Duodenal imaging on the spotlight: from A to Z

Abstract

Abdominal computed tomography (CT) is frequently performed to evaluate gastrointestinal pathologic conditions. The majority of the gastrointestinal radiology literature has concentrated on the colon, stomach, and distal small bowel. The duodenum is often overlooked on imaging, namely on CT, but its anatomy (intra and retroperitoneal) and location in such close proximity to other viscera results in involvement by a multitude of primary and secondary processes, some of them exclusive to this bowel segment. While some conditions, like duplications, lipomas, and diverticula, are usually asymptomatic and are incidentalomas that have no pathologic significance, others are symptomatic and very relevant and should be recognized by every general radiologist: development conditions such as annular pancreas and gut malrotation; inflammatory processes such as ulcers and secondary involvement from pancreatitis; neoplastic conditions such as adenocarcinoma, lymphoma, or local extension from adjacent malignancies. They all can be reliably diagnosed with CT. In this article, we demonstrate the typical imaging features of various diseases involving the duodenum, such as developmental, traumatic, inflammatory, infectious, neoplastic, and postsurgical pathologic conditions in alphabetical order, focusing mainly on upper gastrointestinal series (UGIS) and CT but also some radiography, ultrasound, and magnetic resonance (MR) imaging.

Keywords: Abdomen; Computed tomography; Duodenum; Gastrointestinal; Magnetic resonance imaging; Ultrasound; Upper gastrointestinal series.

Fig. 1

Adenocarcinoma. Abdominal CT performed before (a) and after (b, c) iv contrast administration shows irregular circumferential asymmetric thickening of D3, causing deformity of the lumen (arrows). There is encasement of the superior mesenteric artery (curved arrow) and tumor thrombosis of the superior mesenteric vein (arrowhead), rendering the lesion surgically unresectable. There is also periduodenal fat stranding and adenopathy (circle). Abdominal CT (d) of another case of duodenal carcinoma with an ulcerated mass at D2 (arrows). Abdominal CT of yet another case of duodenal carcinoma (e); there is circumferential duodenal thickening (arrows) which caused luminal stenosis with proximal dilatation (asterisk). MRCP of another patient (f) showing a polypoid duodenal lesion (curved arrow) that caused CBD dilatation (arrow), which proved to be a duodenal adenocarcinoma

Fig. 2

Ampullary tumors. Contrast-enhanced CT (a, b) reveals an enhancing soft-tissue mass (arrows), originating in the medial wall of the descending duodenum. This was a case of an ampullary adenocarcinoma. Contrast-enhanced CT of another patient with an ampullary carcinoma (c), shows a soft-tissue mass (arrow) originating in the medial wall of the descending duodenum and protruding into the water-filled duodenum. ERCP (d) revealed an enlarged and irregular suspicious papilla (curved arrow) and CBD dilatation (arrows). MRCP (e) of another patient shows dilatation of the CBD and intra-hepatic ducts (arrows) due to an abrupt stop at the distal CBD (curved arrow), which was caused by an ampullary villous adenoma

Fig. 3

Afferent Loop Syndrome. Abdominal CT (a, b) of a patient who had received partial gastrectomy with Billroth II reconstruction—A fluid-filled tubular structure in the right upper quadrant and crossing the midline is seen, with associated gallbladder distension (asterisk). There is an enhancing lesion at the anastomosis. This was an afferent loop syndrome caused by gastric tumor recurrence. UGI series of the same patient (c). There is non-filling of the afferent loop (asterisk) and a filling defect at the location of the anastomosis (arrow). Abdominal CT (d, e) of another patient with afferent loop syndrome, because of an internal hernia with volvulus (note the twisted configuration of the bowel loops at the left hypochondrium (arrows)). There is fluid-filled dilatation of the afferent loop associated with gallbladder distension and intrahepatic and extrahepatic duct dilatation (asterisks)

Fig. 4

Biliary ileus. CT coronal reformation (a) shows air in the gallbladder (arrowhead) and communication between its lumen and D2—cholecystoduodenal fistula (arrow). Axial CT scans (b) show a 2 cm-wide elliptical gallstone impacted at the distal jejunum (arrow). Coronal reformation 9c) shows air-filled dilated small bowel loops (asterisk)

Fig. 5

Bouveret syndrome. CT coronal reformation (a) shows marked gastric dilatation (asterisks) caused by a round lesion at the duodenal bulb (arrowhead); there is also densification and indefinition of the contour of the gallbladder (arrow). Unenhanced CT (b) shows the lesion is spontaneously hyperdense-endoluminal gallstone at the duodenal bulb (arrowhead). A small fistulous tract filled with air (c) (arrowhead) is seen between the duodenal bulb and the expected location of the gallbladder, which had ruptured and formed a phlegmon (arrow)

Fig. 6

Cystic dystrophy of the duodenal wall. Abdominal CT of a patient with abdominal pain (a–c)—there is parietal thickening and several cystic lesions surrounding the duodenum (arrows), best evaluated after contrast administration (b, c). These cysts have a preferential localization in the mesenteric side. Densification of the periduodenal fat and a small amount of fluid surrounding the duodenum (arrowheads) is also seen. Abdominal CT of another patient (d)—duodenal intramural cyst-like lesions with fluid density (arrows). The cysts narrow and shift the duodenal lumen to the right. In abdominal MR (f, e), cystic lesions (arrows) present high signal intensity on T2w images

Fig. 7

Choledococele. Unenhanced (a) and enhanced CT (b) shows a fluid-filled sac within the medial wall of the descending duodenum. CT coronal reformation (c) shows protrusion of a dilated distal segment of the common bile duct into the duodenum. Abdominal MR (d), coronal HASTE heavily T2-weighted sequence, shows distal CBD dilatation which protrudes into the duodenum

Fig. 8

Duplication cyst. Abdominal CT (a, b) fortuitus finding of a peri-duodenal cystic lesion (arrows), with mural enhancement, which caused extrinsic compression on the descending duodenum. Abdominal CT of the same patient some months after (c–e), when he started complaining of abdominal pain, shows increasement in size and spontaneously hyperdense content on unenhanced images (arrow on c). Histopathological study of the resected specimen revealed a duodenal duplication cyst complicated with hemorrhage

Fig. 9

Diverticula. Upper gastrointestinal series with barium contrast (a) shows an outpouching of the upper wall of the third part of the duodenum (arrow). Abdominal CT (b) shows an air and fluid-filled diverticulum on the inner aspect of the descending duodenum (asterisk), adjacent to the CBD (arrow). In another patient (c), an heterogeneous fluid and air-filled diverticulum on the inner aspect of the descending duodenum (arrow) mimicked an abscess. MRCP (d) in a patient that had bile duct dilatation (arrows) with associated cholangitis due to a periampullary diverticulum (asterisk)

Fig. 10

Ectopic pancreas. Abdominal CT of a patient who underwent the exam for an unrelated reason. A soft-tissue nodule, with a flat-ovoid shape and microlobulations, is seen in the serosa of the first portion of the duodenum. It has an enhancement pattern similar to that of the normal pancreatic tissue (arrowheads on a, b) in the late arterial (a) and portal venous phases (b). The lesion (arrow) is supplied by a branch of the gastroduodenal artery (arrowhead on c). This was heterotopic pancreatic tissue in the duodenal bulb serosa

Fig. 11

Extension from adjacent tumor. Abdominal CT (a, b) shows circumferential wall thickening of the gastric antrum (arrows) extending through the pylorus into D1 and D2, where a polypoid-like lesion (arrowhead) narrows the lumen. CT of another patient (c) shows evidence of gastric adenocarcinoma (arrows) with duodenal invasion and hemorrhage (arrowheads) inside the duodenal lumen. Abdominal CT of other patient (d) shows a hypodense soft-tissue density mass (arrowhead) which was a pancreatic adenocarcinoma with invasion of the medial wall of D2 (arrow). Abdominal CT of a patient with a neoplasm of the hepatic flexure of the colon (e, f). An undefined mass apparently involves the duodenum (asterisk) and the colon. A small amount of positive oral contrast agent (arrowhead) is present within the mass. An image obtained caudally (f) shows oral contrast agent in the colon (arrowhead) without evidence of contrast in the jejunum (arrow), a feature related to a colo-duodenal fistula

Fig. 12

Fistula (Aorto-duodenal). Unenhanced CT (a) of patient with hematemesis shows an aorto-bi-femoral stent (curved arrow) inside the infra-renal aorta, with exclusion of atherosclerotic plaque (arrow), in close proximity to the third part of the duodenum (asterisk). Arterial phase CT (MIP) (b) shows an aortoduodenal fistula (arrow), with blood leaking into D3 (arrowheads) in the topography of the proximal end of the aortic stent. Portal phase CT (c) shows increased pooling of blood in the duodenum and jejunum (arrowheads). Sagittal reformat in arterial phase CT (d) better shows the fistulous tract of the blood into D3 (arrow)

Fig. 13

GIST. Unenhanced abdominal CT (a) shows an endoluminal homogeneous soft-tissue lesion on the transition D2–D3. Abdominal CT with iv contrast (b, c) shows homogeneous enhancement of the lesion (arrow). Barium study (d) shows a well-circumscribed round intramural mass (arrow) in the transition D2–D3. Histopathological study of the resected specimen revealed a benign GIST

Fig. 14

GIST. Unenhanced abdominal CT (a) shows a heterogeneous soft-tissue lesion with punctiform calcifications on the horizontal portion of the duodenum (arrow). Abdominal CT after iv contrast (b) shows peripheral enhancement and central necrosis (arrows). Coronal reformation of the same patient (c) better depicts the origin of the lesion (arrow) from the duodenal wall and the endophytic component. Histopathological study revealed a duodenal malignant GIST with pancreatic invasion, central necrosis, and small calcifications. Abdominal CT (d) of another large malignant GIST with exophytic growth pattern (arrowhead), which also shows several other small enhancing parietal metastases, in D2 (arrows)

Fig. 15

Hamartoma of Brunner’s glands. Unenhanced CT (a) shows a voluminous polypoid lesion originating in the duodenal bulb and reaching D4, with soft-tissue density and a lobulated contour (arrows). MRI of the same patient shows that the lesion (arrows) is heterogeneously hypointense on T1w images (b), hyperintense on FS T2w images (c), with enhancement after iv administration of gadolinium (d)

Fig. 16

Intussusception. UGIS (a) rounded filling defect in the lumen of the duodenal bulb (asterisk), with regular outlines. The telescoping of mucosal folds (arrowhead) and the prepyloric collar-shaped outpouching (arrows) indicates this is an intussusception of a tumor from the gastric antrum. Abdominal CT (b) of the same patient with a prolapsing polypoid soft-tissue density mass with slightly heterogeneous enhancement (arrow). This was a gastric GIST. Abdominal CT of another gastric GIST (c, d) prolapsing to the duodenum (arrowhead). The coronal reformation shows a typical “target-like” appearance (arrows). Abdominal radiograph (e) of the same patient of 9c, d)—Retrospectively, the intraduodenal mass well-delineated by luminal air was already evident (arrows)

Fig. 17

Juvenile polyposis. UGIS (a) with multiple filling defects at the duodenal bulb (circles). Unenhanced CT of another patient (b) shows a fluid density endoluminal lesion at the duodenal bulb (arrow). Enhanced CT of the same patient (c) shows several polyps at the duodenum and stomach. The biggest is located in the duodenal bulb and presents central fluid density with very little enhancement (arrow)

Fig. 18

Kartagener syndrome. Abdominal CT of a patient with situs inversus. There are hypodense liver lesions (arrows) corresponding to metastases from colon cancer (a, c). The duodenum accompanies the mirror image of the other abdominal organs. Asterisk = descending duodenum. L = liver; S = spleen; St = stomach; Ph = head of the pancreas; Pt = tail of the pancreas; Gb = gallbladder. Thoracic CT of another patient (d) with situs inversus and Kartagener syndrome shows bronchiectasis in the middle lobe of the left lung (circle)

Fig. 19

Lipoma. CT enteroclysis, axial (a) and coronal reformation (b) a small endoluminal nodule, with fat density is seen protruding of the wall at D4 (arrows). Abdominal CT of another patient (c) shows a duodenal mass with homogeneous fat attenuation in the horizontal duodenum (arrow). MR coronal HASTE image (d) shows the mass has high signal intensity (arrows), equal to the mesenteric fat

Fig. 20

Lymphoma. Contrast-enhanced CT (a, b) shows homogeneous and asymmetric thickening of the duodenal wall with mild dilatation of the lumen (arrows); there is biliary and Wirsung duct dilatation (arrowheads); paraduodenal adenopathy is also evident (asterisks). UGIS of the same patient (c) shows loss of the normal mucosal pattern of folds at the descending duodenum (arrows). UGIS some months after the first UGIS, while on chemotherapy (d) shows abrupt luminal narrowing at the horizontal duodenum (arrow), with dilatation of the proximal duodenal segments. Because of increased pressure at the stenosis, there was contrast reflux to the biliary ducts and Wirsung duct (arrowheads)

Fig. 21

Metastasis. Abdominal and pelvic CT (a, b) of a patient with sigmoid colon cancer, performed to stage the disease, clearly demonstrated the sigmoid tumor (arrowheads) but failed to show distant metastases. However, MPR and retrospective analysis revealed a discrete circumferential thickening on D3 and D4 (arrows) which was not recognized initially. This duodenal lesion progressed to become an “apple core” lesion (arrows) causing obstructive symptoms, as evaluated by a barium study performed 2 months later (c)

Fig. 22

Celiac disease. Abdominal CT before (a) and after iv contrast administration (b) of a 14-year-old boy shows thickening and irregularity of the duodenal mucosa (arrows), with intense enhancement. Abdominal ultrasound of the same patient (c) detected several lymphadenopathies (arrowheads). Duodenal biopsy revealed disappearance of the “villi” associated with crypt hyperplasia, consistent with celiac disease. Abdominal ultrasound of another patient (d) who had three incidental transient small bowel intussusceptions (arrowhead), that were not present in a subsequent CT enterography a week later. Duodenal mucosa biopsy showed findings consistent with celiac disease

Fig. 23

Neuroendocrine tumor. Arterial phase CT (a, b) of a patient with type I multiple endocrine neoplasia, with hypergastrinemia, shows two small hypervascular nodular lesions on the wall of D2 and D1 (arrows). Coronal reformation (c) better shows the duodenal bulb lesion (arrow) and another similar lesion at the pancreatic head (arrowhead). Histopathological study following pancreatoduodenectomy revealed duodenal and pancreatic neuroendocrine tumors (gastrinomas). Abdominal CT of another patient shows a mass (arrows) in the medial wall of D2 with intense contrast enhancement in the arterial phase (d) and venous phase (e) of the dynamic study. The high spatial resolution provided by CT clearly shows that the lesion is independent from the pancreas

Fig. 24

Internal hernia. Abdominal CT of a patient with a left paraduodenal internal hernia there is no fat between the fluid-filled dilated small bowel loop and the anterior abdominal wall (arrows on a). The small bowel loops are seen lateral to the descending colon with medial deviation of the colon (arrowhead on b). There is twisting of the bowel loops and mesentery—whirl sign (curved arrow on c). Another patient with CT findings of a right paraduodenal internal hernia fluid-filled dilated loop of small bowel with a U/C-shape configuration which represents a closed loop obstruction (d). Both ends of a fluid-filled distended closed-loop taper fusiformly, in a similar way to a beak—the beak sign (arrows on e). There is also twisting of the mesenteric vessels at the mesenteric root—whirl sign (curved arrow on f). The fact that there is diminished enhancement of the bowel wall (arrowheads), densification of the mesentery (asterisk) and free fluid (arrows) suggests strangulation (d)

Fig. 25

Paraduodenal pancreatitis. Abdominal CT of a patient with clinical and laboratory findings suggestive of pancreatitis (a–c). The pancreas has normal volume, morphology, and texture. There is retroperitoneal fluid in the right anterior pararenal space (small arrows) and in the pancreatoduodenal groove (big arrows). The posterior wall of the descending duodenum is slightly thickened (arrowhead) and the pancreatoduodenal groove reveals discrete late enhancement (curved arrow on c), suggestive of fibrotic changes. Abdominal CT of another patient with paraduodenal pancreatitis (d–f) shows an ill-defined soft-tissue mass within the groove (arrowheads) and descending duodenal medial wall thickening (arrows)

Fig. 26

Annular pancreas. Abdominal CT of an adult patient shows pancreatic tissue completely surrounding D2 (asterisk), in an annular fashion (arrows), with enhancement equal to the pancreas on both the arterial (a) and portal venous (b) phases

Fig. 27

Chron’s Disease. Plain abdominal CT shows the fat halo sign (arrows) in the wall of the D3 (a) and D4 (b), in a patient with quiescent Crohn’s disease. CT enterography (c) of a CD patient with active disease who previously had a segmental enterectomy—note the surgical clips at the ileal-ileal anastomosis (curved arrows). There is a fistula between the thickened ileal segment near the anastomosis and the duodenum. MIP coronal reformation (d) shows mesenteric engorgement (asterisks) and adenopathy (arrowhead) near a thickened bowel wall segment (arrows). Abdominal CT of another patient with active disease (e) shows gastric outlet obstruction (asterisk) and a stricture in D2 that shows the target sign (arrow). Barium study of the same patient (f) shows the short stricture (arrow) and dilatation of the proximal duodenum (asterisk)

Fig. 28

Rupture. Abdominal CT (a, b) of a patient who had ingested a fishbone (arrow). It perforated the duodenal bulb (asterisk) and lodged on the left lobe of the liver. Note the adjacent liver abscess (arrowheads) that formed as a result. CT of another patient (c) shows an endoluminal calcic density structure—fishbone (arrow) at D3, with a small amount of adjacent extraluminal gas (arrowhead) and fat stranding (curved arrow), indicative of retroperitoneal rupture. CT of yet another patient who had underwent ERCP (d) shows a discontinuity of the posterior wall of D3 (arrow) and extensive pneumoretroperitoneum (asterisk)

Fig. 29

Superior mesenteric artery syndrome. Arterial phase of an abdominal CT study of a female adolescent (a) shows dilatation of the duodenum (asterisk) upstream to the point where it crosses the SMA and the aorta (arrow). Note paucity of abdominal fat. Oblique sagittal reformation of another patient (b) shows reduction of the normal aortomesenteric angle (9º) and aortomesenteric distance (6 mm). Fluoroscopic series of a 10-year-old girl after surgical correction of kyphosis c shows obstruction at D3 with delayed passage of contrast through the stenosis (asterisk) and proximal dilatation of D2(arrows). This was due to SMA syndrome caused by lengthening of the vertebral column

Fig. 30

Accessory Spleen. Unenhanced (a), arterial phase (b), portal venous phase (c), and late phase acquisitions (d) CT show fortuitus finding of a peri-duodenal solid lesion, between the uncinate process and the third portion of the duodenum (arrows), with a smooth, round shape, and a pattern of enhancement similar to the normal spleen (arrowheads) on all phases. Histopathological study of the resected surgical specimen revealed splenic tissue

Fig. 31

Trauma. Chest radiograph (a) of a car accident victim shows a gastric tube with a thoracic loop (arrowheads). Contrast-enhanced CT of the same patient (b) confirms traumatic diaphragmatic hernia; note the absence of interposition of lungs between the stomach and the chest wall—the so-called “dependent viscera sign” (arrows). Abdominal CT (c) shows that D2 is surrounded by fluid (asterisk) and its wall presents the target sign (arrowheads). The upper GI study (d) of the same patient revealed uniform, regular, fold thickening at D2 and D3, similar to a stack of coins (arrows), representing intramural edema/hematoma

Fig. 32

Ulcers and duodenitis. Abdominal CT of a case of duodenitis (a): the lumen of the duodenum is irregular; the wall is thickened (arrow) and there is adjacent fat stranding (asterisk). Plain abdominal CT of another patient (b) clearly shows a duodenal ulcer perforation (arrows) and accumulation of gas and oral contrast in the right anterior pararenal space (asterisk). The corresponding upper GI study performed with water-soluble contrast agent (c) shows retroperitoneal leakage of contrast medium (asterisk)

Fig. 33

Vasculitis (lupus). Abdominal CT of a patient with systemic lupus erythematosus and antiphospholipid syndrome (a). There is evidence of multifocal thickening of several bowel loops with a target appearance (arrowheads), including the stomach, colon and D2 (arrows). Note also bilateral hydronephrosis (asterisks in b). Abdominal CT (c) of the same patient following 3 weeks of steroid treatment with no clinical improvement revealed resolution of some of the previous affected segments, while other bowel segments showed wall thickening for the first time

Fig. 34

Intraluminal diverticulum. UGIS (a) shows a barium-filled sac surrounded by a radiolucent halo in D2 (arrow). Duodenal luminal dilatation and mucosal fold thickening are also noted (arrowheads). Abdominal CT (b) of the same patient with analogous findings. Sagittal reformation (c) clearly shows the attachment of the intraluminal diverticulum to the duodenal wall (arrowhead). UGIS of another patient (d) with an intraluminal diverticulum shows a radiolucent line surrounded by barium both inside and outside (arrows)

Fig. 35

Indirect signs of duodenal disease on X-ray. Chest radiograph (a) shows a small amount of gas beneath the diaphragm (arrows) and the continuous diaphragm sign is also seen (arrowheads). At surgery, a perforated duodenal bulb ulcer was identified. Abdominal radiograph (b) shows pneumoretroperitoneum (asterisks) after duodenal rupture following ERCP. Abdominal radiograph (c) shows a stomach with augmented volume (arrowheads)—gastric outflow obstruction caused by multiple polyps of the duodenum in a patient with juvenile polyposis. Abdominal radiograph (d) shows an air-fluid level in the gallbladder (arrow) and a gallstone at the right iliac fossa (arrowhead), indicative of a gallstone ileus, because of a cholecystoduodenal fistula. Abdominal radiograph (e) shows a large horizontal prosthesis in the upper abdomen (arrowheads) and two smaller vertical prosthesis (arrows) in the horizontal and descending duodenum, which were a palliative treatment for an obstructive duodenal adenocarcinoma. Abdominal radiograph (f) shows an intraluminal soft-tissue density at D2. This was a gastric GIST prolapsing into the duodenum

Fig. 36

Roux-en-Y anastomosis. UGIS with water soluble contrast of a patient who underwent partial gastrectomy with Roux-en-Y anastomosis for an adenocarcinoma of the stomach (a): only the gastric stump (curved arrow) and gastro-jejunal loop are opacified (arrows); the biliopancreatic loop is not (asterisks in its supposed location). Fluoroscopic study with water soluble contrast of an obese woman who underwent gastric bypass with Roux-en-Y anastomosis (b): note the jejunal mucosal pattern (arrowheads) right after the supposed location of the gastro-jejunal anastomosis (asterisk). Abdominal CT of the same patient (c): the surgical clips are seen at the anastomosis between the gastric stump (arrows) and the jejunal loop (arrowheads). CT coronal reformation (d) shows the gastro-jejunal anastomosis (arrowhead) and the biliopancreatic limb, which includes the duodenum in its normal location (arrows)

Fig. 37

Gut malrotation. Barium study of an 8-year-old (a) with intestinal malrotation shows that the duodenum does not cross the midline (arrow). Abdominal CT of an adult patient (b) reveals absence of the 2nd part of the duodenum between the aorta and SMA (asterisks). The duodenum (arrows) crosses anterior to the SM vessels, which show an inverted relationship, with the artery located on the right and the vein on the left side (arrowhead). Incidentally, this patient also had an abnormal course of the portal vein and absence of the inferior vena cava. Abdominal CT of another adult with left flank pain and fever (c, d) shows that the duodenum does not cross the midline (arrow). The small bowel is located predominantly on the right quadrants (asterisks) while the large bowel is located on the left quadrants (arrowheads). On the left flank, an enhancing and thickened, fluid-filled tubular structure (curved arrow) is seen coming out of the cecal pole, which was located on the midline—this was a rare case of an appendicitis on the left quadrants in a patient with nonrotation