image.

 

Figure 4B
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  		Figure 4b.  Lipomatous ICV. Endoscopic (a) and axial 2D CT colonographic (b) images depict a prominent lipomatous ICV (arrow). Note the substantial deposit of yellow fat on the endoscopic image and the fat attenuation on the CT colonographic image.

 
The cecum is the first part of the large intestine and is most commonly situated in the right iliac fossa below the ICV, resting on the iliac and greater psoas muscles. On average, the cecum is 6.25 cm long and 7.5 cm wide. Its blind end is typically directed downward. The cecum is frequently attached to the iliac fossa laterally and medially by peritoneal cecal folds. These folds form the retrocecal recess, a small cul-de-sac of the peritoneal cavity posterior to the cecum that is often deep enough to admit a finger. Because the cecum is usually enveloped almost entirely by the peritoneum, it can be lifted freely and may demonstrate considerable movement. During CT colonography, this mobility may cause polyps to be misinterpreted as stool, since a polyp will appear to move between supine and prone images when in fact the entire cecum is rotating while the polyp remains fixed (Fig 5). The cecum possesses thickened bands of longitudinal muscle called teniae coli that are contiguous with the distal colon and converge at the base of the vermiform appendix to form a complete, outer longitudinal layer of muscle.


Figure 5A
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  		Figure 5a.  Polypoid tubular adenoma in a mobile cecum. (a) Three-dimensional CT colonographic image reveals a 1-cm polypoid lesion in the cecum (arrow). (b, c) On corresponding axial 2D supine (b) and prone (c) CT colonographic images (shown in the same orientation), the mass (arrow) appears to move with the change in patient position, a finding that suggests stool. However, closer inspection reveals that the cecum itself rotates with the change in position. Note that the location of the mass remains constant with respect to the terminal ileum and ICV (arrowhead). Biopsy findings showed the mass to be a tubular adenoma.

 

Figure 5B
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  		Figure 5b.  Polypoid tubular adenoma in a mobile cecum. (a) Three-dimensional CT colonographic image reveals a 1-cm polypoid lesion in the cecum (arrow). (b, c) On corresponding axial 2D supine (b) and prone (c) CT colonographic images (shown in the same orientation), the mass (arrow) appears to move with the change in patient position, a finding that suggests stool. However, closer inspection reveals that the cecum itself rotates with the change in position. Note that the location of the mass remains constant with respect to the terminal ileum and ICV (arrowhead). Biopsy findings showed the mass to be a tubular adenoma.

 

Figure 5C
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  		Figure 5c.  Polypoid tubular adenoma in a mobile cecum. (a) Three-dimensional CT colonographic image reveals a 1-cm polypoid lesion in the cecum (arrow). (b, c) On corresponding axial 2D supine (b) and prone (c) CT colonographic images (shown in the same orientation), the mass (arrow) appears to move with the change in patient position, a finding that suggests stool. However, closer inspection reveals that the cecum itself rotates with the change in position. Note that the location of the mass remains constant with respect to the terminal ileum and ICV (arrowhead). Biopsy findings showed the mass to be a tubular adenoma.

 
The appendix is a narrow blind tube that joins the cecum about 2.5 cm inferior to the ICV. Typically, the dominant saccule of the cecum is to the right of the anterior and posterolateral longitudinal bands, displacing the appendix to the left toward the ileocolic junction. The body of the appendix varies in position but is usually retrocecal or pelvic. The length of the appendix also varies, averaging 8 cm. Unlike the cecum, which has no mesentery, the appendix usually has its own short triangular mesentery called the mesoappendix. Although the appendix is considered a vestigial organ, it has the appearance of a well-developed lymphoid organ in infants and children and may have important immunologic functions (5,6).


   Polyps and Masses
Top
 Abstract
 Introduction
 Normal Anatomy
 Polyps and Masses
Appendix
 Conclusions
 References
 
ICV and Cecum
Polyps.— Colonic polyps are generally classified macroscopically as pedunculated or sessile (7). Pedunculated polyps are attached to the colonic wall by a stalk, whereas sessile polyps (Fig 6) have broad-based colonic wall attachments. Flat polyps (Fig 7) are masses whose height is no greater than one-half their width; thus, they may be difficult to visualize at CT colonography (8). Two-dimensional images obtained with intermediate and soft-tissue windowing maximize the conspicuity of lesions and should, therefore, be carefully evaluated.


Figure 6A
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  		Figure 6a.  Sessile cecal polyp (adenoma). Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 2.6-cm sessile cecal polyp (arrow) adjacent to the ICV (arrowhead in c). Note that the lobulated surface of the polyp is better depicted at endoscopy than at CT colonography, which is generally the case. However, superficial lobulations on larger polyps can suggest underlying villous components associated with an increased risk of malignancy. The polyp was resected endoscopically and proved to be a tubulovillous adenoma.

 

Figure 6B
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  		Figure 6b.  Sessile cecal polyp (adenoma). Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 2.6-cm sessile cecal polyp (arrow) adjacent to the ICV (arrowhead in c). Note that the lobulated surface of the polyp is better depicted at endoscopy than at CT colonography, which is generally the case. However, superficial lobulations on larger polyps can suggest underlying villous components associated with an increased risk of malignancy. The polyp was resected endoscopically and proved to be a tubulovillous adenoma.

 

Figure 6C
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  		Figure 6c.  Sessile cecal polyp (adenoma). Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 2.6-cm sessile cecal polyp (arrow) adjacent to the ICV (arrowhead in c). Note that the lobulated surface of the polyp is better depicted at endoscopy than at CT colonography, which is generally the case. However, superficial lobulations on larger polyps can suggest underlying villous components associated with an increased risk of malignancy. The polyp was resected endoscopically and proved to be a tubulovillous adenoma.

 

Figure 7A
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  		Figure 7a.  Flat polyp. Three-dimensional (a) and axial 2D supine (b) CT colonographic images demonstrate an 8 x 2-mm flat polyp within the cecum (arrow). Flat polyps may be subtle on 3D images, often requiring verification on the 2D display. Endoscopy showed a 1 x 0.3-cm plaquelike lesion along the base of a cecal fold with minimal elevation.

 

Figure 7B
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  		Figure 7b.  Flat polyp. Three-dimensional (a) and axial 2D supine (b) CT colonographic images demonstrate an 8 x 2-mm flat polyp within the cecum (arrow). Flat polyps may be subtle on 3D images, often requiring verification on the 2D display. Endoscopy showed a 1 x 0.3-cm plaquelike lesion along the base of a cecal fold with minimal elevation.

 
Adenomatous polyps and hyperplastic polyps are generally indistinguishable macroscopically; however, adenomatous polyps are the most commonly seen neoplastic polyp at histologic analysis, whereas hyperplastic polyps (Fig 8) are the most commonly seen nonneoplastic polyp. Adenomatous polyps are also classified microscopically as tubular, tubulovillous (Fig 6), or villous. Tubular adenomas are more common than villous adenomas, but the latter are more likely to have high-grade dysplasia (9).


Figure 8A
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  		Figure 8a.  Hyperplastic polyp. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a flat 5-mm lesion (arrow) involving a cecal fold. Histologic findings helped identify the polyp as hyperplastic.

 

Figure 8B
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  		Figure 8b.  Hyperplastic polyp. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a flat 5-mm lesion (arrow) involving a cecal fold. Histologic findings helped identify the polyp as hyperplastic.

 

Figure 8C
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  		Figure 8c.  Hyperplastic polyp. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a flat 5-mm lesion (arrow) involving a cecal fold. Histologic findings helped identify the polyp as hyperplastic.

 
Lipomas.— Lipomas are benign tumors composed of well-differentiated adipose tissue and are seen in the gastrointestinal tract at autopsy in up to 4.4% of cases (10). The largest percentage (45%) of lipomas in the colon involve the cecum, which is also the most common location when there are multiple lesions. Lipomas vary greatly in size; they average about 4 cm but can grow as large as 30 cm. Lipomas are almost always submucosal, with only about 10% being subserosal. CT demonstrates a well-defined spheric or ovoid mass with fat attenuation (11). Although malignant transformation has not been described in these lesions, lipomas larger than 2 cm may become symptomatic (eg, because of intussusception or obstruction); thus, endoscopic or surgical resection is generally recommended for larger lesions (12).

Primary Malignancy.— More than 90% of colorectal cancers are adenocarcinomas, most of which arise from adenomatous polyps (13). The clinical manifestation varies with colonic location. Because of the relatively smaller caliber of the left colon, left-sided adenocarcinomas more often manifest circumferentially with obstruction, whereas in the larger-caliber right colon, adenocarcinomas can grow to a larger size without causing obstruction and patients may present with iron deficiency anemia. Similar to their polyp precursors, adenocarcinomas may appear morphologically as a sessile mass or a flat lesion (Fig 9). Larger adenocarcinomas may become annular or ulcerated or both.


Figure 9A
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  		Figure 9a.  Flat adenocarcinoma. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 4-cm partially circumferential flat mass (arrow) involving a cecal fold. The cecum is mobile and medially displaced because of the relatively longer mesentery.

 

Figure 9B
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  		Figure 9b.  Flat adenocarcinoma. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 4-cm partially circumferential flat mass (arrow) involving a cecal fold. The cecum is mobile and medially displaced because of the relatively longer mesentery.

 

Figure 9C
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  		Figure 9c.  Flat adenocarcinoma. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 4-cm partially circumferential flat mass (arrow) involving a cecal fold. The cecum is mobile and medially displaced because of the relatively longer mesentery.

 
Primary signet ring carcinoma is a rare variant of mucin-secreting adenocarcinoma that accounts for up to 2.6% of colorectal malignancies (Fig 10) (14). It is named for its microscopic appearance, in which the nucleus of the cell is displaced to the periphery by the large amount of intracytoplasmic mucin produced by the tumor. By definition, at least 50% of the cells in a signet ring carcinoma are signet ring cells. Compared with the more common colorectal adenocarcinoma, the signet ring variety occurs in younger patients and spreads more readily to the peritoneal surfaces and lymph nodes, but hepatic parenchymal metastases occur less frequently. The clinical aggressiveness of signet ring carcinoma, coupled with its high prevalence of local recurrence, often make for a poor prognosis. At radiology, signet ring carcinoma may mimic an underlying colonic inflammatory process, usually manifesting as an elongated infiltrating mass (>5 cm) with concentric, rigid wall thickening and a scirrhous or linitis plastica appearance (15). For this reason, the lesion may be misdiagnosed as colonic Crohn disease or ischemic colitis. In addition, these lesions may be overlooked endoscopically because the mucosal surface may appear intact, thus necessitating deep-tissue biopsies for correct diagnosis.


Figure 10A
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  		Figure 10a.  Signet ring cell carcinoma. Three-dimensional (a) and axial 2D (b) CT colonographic images show a 2-cm polypoid mass (arrow) within the cecum. Histopathologic examination showed the mass to be signet ring cell carcinoma.

 

Figure 10B
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  		Figure 10b.  Signet ring cell carcinoma. Three-dimensional (a) and axial 2D (b) CT colonographic images show a 2-cm polypoid mass (arrow) within the cecum. Histopathologic examination showed the mass to be signet ring cell carcinoma.

 
Lymphoma.— The most common location for primary extranodal non-Hodgkin lymphoma is the gastrointestinal tract (50% of cases). The stomach is the most frequently involved site, followed (in decreasing order of frequency) by the small bowel, the ileocecal region, the large bowel or rectum, and the esophagus. Primary colonic involvement is rare, representing only about 0.4% of cases (16). At imaging, a gastrointestinal tract lymphoma (Fig 11) may manifest as a polypoid mass, a circumferential infiltrative lesion, a large cavitary lesion, a diffuse nodular lesion, or any combination thereof (17,18). However, even circumferential masses rarely cause obstruction.


Figure 11A
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  		Figure 11a.  Lymphoma involving the ICV. Three-dimensional (a) and axial 2D (b) CT colonographic images show mild focal thickening of the distal terminal ileum and ICV (arrows). The subtle wall thickening is best appreciated on the axial 2D image because of better visibility of the wall or valve compared with other adjacent small bowel segments. Note the prominent adjacent mesenteric lymph nodes (arrowhead in b). Biopsy findings demonstrated non-Hodgkin lymphoma.

 

Figure 11B
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  		Figure 11b.  Lymphoma involving the ICV. Three-dimensional (a) and axial 2D (b) CT colonographic images show mild focal thickening of the distal terminal ileum and ICV (arrows). The subtle wall thickening is best appreciated on the axial 2D image because of better visibility of the wall or valve compared with other adjacent small bowel segments. Note the prominent adjacent mesenteric lymph nodes (arrowhead in b). Biopsy findings demonstrated non-Hodgkin lymphoma.

 

   Appendix
Top
 Abstract
 Introduction
 Normal Anatomy
 Polyps and Masses
 Appendix
Conclusions
 References
 
Mucocele of the Appendix.— Mucocele is a descriptive term that indicates mucus-containing cystic dilatations of the appendix, gallbladder, sinus cavities, or salivary glands. An appendiceal mucocele is most commonly observed in women over 50 years old, with a prevalence of about 0.25% in appendectomy specimens. Mucoceles may be either benign retention cysts (cystadenoma) or neoplastic cysts (cystadenocarcinoma) (19,20). When confined to the appendix (Fig 12), mucoceles may mimic appendicitis, although the lack of adjacent inflammation and the visualization of mural calcification may favor a diagnosis of tumor (20,21).


Figure 12A
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  		Figure 12a.  Mucocele of the appendix. Three-dimensional (a) and axial 2D (b) CT colonographic images show a 2.5-cm polypoid lesion (arrow) at the cecal base in the expected location of the appendix. Note the low internal attenuation on the axial image. After surgical excision, the lesion was confirmed to be a mucocele of the appendix.

 

Figure 12B
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  		Figure 12b.  Mucocele of the appendix. Three-dimensional (a) and axial 2D (b) CT colonographic images show a 2.5-cm polypoid lesion (arrow) at the cecal base in the expected location of the appendix. Note the low internal attenuation on the axial image. After surgical excision, the lesion was confirmed to be a mucocele of the appendix.

 
The differential diagnosis includes mesenteric cyst, duplication cyst, and right ovarian cyst or hydrosalpinx (if the appendix overlies the right side of the pelvis). Neoplastic mucoceles that perforate can result in dissemination of tumor cells into the peritoneal cavity (ie, pseudomyxoma peritonei). Cystadenomas are generally confined to the periappendiceal region, whereas cystadenocarcinomas may spread diffusely (22). Characteristic findings in malignant dissemination include scalloping of the periphery of visceral organs, with peritoneal implants occasionally displaying peripheral calcifications. Surgical excision is the preferred treatment; however, accurate preoperative diagnosis is important so as to avoid unintended rupture during surgery with resultant pseudomyxoma peritonei (23).

Appendiceal Stump.— A filling defect at the cecal base is a potential pitfall at CT colonography. After inversion-ligation appendectomy (24), the appendiceal stump (Fig 13) may mimic a polyp; thus, correlation with surgical history or endoscopic findings is required for lesions identified at the base of the cecum. The inversion-ligation technique is seldom used anymore, but many adults who are now presenting for CT colonography underwent appendectomy decades ago when this technique was common (24).


Figure 13A
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  		Figure 13a.  Appendiceal stump. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 1.5-cm lesion (arrow) at the base of the cecum. The lesion was thought to represent a polyp at CT colonography, but endoscopy showed it to be an inverted appendiceal stump.

 

Figure 13B
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  		Figure 13b.  Appendiceal stump. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 1.5-cm lesion (arrow) at the base of the cecum. The lesion was thought to represent a polyp at CT colonography, but endoscopy showed it to be an inverted appendiceal stump.

 

Figure 13C
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  		Figure 13c.  Appendiceal stump. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images show a 1.5-cm lesion (arrow) at the base of the cecum. The lesion was thought to represent a polyp at CT colonography, but endoscopy showed it to be an inverted appendiceal stump.

 
Inflammation or Infection
Cecal Diverticulitis.— Cecal diverticula are relatively uncommon, with a reported prevalence of only about 5% in patients with diverticular disease (25–27). In contrast to the more common pseudodiverticula of the left colon, which do not contain circular muscle, diverticula in the cecum are usually considered true diverticula (ie, they contain all layers of the colonic wall). About 80% of all diverticula in the right colon are located near the ICV and are generally asymptomatic (26–28). However, when the lumen is obstructed, typically by a fecalith, the clinical manifestation is often indistinguishable from that of acute appendicitis. Furthermore, the average age of patients who present with right-sided diverticulitis is similar to that of patients with acute appendicitis (ie, both conditions occur in a younger patient population). In addition to a normal-appearing appendix, inflammatory changes adjacent to a diverticulum (Fig 14) are helpful CT findings for making the correct diagnosis.


Figure 14
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  		Figure 14.  Right lower quadrant diverticulitis. Axial contrast material–enhanced CT scan obtained in a patient with clinically suspected acute appendicitis shows thickening of the right colon with pericolonic inflammatory changes (arrowhead) and a hyperenhancing diverticulum (arrow), findings that are consistent with diverticulitis. The appendix was normal.

 
Ischemic Colitis.— The most common form of gastrointestinal tract ischemia is ischemic colitis (50% of cases) (29,30). Ischemic colitis is mainly a disease of the elderly that manifests along a spectrum from reversible (mucosal or submucosal hemorrhage, transient ischemia) to irreversible (fulminant colitis, stricture, gangrene) injury. Although variations in collateral blood supply allow involvement of any colonic segment, the splenic flexure and left colon are the most frequently affected sites. CT findings of abnormal colonic wall or fold thickening and attenuation with pericolonic inflammatory changes are not pathognomonic but are highly suggestive in the appropriate clinical context (Fig 15) (29,30). Although intramural air may be observed in certain benign conditions, in patients with bowel ischemia it indicates probable bowel necrosis and a fatal prognosis (Fig 16). Treatment depends on the severity and pathogenesis of this process. Mild cases respond well to conservative treatment, with two-thirds of all patients recovering spontaneously within 24–48 hours. For patients who do not respond to conservative treatment, or who have signs of frank peritonitis or bowel perforation, surgical intervention is indicated (31).


Figure 15A
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  		Figure 15a.  Ischemic colitis of the cecum in a 57-year-old patient who had presented to another hospital with abdominal pain and fever, where a cecal mass was identified at abdominal CT. (a) Axial contrast-enhanced CT scan shows irregular cecal wall thickening (arrows). (b) On an image from a subsequent endoscopic study, the wall thickening seen in a appears masslike (arrows). Although the thickened cecal wall was thought to represent an underlying malignancy, histopathologic examination at the time indicated ischemic changes only, and the patient was treated conservatively. (c) Follow-up CT scan obtained 2 weeks after endoscopy demonstrates resolution of the abnormal findings.

 

Figure 15B
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  		Figure 15b.  Ischemic colitis of the cecum in a 57-year-old patient who had presented to another hospital with abdominal pain and fever, where a cecal mass was identified at abdominal CT. (a) Axial contrast-enhanced CT scan shows irregular cecal wall thickening (arrows). (b) On an image from a subsequent endoscopic study, the wall thickening seen in a appears masslike (arrows). Although the thickened cecal wall was thought to represent an underlying malignancy, histopathologic examination at the time indicated ischemic changes only, and the patient was treated conservatively. (c) Follow-up CT scan obtained 2 weeks after endoscopy demonstrates resolution of the abnormal findings.

 

Figure 15C
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  		Figure 15c.  Ischemic colitis of the cecum in a 57-year-old patient who had presented to another hospital with abdominal pain and fever, where a cecal mass was identified at abdominal CT. (a) Axial contrast-enhanced CT scan shows irregular cecal wall thickening (arrows). (b) On an image from a subsequent endoscopic study, the wall thickening seen in a appears masslike (arrows). Although the thickened cecal wall was thought to represent an underlying malignancy, histopathologic examination at the time indicated ischemic changes only, and the patient was treated conservatively. (c) Follow-up CT scan obtained 2 weeks after endoscopy demonstrates resolution of the abnormal findings.

 

Figure 16
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  		Figure 16.  Colonic infarct with pneumatosis coli in an elderly patient who presented with acute abdominal pain and bleeding of the gastrointestinal tract. Coronal reformatted CT image shows abnormal intramural air (arrows). Frank colonic necrosis was found at surgical exploration.

 
Crohn Colitis.— Although Crohn disease (Fig 17) may involve any part of the gastrointestinal tract, cecal or colonic involvement is found in 60%–70% of patients, 20% of which cases are isolated to the colon (granulomatous colitis) (32). Clinical history, pattern of involvement, associated complications, laboratory or culture results, and biopsy findings are all helpful in differentiating Crohn colitis from potential mimics (eg, infectious or ischemic colitides, ulcerative colitis). CT findings include abnormal wall thickening (generally >1 cm) with skip areas of colonic stenosis and dilatation. Active disease may manifest as mucosal hyperenhancement or mural stratification (25,30). Associated findings include pericolonic fat stranding, fistulas, abscesses, fibrofatty proliferation, and mesenteric adenopathy. Although it is not clearly established, many gastroenterologists believe that patients with longstanding Crohn colitis have a similar risk of developing colorectal carcinoma as do patients with longstanding ulcerative colitis (33).


Figure 17A
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  		Figure 17a.  Crohn colitis of the cecum mimicking tumor. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 2.5-cm lobulated sessile lesion in the base of the cecum (arrow in a and c) with marked edema and ulceration about the cecal base (arrow in b). The lesion was initially thought to be a malignant mass; however, histologic findings demonstrated mild acute colitis compatible with Crohn disease.

 

Figure 17B
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  		Figure 17b.  Crohn colitis of the cecum mimicking tumor. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 2.5-cm lobulated sessile lesion in the base of the cecum (arrow in a and c) with marked edema and ulceration about the cecal base (arrow in b). The lesion was initially thought to be a malignant mass; however, histologic findings demonstrated mild acute colitis compatible with Crohn disease.

 

Figure 17C
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  		Figure 17c.  Crohn colitis of the cecum mimicking tumor. Three-dimensional CT colonographic (a), endoscopic (b), and axial 2D CT colonographic (c) images reveal a 2.5-cm lobulated sessile lesion in the base of the cecum (arrow in a and c) with marked edema and ulceration about the cecal base (arrow in b). The lesion was initially thought to be a malignant mass; however, histologic findings demonstrated mild acute colitis compatible with Crohn disease.

 
Neutropenic Colitis.— Patients being treated for underlying leukemia or lymphoma may rarely present with neutropenic colitis (typhlitis) as an acute complication of neutropenia (Fig 18) (34). Other associated conditions include acquired immunodeficiency syndrome, aplastic anemia, prior renal transplantation, and infectious mononucleosis. The cecum is the most common site of involvement, with CT findings including bowel wall thickening, intramural air (pneumatosis), and pericecal inflammatory fat stranding or fluid (35,36). The inflammatory changes may also encompass the ascending colon and the distal ileum and have been found isolated to the small bowel without right colon involvement (36). The management of neutropenic colitis has evolved considerably over the past 25 years. Initially, aggressive surgical intervention was performed because it was thought that all cases inevitably progressed to bowel necrosis and perforation. Subsequent anecdotal case reports and reviews have demonstrated that timely conservative management can be successful, with selective surgical intervention reserved for perforation, abscess, gastrointestinal bleeding, or obstruction (37–40).


Figure 18
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  		Figure 18.  Neutropenic colitis. Axial contrast-enhanced CT scan demonstrates marked irregular thickening of a medially oriented cecum (arrows) with associated pericecal inflammatory stranding and fluid. The marked wall thickening with resultant luminal narrowing is known as "cone cecum." The differential diagnosis includes inflammatory bowel disease (Crohn disease and ulcerative colitis), amebiasis, tuberculosis, lymphoma, cecal carcinoma, sequelae of radiation therapy, and metastases.

 
Cecal Obstruction
Cecal Volvulus.— Cecal volvulus is a rare but potentially fatal condition that accounts for up to 2% of cases of bowel obstruction and 11% of cases of intestinal volvulus (41,42). In contrast to sigmoid volvulus, which occurs in elderly patients (>70 years of age) with redundant colon, cecal volvulus occurs in younger patients (30–60 years of age) with developmentally long cecal mesentery. Other predisposing factors include prior surgery, recent colonoscopy, congenital cecal duplication cyst, and mesenteric masses. In these patients, the cecum rotates around the long axis of the ascending colon, with a resultant high mortality rate caused by associated vascular compromise. A variant of cecal volvulus has been described as a cecal bascule, which is thought to occur owing to anteromedial folding of the cecum in relation to the ascending colon as opposed to a more conventional adynamic ileus of the cecum (43). Although conventional radiographic findings may be diagnostic, CT is increasingly being used to help evaluate acute abdominal conditions; thus, it is important to be able to recognize the CT findings of volvulus (Fig 19) (42,44). The CT "whirl sign" (45) refers to the twisted appearance of the mesenteric vessels as sequelae of small or large bowel torsion. Identification of an abnormally dilated and displaced cecum leads to the correct diagnosis.


Figure 19A
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  		Figure 19a.  Cecal volvulus. Coronal reformatted CT image (a) and axial contrast-enhanced CT scans (b, c) demonstrate a markedly enlarged and dilated air- and fluid-filled cecum (arrow in a and b) extending from the right lower quadrant to the left upper quadrant. Note the abrupt transition between the collapsed, twisted segment of the colon (short arrows in c) and the dilated, obstructed segment (long arrow in c). There is also a subtle whorl of mesenteric vessels (whirl sign) in the right lower quadrant (arrowheads in c) related to torsion of the mesentery caused by the rotated cecum.

 

Figure 19B
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  		Figure 19b.  Cecal volvulus. Coronal reformatted CT image (a) and axial contrast-enhanced CT scans (b, c) demonstrate a markedly enlarged and dilated air- and fluid-filled cecum (arrow in a and b) extending from the right lower quadrant to the left upper quadrant. Note the abrupt transition between the collapsed, twisted segment of the colon (short arrows in c) and the dilated, obstructed segment (long arrow in c). There is also a subtle whorl of mesenteric vessels (whirl sign) in the right lower quadrant (arrowheads in c) related to torsion of the mesentery caused by the rotated cecum.

 

Figure 19C
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  		Figure 19c.  Cecal volvulus. Coronal reformatted CT image (a) and axial contrast-enhanced CT scans (b, c) demonstrate a markedly enlarged and dilated air- and fluid-filled cecum (arrow in a and b) extending from the right lower quadrant to the left upper quadrant. Note the abrupt transition between the collapsed, twisted segment of the colon (short arrows in c) and the dilated, obstructed segment (long arrow in c). There is also a subtle whorl of mesenteric vessels (whirl sign) in the right lower quadrant (arrowheads in c) related to torsion of the mesentery caused by the rotated cecum.

 
Cecal Intussusception.— Adult intussusception (Fig 20) accounts for 1% of cases of bowel obstruction and 5% of cases of intestinal intussusception (46). In intussusception, a segment of proximal bowel (intussusceptum) and its mesentery prolapse into a segment of distal bowel (intussuscipiens). Traditionally, surgical resection has been the accepted therapy for adult intussusception, which most commonly occurs as the result of a pathologic lead point (eg, Meckel diverticulum, polyp, lipoma, appendix, malignant tumor or lymphoma). However, intussusceptions detected at CT that involve the proximal small bowel or extend for only a short segment are often self-limited; they lack an associated lead point and do not require surgical intervention (47,48). Distal small bowel and colonic intussusceptions often have a lead point, most commonly a benign tumor with the former and a malignant tumor with the latter. The three CT manifestations of intussusception (49,50) are (in ascending order of acuity and severity) (a) the "target" appearance, with a concentric pattern of bowel wall, lumen, and mesenteric fat or vessels; (b) the "sausage" appearance, with an elongated target appearance (later phase); and (c) the reniform appearance, with vascular compromise and edema or mural thickening.


Figure 20A
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  		Figure 20a.  Ileocolic intussusception. Axial (a) and coronal (b) reformatted CT images show ileocolic intussusception caused by a large cecal adenocarcinoma (arrow in b), which acts as the lead point in this case. Note the mesenteric fat and vessels (arrow in a) and the terminal ileum (arrowhead in a) associated with the intussuscipiens.

 

Figure 20B
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  		Figure 20b.  Ileocolic intussusception. Axial (a) and coronal (b) reformatted CT images show ileocolic intussusception caused by a large cecal adenocarcinoma (arrow in b), which acts as the lead point in this case. Note the mesenteric fat and vessels (arrow in a) and the terminal ileum (arrowhead in a) associated with the intussuscipiens.

 

   Conclusions
Top
 Abstract
 Introduction
 Normal Anatomy
 Polyps and Masses
 Appendix
 Conclusions
References
 
The diagnosis of diseases involving the cecum, appendix, and ICV can be challenging due to the variable distention of the bowel in this region and to cecal mobility caused by laxity of the mesenteric attachments. Familiarity with the common cross-sectional imaging appearances of various diseases in the right colon and with the diagnostic pitfalls endemic to this region is useful in making the correct diagnosis.


   Acknowledgments
 
We thank Bonnie L. Schimek for medical graphics assistance; and the Section of Scientific Publications, Mayo Clinic, Rochester, Minnesota, for providing editing, proofreading, and reference verification services.


   Footnotes
 

Abbreviations: ICV = ileocecal valve, 2D = two-dimensional, 3D = three-dimensional


   References
Top
 Abstract
 Introduction
 Normal Anatomy
 Polyps and Masses
 Appendix
 Conclusions
 References
 

  1. In: Clemente CD, ed. Gray’s anatomy of the human body. 30th ed. Philadelphia, Pa: Lea & Febiger, 1985; 1187–1188.
  2. Yitta S, Tatineny KC, Cipriani NA, Dachman AH. Characterization of normal ileocecal valve density on CT colonography. J Comput Assist Tomogr 2006;30:58–61.[CrossRef][Medline]
  3. Regge D, Gallo TM, Nieddu G, et al. Ileocecal valve imaging on computed tomographic colonography. Abdom Imaging 2005;30:20–25.[CrossRef][Medline]
  4. Summers RM, Yao J, Johnson CD. CT colonography with computer-aided detection: automated recognition of ileocecal valve to reduce number of false-positive detections. Radiology 2004;233: 266–272.[Abstract/Free Full Text]
  5. Geboes K. Appendiceal function and dysfunction: what are the implications for inflammatory bowel disease? Nat Clin Pract Gastroenterol Hepatol 2005;2:338–339.[CrossRef][Medline]
  6. Gebbers JO, Laissue JA. Bacterial translocation in the normal human appendix parallels the development of the local immune system. Ann N Y Acad Sci 2004;1029:337–343.[CrossRef][Medline]
  7. Bresalier RS. Malignant and premalignant lesions of the colon. In: Friedman SL, McQuaid KR, Grendell JH, eds. Current diagnosis and treatment in gastroenterology. 2nd ed. New York, NY: Lange Medical Books/McGraw Hill, 2003; 407–435.
  8. Park SH, Ha HK, Kim MJ, et al. False-negative results at multi–detector row CT colonography: multivariate analysis of causes for missed lesions. Radiology 2005;235:495–502.[Abstract/Free Full Text]
  9. Cappell MS. From colonic polyps to colon cancer: pathophysiology, clinical presentation, and diagnosis. Clin Lab Med 2005;25:135–177.[CrossRef][Medline]
  10. Hara AK, Johnson CD, Reed JE. Colorectal lesions: evaluation with CT colography. RadioGraphics 1997;17:1157–1167.[Abstract]
  11. Fultz PJ, Hampton WR, Skucas J, Sickel JZ. Differential diagnosis of fat-containing lesions with abdominal and pelvic CT. RadioGraphics 1993; 13:1265–1280.[Abstract/Free Full Text]
  12. Abou-Nukta F, Gutweiler J, Khaw J, Yavorek G. Giant lipoma causing a colo-colonic intussusception. Am Surg 2006;72:83–84.[Medline]
  13. Jass JR, Sobin LH, eds. Histological typing of intestinal tumours. 2nd ed. Berlin, Germany: Springer-Verlag, 1989.
  14. Wolfman EF Jr, Astler VB, Coller FA. Mucoid adenocarcinoma of the colon and rectum. Surgery 1957;42:846–852.[Medline]
  15. Giacchero A, Aste H, Baracchini P, et al. Primary signet-ring carcinoma of the large bowel: report of nine cases. Cancer 1985;56:2723–2726.[CrossRef][Medline]
  16. Schroy PC III, Freedman AS. Classification and pathology of gastrointestinal lymphomas. In: Rose BD, ed. UpToDate. Waltham, Mass: UpToDate, 2006.
  17. Mendelson RM, Fermoyle S. Primary gastrointestinal lymphomas: a radiological-pathological review. I. Stomach, oesophagus and colon. Australas Radiol 2005;49:353–364.[CrossRef][Medline]
  18. Lee HJ, Han JK, Kim TK, et al. Primary colorectal lymphoma: spectrum of imaging findings with pathologic correlation. Eur Radiol 2002;12:2242–2249.[Medline]
  19. Chiou YY, Pitman MB, Hahn PF, Kim YH, Rhea JT, Mueller PR. Rare benign and malignant appendiceal lesions: spectrum of computed tomography findings with pathologic correlation. J Comput Assist Tomogr 2003;27:297–306.[CrossRef][Medline]
  20. Rampone B, Roviello F, Marrelli D, Pinto E. Giant appendiceal mucocele: report of a case and brief review. World J Gastroenterol 2005;11: 4761–4763.[Medline]
  21. Isaacs KL, Warshauer DM. Mucocele of the appendix: computed tomographic, endoscopic, and pathologic correlation. Am J Gastroenterol 1992; 87:787–789.[Medline]
  22. Dachman AH, Lichtenstein JE, Friedman AC. Mucocele of the appendix and pseudomyxoma peritonei. AJR Am J Roentgenol 1985;144:923–929.[Abstract/Free Full Text]
  23. Lau H, Yuen WK, Loong F, Lee F. Laparoscopic resection of an appendiceal mucocele. Surg Laparosc Endosc Percutan Tech 2002;12:367–370.[CrossRef][Medline]
  24. Prout TM, Taylor AJ, Pickhardt PJ. Inverted appendiceal stumps simulating large pedunculated polyps on screening CT colonography. AJR Am J Roentgenol 2006;186:535–538.[Free Full Text]
  25. Gluecker TM, Williamson EE, Fletcher JG, et al. Diseases of the cecum: a CT pictorial review. Eur Radiol 2003;13(suppl 4):L51–L61.[CrossRef]
  26. Updegrove JH. Diverticulitis of the cecum. Ann Surg 1955;141:251–253.[Medline]
  27. Graham SM, Ballantyne GH. Cecal diverticulitis: a review of the American experience. Dis Colon Rectum 1987;30:821–826.[Medline]
  28. Sardi A, Gokli A, Singer JA. Diverticular disease of the cecum and ascending colon: a review of 881 cases. Am Surg 1987;53:41–45.[Medline]
  29. Balthazar EJ, Yen BC, Gordon RB. Ischemic colitis: CT evaluation of 54 cases. Radiology 1999; 211:381–388.[Abstract/Free Full Text]
  30. Horton KM, Corl FM, Fishman EK. CT evaluation of the colon: inflammatory disease. RadioGraphics 2000;20:399–418.[Abstract/Free Full Text]
  31. Brandt LJ, Boley SJ. Colonic ischemia. Surg Clin North Am 1992;72:203–229.[Medline]
  32. Judge TA, Lichtenstein GR. Inflammatory bowel disease. In: Friedman SL, McQuaid KR, Grendell JH, eds. Current diagnosis and treatment in gastroenterology. 2nd ed. New York, NY: Lange Medical Books/McGraw Hill, 2003; 108–130.
  33. Peppercorn MA, Odze RD. Colorectal cancer surveillance in inflammatory bowel disease. In: Rose BD, ed. UpToDate. Waltham, Mass: UpToDate, 2006.
  34. McCarville MB, Adelman CS, Li C, et al. Typhlitis in childhood cancer. Cancer 2005;104:380–387.[CrossRef][Medline]
  35. Kirkpatrick ID, Greenberg HM. Gastrointestinal complications in the neutropenic patient: characterization and differentiation with abdominal CT. Radiology 2003;226:668–674.[Abstract/Free Full Text]
  36. Sigirci A, Akinci A, Ozgen U, Ozen M. Neutropenic enterocolitis (typhlitis) associated with infectious mononucleosis. Pediatr Radiol 2006;36:155–157.[CrossRef][Medline]
  37. O’Brien S, Kantarjian HM, Anaissie E, Dodd G, Bodey GP. Successful medical management of neutropenic enterocolitis in adults with acute leukemia. South Med J 1987;80:1233–1235.[CrossRef][Medline]
  38. Koea JB, Shaw JH. Surgical management of neutropenic enterocolitis. Br J Surg 1989;76:821–824.[Medline]
  39. Kulaylat M, Doerr R, Ambrus J. A case presentation and review of neutropenic enterocolitis. J Med 1997;28:1–19.[CrossRef][Medline]
  40. Williams N, Scott AD. Neutropenic colitis: a continuing surgical challenge. Br J Surg 1997;84: 1200–1205.[CrossRef][Medline]
  41. Ballantyne GH, Brandner MD, Beart RW Jr, Ilstrup DM. Volvulus of the colon: incidence and mortality. Ann Surg 1985;202:83–92.[Medline]
  42. Impieri M, Zambarda E. Cecal volvulus: report of a case and review of the literature. Acta Chir Belg 1984;84:79–82.[Medline]
  43. Perret RS, Kunberger LE. Case 4: cecal volvulus. AJR Am J Roentgenol 1998;171:855, 859, 860.[Medline]
  44. Moore CJ, Corl FM, Fishman EK. CT of cecal volvulus: unraveling the image. AJR Am J Roentgenol 2001;177:95–98.[Free Full Text]
  45. Frank AJ, Goffner LB, Fruauff AA, Losada RA. Cecal volvulus: the CT whirl sign. Abdom Imaging 1993;18:288–289.[Medline]
  46. Azar T, Berger DL. Adult intussusception. Ann Surg 1997;226:134–138.[CrossRef][Medline]
  47. Lvoff N, Breiman RS, Coakley FV, Lu Y, Warren RS. Distinguishing features of self-limiting adult small-bowel intussusception identified at CT. Radiology 2003;227:68–72.[Abstract/Free Full Text]
  48. Sandrasegaran K, Kopecky KK, Rajesh A, Lappas J. Proximal small bowel intussusceptions in adults: CT appearance and clinical significance. Abdom Imaging 2004;29:653–657.[CrossRef][Medline]
  49. Iko BO, Teal JS, Siram SM, Chinwuba CE, Roux VJ, Scott VF. Computed tomography of adult colonic intussusception: clinical and experimental studies. AJR Am J Roentgenol 1984;143:769–772.[Abstract/Free Full Text]
  50. Cox TD, Winters WD, Weinberger E. CT of intussusception in the pediatric patient: diagnosis and pitfalls. Pediatr Radiol 1996;26:26–32.[CrossRef][Medline]




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