| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Gastrointestinal Imaging |
1 From the Departments of Radiology (L.C.E., M.S.L., S.E.R., I.L.) and Medicine (J.N.S., M.L.K.), Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104. Received April 2, 2002; revision requested June 12; revision received June 19; accepted July 25. Address correspondence to M.S.L. (e-mail: levine@oasis.rad.upenn.edu).
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
MATERIALS AND METHODS: A search of radiology and endoscopy files showed 106 patients who underwent double-contrast barium enema examination and colonoscopy. The radiographic images were reviewed by two authors to determine the morphology of the ileocecal valve and to evaluate whether it appeared normal or abnormal. The radiographic data were then correlated with endoscopic and pathologic findings.
RESULTS: The ileocecal valve was visible in 91 (86%) of 106 patients. It was round or ovoid in 71 patients (78%) and triangular in 20 (22%). In the 88 patients with a normal valve at colonoscopy, mean valve height was 1.7 cm, and mean width was 2.8 cm. The valve was smooth in 75 patients (85%) and smoothly lobulated in 13 (15%). The lips of the valve were symmetric in 77 patients (88%) and asymmetric in 11 (12%). All 87 patients with a normal valve at double-contrast barium enema examination had a normal valve at colonoscopy, whereas the two patients with a valve suspicious for tumor at barium enema examination had neoplasms (one carcinoma and one villous adenoma) at colonoscopy.
CONCLUSION: The ileocecal valve may show a spectrum of normal findings at double-contrast barium enema examination and may appear as a round, ovoid, or triangular structure with a maximal height of nearly 4 cm. The valve may be large, asymmetric, or smoothly lobulated, even in the absence of tumor.
© RSNA, 2003
Index terms: Barium enema examination, 752.1283 • Colon, radiography, 752.1283, 752.92 • Colonoscopy, 752.1289
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
A computerized search of radiology and endoscopy files from January 1998 to September 2001 at our university hospital showed 476 patients who underwent double-contrastbarium enema examination and colonoscopy within a 6-month interval. Three hundred seventy of these patients were excluded from the analysis for any of the following reasons: (a) incomplete barium enema or colonoscopic examination, in which the cecum and ileocecal valve were not visualized; (b) radiographic or endoscopic findings of distal ileal or right-sided colonic involvement in inflammatory bowel disease, diverticulitis, radiation enteropathy, or other inflammatory or infectious conditions that could affect the ileocecal valve; and (c) lack of availability of either the endoscopic reports or radiographs from these examinations. The remaining 106 patients comprised our study group. The mean interval between the double-contrast barium enema examination and colonoscopy for these 106 patients was 2.2 months (range, 1–6 months). The mean age of the patients was 59 years (range, 25–89 years). Forty-eight patients were men, and 58 were women.
Endoscopy and Pathology Report Review
The endoscopy reports for these 106 patients were reviewed by one author (L.C.E.) to determine if the ileocecal valve appeared normal or abnormal at colonoscopy. The ileocecal valve was considered to have a normal endoscopic appearance when there was smooth intact mucosa overlaying the valve without evidence of a mucosal or submucosal mass, ulceration, or other pathologic findings. If the ileocecal valve appeared normal at colonoscopy, no endoscopic biopsy specimens were obtained. If the valve appeared abnormal, however, endoscopic biopsy specimens were obtained from this region. In such cases, the pathology reports were reviewed by one author (L.C.E.) to determine the final pathologic findings. If the biopsy specimens showed normal mucosa or fatty infiltration of the ileocecal valve, the valve was considered normal despite an abnormal appearance at colonoscopy. Thus, the ileocecal valve was considered normal or abnormal on the basis of a combination of the endoscopic and pathologic findings as the standard of reference.
Imaging
Double-contrast barium enema examinations were performed with digital fluoroscopic equipment (Diagnost 76 Plus; Philips, Eindhoven, the Netherlands) and a 100% wt/vol barium suspension (Polibar Plus; E-Z-Em, Westbury, NY). The examinations included acquisition of multiple fluoroscopic spot radiographs of the colon, as well as a series of conventional overhead radiographs, as has been described previously (3). The technical quality of the double-contrast barium images for visualization of the cecum was graded by two authors (M.S.L., S.E.R.) in consensus as being excellent in 38 patients (36%), good in 53 (50%), fair in 13 (12%), and poor in two (2%). The images were rated as excellent if there was optimal mucosal coating of the cecum with no fecal debris and no excess barium in this region; good if there was adequate mucosal coating with little or no fecal debris and little or no excess barium; fair if there was suboptimal mucosal coating or mild to moderate fecal debris and/or excess barium; and poor if there was poor mucosal coating or marked fecal debris and/or excess barium.
The images from these 106 double-contrast barium enema examinations were reviewed by two authors (M.S.L., S.E.R.) in consensus (gastrointestinal radiologists with 18–20 years of experience) who had no knowledge of the final endoscopic or pathologic findings. The images were reviewed to determine if the ileocecal valve was visible and if there was reflux of barium into the terminal ileum or appendix. When the ileocecal valve was not identified, the images were reviewed to determine if the valve could not be visualized because of retained barium or fecal debris in the cecum, a low-lying pelvic cecum obscured by overlapping ileal loops, or other technical factors.
When the ileocecal valve was identified, it was evaluated for the following parameters: location (medial, posterior, or lateral; number of haustral folds from the cecal tip; and distance from the cecal tip as measured on overhead images), size (height from the superior to inferior lips and width from the medial to lateral borders as measured on overhead images), shape (round, ovoid, or triangular), symmetry (symmetric or asymmetric), contour (smooth or lobulated), and the presence or absence of other morphologic features, such as centrally radiating folds or a central slitlike collection of barium. The cecum was also evaluated for the presence of a discrete mass or other lesions in the region of the ileocecal valve. When the appendix was visualized, its location (medial, lateral, or cecal tip) and relationship to the ileocecal valve were also noted. The images were also reviewed to determine the relationship between the location of the ileocecal valve and cecal mobility (ie, whether the cecum was fixed to the retroperitoneum or whether it was a mobile structure on a long section of the mesentery). The cecum was considered mobile if its position in the abdomen changed substantially on spot radiographs or overhead images.
In the patients with radiographically visible ileocecal valves, the findings on double-contrast barium enema images were subsequently stratified for patients who had a normal ileocecal valve and those who had an abnormal valve by using the endoscopic and pathologic findings as the standard of reference. Finally, the ileocecal valves visualized on double-contrast barium enema images were classified by the same two authors in consensus, without knowledge of the endoscopic or pathologic findings of having a normal appearance, an appearance suspicious for tumor, or an appearance equivocal for tumor. The radiographic diagnoses were then compared by one author (L.C.E.) with the endoscopic and pathologic findings.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
Radiographic Findings
The ileocecal valve was visible in 91 (86%) of 106 double-contrast barium enema examinations (Table 1). In 10 patients, the valve could not be identified because of retained barium or fecal debris in the cecum (four patients), a low-lying pelvic cecum obscured by overlapping ileal loops (three patients), and other technical factors that prevented adequate double-contrast visualization of the cecum (three patients). In the remaining five patients, the cecum was well visualized with the double-contrast examination, but no ileocecal valve could be identified (Fig 1), presumably because the valve was too small or flat to produce a visible protrusion in the cecum.
|
|
The ileocecal valve was round or ovoid in 71 patients (78%) (Figs 2, 3) and triangular in 20 (22%) (Fig 4). In all patients, the valve appeared on double-contrast images as a filling defect in the barium pool or as a protruding structure etched in white. The valve contained centrally radiating folds in 11 patients (12%) (Fig 5) and a slitlike collection of barium at the central orifice of the valve in seven (8%) (Fig 6). The valve was located at the first haustral fold in the cecum in 30 patients (33%), the second fold in 59 (65%), and the third fold in two (2%). The mean distance from the ileocecal valve to the cecal tip was 6.2 cm (range, 3.5–11 cm).
|
|
|
|
|
Comparison of Radiographic Findings with Endoscopic and Pathologic Findings
Normal ileocecal valves.—In the 88 patients with a radiographically visible ileocecal valve that appeared normal by using the endoscopic and pathologic findings as the standard of reference, the mean height of the valve was 1.7 cm (range, 0.7–3.7 cm), and the mean width was 2.8 cm (range, 1.1–6.0 cm) (Figs 2, 3; Table 2). The height of the ileocecal valve exceeded 3 cm in two patients (2%). The valve had a smooth contour in 75 patients (85%) (Figs 2–6) and a lobulated contour with a smooth surface in 13 (15%) (mildly lobulated in nine, moderately lobulated in three, and markedly lobulated in one) (Figs 7, 8). Eleven of these 13 patients had asymmetric lobulation that involved predominantly the superior lip of the valve in five and the inferior lip in six. The lips of the valve were relatively symmetric in size in 77 patients (88%) and asymmetric in 11 (12%). In total, 26 (30%) of 88 patients with normal ileocecal valves at colonoscopy had valves that were more than 3 cm in height, asymmetric, and/or smoothly lobulated to varying degrees at double-contrast barium enema examination.
|
|
|
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
In our study, the ileocecal valve was visible at double-contrast barium enema examination in 91 (86%) of 106 patients. However, reflux of barium into the terminal ileum could be demonstrated in only 75% of patients in whom the valve was identified. Unlike on single-contrast barium enema images, the ileocecal valve was often visualized on double-contrast images in the absence of filling of the terminal ileum. In two-thirds of patients, our inability to visualize the ileocecal valve on double-contrast barium enema images resulted from technical artifacts, such as retained barium or fecal debris in the cecum or a low-lying cecum that was obscured by overlapping loops of barium-filled small bowel in the pelvis. In the remaining one-third of patients, however, no visible protrusion was identified in the cecum at the expected location of the valve, despite adequate visualization of the cecum at double-contrast examination. In such cases, the ileocecal valve is presumably too small or flat to be visible as a protruded defect in the cecum. Even with adequate double-contrast technique, the ileocecal valve may therefore not be identifiable on double-contrast barium enema images in a small percentage of patients.
During embryologic development, the cecum and ascending colon usually become fixed to the retroperitoneum. Occasionally, however, the cecum and ascending colon may be suspended on a long section of mesentery, which allows the cecum to have varying degrees of mobility as an intraperitoneal structure within the abdomen (5). In our study, a mobile cecum was observed at double-contrast barium enema examination in 14 (15%) of 91 patients in whom the ileocecal valve was identified. Almost all patients with a medial ileocecal valve had a fixed cecum, whereas most patients with a lateral ileocecal valve had a mobile cecum. Furthermore, when appendiceal filling occurred, the appendix was almost always located on the same side of the cecum as the ileocecal valve or, rarely, at the cecal tip. This is presumably because the root of the appendix migrates to the same side of the cecum as the ileocecal valve during fetal development (6). This anatomic relationship can be helpful for evaluating possible lesions of appendiceal origin at barium enema examination, since such lesions will almost never be located on the side of the cecum opposite the ileocecal valve.
When visible at double-contrast barium enema examination, all of the ileocecal valves in our study were manifested either by a round or ovoid or, less commonly, triangular structure that was etched in white or appeared as a filling defect in the barium pool. The valve was almost always located on the same side of the cecum as the barium-filled appendix within one or two haustral folds of the cecal tip. In a small percentage of cases, the ileocecal valve could be recognized en face by a slitlike collection of barium at the central orifice of the valve or by a collection of centrally radiating folds. In the past, it has been postulated that these centrally radiating folds indicate a contracting muscularis mucosae free of infiltration by tumor (7).
Despite these characteristic features of the ileocecal valve on double-contrast barium enema images, this structure was manifested by a spectrum of findings in terms of size, symmetry, and contour. The normal ileocecal valve varied considerably in size, ranging from approximately 1–4 cm in height and 1–6 cm in width. When the valve is assessed, however, it should be recognized that apparent enlargement of this structure may be caused by varying degrees of magnification, depending on the height of the fluoroscopic tower above the patient. Although most of the normal ileocecal valves in our study were smooth and symmetric, 15% contained varying degrees of lobulation, and 12% were asymmetric. It is therefore important to recognize that the ileocecal valve may have a maximal height of nearly 4 cm, it may be asymmetric, and it may have a smoothly lobulated contour on double-contrast barium enema images in the absence of tumor or other pathologic lesions in this region.
In our study, all patients with normal-appearing ileocecal valves at double-contrast barium enema examination were found to have normal valves at colonoscopy, whereas both patients with ileocecal valves suspicious for tumor at double-contrast barium enema examination were found to have neoplasms (one adenocarcinoma and one villous adenoma) involving the valve at colonoscopy. Both of these patients had valves that were enlarged, asymmetric, and markedly lobulated with a nodular surface. Such radiographic findings should therefore lead to early endoscopy and biopsy for a definitive diagnosis so these patients can be treated appropriately.
Of the remaining two patients with ileocecal valve equivocal for tumor at double-contrast barium enema examination, one was found to have prolapsed ileal mucosa in the cecum, and the other was found to have a normal valve at colonoscopy. Although neither of these patients had neoplasms, some patients with tumors involving the ileocecal valve may have relatively subtle findings at double-contrast barium enema examination with focal lobulation, mass effect, or asymmetry of the valve or small plaquelike, polypoid, or ulcerated lesions in this region. When the radiographic findings are equivocal, we therefore believe that radiologists should accept a certain percentage of false-positive diagnoses and recommend colonoscopy to avoid missing early tumors involving the ileocecal valve.
Another well-recognized cause of an enlarged ileocecal valve on barium enema images is fatty infiltration of the valve, a benign degenerative condition of doubtful clinical importance in most cases (8). Unfortunately, we were unable to determine the prevalence of fatty infiltration of the ileocecal valve in our patients, since endoscopic biopsy specimens were not obtained from the valve when it appeared normal at colonoscopy. Diffuse or focal fatty infiltration of the ileocecal valve should also be differentiated from an encapsulated lipoma involving the valve, which is typically seen on double-contrast images as a smooth round or ovoid submucosal mass abutting one lip of the valve (9). Computed tomography may help confirm the presence of adipose tissue in patients with fatty infiltration or an actual lipoma of the ileocecal valve (10,11).
Ileal prolapse through the ileocecal valve is another uncommon condition that can occasionally mimic the appearance of tumor involving the valve on barium enema images, as was the case in one of our patients (12). Ileal prolapse into the cecum may be caused by ileal tumors, such as lipomas or carcinoids or by enlarged lymphoid deposits in the terminal ileum (as in our patient) (13). However, other patients may have idiopathic prolapse of ileum into the cecum without a recognizable lead point (12).
Our study is limited by a lack of histologic specimens from the ileocecal valve when it appeared normal at colonoscopy. We therefore relied on the endoscopic appearance of the valve as the standard of reference and did not perform endoscopic biopsy in the vast majority of cases. Ideally, we would also have preferred a shorter time period between the double-contrast barium enema examination and colonoscopy rather than an interval of up to 6 months, but this would have severely restricted the number of patients included in our study. Carcinoma of the colon is also known to develop over a period of years by way of a well-documented adenoma-carcinoma sequence (14,15). It is therefore unlikely that any new tumors developed in the relatively brief intervals between barium enema examination and colonoscopy. Finally, our success in predicting whether the ileocecal valve had a normal appearance or was infiltrated by tumor on double-contrast barium enema images was skewed by the fact that the vast majority of patients in this retrospective study had normal ileocecal valves.
In conclusion, the ileocecal valve may manifest with a spectrum of normal findings at double-contrast barium enema examination and may appear as a round, ovoid, or triangular structure with a maximal height of nearly 4 cm, often associated with varying degrees of asymmetry or lobulation. It is therefore important to recognize that the ileocecal valve may be large, asymmetric, or smoothly lobulated on double-contrast barium enema images, even in the absence of tumor. If the valve is more than 4 cm in height and markedly asymmetric or lobulated with a nodular mucosal surface, however, colonoscopy should be performed to avoid missing neoplasms in this region.
|
FOOTNOTES |
|---|
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  S. D. O'Connor, R. M. Summers, J. Yao, P. J. Pickhardt, and J. R. Choi CT Colonography with Computer-aided Polyp Detection: Volume and Attenuation Thresholds to Reduce False-Positive Findings Owing to the Ileocecal Valve Radiology, November 1, 2006; 241(2): 426 - 432. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Summers, J. Yao, and C. D. Johnson CT Colonography with Computer-aided Detection: Automated Recognition of Ileocecal Valve to Reduce Number of False-Positive Detections Radiology, October 1, 2004; 233(1): 266 - 272. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
