(Radiographics. 2001;21:S147-S160.)
© RSNA, 2001
Helping the Gastrointestinal Surgeon |
CT of the Duodenum: An Overlooked Segment Gets Its Due1
Mahesh V. Jayaraman, MD,
William W. Mayo-Smith, MD,
Jonathan S. Movson, MD,
Damian E. Dupuy, MD and
Michael T. Wallach, MD
1 From the Department of Diagnostic Imaging, Brown University School of Medicine, Rhode Island Hospital, 593 Eddy St, Providence, RI 02903. Presented as an education exhibit at the 2000 RSNA scientific assembly. Received January 31, 2001; revision requested February 22 and received March 12; accepted April 3. Address correspondence to W.W.M-S. (e-mail: william_mayo-smith@brown.edu).
 |
Abstract
|
|---|
Abdominal computed tomography (CT) is frequently performed to evaluate gastrointestinal pathologic conditions, and the majority of the gastrointestinal radiology literature has concentrated on the colon, stomach, and distal small bowel. In a description of CT findings of duodenal pathologic conditions, congenital, traumatic, inflammatory, and neoplastic diseases are presented. Congenital duodenal anomalies such as duplications and diverticula are usually asymptomatic, while annular pancreas and malrotation may manifest in the 1st decade of life. CT plays a vital role in the diagnosis of traumatic duodenal injury. Primary inflammatory processes of the duodenum such as ulcers and secondary involvement from pancreatitis can reliably be diagnosed at CT. Infectious diseases of the duodenum are difficult to diagnose, as the findings are not specific. While small bowel malignancies are relatively rare, lipoma, adenoma, and adenocarcinoma, as well as local extension from adjacent malignancies, can be diagnosed at CT. Careful CT technique and attention to the duodenum can result in reliable prospective diagnoses.
Index Terms: Duodenum, abnormalities, 73.14 • Duodenum, CT, 73.12112 • Duodenum, neoplasms, 73.30 • Duodenum, perforation, 73.71
|
Introduction
|
|---|
The duodenum is often overlooked on computed tomographic (CT) scans, and its length belies its importance in the gastrointestinal tract. Its location, with both intraperitoneal and retroperitoneal segments and proximity to the gallbladder, pancreas, stomach, spine, aorta, liver, and other segments of the gastrointestinal tract, results in duodenal involvement by a multitude of primary and secondary processes. In this article, we demonstrate the CT imaging features of various developmental, traumatic, inflammatory, infectious, neoplastic, and postsurgical pathologic conditions that involve the duodenum.
|
Normal Anatomic Features
|
|---|
The name duodenum, meaning "two plus ten," originated because the length of this part of the small bowel was thought to be equal to 12 fingers’ breadth. It is the widest portion of the small bowel, has no mesentery, and is only partially covered by the peritoneum (1,2). The duodenum is 25–30 cm long and is divided into four sections. The first (superior) portion of the duodenum extends from the pylorus to the neck of the gallbladder and is primarily composed of the duodenal bulb. The second (descending) portion extends from the neck of the gallbladder to the genu, usually at the level of the fourth lumbar vertebra, and abnormalities in this portion are mainly due to pathologic conditions in adjacent structures, including the pancreas and biliary system. The third (horizontal) portion of the duodenum extends from the fourth lumbar vertebra to the level of the aorta and is often affected by trauma, given its retroperitoneal location and proximity to the spine. The fourth (ascending) portion extends from the aorta to the ligament of Treitz.
|
CT Technique
|
|---|
Most conventional abdominal CT scans are obtained with the use of radiopaque oral contrast material to delineate the gastrointestinal tract. When there is suspicion of a duodenal lesion, several techniques can be used to optimize imaging of this commonly overlooked structure. Large amounts of oral contrast material are helpful in opacifying the duodenum, and bicarbonate granules, through the release of carbon dioxide, can distend the stomach and duodenum (3). If a mucosal abnormality is suspected, low-attenuation oral contrast agents, such as water or whole milk, can be used (4). These agents create excellent contrast with the duodenal wall, particularly when intravenous contrast material is injected at 4 mL/sec during a dynamic helical acquisition (Fig 1). For routine imaging, a pitch of 1.0 with a collimation of 5 mm is typically chosen, although thinner-collimation images (
3.0 mm) can be obtained if greater anatomic resolution is needed. Multiplanar reconstructions, including planes oblique and coronal to the plane of the duodenum, are now possible with the thin-collimation, helical acquisition techniques. Dynamic administration of intravenous contrast material with helical thin collimation is useful in the identification of vascular structures and the enhancement pattern of lesions within and adjacent to the duodenum. Placement of the patient in the right poste rior oblique position to maximize opacification is also helpful to image the first and second portions of the duodenum (3), and the left posterior oblique position is helpful when carbon dioxide is used to distend the duodenum.
View larger version (166K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Normal duodenum in a 63-year-old man. CT scan obtained with oral administration of whole milk, the patient in the right posterior oblique position, and 5-mm helical acquisition with intravenous contrast material shows the lumen, mural enhancement, and the gastroduodenal artery (arrow).
|
|
|
Developmental Anomalies
|
|---|
Duplications and Diverticula
The duodenum arises from the embryonic midgut and is composed of both endodermal and mesodermal tissue. At 8 weeks of gestation, the duodenal mucosa proliferates and occludes the lumen, with recanalization occurring by the 10th week. True duodenal diverticula and duplications are believed to be due to abnormalities of recanalization of the duodenal lumen (2). The most frequent location of the more common duodenal pseudodiverticula is along the medial wall of the second and third portions of the duodenum, usually within 2.0 cm of the ampulla of Vater (hepatopancreatic ampulla). Most patients are asymptomatic, and the diagnosis can be performed easily at CT (Fig 2). A duodenal diverticulum can be important in patients who undergo endoscopic retrograde cholangiopancreatography (ERCP) because cannulation of the bile ducts is difficult if the ampulla drains into the diverticulum. Occasionally, patients can present with duodenal diverticulitis, which can be complicated by perforation into the retroperitoneal space (5). Intraluminal diverticula are rare and usually limited to the second or third portion. At barium examination, such diverticula show the classic "windsock" deformity, with the contrast material–filled diverticulum seen to project into the true lumen. The diagnosis can also be made with CT, at which either a collapsed or contrast material–filled diverticulum can be seen (6).
View larger version (133K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2. Large duodenal diverticulum in a 77-year-old man. CT scan obtained with oral and intravenous contrast material shows two "duodenal lumina." The true lumen is lateral to the diverticulum (straight arrow). The diverticulum contains an air-fluid level and causes medial displacement of the pancreatic head (curved arrow). Duodenal diverticula are common findings on abdominal CT scans.
|
|
While duplications are rare in the gastrointestinal tract, approximately 12% occur in the gastroduodenal region. Duodenal duplication arises most often in the medial wall of the second and third portions of the duodenum and typically appears as a well-circumscribed cystic mass with fluid attenuation (7,8). The duplications typically do not communicate with the duodenal lumen and are often incidental findings at abdominal CT (Fig 3). On rare occasions, carcinoma can arise inside a duplication cyst, and the presence of vegetation or mural nodules should raise concern (9).
View larger version (115K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a. Duodenal duplication in a 16-year-old boy. (a) CT scan obtained without oral contrast material shows two fluid-attenuation structures in the second portion of the duodenum. The duplicated segment (curved arrow) is medial to the true lumen and contains debris. The true lumen is narrowed and more lateral (straight arrow). (b) Transverse abdominal ultrasound image obtained through the duodenum correlates with the CT finding of debris within the cystic medial duplicated segment (curved arrow) and the lateral true lumen (straight arrow). (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows narrowing of the true lumen (straight arrow) by the duplicated duodenal segment (curved arrow), which causes a smooth mass effect (suggestive of an intramural or extrinsic process) and does not communicate with the gastrointestinal tract.
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b. Duodenal duplication in a 16-year-old boy. (a) CT scan obtained without oral contrast material shows two fluid-attenuation structures in the second portion of the duodenum. The duplicated segment (curved arrow) is medial to the true lumen and contains debris. The true lumen is narrowed and more lateral (straight arrow). (b) Transverse abdominal ultrasound image obtained through the duodenum correlates with the CT finding of debris within the cystic medial duplicated segment (curved arrow) and the lateral true lumen (straight arrow). (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows narrowing of the true lumen (straight arrow) by the duplicated duodenal segment (curved arrow), which causes a smooth mass effect (suggestive of an intramural or extrinsic process) and does not communicate with the gastrointestinal tract.
|
|
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3c. Duodenal duplication in a 16-year-old boy. (a) CT scan obtained without oral contrast material shows two fluid-attenuation structures in the second portion of the duodenum. The duplicated segment (curved arrow) is medial to the true lumen and contains debris. The true lumen is narrowed and more lateral (straight arrow). (b) Transverse abdominal ultrasound image obtained through the duodenum correlates with the CT finding of debris within the cystic medial duplicated segment (curved arrow) and the lateral true lumen (straight arrow). (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows narrowing of the true lumen (straight arrow) by the duplicated duodenal segment (curved arrow), which causes a smooth mass effect (suggestive of an intramural or extrinsic process) and does not communicate with the gastrointestinal tract.
|
|
Malrotation
During the 6th week of intrauterine gestation, differential growth rates of the anterior and posterior sides of the duodenum result in a rotation of the duodenum across the midline, with the ligament of Treitz lying in the left upper quadrant. If there is abnormal rotation, the duodenum does not cross the midline but remains in the right side of the abdomen. Malrotation is reliably imaged at CT when the duodenum is not visible between the aorta and the superior mesenteric artery, an anatomic relationship that is consistently seen on all abdominal CT scans with normal findings (10). Secondary findings of malrotation include reversed location of the superior mesenteric artery and vein and presence of the colon in the left side of the abdomen and the small bowel in the right side (Fig 4). Patients with malrotation can present with small bowel volvulus and ischemia secondary to torsion of the small bowel on its abnormally short mesentery (11). Duodenal obstruction can also occur on the basis of congenital peritoneal bands.
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4. Gastrointestinal malrotation in a 51-year-old woman. CT scan shows the small bowel in the right side of the abdomen and the colon in the left side. The duodenum does not cross the midline between the superior mesenteric artery and the aorta. The superior mesenteric artery is to the right of the superior mesenteric vein (arrow) rather than in its typical location to the left.
|
|
Annular Pancreas
The pancreas develops from dorsal and ventral buds. In normal development, the ventral bud is typically bifid, with atrophy of one of the buds followed by fusion with the dorsal component. Theories of annular pancreas development suggest that either the two ventral buds persist, with encircling of the duodenum, or the remaining ventral bud adheres to the duodenum early in development, with a portion of ventral pancreatic tissue failing to rotate completely, resulting in annular obstruction. Patients with annular pancreas can present in the 1st decade of life with duodenal stenosis and vomiting, although in approximately 50% of cases, the diagnosis is not made until adulthood (12). Diagnosis of the entity prospectively at CT is difficult owing to the paucity of intraabdominal fat in pediatric patients and the narrow width of the pancreatic band (Fig 5). The use of low-attenuation oral contrast material and imaging in the arterial phase to view the enhancing pancreatic tissue are sometimes helpful, but ERCP allows for accurate delineation of the pancreatic ductal anatomy (13).
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5a. Annular pancreas in a 48-year-old man. (a) Image from a single-contrast-material upper gastrointestinal examination shows narrowing of the proximal second portion of the duodenum (arrow). (b) CT scan obtained with only oral contrast material helps confirm obstruction of the gastric outlet and a dilated proximal duodenum. (c) CT scan obtained caudad to b during the same examination shows a band of ectopic pancreatic tissue posterior to the second portion of the duodenum (arrow).
|
|
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5b. Annular pancreas in a 48-year-old man. (a) Image from a single-contrast-material upper gastrointestinal examination shows narrowing of the proximal second portion of the duodenum (arrow). (b) CT scan obtained with only oral contrast material helps confirm obstruction of the gastric outlet and a dilated proximal duodenum. (c) CT scan obtained caudad to b during the same examination shows a band of ectopic pancreatic tissue posterior to the second portion of the duodenum (arrow).
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5c. Annular pancreas in a 48-year-old man. (a) Image from a single-contrast-material upper gastrointestinal examination shows narrowing of the proximal second portion of the duodenum (arrow). (b) CT scan obtained with only oral contrast material helps confirm obstruction of the gastric outlet and a dilated proximal duodenum. (c) CT scan obtained caudad to b during the same examination shows a band of ectopic pancreatic tissue posterior to the second portion of the duodenum (arrow).
|
|
|
Duodenal Trauma
|
|---|
Duodenal trauma may result from penetrating or blunt injury. During blunt trauma, the duodenum may be crushed against the vertebral body, causing contusion or transection. Rapid deceleration in motor vehicle accidents can also result in duodenal trauma. Detection of blunt traumatic injury to the duodenum is difficult at physical examination, and the choice of treatment is dependent on whether there is a contusion or a perforation. Intramural hematoma without perforation is usually managed conservatively, but traumatic duodenal perforation is a surgical emergency (14). These diagnoses are extremely difficult to determine clinically, since peritoneal signs are frequently absent because of the retroperitoneal location of the pancreas and duodenum. In addition, high morbidity and mortality are associated with missed duodenal injuries (15,16). The combination of high mortality and difficulty in establishing the clinical diagnosis increases the importance of the radiologist in detection of this injury. CT is the primary imaging modality for assessment of abdominal trauma, and the diagnosis of duodenal injury should be suspected when any of the following findings are observed: (a) air adjacent to the duodenum in the retroperitoneum, (b) extravasation of oral contrast material in the retroperitoneum, (c) fluid in the retroperitoneum, (d) edema in the duodenal wall, (e) stranding of the peripancreatic fat, and (f) pancreatic transection (17–19) (Fig 6).
View larger version (112K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6. Ruptured duodenum in a 27-year-old female victim of a motor vehicle accident. CT scan shows fluid in the duodenum and leakage of fluid into the right anterior pararenal space (arrow).
|
|
Iatrogenic duodenal perforation is a rare complication of endoscopy and is usually suspected at the time of endoscopic examination. Perforation may be due to rupture from the endoscope or from an extended sphincterotomy. Typical CT findings include retroperitoneal air and fluid adjacent to the duodenum (Fig 7). Most patients undergo nonoperative treatment, surgery being reserved for those with persistent pain, signs of infection, or large perforations of the lateral duodenal wall (20,21).
|
Inflammatory Processes
|
|---|
The most common inflammatory process to affect the duodenum is secondary involvement from pancreatitis. Pancreatic inflammation and release of exocrine enzymes cause mild (Fig 8) to severe duodenal edema that obstructs the gastric outlet. In addition, severe pancreatitis can cause an intramural hematoma from disruption of the intramural vasculature by the elastase present in pancreatic enzymes (22) (Fig 9).
View larger version (128K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8. Acute pancreatitis and duodenal edema in a 50-year-old woman. CT scan shows an enlarged head of the pancreas with stranding of the peripancreatic fat. The wall of the duodenum is thickened, and limited mural enhancement is seen secondary to edema (arrow).
|
|
View larger version (142K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9. Acute pancreatitis and hemorrhage into the lateral duodenal wall, which caused mass effect and narrowing of the duodenal lumen, in a 46-year-old man. CT scan shows extensive stranding of the peripancreatic fat secondary to pancreatitis. Massive enlargement of the lateral wall of the duodenum is accompanied by a focal area of increased attenuation at the site of the bleeding (black arrow). The duodenal lumen, which contains low-attenuation fluid, is narrowed and displaced medially (white arrow).
|
|
The reported prevalence of Crohn disease that involves the duodenum ranges from 0.5% to 4%, although this range is based primarily on findings of barium studies, and series based on findings of routine endoscopy have suggested a higher incidence, ranging from 5% to 60% (23). Primary involvement tends to manifest as ulcer or stricture formation, while secondary involvement typically occurs as a fistulous communication from an adjacent affected loop of small bowel or colon (24).
Duodenal ulcers are common pathologic entities that occur most frequently in the duodenal bulb. Perforated duodenal ulcers can be diagnosed at CT from the presence of (a) wall thickening, (b) periduodenal fluid, (c) retroperitoneal air, or (d) free intraperitoneal air (25) (Fig 10). Duodenitis from inflammation without ulcer formation is manifested by thickening of the duodenal bulb wall. Inflammation of the duodenal papillae can occur in patients with acquired immunodeficiency syndrome or who are undergoing radiation therapy. On rare occasions, severe duodenal ulcers can result in strictures and obstruction of the gastric outlet (Fig 11). Postbulbar ulcers are rare, and when they occur, alternate causes such as Crohn disease and Zollinger-Ellison syndrome should be considered (26).
View larger version (158K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10. Abdominal pain and a perforated duodenal ulcer in a 79-year-old man. CT scan obtained with oral contrast material shows intraperitoneal extravasation of contrast material from the lateral portion of the duodenum (white arrow) and leakage of contrast material around the liver (black arrow).
|
|
View larger version (145K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11. Duodenal ulcer that caused obstruction of the gastric outlet in a 79-year-old man. CT scan obtained with oral contrast material shows a dilated stomach and a thickened wall of the duodenal bulb with stranding of the periduodenal fat (arrow).
|
|
The gallbladder is adjacent to the lateral margin of the first and second portions of the duodenum. Severe cases of cholecystitis can result in secondary inflammation of duodenal tissue adjacent to the inflamed gallbladder wall. If this process is long-standing and severe, a gallstone may erode through the gallbladder wall and into the duodenum, resulting in a "gallstone ileus." CT findings include (a) pneumobilia, (b) small bowel obstruction, (c) ectopic gallstone, (d) cholecystoduodenal (or choledochoduodenal) fistula, and (e) thickened duodenal wall (27,28) (Fig 12). Bouveret syndrome, or obstruction of the gastric outlet caused by a gallstone in the duodenum, can also be imaged at CT (29,30).
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Right upper quadrant pain and a gallstone ileus in a 70-year-old man. (a) CT scan obtained with oral and intravenous contrast material shows a contracted, thick-walled gallbladder (straight arrow) and a fistula to the duodenum (curved arrow). (b) CT scan obtained caudad to a shows a gallstone within the duodenum (arrow) with proximal duodenal and gastric dilatation. (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows a nasogastric tube in the stomach and filling of the contracted gallbladder through the fistula (curved arrow). The gallstone (straight arrow) has moved to the fourth portion of the duodenum, causing partial duodenal and gastric obstruction.
|
|
View larger version (129K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Right upper quadrant pain and a gallstone ileus in a 70-year-old man. (a) CT scan obtained with oral and intravenous contrast material shows a contracted, thick-walled gallbladder (straight arrow) and a fistula to the duodenum (curved arrow). (b) CT scan obtained caudad to a shows a gallstone within the duodenum (arrow) with proximal duodenal and gastric dilatation. (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows a nasogastric tube in the stomach and filling of the contracted gallbladder through the fistula (curved arrow). The gallstone (straight arrow) has moved to the fourth portion of the duodenum, causing partial duodenal and gastric obstruction.
|
|
View larger version (154K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12c. Right upper quadrant pain and a gallstone ileus in a 70-year-old man. (a) CT scan obtained with oral and intravenous contrast material shows a contracted, thick-walled gallbladder (straight arrow) and a fistula to the duodenum (curved arrow). (b) CT scan obtained caudad to a shows a gallstone within the duodenum (arrow) with proximal duodenal and gastric dilatation. (c) Image from a single-contrast-material upper gastrointestinal study in the anteroposterior projection shows a nasogastric tube in the stomach and filling of the contracted gallbladder through the fistula (curved arrow). The gallstone (straight arrow) has moved to the fourth portion of the duodenum, causing partial duodenal and gastric obstruction.
|
|
|
Infectious Processes
|
|---|
Infectious processes in the duodenum are rarely diagnosed prospectively from CT scans. Most infectious processes result in inflammation of the duodenum and secondary duodenal wall edema. The most common infectious cause of duodenitis is Helicobacter pylori. Less common infections include giardiasis and tropical sprue. The findings tend to be nonspecific, such as wall thickening and luminal dilatation. Correlation with clinical history is helpful in diagnosis (31).
|
Hematologic Abnormalities
|
|---|
Henoch-Schönlein purpura is a systemic hypersensitivity disease of unknown pathogenesis. Deposition of immune complexes within small vessels throughout the body results in abnormal permeability of small blood vessels. This altered permeability can result in a purpuric rash, glomerulonephritis, and hemorrhage in the gastrointestinal tract. At abdominal CT, one can see multifocal areas of bowel wall thickening and mesenteric edema (32). The diagnosis of Henoch-Schönlein purpura should be considered when these findings are seen in young patients with abdominal pain (Fig 13).
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13. Henoch-Schönlein purpura in an 18-year-old man who presented with abdominal pain. CT scan obtained with oral and intravenous contrast material shows marked thickening of the duodenal wall in the second and fourth portions (arrows). The lumen was narrowed, but there was no obstruction of the gastric outlet.
|
|
|
Neoplastic Processes
|
|---|
Small bowel malignancies are 50 times less common than colonic neoplasms, but the duodenum is a common site of tumors in the small bowel, accounting for approximately 20% of these neoplasms (33,34). Neoplastic processes in the duodenum can be separated into benign and malignant pathogeneses. The most common symptomatic benign neoplasm of the duodenum is a benign gastrointestinal stromal tumor (leiomyoma). Patients with these tumors often present with gastrointestinal bleeding and, occasionally, abdominal pain. At CT, the neoplasm may be seen as a heterogeneous mass with moderate enhancement and an annular narrowing of the lumen with abrupt concentric or irregular edges (35). Duodenal lipomas are benign lesions that can be reliably diagnosed on CT scans as a smooth-margined mass with a low Hounsfield unit measurement (36) (Fig 14). They usually produce no symptoms and most often occur in men in their 7th decade. There are three types of duodenal adenomas: tubular type, villous adenoma, and Brunner gland adenoma. Villous adenomas have a malignant potential and are treated with surgical resection (33) (Fig 15), while tubular adenomas and Brunner gland adenomas are typically resected for symptomatic reasons.
View larger version (154K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14. Incidental duodenal lipoma in a 71-year-old woman. CT scan of the abdomen obtained with oral and intravenous contrast material shows a low-attenuation lesion with well-circumscribed margins in the duodenum (arrow). The lesion had an attenuation of -32 HU and was stable for more than 1 year.
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15a. Villous adenoma of the duodenum in a 71-year-old woman. (a) Image from a single-contrast-material upper gastrointestinal examination in the anteroposterior projection reveals a filling defect in the duodenum (arrow), at the junction of the second and third portions. (b) CT scan obtained with oral and intravenous contrast material shows a soft-tissue mass (white arrow) arising from the medial wall of the duodenum. The duodenal lumen is narrowed (black arrow).
|
|
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15b. Villous adenoma of the duodenum in a 71-year-old woman. (a) Image from a single-contrast-material upper gastrointestinal examination in the anteroposterior projection reveals a filling defect in the duodenum (arrow), at the junction of the second and third portions. (b) CT scan obtained with oral and intravenous contrast material shows a soft-tissue mass (white arrow) arising from the medial wall of the duodenum. The duodenal lumen is narrowed (black arrow).
|
|
While the small bowel can be involved in various polyposis syndromes, Peutz-Jeghers syndrome is the only one that affects it primarily (33). This syndrome of mucocutaneous melanin pigmentation and associated hamartomatous gastrointestinal polyps is an autosomal-dominant abnormality. Presenting symptoms are bleeding and obstruction from intussusception. At CT, one may see intraluminal polyps (37) (Fig 16), and the multiplicity of these lesions should suggest a polyposis syndrome.
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16a. Peutz-Jeghers syndrome with duodenal and small-bowel polyps in a 37-year-old woman. (a) CT scan shows a soft-tissue filling defect in the duodenal lumen (arrow) outlined by water. (b) CT scan obtained caudad to a shows several polyps in the proximal small bowel (arrow).
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16b. Peutz-Jeghers syndrome with duodenal and small-bowel polyps in a 37-year-old woman. (a) CT scan shows a soft-tissue filling defect in the duodenal lumen (arrow) outlined by water. (b) CT scan obtained caudad to a shows several polyps in the proximal small bowel (arrow).
|
|
Malignant primary neoplasms of the duodenum are rare. Adenocarcinoma is the most common primary malignant neoplasm of the duodenum, with 50%–70% of small bowel adenocarcinomas occurring either in the duodenum or proximal jejunum. The peak prevalence is in the 7th decade, and patients present with signs of bleeding, jaundice, or obstruction. Patients with this neoplasm tend to present at an advanced stage, with more than 50% of them having metastases at the time of diagnosis (33). At CT, one sees a polypoid or intramural mass (Fig 17). Rare tumors such as paragangliomas can also occur in the duodenum. These neoplasms can occur in external, intramural, or intraluminal locations, typically in the second or third portions of the duodenum. At CT and magnetic resonance (MR) imaging, these tumors are soft-tissue-attenuation masses with homogeneous enhancement and have a characteristic smoothly margined "dumbbell" appearance (38) (Fig 18).
View larger version (118K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18a. Duodenal paraganglioma in a 54-year-old man. (a) CT scan shows a subtle, smoothly margined soft-tissue mass (arrows) in the second and third portions of the duodenum without obstruction. (b) Coronal HASTE (half-Fourier acquisition single-shot turbo spin-echo) MR image (4.3/285.0/00:24 [repetition time msec/echo time msec/acquisition time]) shows hyperattenuating fluid in the duodenum outlining the sausage-shaped duodenal mass (arrow). (c) Image from a single-contrast-material upper gastrointestinal examination in the left posterior oblique projection obtained in a different patient with a paraganglioma shows the similar appearance of this lesion for comparison. An intraluminal filling defect is seen in the third portion of the duodenum (arrow).
|
|
View larger version (122K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18b. Duodenal paraganglioma in a 54-year-old man. (a) CT scan shows a subtle, smoothly margined soft-tissue mass (arrows) in the second and third portions of the duodenum without obstruction. (b) Coronal HASTE (half-Fourier acquisition single-shot turbo spin-echo) MR image (4.3/285.0/00:24 [repetition time msec/echo time msec/acquisition time]) shows hyperattenuating fluid in the duodenum outlining the sausage-shaped duodenal mass (arrow). (c) Image from a single-contrast-material upper gastrointestinal examination in the left posterior oblique projection obtained in a different patient with a paraganglioma shows the similar appearance of this lesion for comparison. An intraluminal filling defect is seen in the third portion of the duodenum (arrow).
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18c. Duodenal paraganglioma in a 54-year-old man. (a) CT scan shows a subtle, smoothly margined soft-tissue mass (arrows) in the second and third portions of the duodenum without obstruction. (b) Coronal HASTE (half-Fourier acquisition single-shot turbo spin-echo) MR image (4.3/285.0/00:24 [repetition time msec/echo time msec/acquisition time]) shows hyperattenuating fluid in the duodenum outlining the sausage-shaped duodenal mass (arrow). (c) Image from a single-contrast-material upper gastrointestinal examination in the left posterior oblique projection obtained in a different patient with a paraganglioma shows the similar appearance of this lesion for comparison. An intraluminal filling defect is seen in the third portion of the duodenum (arrow).
|
|
Lymphomatous involvement of the duodenum can occur with both primary duodenal lymphoma and involvement from systemic disease. Associations exist with immunodeficiency states, notably infection with the human immunodeficiency virus, celiac disease, and parasitic infestation (33). Most often, CT shows large, segmental nodular wall thickening, with a gradual junction with normal mucosa (35). Alternatively, a large eccentric mass with extension into adjacent tissues can be seen.
Secondary involvement of the duodenum with other primary malignancies can occur by means of local extension or metastases from distant sites. Pancreatic adenocarcinomas can be locally aggressive, and extension to the duodenum can be seen at CT (39) (Fig 19). Colon carcinoma can cause local mass effect or invasion, occasionally with formation of a coloduodenal fistula (40) (Fig 20). Ovarian carcinoma typically produces peritoneal disease but can occasionally manifest with metastatic disease to the duodenum (41) (Fig 21). In addition, periduodenal lymph nodes are a common site of metastasis, and differentiating involved nodes from a primary duodenal mass can be difficult at CT. MR imaging can be a useful adjunct in the differentiation of primary duodenal pathologic conditions from periduodenal lymphadenopathy when CT findings are equivocal (Fig 22). Metastatic disease from melanoma to the small bowel is a common finding in autopsy series and can cause single or multiple intraluminal masses. Alternatively, it can manifest with lymphadenopathy or peritoneal implants (42).
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19. Pancreatic adenocarcinoma invading the duodenum in a 42-year-old man. CT scan shows a mass arising from the pancreas and invading the medial wall of the duodenum (arrow) with luminal narrowing.
|
|
View larger version (151K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20. Colon carcinoma complicated by a coloduodenal fistula in a 56-year-old man. CT scan obtained with oral contrast material shows a fistulous communication (arrow) between the colon and duodenum.
|
|
View larger version (154K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 21. Ovarian carcinoma metastatic to the duodenum confirmed by means of endoscopic biopsy in a 58-year-old woman. CT scan shows a large soft-tissue mass filling the third portion of the duodenum (arrow). This manifestation is unusual for metastatic ovarian carcinoma, as there was no intraperitoneal disease or adenopathy.
|
|
View larger version (119K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 22a. Metastatic colon carcinoma mimicking a duodenal or pancreatic head mass in a 64-year-old man. (a) CT scan shows a soft-tissue-attenuation mass causing lateral displacement of the duodenum (arrow). The mass is isoattenuating relative to the pancreatic head. (b) T1-weighted spin-echo MR image (450/20/5:38) obtained through the same level as in a shows the different signal intensities of the confluent lymph nodes (straight arrow) and the pancreatic head (curved arrow). MR imaging is excellent in the evaluation of equivocal findings at CT.
|
|
View larger version (107K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 22b. Metastatic colon carcinoma mimicking a duodenal or pancreatic head mass in a 64-year-old man. (a) CT scan shows a soft-tissue-attenuation mass causing lateral displacement of the duodenum (arrow). The mass is isoattenuating relative to the pancreatic head. (b) T1-weighted spin-echo MR image (450/20/5:38) obtained through the same level as in a shows the different signal intensities of the confluent lymph nodes (straight arrow) and the pancreatic head (curved arrow). MR imaging is excellent in the evaluation of equivocal findings at CT.
|
|
|
Postsurgical Changes of the Duodenum
|
|---|
CT is the mainstay of imaging of the postoperative abdomen. Most postoperative complications, including abscess, wound dehiscence, hematoma, hernia, anastomotic leakage, and bowel obstruction, are well depicted with CT (43).
Surgical treatment for an early gastric carcinoma includes resection with gastrojejunostomy. The afferent limb of the gastrojejunostomy is the section of the duodenum that drains the biliary and pancreatic systems. The efferent limb extends from the gastric anastomosis to the remainder of the bowel. Recurrent carcinoma or ulceration of the gastrojejunostomy anastomosis can result in obstruction of the afferent limb with secondary dilatation from the biliary and pancreatic secretions (44). A dilated afferent limb is a worrisome CT sign for tumor recurrence, even when the tumor cannot be imaged (Fig 23). Patients with a dilated afferent limb at CT should undergo endoscopy for evaluation of recurrent tumor at the anastomosis.
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 23a. Gastric carcinoma 1 year after antrectomy and gastrojejunostomy with afferent limb obstruction in a 58-year-old woman. (a) CT image shows biliary dilatation and thickening of the gastric wall at the gastrojejunostomy anastomosis (arrow). (b) CT image obtained caudad to a shows a dilated afferent limb containing low-attenuation bile. The limb was obstructed owing to recurrent gastric carcinoma at the gastrojejunostomy anastomosis.
|
|
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 23b. Gastric carcinoma 1 year after antrectomy and gastrojejunostomy with afferent limb obstruction in a 58-year-old woman. (a) CT image shows biliary dilatation and thickening of the gastric wall at the gastrojejunostomy anastomosis (arrow). (b) CT image obtained caudad to a shows a dilated afferent limb containing low-attenuation bile. The limb was obstructed owing to recurrent gastric carcinoma at the gastrojejunostomy anastomosis.
|
|
|
Conclusion
|
|---|
The duodenum is frequently overlooked during interpretation of abdominal CT examinations. Knowledge about techniques for optimal imaging of the duodenum and about diseases and congenital anomalies that affect it can result in increased diagnostic yield of abdominal CT.
|
Footnotes
|
|---|
Abbreviation: ERCP = endoscopic retrograde cholangiopancreatography
|
References
|
|---|
Top
Abstract
Introduction
