DOI: 10.1148/rg.231025078
(Radiographics. 2003;23:59-72.)
© RSNA, 2003
US of Gastrointestinal Tract Abnormalities with CT Correlation1
Martin E. O’Malley, MD, FRCPC and
Stephanie R. Wilson, MD, FRCPC
1 From the Department of Medical Imaging, University Health Network and Mount Sinai Hospital at the University of Toronto, Toronto General Hospital, ES 1-401a, 200 Elizabeth St, Toronto, Ontario, Canada M5G 2C4. Recipient of a Certificate of Merit award for an education exhibit at the 2000 RSNA scientific assembly. Received April 12, 2002; revision requested May 14 and received June 19; accepted June 19. Address correspondence to M.E.O. (e-mail: martin.o’malley@uhn.on.ca).
 |
Abstract
|
|---|
Ultrasonography (US) is often the first imaging study performed in patients with abdominal pain or vague symptoms related to the gastrointestinal tract. An awareness of the US appearances of diseases of the intestine is essential to achieve the proper diagnosis and to enable appropriate triage of cases. Pathologic processes that affect the intestine generally result in decreased peristalsis and bowel wall thickening, both of which tend to decrease the luminal gas content. These changes permit evaluation of the intestine and surrounding structures with transabdominal and transvaginal US. US is useful in diagnosis of infectious and inflammatory conditions, such as appendicitis, Crohn disease, diverticulitis, epiploic appendagitis, pseudomembranous colitis, small bowel obstruction, small bowel vasculitis, and celiac disease. US is also helpful in diagnosis of tumors, such as gastric cancer, bowel lymphoma, and colon cancer. Familiarity with the US appearances of diseases that affect the intestine may allow specific diagnosis based on the degree and distribution of bowel wall thickening and associated changes of the perienteric tissues.
© RSNA, 2003
Index Terms: Gastrointestinal tract, inflammation, 70.2 • Gastrointestinal tract, neoplasms, 70. 30 • Gastrointestinal tract, US, 70.1298
|
VIRTUAL JOURNAL CLUB FEATURE
|
|---|
See vjc.rsna.org to discuss your comments and questions with the authors online February 3–21, 2003.
|
Introduction
|
|---|
Most radiologists who perform abdominal imaging studies are familiar with the computed tomographic (CT) appearance of bowel abnormalities. However, fewer may be familiar with the corresponding ultrasonographic (US) appearance. A commonly held belief is that bowel gas and peristalsis interfere with US evaluation of the intestine. Although this may be true in the normal state, the diseased intestine typically has a thickened wall, a narrowed lumen, and decreased peristalsis, allowing US evaluation of the diseased intestine in most patients. In our practice, we have found US to be extremely useful for evaluation of diseases that affect the gastrointestinal tract.
The purpose of this article is to demonstrate the US features of bowel abnormalities with CT used for correlation. Specific topics discussed are US technique, general principles, infectious and inflammatory conditions, and tumors.
|
US Technique
|
|---|
Examination of the intestine is usually performed after the standard examination of the solid abdominal organs. The choice of transducer is based on the patient’s body habitus: A 3-MHz curvilinear transducer is used for heavy patients, whereas a 5- or 7-MHz transducer is used for average or thin patients. A high-frequency linear-array transducer is used for superficial abnormalities, and a transvaginal transducer can be used for deep pelvic disease in women.
The examination can be generalized or more focused when localizing signs are present. The large intestine is examined by starting in the right upper quadrant with identification of the ascending colon, recognized by its constancy of position and the presence of haustra. The examination proceeds along the ascending colon to the right lower quadrant, where the cecum is identified as a blind-ending loop of large intestine. The terminal ileum is then identified, and the region of the appendix is examined. Once the right lower quadrant has been adequately assessed, the ascending portion of the colon is followed along the transverse and descending portions of the colon. The sigmoid colon is followed into the pelvis, and the rectum is visualized through the distended urinary bladder. The potential location of small bowel loops is then scanned. Small bowel loops can be recognized by the presence of valvulae conniventes when the lumen is filled with fluid. As with any US examination, repositioning the patient and compression with the transducer should be performed to optimally visualize the region of interest. Color Doppler US can be used to assess inflammatory disease when present and to support the suspicion of a tumor. The perienteric soft tissues are assessed for the presence of enlarged lymph nodes and for inflammation or infiltration of the perienteric fat.
|
General Principles
|
|---|
At US, the normal intestine has a layered appearance, is compressible, and shows intermittent peristalsis. The normal large intestine has a wall thickness of 4 mm or less, whereas the small intestine has a thinner wall (1).
The abnormal intestine may have one or more of the following features: increased thickness (>4 mm), loss of the layered appearance, and lack of compressibility (2). Assessment of the degree and distribution of wall thickening is important in determining the underlying cause. When a focal mass is noted, its location relative to the bowel wall should be determined and classified in one of the following categories: intraluminal, mural, or exophytic.
When the perienteric fat becomes inflamed or infiltrated, it becomes hyperechoic and produces a mass effect. Enlarged mesenteric lymph nodes may be associated with infectious, inflammatory, or neoplastic processes.
|
Infectious and Inflammatory Conditions
|
|---|
Appendicitis
The diagnosis of appendicitis is established when a distended (diameter > 6 mm), noncompressible appendix is identified (Fig 1). Appendicoliths may be present and are seen as echogenic, shadow-producing structures within the lumen of the appendix (3). In acute appendicitis, the periappendiceal fat becomes inflamed and echogenic. When compression is applied, the appendix and the inflamed fat will move as a relatively fixed structure. In equivocal cases, the use of color Doppler US is useful in demonstrating a hyperemic wall when appendicitis is present (4). Localized pain with compression of the transducer is also a helpful secondary finding in diagnosing appendicitis when the gray-scale features are equivocal (5).
View larger version (169K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1a. Appendicitis in a 25-year-old woman with right lower quadrant pain. (a) US image of the long axis of the appendix shows a noncompressible appendix with a diameter of 7 mm (between cursors). The patient had focal tenderness in this location. (b) Color Doppler US image of the short axis of the appendix shows hyperemia in the wall of the appendix. The US findings were diagnostic of acute appendicitis. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material before acquisition of the US images show that the appendix (arrow) measures 7 mm in diameter. The lumen is not filled with air or enteric contrast material. The wall is slightly thickened, but there is no inflammation of the periappendiceal fat. The CT findings were consistent with mild appendicitis, but the clinical condition of the patient was thought to be improving. The US study was therefore performed for further evaluation. Acute, nonperforated appendicitis was found at surgery.
|
|
View larger version (198K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1b. Appendicitis in a 25-year-old woman with right lower quadrant pain. (a) US image of the long axis of the appendix shows a noncompressible appendix with a diameter of 7 mm (between cursors). The patient had focal tenderness in this location. (b) Color Doppler US image of the short axis of the appendix shows hyperemia in the wall of the appendix. The US findings were diagnostic of acute appendicitis. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material before acquisition of the US images show that the appendix (arrow) measures 7 mm in diameter. The lumen is not filled with air or enteric contrast material. The wall is slightly thickened, but there is no inflammation of the periappendiceal fat. The CT findings were consistent with mild appendicitis, but the clinical condition of the patient was thought to be improving. The US study was therefore performed for further evaluation. Acute, nonperforated appendicitis was found at surgery.
|
|
View larger version (121K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1c. Appendicitis in a 25-year-old woman with right lower quadrant pain. (a) US image of the long axis of the appendix shows a noncompressible appendix with a diameter of 7 mm (between cursors). The patient had focal tenderness in this location. (b) Color Doppler US image of the short axis of the appendix shows hyperemia in the wall of the appendix. The US findings were diagnostic of acute appendicitis. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material before acquisition of the US images show that the appendix (arrow) measures 7 mm in diameter. The lumen is not filled with air or enteric contrast material. The wall is slightly thickened, but there is no inflammation of the periappendiceal fat. The CT findings were consistent with mild appendicitis, but the clinical condition of the patient was thought to be improving. The US study was therefore performed for further evaluation. Acute, nonperforated appendicitis was found at surgery.
|
|
View larger version (128K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1d. Appendicitis in a 25-year-old woman with right lower quadrant pain. (a) US image of the long axis of the appendix shows a noncompressible appendix with a diameter of 7 mm (between cursors). The patient had focal tenderness in this location. (b) Color Doppler US image of the short axis of the appendix shows hyperemia in the wall of the appendix. The US findings were diagnostic of acute appendicitis. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material before acquisition of the US images show that the appendix (arrow) measures 7 mm in diameter. The lumen is not filled with air or enteric contrast material. The wall is slightly thickened, but there is no inflammation of the periappendiceal fat. The CT findings were consistent with mild appendicitis, but the clinical condition of the patient was thought to be improving. The US study was therefore performed for further evaluation. Acute, nonperforated appendicitis was found at surgery.
|
|
Crohn Disease
Crohn disease produces transmural inflammation of the affected intestine, resulting in bowel wall thickening. Because of the transmural involvement, the perienteric fat becomes inflamed, appearing echogenic and thickened, resulting in separation of adjacent bowel loops (Fig 2). Over time, the perienteric fat tends to proliferate ("creeping" fat), which contributes to its masslike appearance in Crohn disease. Evaluation of the mesentery is important because adenopathy is seen in about 20% of patients. During the active phase of Crohn disease, the submucosa typically appears thickened, producing a hyperechoic band that is thought to represent lymphedema. In the chronic phase of the disease, the bowel wall most commonly appears thickened and hypoechoic due to fibrosis. Fistulas are common and produce hypoechoic tracts extending from the bowel wall to adjacent structures (6). Bubbles of gas are occasionally observed within these tracts during real-time imaging.
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2a. Acute Crohn disease involving the terminal ileum in a 25-year-old woman with right lower quadrant pain. (a) On a US image obtained through the long axis of the terminal ileum, it is thickened (arrow) with thick, echogenic submucosa related to lymphedema. A small phlegmonous collection (C) is present within the inflamed echogenic perienteric fat. (b) Axial CT scan shows thickening of the terminal ileum (arrow) and inflammation of the perienteric fat. (c) Axial CT scan obtained superior to b shows the phlegmon (arrow), which contains a tiny amount of air. (Fig 2a and 2b reprinted, with permission, from reference 17.)
|
|
View larger version (113K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2b. Acute Crohn disease involving the terminal ileum in a 25-year-old woman with right lower quadrant pain. (a) On a US image obtained through the long axis of the terminal ileum, it is thickened (arrow) with thick, echogenic submucosa related to lymphedema. A small phlegmonous collection (C) is present within the inflamed echogenic perienteric fat. (b) Axial CT scan shows thickening of the terminal ileum (arrow) and inflammation of the perienteric fat. (c) Axial CT scan obtained superior to b shows the phlegmon (arrow), which contains a tiny amount of air. (Fig 2a and 2b reprinted, with permission, from reference 17.)
|
|
View larger version (118K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2c. Acute Crohn disease involving the terminal ileum in a 25-year-old woman with right lower quadrant pain. (a) On a US image obtained through the long axis of the terminal ileum, it is thickened (arrow) with thick, echogenic submucosa related to lymphedema. A small phlegmonous collection (C) is present within the inflamed echogenic perienteric fat. (b) Axial CT scan shows thickening of the terminal ileum (arrow) and inflammation of the perienteric fat. (c) Axial CT scan obtained superior to b shows the phlegmon (arrow), which contains a tiny amount of air. (Fig 2a and 2b reprinted, with permission, from reference 17.)
|
|
Diverticulitis
Diverticulitis is present when there is perforation of a diverticulum (Fig 3). Diverticula are seen as outpouchings from the bowel wall and occur most commonly in the sigmoid colon. Diverticula may contain echogenic material, which is thought to represent air, fecal material, or enteroliths. Muscular hypertrophy, inflammation, and edema produce segmental hypoechoic bowel wall thickening (7). When the pericolonic fat becomes inflamed, it usually appears echogenic and masslike. Abscesses are recognized as fluid collections that contain echogenic foci, producing so-called dirty shadowing from contained air. Fistula formation with adjacent structures such as the bladder is a recognized complication of diverticulitis.
View larger version (117K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a. Diverticulitis in a 79-year-old woman with a history of diverticulitis and new onset of lower abdominal pain and urosepsis. (a) US image of the left lower quadrant obtained through the long axis of the sigmoid colon shows thickening of the muscular layer (arrows), which appears markedly hypoechoic. (b) Axial US image obtained through the sigmoid colon shows muscular hypertrophy (arrow) and an echogenic diverticulum (arrowhead). (c) Transvaginal US image shows a tract that contains air (arrowhead) and extends from the thickened sigmoid colon (arrow) to the bladder (B), which is filled with echogenic air and debris. (d) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows sigmoid diverticula (arrowheads) and air in the bladder (B), which confirm the diagnosis of a colovesical fistula secondary to diverticulitis.
|
|
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b. Diverticulitis in a 79-year-old woman with a history of diverticulitis and new onset of lower abdominal pain and urosepsis. (a) US image of the left lower quadrant obtained through the long axis of the sigmoid colon shows thickening of the muscular layer (arrows), which appears markedly hypoechoic. (b) Axial US image obtained through the sigmoid colon shows muscular hypertrophy (arrow) and an echogenic diverticulum (arrowhead). (c) Transvaginal US image shows a tract that contains air (arrowhead) and extends from the thickened sigmoid colon (arrow) to the bladder (B), which is filled with echogenic air and debris. (d) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows sigmoid diverticula (arrowheads) and air in the bladder (B), which confirm the diagnosis of a colovesical fistula secondary to diverticulitis.
|
|
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3c. Diverticulitis in a 79-year-old woman with a history of diverticulitis and new onset of lower abdominal pain and urosepsis. (a) US image of the left lower quadrant obtained through the long axis of the sigmoid colon shows thickening of the muscular layer (arrows), which appears markedly hypoechoic. (b) Axial US image obtained through the sigmoid colon shows muscular hypertrophy (arrow) and an echogenic diverticulum (arrowhead). (c) Transvaginal US image shows a tract that contains air (arrowhead) and extends from the thickened sigmoid colon (arrow) to the bladder (B), which is filled with echogenic air and debris. (d) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows sigmoid diverticula (arrowheads) and air in the bladder (B), which confirm the diagnosis of a colovesical fistula secondary to diverticulitis.
|
|
View larger version (154K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3d. Diverticulitis in a 79-year-old woman with a history of diverticulitis and new onset of lower abdominal pain and urosepsis. (a) US image of the left lower quadrant obtained through the long axis of the sigmoid colon shows thickening of the muscular layer (arrows), which appears markedly hypoechoic. (b) Axial US image obtained through the sigmoid colon shows muscular hypertrophy (arrow) and an echogenic diverticulum (arrowhead). (c) Transvaginal US image shows a tract that contains air (arrowhead) and extends from the thickened sigmoid colon (arrow) to the bladder (B), which is filled with echogenic air and debris. (d) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows sigmoid diverticula (arrowheads) and air in the bladder (B), which confirm the diagnosis of a colovesical fistula secondary to diverticulitis.
|
|
Right-sided Diverticulitis
Right-sided diverticulitis is an uncommon condition that is different from left-sided diverticulitis in many ways: It tends to occur in younger patients, is more common in women, and is thought to be more common in the Asian population. Right-sided diverticula are usually solitary and congenital in origin. Clinically, right-sided diverticulitis may manifest with symptoms mimicking appendicitis. The distinction between the two entities is important because right-sided diverticulitis is treated conservatively and abscess formation is rare (8). At US, right-sided diverticulitis is diagnosed when a diverticulum is seen arising from the right colon with inflammation of the surrounding pericolonic fat (Fig 4). Focal tenderness can be elicited, and color Doppler US may show increased flow in the adjacent pericolonic fat.
View larger version (186K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4a. Right-sided diverticulitis in a 32-year-old woman with right lower quadrant pain and fever. (a) Axial US image obtained through the right lower quadrant shows a diverticulum (d) arising from the ascending colon (c) with surrounding inflamed echogenic fat (arrows), which indicate right-sided colonic diverticulitis. The patient had focal tenderness when the transducer was placed over this area. (b) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows the diverticulum, which arises from the ascending colon with inflammation of the surrounding fat (arrow). The appendix was normal.
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4b. Right-sided diverticulitis in a 32-year-old woman with right lower quadrant pain and fever. (a) Axial US image obtained through the right lower quadrant shows a diverticulum (d) arising from the ascending colon (c) with surrounding inflamed echogenic fat (arrows), which indicate right-sided colonic diverticulitis. The patient had focal tenderness when the transducer was placed over this area. (b) Axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows the diverticulum, which arises from the ascending colon with inflammation of the surrounding fat (arrow). The appendix was normal.
|
|
Epiploic Appendagitis
Epiploic appendages are fatty tags that are attached to the serosal surface of the colon. Torsion or venous thrombosis of an epiploic appendage causes ischemia or infarction, resulting in localized inflammation. Epiploic appendagitis can cause severe pain and mimic other abdominal conditions. It is important to correctly diagnose cases of epiploic appendagitis, since treatment is conservative. When US is performed in a patient with epiploic appendagitis, the patient can direct the sonographer to the site of pain, which is typically localized. At US, the inflamed epiploic appendage appears as an echogenic fingerlike projection arising from the colonic wall (9). The adjacent pericolonic fat also becomes echogenic and masslike when inflamed (Fig 5).
View larger version (195K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5a. Epiploic appendagitis in a 29-year-old man with left lower quadrant pain. (a) Axial US image obtained over the point of maximum tenderness in the left lower quadrant shows an echogenic fingerlike epiploic appendage, which arises from the colon (C) and is surrounded by inflamed echogenic fat (arrow). (b) Corresponding axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows the epiploic appendage as a fingerlike structure of fat attenuation that arises from the colon with inflammation of the perienteric fat (arrow), findings diagnostic of epiploic appendagitis.
|
|
View larger version (93K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5b. Epiploic appendagitis in a 29-year-old man with left lower quadrant pain. (a) Axial US image obtained over the point of maximum tenderness in the left lower quadrant shows an echogenic fingerlike epiploic appendage, which arises from the colon (C) and is surrounded by inflamed echogenic fat (arrow). (b) Corresponding axial CT scan obtained after administration of oral, rectal, and intravenous contrast material shows the epiploic appendage as a fingerlike structure of fat attenuation that arises from the colon with inflammation of the perienteric fat (arrow), findings diagnostic of epiploic appendagitis.
|
|
Pseudomembranous Colitis
Pseudomembranous colitis is caused by a cytotoxin of Clostridium difficile and most often occurs as a complication of antibiotic therapy. Although it typically produces a pancolitis, segmental involvement may also occur. The wall of the affected colon becomes markedly thickened, causing narrowing of the lumen, and the submucosa shows a prominent gyral pattern (Fig 6). The colonic changes are frequently accompanied by ascites (10,11). In addition, the degree of colonic wall thickening is more marked in pseudomembranous colitis compared with that due to most other causes of colitis. Because other entities including ischemic and infectious colitis may produce similar imaging findings, the clinical setting and stool cultures are helpful in establishing the correct diagnosis.
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6a. Pseudomembranous colitis in a 59-year-old woman with abdominal pain and diarrhea who was receiving intravenous antibiotics for urosepsis. (a, b) Axial (a) and longitudinal (b) US images obtained through the ascending colon (ac) and transverse colon (tc) show marked wall thickening and a prominent gyral pattern characteristic of pseudomembranous colitis. (c) Corresponding axial CT scan shows marked thickening of the ascending colon (ac) and transverse colon (tc). Stool cultures were positive for C difficile.
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6b. Pseudomembranous colitis in a 59-year-old woman with abdominal pain and diarrhea who was receiving intravenous antibiotics for urosepsis. (a, b) Axial (a) and longitudinal (b) US images obtained through the ascending colon (ac) and transverse colon (tc) show marked wall thickening and a prominent gyral pattern characteristic of pseudomembranous colitis. (c) Corresponding axial CT scan shows marked thickening of the ascending colon (ac) and transverse colon (tc). Stool cultures were positive for C difficile.
|
|
View larger version (101K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6c. Pseudomembranous colitis in a 59-year-old woman with abdominal pain and diarrhea who was receiving intravenous antibiotics for urosepsis. (a, b) Axial (a) and longitudinal (b) US images obtained through the ascending colon (ac) and transverse colon (tc) show marked wall thickening and a prominent gyral pattern characteristic of pseudomembranous colitis. (c) Corresponding axial CT scan shows marked thickening of the ascending colon (ac) and transverse colon (tc). Stool cultures were positive for C difficile.
|
|
Small Bowel Obstruction
In adults, the most common causes of small bowel obstruction are adhesions, hernias, and neoplasms. At US, one sees dilated, fluid-filled small bowel loops, which are recognized by the presence of the valvulae conniventes (Fig 7). The bowel wall may become edematous due to vascular and lymphatic obstruction, and ascites may be an accompanying feature of intestinal obstruction. In patients with mechanical bowel obstruction, hyperperistalsis with a to-and-fro motion of the bowel contents is often observed during real-time imaging. Once the obstruction becomes high-grade or complete, peristalsis may be absent.
View larger version (131K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Small bowel obstruction in a 51-year-old man with abdominal pain 10 days after liver transplantation. (a) Axial US image obtained through the lower abdomen shows thickened, dilated small bowel loops (arrows) within the abdominal cavity. A hernia sac (h) is identified anterior to the abdominal wall. (b) Axial US image obtained through the hernia sac shows septated ascites (h) and thickened, dilated small bowel loops (arrow). (c, d) Corresponding axial CT scans obtained with intravenous contrast material show identical findings of small bowel obstruction (arrows) secondary to an incisional hernia (h).
|
|
View larger version (109K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Small bowel obstruction in a 51-year-old man with abdominal pain 10 days after liver transplantation. (a) Axial US image obtained through the lower abdomen shows thickened, dilated small bowel loops (arrows) within the abdominal cavity. A hernia sac (h) is identified anterior to the abdominal wall. (b) Axial US image obtained through the hernia sac shows septated ascites (h) and thickened, dilated small bowel loops (arrow). (c, d) Corresponding axial CT scans obtained with intravenous contrast material show identical findings of small bowel obstruction (arrows) secondary to an incisional hernia (h).
|
|
View larger version (100K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7c. Small bowel obstruction in a 51-year-old man with abdominal pain 10 days after liver transplantation. (a) Axial US image obtained through the lower abdomen shows thickened, dilated small bowel loops (arrows) within the abdominal cavity. A hernia sac (h) is identified anterior to the abdominal wall. (b) Axial US image obtained through the hernia sac shows septated ascites (h) and thickened, dilated small bowel loops (arrow). (c, d) Corresponding axial CT scans obtained with intravenous contrast material show identical findings of small bowel obstruction (arrows) secondary to an incisional hernia (h).
|
|
View larger version (91K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7d. Small bowel obstruction in a 51-year-old man with abdominal pain 10 days after liver transplantation. (a) Axial US image obtained through the lower abdomen shows thickened, dilated small bowel loops (arrows) within the abdominal cavity. A hernia sac (h) is identified anterior to the abdominal wall. (b) Axial US image obtained through the hernia sac shows septated ascites (h) and thickened, dilated small bowel loops (arrow). (c, d) Corresponding axial CT scans obtained with intravenous contrast material show identical findings of small bowel obstruction (arrows) secondary to an incisional hernia (h).
|
|
Small Bowel Vasculitis
Systemic lupus erythematosus is a connective tissue disorder that can cause necrotizing vasculitis of the small vessels of the bowel wall. In the acute setting, vasculitis leads to ischemia, producing edema and hemorrhage into the bowel wall. Most common in the small intestine, massive enlargement of the valvulae conniventes is characteristic of vasculitis and resulting mucosal edema (Fig 8).
View larger version (153K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Systemic lupus erythematosus in a 20-year-old woman with severe abdominal pain. (a, b) Longitudinal (a) and axial (b) US images show dilated small bowel loops (arrows) with markedly edematous mucosal folds. (c) Axial CT scan obtained with intravenous contrast material shows similar findings of thickened edematous mucosal folds (arrows). Mesenteric vasculitis was diagnosed, and the patient was treated with high-dose steroid therapy. Within 1 week, there was complete resolution of the symptoms and imaging findings. (Reprinted, with permission, from reference 17.)
|
|
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Systemic lupus erythematosus in a 20-year-old woman with severe abdominal pain. (a, b) Longitudinal (a) and axial (b) US images show dilated small bowel loops (arrows) with markedly edematous mucosal folds. (c) Axial CT scan obtained with intravenous contrast material shows similar findings of thickened edematous mucosal folds (arrows). Mesenteric vasculitis was diagnosed, and the patient was treated with high-dose steroid therapy. Within 1 week, there was complete resolution of the symptoms and imaging findings. (Reprinted, with permission, from reference 17.)
|
|
View larger version (120K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8c. Systemic lupus erythematosus in a 20-year-old woman with severe abdominal pain. (a, b) Longitudinal (a) and axial (b) US images show dilated small bowel loops (arrows) with markedly edematous mucosal folds. (c) Axial CT scan obtained with intravenous contrast material shows similar findings of thickened edematous mucosal folds (arrows). Mesenteric vasculitis was diagnosed, and the patient was treated with high-dose steroid therapy. Within 1 week, there was complete resolution of the symptoms and imaging findings. (Reprinted, with permission, from reference 17.)
|
|
Celiac Disease
Celiac disease or gluten enteropathy causes small bowel malabsorption, leading to hypomotility and dilatation of the bowel lumen. The villi of the ileum hypertrophy to compensate for jejunal villous atrophy. Transient, nonobstructive intussusception occurs in about 20% of patients with celiac disease. Reported US findings include prominent small bowel folds, hypomotility, and excess fluid in the bowel lumen (12). Intussusception is seen as concentric hypoechoic rings separated by a hyperechoic ring, representing the muscular layers of the intussusceptum and the intussuscipiens with the trapped mesenteric fat, respectively (13) (Fig 9).
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Celiac disease in a 35-year-old woman with diarrhea, weight loss, and anemia. (a) Axial US image shows dilated, fluid-filled small bowel loops with prominent mucosal folds (arrows). (b) Axial US image shows one of the multiple transient small bowel intussusceptions that were present. The echogenic mesenteric fat is seen trapped between the intussusceptum (i) and the intussuscipiens (o). (c, d) Corresponding axial CT scans obtained after administration of intravenous and oral contrast material show the dilated, fluid-filled small bowel loops (SB) as well as the intussusceptum (i) within the intussuscipiens (o) in the left lower quadrant. The suspected diagnosis of celiac disease, which was based on the imaging findings, was confirmed with biopsy of the small intestine, and the patient responded to a gluten-free diet. (Fig 9b reprinted, with permission, from reference 17.)
|
|
View larger version (158K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Celiac disease in a 35-year-old woman with diarrhea, weight loss, and anemia. (a) Axial US image shows dilated, fluid-filled small bowel loops with prominent mucosal folds (arrows). (b) Axial US image shows one of the multiple transient small bowel intussusceptions that were present. The echogenic mesenteric fat is seen trapped between the intussusceptum (i) and the intussuscipiens (o). (c, d) Corresponding axial CT scans obtained after administration of intravenous and oral contrast material show the dilated, fluid-filled small bowel loops (SB) as well as the intussusceptum (i) within the intussuscipiens (o) in the left lower quadrant. The suspected diagnosis of celiac disease, which was based on the imaging findings, was confirmed with biopsy of the small intestine, and the patient responded to a gluten-free diet. (Fig 9b reprinted, with permission, from reference 17.)
|
|
View larger version (103K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9c. Celiac disease in a 35-year-old woman with diarrhea, weight loss, and anemia. (a) Axial US image shows dilated, fluid-filled small bowel loops with prominent mucosal folds (arrows). (b) Axial US image shows one of the multiple transient small bowel intussusceptions that were present. The echogenic mesenteric fat is seen trapped between the intussusceptum (i) and the intussuscipiens (o). (c, d) Corresponding axial CT scans obtained after administration of intravenous and oral contrast material show the dilated, fluid-filled small bowel loops (SB) as well as the intussusceptum (i) within the intussuscipiens (o) in the left lower quadrant. The suspected diagnosis of celiac disease, which was based on the imaging findings, was confirmed with biopsy of the small intestine, and the patient responded to a gluten-free diet. (Fig 9b reprinted, with permission, from reference 17.)
|
|
View larger version (107K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9d. Celiac disease in a 35-year-old woman with diarrhea, weight loss, and anemia. (a) Axial US image shows dilated, fluid-filled small bowel loops with prominent mucosal folds (arrows). (b) Axial US image shows one of the multiple transient small bowel intussusceptions that were present. The echogenic mesenteric fat is seen trapped between the intussusceptum (i) and the intussuscipiens (o). (c, d) Corresponding axial CT scans obtained after administration of intravenous and oral contrast material show the dilated, fluid-filled small bowel loops (SB) as well as the intussusceptum (i) within the intussuscipiens (o) in the left lower quadrant. The suspected diagnosis of celiac disease, which was based on the imaging findings, was confirmed with biopsy of the small intestine, and the patient responded to a gluten-free diet. (Fig 9b reprinted, with permission, from reference 17.)
|
|
|
Tumors
|
|---|
Gastric Cancer
Although transabdominal US is not generally used to diagnose gastric cancer, patients with gastric cancer may present for US examination due to nonspecific upper abdominal symptoms. Gastric cancer produces a localized or diffuse hypoechoic mass with destruction of the normal layered appearance of the bowel wall (Fig 10). When regional lymph nodes are involved, they become enlarged, round, and hypoechoic.
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Gastric cancer in a 68-year-old man with early satiety and anemia. (a) US image obtained through the long axis of the stomach shows a large hypoechoic tumor (arrows) that replaces the gastric wall; echogenic air in the lumen creates a pseudokidney appearance. (b) Axial CT scan obtained with intravenous contrast material shows that the tumor (arrows) involves the distal stomach. The pathologic diagnosis was poorly differentiated gastric adenocarcinoma.
|
|
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10b. Gastric cancer in a 68-year-old man with early satiety and anemia. (a) US image obtained through the long axis of the stomach shows a large hypoechoic tumor (arrows) that replaces the gastric wall; echogenic air in the lumen creates a pseudokidney appearance. (b) Axial CT scan obtained with intravenous contrast material shows that the tumor (arrows) involves the distal stomach. The pathologic diagnosis was poorly differentiated gastric adenocarcinoma.
|
|
Bowel Lymphoma
Most gastrointestinal lymphomas are B-cell tumors and involve the small intestine more commonly than the large intestine (14). At US, these tumors are hypoechoic and show a variety of growth patterns including circumferential wall thickening as well as nodular or bulky tumor spread. Circumferential involvement is the most common pattern demonstrated at US (15). The affected lumen may show aneurysmal dilatation, which is thought to be a result of destruction of the autonomic nerve plexus by the tumor. Lymphadenopathy in the adjacent perienteric structures may also be observed (Fig 11).
View larger version (131K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11a. Known non-Hodgkin lymphoma involving the small intestine in a 51-year-old man. (a, b) US images obtained through the long axis (a) and short axis (b) of the small intestine in the right upper quadrant show asymmetric thickening of the bowel wall (arrow) and aneurysmal dilatation of the lumen (L). There is lymphadenopathy (arrowhead) in the adjacent mesentery. (c) Axial CT scan obtained with oral and intravenous contrast material shows that the tumor (arrow) involves the small intestine with aneurysmal dilatation of the lumen (L) and lymphadenopathy (arrowhead).
|
|
View larger version (129K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11b. Known non-Hodgkin lymphoma involving the small intestine in a 51-year-old man. (a, b) US images obtained through the long axis (a) and short axis (b) of the small intestine in the right upper quadrant show asymmetric thickening of the bowel wall (arrow) and aneurysmal dilatation of the lumen (L). There is lymphadenopathy (arrowhead) in the adjacent mesentery. (c) Axial CT scan obtained with oral and intravenous contrast material shows that the tumor (arrow) involves the small intestine with aneurysmal dilatation of the lumen (L) and lymphadenopathy (arrowhead).
|
|
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11c. Known non-Hodgkin lymphoma involving the small intestine in a 51-year-old man. (a, b) US images obtained through the long axis (a) and short axis (b) of the small intestine in the right upper quadrant show asymmetric thickening of the bowel wall (arrow) and aneurysmal dilatation of the lumen (L). There is lymphadenopathy (arrowhead) in the adjacent mesentery. (c) Axial CT scan obtained with oral and intravenous contrast material shows that the tumor (arrow) involves the small intestine with aneurysmal dilatation of the lumen (L) and lymphadenopathy (arrowhead).
|
|
Colon Cancer
Adenocarcinoma is the most common malignant tumor of the colon. Morphologically, the tumor produces an annular or polypoid colonic mass. At US, an annular tumor appears as a hypoechoic mass with central linear echoes, representing the tumor and air in the residual lumen, respectively (Figs 12, 13). Polypoid tumors appear as focal, irregular colonic wall thickening. An abrupt loss of the normal layered appearance of the bowel wall is typical of a neoplastic process (16).
View larger version (128K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Colon cancer in a 69-year-old woman with abdominal pain and a sensation of "fullness" in the right lower quadrant. (a) Axial US image obtained through the right side of the abdomen shows a markedly dilated transverse colon (tc) filled with liquid stool. (b) Midline axial US image shows an annular, hypoechoic mass (arrowheads) that produces an abrupt zone of transition in the transverse colon (tc), an appearance consistent with obstructing colon cancer. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material show obstruction of the transverse colon (tc) secondary to a tight, annular adenocarcinoma of the colon (arrowhead), which was confirmed at surgery.
|
|
View larger version (118K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Colon cancer in a 69-year-old woman with abdominal pain and a sensation of "fullness" in the right lower quadrant. (a) Axial US image obtained through the right side of the abdomen shows a markedly dilated transverse colon (tc) filled with liquid stool. (b) Midline axial US image shows an annular, hypoechoic mass (arrowheads) that produces an abrupt zone of transition in the transverse colon (tc), an appearance consistent with obstructing colon cancer. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material show obstruction of the transverse colon (tc) secondary to a tight, annular adenocarcinoma of the colon (arrowhead), which was confirmed at surgery.
|
|
View larger version (124K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12c. Colon cancer in a 69-year-old woman with abdominal pain and a sensation of "fullness" in the right lower quadrant. (a) Axial US image obtained through the right side of the abdomen shows a markedly dilated transverse colon (tc) filled with liquid stool. (b) Midline axial US image shows an annular, hypoechoic mass (arrowheads) that produces an abrupt zone of transition in the transverse colon (tc), an appearance consistent with obstructing colon cancer. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material show obstruction of the transverse colon (tc) secondary to a tight, annular adenocarcinoma of the colon (arrowhead), which was confirmed at surgery.
|
|
View larger version (112K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12d. Colon cancer in a 69-year-old woman with abdominal pain and a sensation of "fullness" in the right lower quadrant. (a) Axial US image obtained through the right side of the abdomen shows a markedly dilated transverse colon (tc) filled with liquid stool. (b) Midline axial US image shows an annular, hypoechoic mass (arrowheads) that produces an abrupt zone of transition in the transverse colon (tc), an appearance consistent with obstructing colon cancer. (c, d) Corresponding axial CT scans obtained with oral, rectal, and intravenous contrast material show obstruction of the transverse colon (tc) secondary to a tight, annular adenocarcinoma of the colon (arrowhead), which was confirmed at surgery.
|
|
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13a. Colon cancer in an 80-year-old man with foul-smelling urine and gross hematuria. (a, b) Sagittal (a) and axial (b) US images obtained through the pelvis show a large, hypoechoic mass of the sigmoid colon (arrow) adjacent to the dome of the bladder (B). Air (arrowheads) is seen along a fistulous tract from the mass to the nondependent portion of the bladder. During real-time US, bubbles of air were seen moving along the fistula. (c, d) Corresponding axial CT scans show that the mass (arrow) invades the bladder (B). There is air within the bladder, a finding indicative of a colovesical fistula. An adenocarcinoma of the sigmoid colon with a colovesical fistula was confirmed at surgery.
|
|
View larger version (145K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13b. Colon cancer in an 80-year-old man with foul-smelling urine and gross hematuria. (a, b) Sagittal (a) and axial (b) US images obtained through the pelvis show a large, hypoechoic mass of the sigmoid colon (arrow) adjacent to the dome of the bladder (B). Air (arrowheads) is seen along a fistulous tract from the mass to the nondependent portion of the bladder. During real-time US, bubbles of air were seen moving along the fistula. (c, d) Corresponding axial CT scans show that the mass (arrow) invades the bladder (B). There is air within the bladder, a finding indicative of a colovesical fistula. An adenocarcinoma of the sigmoid colon with a colovesical fistula was confirmed at surgery.
|
|
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13c. Colon cancer in an 80-year-old man with foul-smelling urine and gross hematuria. (a, b) Sagittal (a) and axial (b) US images obtained through the pelvis show a large, hypoechoic mass of the sigmoid colon (arrow) adjacent to the dome of the bladder (B). Air (arrowheads) is seen along a fistulous tract from the mass to the nondependent portion of the bladder. During real-time US, bubbles of air were seen moving along the fistula. (c, d) Corresponding axial CT scans show that the mass (arrow) invades the bladder (B). There is air within the bladder, a finding indicative of a colovesical fistula. An adenocarcinoma of the sigmoid colon with a colovesical fistula was confirmed at surgery.
|
|
View larger version (118K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13d. Colon cancer in an 80-year-old man with foul-smelling urine and gross hematuria. (a, b) Sagittal (a) and axial (b) US images obtained through the pelvis show a large, hypoechoic mass of the sigmoid colon (arrow) adjacent to the dome of the bladder (B). Air (arrowheads) is seen along a fistulous tract from the mass to the nondependent portion of the bladder. During real-time US, bubbles of air were seen moving along the fistula. (c, d) Corresponding axial CT scans show that the mass (arrow) invades the bladder (B). There is air within the bladder, a finding indicative of a colovesical fistula. An adenocarcinoma of the sigmoid colon with a colovesical fistula was confirmed at surgery.
|
|
|
Conclusions
|
|---|
US is often the first imaging test performed in patients with abdominal pain and undiagnosed bowel disease. Many diseases produce changes in the bowel wall that can be evaluated with US. Familiarity with the US appearance of diseases that affect the intestine may allow specific diagnosis based on the degree and distribution of bowel wall thickening and associated changes of the perienteric tissues.
|
References
|
|---|
- Fleischer AC, Muhletaler CA, James AE, Jr. Sonographic assessment of the bowel wall. AJR Am J Roentgenol 1981; 136:887-891.[Abstract/
Top
Abstract
VIRTUAL JOURNAL CLUB FEATURE
