The way to "GOO": mechanisms leading to gastric outlet obstruction and corresponding imaging findings

Transcription

1 The way to "GOO": mechanisms leading to gastric outlet obstruction and corresponding imaging findings Poster No.: C-2422 Congress: ECR 2013 Type: Educational Exhibit Authors: C. N. Tentugal, L. Silva, J. Brito, C. Soares, M. O. E. Castro, F. Aleixo; Portimão/PT Keywords: Abdomen, Gastrointestinal tract, CT, Ultrasound, Conventional radiography, Education, Obstruction / Occlusion DOI: /ecr2013/C-2422 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 82

2 Learning objectives To review the different mechanisms that may lead to gastric outlet obstruction (GOO). To discuss the use of CT and other imaging modalities (such as ultrasound, barium studies and upper endoscopy) in the diagnosis of GOO. To recognize the imaging findings of various conditions that can cause GOO. Page 2 of 82

3 Background GOO is not a single entity. It is the pathophysiological and clinical consequence of any disease or process that produces a mechanical impediment to gastric emptying. Nausea and vomiting are the cardinal symptoms of GOO. Page 3 of 82

4 Imaging findings OR Procedure details RELEVANT ANATOMY The stomach is a muscular, hollow and dilated part of the digestive tube. It is located mainly in the left upper quadrant beneath the diaphragm and is attached superiorly to the esophagus and distally to the duodenum. The stomach is divided into the following parts: Cardia Fundus Body Antrum Pylorus Inflammation, scarring, or infiltration of the antrum and pylorus are associated with the development of gastric outlet obstruction. The duodenum begins immediately beyond the pylorus and is mostly a retroperitoneal organ with a C-shaped structure, outlining the head of the pancreas. It is intimately related to the gallbladder, liver, pancreas and colon. Therefore, any process occuring in any adjacent structure may cause outlet obstruction due to extrinsic involvement. Page 4 of 82

5 Fig. 1: Contrast-enhanced CT images depict the cross-sectional anatomy of the stomach and its adjacent organs. D-duodenum; Gb-gallbladder; P-pancreas. References: C. N. Tentugal, Department of Radiology, CHBA, Portimão, Portugal GASTRIC OUTLET OBSTRUCTION - Overview Gastric outlet obstruction (GOO) usually presents with non-bilious vomiting, nausea, colicky epigastric pain, loss of appetite and occasionally, upper gastrointestinal bleeding. The causes which lead to a mechanical impediment of the gastric emptying can be classified as benign or malignant. In the current days most patients with GOO have a malignant cause, unlike in the past, when peptic ulcer disease was more prevalent. This has to do with the disseminated use of proton pump inhibitors and Helicobacter pylori eradication therapy. Page 5 of 82

6 GASTRIC OUTLET OBSTRUCTION - Differential diagnosis 1. Inflammatory disorders 1.1 Peptic ulcer disease Peptic ulcer disease with or without secondary stricture is the most common cause of benign GOO. Fig. 2: Peptic ulcer causing GOO in a 57-year-old patient. (A) Axial non-enhanced, (B) Axial contrast-enhanced and (C) coronal contrast-enhanced CT images reveal a very dilated stomach (s) caused by focal narrowing of the gastric antrum and pylorus. Note the enhancing wall (arrow) and the adjacent small air bubbles which suggest an active peptic ulcer. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 1.2 Pancreatitis Pancreatic inflammation and the release of exocrine enzymes can cause mild to severe duodenal edema and scarring which may compromise the gastric outlet. Paraduodenal pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum and the common bile duct. In paraduodenal pancreatitis the main symptoms result from marked duodenal stenosis and impaired motility with patients presenting with nausea and vomiting. Occasionally jaundice is present, but often fluctuates, as biliary outflow obstruction is intermittent. Page 6 of 82

7 Fig. 3: Paraduodenal pancreatitis in a 52-year-old male patient who presented with epigastric pain and vomiting.(a) Axial contrast-enhanced CT shows a very dilated stomach (s). (B)Contrast-enhanced CT caudal to (A) reveals an inflammatory process within the paraduodenal groove (arrowhead), consistent with paraduodenal pancreatitis which is the cause of the gastric outlet obstruction. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 1.3 Crohn's disease The gastroduodenal junction and the duodenum are rarely affected by Crohn's disease. 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. Page 7 of 82

8 Fig. 4: 46-year-old woman with Crohn's disease.(a) and (B) contrast-enhanced abdominal CT shows a distended, in keeping with gastric outlet obstruction. There is a stricture in the 2nd portion of the duodenum which shows the "target" sign (curved arrow in B), that corresponds to the enhanced mucosa and serosa with a hypodense and oedematous submucosa between them.(c) Barium study demonstrates the short stricture (curved arrow) and dilatation of the proximal duodenum.(d) Pathologic study of the surgical specimen revealed typical transparietal features of Crohn's disease, with a very thickened submucosal layer. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 1.4 Duodenitis Inflamation of the duodenum is manifested by thickening of the duodenal wall. If there is no visible cause for this process as a peptic ulcer or adjacent inflammatory process it is important to think of medical causes, such as: Infectious disease (most commonly Helicobacter pylori) Acquired immunodeficiency syndrome Hematologic abnormality (Henoch-Schonlein purpura) The described inflammatory findings tend to be nonspecific, and correlation with the clinical history is essential for the diagnosis. Page 8 of 82

9 Fig. 5: 50-year-old alcoholic man with chronic pancreatitis. (A-E) Axial contrastenhanced CT images show marked thickening and intense enhancement of the duodenal wall observed in both the arterial (A) and portal venous phase (B-E), displaying a pseudo-tumoral appearance (arrows). Note also ascites and severe gastritis, which manifests by thickening and layering of the gastric wall with enhancing mucosa and low attenuating submucosa due to oedema and inflammation. The retroperitoneal fluid collection in (A) corresponds to a pancreatic pseudocyst. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 1.5 Bouveret syndrome Bouveret syndrome refers to gastric outlet obstruction produced by a gallstone impacted in the distal stomach or proximal duodenum trough a cholecystogastric or cholecystoduodenal fistula. Page 9 of 82

10 Fig. 6: Bouveret syndrome. (A) and (B) Transabdominal ultrasound obtained over the epigastric region shows a dilated stomach (s) and a curvilinear focus of increased echogenicity with posterior shadowing (arrowhead), suggestive of a gallstone in the gastric antrum, near the pylorus. (C) Non-enhanced CT clearly demonstrates a calcified gallstone within the antrum (arrowhead) causing GOO, which is manifested by a very dilated stomach (s). (D-F) CT scan additionally shows pneumobilia in the common bile duct, gallbladder and intrahepatic bile ducts (arrows). These features suggest the existence of a fistula between the billiary system and the stomach. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2. Neoplastic processes within the duodenum and gastroduodenal junction Page 10 of 82

11 2.1 Adenocarcinoma Adenocarcinoma is the most common primary gastric tumor (approximately 95%). Gastric adenocarcinoma is a very agressive tumor which can easily cause GOO due to focal wall thickening in the antrum and pylorus. Primary adenocarcinoma of the duodenum is not common, nevertheless GOO can be a very rare manifestation of this malignancy. Fig. 7: Gastric carcinoma. (A) Axial non-enhanced and (B) axial contrast-enhanced CT at the same level of acquisition reveals thickening and enhancement of the gastric antrum (arrow) that results in GOO. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 11 of 82

12 Fig. 8: 74-year-old male with gastric carcinoma. (A) and (B) axial contrast-enhanced CT demonstrates circumferential wall thickening of the gastric antrum (arrowheads) extending through the pylorus to the duodenum, where polypoid-like lesions (thin arrow) narrow the lumen. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Fig. 9: 67-year-old man with melena and abdominal pain.(a) Non-enhanced,(B) and (C) contrast-enhanced axial CT demonstrates an irregular and asymmetric thickening of the 3rd portion of the duodenum, which causes destortion of the lumen (arrowheads). Encasement of the superior mesenteric artery (thin arrow in B) turns the lesion surgically unresectable. It is also evident the encasement and thrombosis of the superior mesenteric vein (thick arrow in C). (D) Endoscopy clearly shows a bleeding neoplasm. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.2 Gastrointestinal stromal tumor (GIST) GIST is the most common mesenchymal neoplasm of the gastrointestinal tract. GISTs can occur anywhere in the gastrointestinal tract. They are frequently submucosal lesions, which often grow endophytically in parallel with the lumen of the affected structure, but they also may manifest as exophytic extraluminal lesions. Page 12 of 82

13 The most common location for these tumors is the stomach. GISTs manifest a wide variety of clinical behavior, from slow-growing indolent tumors to aggressive malignant cancers with the propensity to invade adjacent organs. Fig. 10: 65-year-old woman presenting with melena and iron deficiency anemia. (A) Barium study shows well-circumscribed mass (arrow) in the transition from the 2nd to the 3rd portion of the duodenal loop. (B) Endoscopy confirms the presence of a submucosal tumor (curved arrow) covered with normal mucosa. (C) Axial nonenhanced,(d) axial contrast-enhanced and (E) coronal contrast-enhanced abdominal CT images show a well-defined soft-tissue mass (arrowheads) with intense and homogeneous enhancement. The absence of exoenteric growth is best appreciated in the coronal image.(f) Histological analysis (100x) reveals c-kit (CD117) expression by tumor cells. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.3 Polypoid lesions A polyp is an abnormal growth of tissue projecting from a mucous membrane. Therefore, any polypoid lesion arising in the duodenum or gastroduodenal junction has the potential of causing GOO, particularly by invagination. Page 13 of 82

14 Polypoid lesions can be single or multiple, specialy when associated with genetic syndromes Brunner's gland hyperplasia and hamartoma Brunner's gland hyperplasia and hamartoma are infrequently encountered polypoid nodules and masses in the proximal duodenum. They account for approximately 5% of all duodenal masses. These polypoid lesions are usually very small but can exceptionally grow to become large masses. Fig. 11: 48-year-old male presenting with melena and iron deficiency anemia.(a) Axial non-enhanced CT displays a bulky polypoid lesion originating in the duodenal bulb and reaching the 4th portion of the duodenum, with soft tissue density and a lobulated contour (arrowheads).(b-d) On MR imaging the lesion (arrows) is heterogeneously hypointense on T1-weighted images (B), hyperintense on fat saturated T2-weighted images (C), enhancing after intravenous administration of gadolinium chelates. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Peutz-Jaegher's syndrome Page 14 of 82

15 Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by gastrointestinal hamartomatous polyps in association with a distinct pattern of skin and mucosal macular melanin deposition. Fig. 12: Peutz-Jaeghers syndrome. (A) Sagittal contrast-enhanced CT shows a large polyp in the 4th portion of the duodenum. (B) Barium study of the stomach and small bowel demonstrates multiple filling defects troughout the intestinal tract. (C) Endoscopy frame showing the image of small polyps in the stomach. (D) Picture demonstrating the mucocutaneous pigmentation in a patient with Peutz-Jaeghers syndrome. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Juvenile polyposis syndrome Juvenile polyposis syndrome is characterized by the appearance of multiple polyps in the gastrointestinal tract, usually in a child, adolescent or young adult. The most common location for polyps in this syndrome is the colon, however they may appear in any part of the digestive tube. Page 15 of 82

16 Fig. 13: 46-year-old man with juvenile polyposis of the stomach and duodenum. (A) Abdominal radiograph shows a distended stomach (arrowhead) due to GOO. (B) Nonenhanced and (C) contrast-enhanced axial CT images reveal several polyps. The larger is located in the duodenal bulb and presents central fluid density (asterisk), a feature also observed in endoscopic ultrasound (D) as anechoic images corresponding to fluid-filled cavities (asterisk). (E) Endoscopy frame shows the multiplicity of polypoid lesions. (F) Gross specimen clearly shows the major polyp (asterisk) prolapsed through the pylorus (thick arrows) to the duodenal bulb. (G) Histology showing the empty cavities of the polyps (asterisks). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.4 Ampullary carcinoma Carcinoma of the ampulla of Vater is a malignant tumor arising in the last centimeter of the common bile duct, where it passes through the wall of the duodenum and ampullary papilla. Patients often present with jaundice, biliary and pancreatic duct dilatation. These tumors are usually small but sometimes can grow to the duodenal lumen, compromising the gastric emptying, which is a rare manifestation. Page 16 of 82

17 Fig. 14: 50-year-old man with ampullary carcinoma. (A) Contrast-enhanced CT reveals an enhancing soft-tissue mass (arrowhead) protruding into the water-filled duodenum. (B) Endoscopic ultrasound shows a solid hypoechoic mass. (C)Endoscopic frame reveals the protruding lesion. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.5 Neuroendocrine tumor There are many different types of endocrine cells in the gastrointestinal tract that are derived from the neural crest, neuroectoderm, and endoderm. These cells can give rise to various neuroendocrine tumors. Neuroendocrine tumors account for 1.2%-1.5% of all gastrointestinal neoplasms. The majority of them occur sporadically. However, they sometimes occur as part of complex familial endocrine cancer syndromes such as type 1 multiple endocrine neoplasia (MEN1) and neurofibromatosis type 1 (NF1). Page 17 of 82

18 Fig. 15: 85-year-old woman with Neurofibromatosis type 1. (A) and (B) contrastenhanced axial CT shows a mass (arrows) in the medial wall of the 2nd portion of the duodenum. The tumor displays intense contrast enhancement in the arterial phase (A), with retention in the venous phase (B) of this dynamic study. The high spatial resolution provided by CT clearly shows that the lesion is independent from the pancreas. (C-G) MR images. The lesion (arrows) displays low signal intensity on T1-weighted images (C) and high signal intensity on T2-weighted images (D). The dynamic study following gadolinium shows intense enhancement of the lesion in the arterial phase (E), with retention in the portal venous phase (F) and some loss during the equilibrium phase (G). (H) Transabdominal and (I) endoscopic ultrasound demonstrates a well-defined and hypoechoic lesion.(j) Somatostatin-receptor (octreotide) scintigraphy confirms the neuroendocrine nature of the tumor. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.6 Lymphoma Non-Hodgkin's lymphoma (NHL) of the gastrointestinal tract accounts for 4% to 20% of all NHLs and is the most common extranodal site of presentation. The stomach is the major organ involved by gastrointestinal lymphoma. Page 18 of 82

19 A significant proportion of gastric lymphomas are of low-grade histology and arise from mucosal-associated lymphoid tissue (MALT). Such MALT lymphomas may be associated with H. pylori infection. Because lymphoma is considered to be a "soft" tumor, it is less likely to result in GOO than is gastric adenocarcinoma. Fig. 16: 64-year-old woman with duodenal lymphoma. (A) and (B) Contrast-enhanced abdominal CT shows concentric thickening of the duodenal wall (arrowheads) with irregular narrowing of the lumen. Lymphadenopathy (thin arrows) also suggests the diagnosis of lymphoma. (C) Barium study shows widening of the C-loop with mucosal irregularity but no evidence of obstructive signs. (D) Endoscopy shows luminal narrowing and extense mucosal ulceration. (E) Histology (H&E 100x) revealed a nonhodgkin's T-cell type lymphoma. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 2.7 Lipoma Lipomas are benign lesions that can be reliably diagnosed on imaging scans as a smooth-margined mass which demonstrates homogeneous fatty attenuation at CT and homogeneous signal intensity identical to fat in all MR imaging pulse sequences. Page 19 of 82

20 Gastrointestinal lipomas account for 4% of all benign gastrointestinal tumors. The most common localization is the colon (64%) and only 4% of lipomas occur in the duodenum. Lipomas rarely cause symptoms, which are closely related to the size of the tumor (most lipomas cause symptoms when over 4 cm in size). Clinical symptoms include epigastric fullness which can gradually become worse leading to GOO, ulceration and hemorrhage. GOO can also be caused by lipoma-associated intussusception. Fig. 17: Assymptomatic duodenal lipoma in a 66-year-old woman. (A) Non-enhanced and (B) contrast enhanced axial CT images show a polypoid mass in the descending Page 20 of 82

21 duodenum with homogeneous fat attenuation that does not enhance after intravenous contrast administration (arrowhead). (C) Coronal T2-weighted image demonstrates the intraluminal mass with high signal intensity similar to mesenteric fat (arrow). (D) Endoscopic ultrasound shows the parietal mass with a heterogeneously echogenic texture suggestive of fat content (arrowhead). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 3. Extrinsic involvement 3.1 Local invasion from a carcinoma GOO may be caused by tumor extension from an adjacent organ such as the pancreas, liver, gallbladder and colon. Pancreatic adenocarcinoma can be locally agressive and is commonly implicated in duodenal and gastroduodenal invasion. Fig. 18: 80-year-old woman with biliary obstruction. (A) Ultrasound showed a hypoechoic mass in the pancreatic head (arrow). (B) Non-enhanced, (C) and (D) contrast-enhanced CT reveals a soft-tissue density mass (arrows), which remains Page 21 of 82

22 hypodense during all phases of the dynamic study. CT clearly reveals tumor invasion of the medial wall of the 2nd portion of the duodenum, best recognised in the arterial phase (C). (E) and (F) Percutaneous transhepatic cholangiogram shows complete obstruction of the common bile duct by the tumor. A percutaneously applied metallic prosthesis crossed the tumour re-establishing bilioenteric flow. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Colon carcinoma can cause local mass effect or invasion, occasionally with formation of a coloduodenal fistula. Fig. 19: 69-year-old man with neoplasm of the hepatic flexure of the colon. (A) and (B) Axial contrast-enhanced CT shows an undefined mass apparently including the duodenum (asterisk) and the colon. A small amount of positive oral contrast agent (arrowhead in A) is present within the mass. The oral contrast agent is seen in the colon (thick arrow in B) without evidence of contrast in the jejunum (thin arrow), a feature related to colo-duodenal fistula. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 3.2 Metastasis Metastatic involvement of the duodenum and gastroduodenal junction is uncommon. The most common manifestations of this entity are gastrointestinal bleeding and anemia. However, GOO is also a possibility. Common primary tumors: Malignant melanoma Carcinoma of the lung Page 22 of 82

23 Genitourinary cancers Breast cancer Kaposi's sarcoma Colonic cancer Renal cell carcinoma Fig. 20: 55-year-old man with a sigmoid colon cancer. (A) and (B) abdominal and pelvic CT performed to stage the disease clearly demonstrated the sigmoid tumor (arrows) but failed to show distant metastases. However, MPR and retrospective analysis revealed a discrete circumferential thickening in the 4th portion of the duodenum (arrowheads) which was not recognised initially.(c) Barium study performed 2 months later shows that the carcinoma progressed to become an "apple core" lesion (arrowheads) causing obstructive symptoms. Pathology revealed similar features on both lesions. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 4. Gastrointestinal twisting and displacement 4.1 Volvulus Gastric volvulus is a clinical entity defined as an abnormal rotation of the stomach of more than 180. Page 23 of 82

24 Gastric volvulus can manifest as an acute abdominal emergency or as a chronic intermittent problem. The presenting symptoms depend on the degree of twisting and the rapidity of onset Acute gastric volvulus Borchardt triad Pain Nausea Inability to pass a nasogastric tube Intra-abdominal gastric volvulus most commonly manifests as the sudden onset of severe epigastric or left upper quadrant pain. Intrathoracic gastric volvulus manifests as sharp chest pain radiating to the left side of the neck, shoulder, arms, and back. This condition is often associated with cardiopulmonary compromise from gastric distention and may mimic an acute myocardial infarction. Page 24 of 82

25 Fig. 21: Acute gastric volvulus in a 78-year-old female patient who presented with acute abdominal pain and nausea. Contrast-enhanced CT shows herniation of part of the stomach above the diaphragm. The stomach is very distended, with air-fluid levels due to GOO. The gastric pylorus (arrow) is seen above the gastroesophageal junction (arrowhead), in keeping with mesenteroaxial rotation of the stomach. F - gastric fundus; A - gastric antrum. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Chronic gastric volvulus Tipically, patients with chronic gastric volvulus present with intermittent epigastric pain and abdominal fullness following meals. Patients may report early satiety, dyspnea, and chest discomfort. Dysphagia may occur if the gastroesophageal junction is distorted. Fig. 22: Gastric volvulus in a 72-year-old patient who presented with abdominal fullness after meals. (A) Chest radiograph reveals an air- filled structure in the right hemithorax (arrow). (B) Barium study confirms the presence of a gastric volvulus which resulted in reversed positions of the greater and lesser curvatures of the stomach (organoaxial rotation). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 25 of 82

26 Fig. 23: Gastric volvulus. CT scan shows a rotated and right-sided intrathoracic stomach. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 4.2 Diaphragmatic hernia Diaphragmatic hernias can be divided into 2 categories: congenital defects and acquired defects. Congenital diaphragmatic hernias occur because of embryologic defects in the diaphragm. Most patients with congenital diaphragmatic hernias present early rather than late in life. However, some adults may present with a congenital hernia that was undetected during childhood. Acquired diaphragmatic hernias can follow all types of trauma, with blunt forces accounting for the majority. Left-sided rupture is more common than right-sided rupture, owing to hepatic protection and increased strength of the right hemidiaphragm. Page 26 of 82

27 Fig. 24: Acute traumatic diaphragmatic hernia. Chest radiograph demonstrates a round air-filled structure in the left hemithorax (arrowhead) consistent with stomach herniation. The mediastinum is pushed to the right (arrow). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 27 of 82

28 Fig. 25: Acute traumatic diaphragmatic hernia. (A) CT topogram reveals the tip of the nasogastric tube (arrow) in the left hemithorax in keeping with a herniated stomach. (B) Contrast-enhanced CT confirms the presence of an intrathoracic stomach and the nasogastric tube within it (arrow). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 4.3 Gastroduodenal intussusception The term intussusception refers to the invagination of a part of the stomach or bowel loop, with its mesenteric fold (intussusceptum) into the lumen of a contiguous portion of bowel (intussuscipiens), as a result of peristalsis. Intraluminal polypoid lesions have a greater tendency to cause invagination of the bowel as peristalsis drags the lesion forward. An intussusception appears as an abnormal targetlike mass with a cross-sectional diameter greater than that of the normal bowel and may be associated with proximal bowel obstruction. Page 28 of 82

29 Fig. 26: Gastroduodenal intussusception caused by GIST in the gastric fundus. (A) Abdominal radiograph demonstrates a dilated duodenum with dense material within it. (B) Color-Doppler ultrasound shows a hypoechogenic and vascularized mass. (C) Coronal, (D) axial and (E) sagittal contrast-enhanced CT images better depict the gastroduodenal intussusception. Note the invagination of the stomach mucosa into the lumen of the contiguous duodenum (arrow in C). The GIST is clearly seen at a lower level (arrow in D). The characteristic "target" sign is also seen (arrow in E). (F) Endoscopy reveals submucosal lesion arising from the gastric fundus. (E) Gross specimen. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 4.4 Left paraduodenal hernia A left paraduodenal hernia is an internal hernia in which small-bowel loops herniate into an unusual fossa to the left of the duodenum referred to as the paraduodenal fossa or Landzert's fossa, that results from a congenital defect in the descending mesocolon. This abnormal peritoneal pocket is bordered anteriorly by a peritoneal fold overlying the inferior mesenteric vein and ascending left colic artery. Proximal small-bowel loops and duodenal segments can enter posteriorly through the mesocolic defect and become entrapped in the Landzert's fossa, and then extend further in the descending mesocolon, causing complications such as small-bowel obstruction, vessel engorgement, or even acute small-bowel ischemia. Page 29 of 82

30 Fig. 27: Left paraduodenal hernia. (A) Abdominal radiograph shows a dilated stomach with air-fluid level. (B) and (C) Contrast enhanced CT displays a herniated small bowel loop (arrowhead) to the left of the duodenum with inflammatory features that include thickened hyperenhancing wall, fat stranding (arrow in B) and engorged vessels (arrow in C). (D) Barium study also demonstrates the left paraduodenal hernia and the features of inflammatory changes of the herniated bowel. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 5. Vascular 5.1 Superior mesenteric artery syndrome Superior mesenteric artery (SMA) syndrome is an uncommon but well recognized clinical entity characterized by compression of the transverse portion of the duodenum between the aorta and the SMA. This results in chronic, intermittent, or acute complete or partial duodenal obstruction. Page 30 of 82

31 Fig. 28: Superior mesenteric artery syndrome in a 83-year-old female with history of weight loss. (A) Barium study showing a dilated stomach. (B) and (C) Axial contrastenhanced CT depicts the dilatation of the stomach (s) and proximal duodenum (d) caused by the compression of the transverse portion of the duodenum between the superior mesenteric artery (arrow) and the aorta (arrowhead). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 6. Iatrogenic causes Imaging techniques are very important in the evaluation of complications derived from medical procedures. Most complications include abscess, wound dehiscence, Page 31 of 82

32 hematoma, hernia, anastomotic leakage or stricture, and obstruction in the gastrointestinal tract. Fig. 29: Malposition of adjustable gastric band in a patient who complained of postprandial vomiting. Barium study reveals the gastric band (arrowheads) in the distal stomach causing large dilatation of the stomach pouch (s). Reservoir port (long arrow) and the connector tube (short arrow) of the adjustable gastric banding system are also seen. References: C. N. Tentugal, Department of Radiology, CHBA, Portimão, Portugal Page 32 of 82

33 Fig. 30: Contrast-enhanced CT of a retroanastomotic internal hernia after Roux-en-Y anastomosis, causing GOO. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 7. Congenital anomalies and pediatric population 7.1 Stomach Congenital obstructive defects Complete obstruction involving the gastric outlet is a rare condition that is usually due to gastric atresia, although it may be also caused by extrinsic pressure from congenital peritoneal bands or by annular pancreatic tissue in the gastric wall. Gastric atresia accounts for less than 1% of all congenital intestinal obstructions and it is limited to the antrum and pyloric region. Page 33 of 82

34 7.1.2 Non-congenital obstructive defects Hypertrophic pyloric stenosis (HPS) is an evolving condition of progressive pyloric muscle hypertrophy, which then narrows and elongates the pyloric canal. It typically occurs in male newborn infants at approximately 6 weeks. Infants present with projectile vomiting, and an epigastric mass feeling like an olive or walnut can be palpated in the majority of patients. Ultrasound is important in the diagnosis of HPS because of its accuracy and acessibility, which contributes to an earlier diagnosis and therefore, treatment. Ultrasound features of HPS: Pyloric muscle thickness > 4mm Pyloric channel length > 15mm Abdominal radiographs may show a fluid-filled or air-distended stomach, suggesting the presence of gastric outlet obstruction. Fig. 31 on page 67 Page 34 of 82

35 Fig. 32: Ultrasound reveals pyloric thickening and increased length of the pyloric channel consistent with hypertrophic pyloric stenosis. The asterisks depict the length of the pyloric channel and the ultrasound callipers the muscle thickness of the pylorus. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 7.2 Duodenum Congenital obstructive defects Complete duodenal obstruction is seen much more frequently than congenital gastric obstruction. At clinical examination there is severe vomiting with no significant abdominal distention. The classic radiographic finding is the "double bubble" sign Fig. 33 on page 69, in which the higher bubble is the stomach and the other bubble is the proximal dilated duodenum. No air is seen more distally in the gastrointestinal tract. The most important cause of complete duodenal obstruction is duodenal atresia, but annular pancreas and midgut volvulus should also be considered. Page 35 of 82

36 Fig. 34: Duodenal atresia. (A) Markedly distended stomach and proximal duodenum (double bubble sign). Note that no gas is evident in the rest of the intestinal tract. (B) and (C) Fluoroscopy images of a barium study show no progression of oral contrast beyond the duodenum (arrowhead). References: P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Partial duodenal obstruction may be produced by duodenal stenosis Fig. 35 on page 71, duodenal web Fig. 36 on page 72, Ladd bands, malrotation, annular pancreas Fig. 37 on page 73, preduodenal portal vein and duplication cyst. Page 36 of 82

37 Fig. 35: Duodenal stenosis. (A) Control, (B) and (C) fluoroscopy images of barium study show abrupt narrowing of the duodenum (arrowhead), with proximal dilatation. Note that gas and contrast are seen after the stenosis (arrow). (D) Small bowel loops filled with gas after treatment. References: P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Most of the previously refered congenital anomalies will be diagnosed during childhood, however some patients will only present symptoms years later or may remain assymptomatic. Page 37 of 82

38 Fig. 38: Annular pancreas in an assymptomatic adult patient.(a) Non-enhanced and (B) contrast-enhanced CT shows pancreatic tissue (arrows) surrounding the duodenum (asterisk). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 38 of 82

39 Fig. 39: Incidental finding of intestinal malrotation in an adult patient. Contrastenhanced CT reveals absence of the horizontal portion of the duodenum between the aorta and superior mesenteric artery (asterisk). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal 7.3 Bezoar A bezoar is defined as a concretion of foreign or indigestible matter found in the digestive tract. There are two main types of bezoars: trichobezoar - a bezoar formed from hair and phytobezoar - formed by indigestible cellulose. Children are at higher risk of forming a bezoar not only because they may swallow foreign bodies during the process of exploring and interacting with the world, but also because they have smaller gastrointestinal lumens. 8. Foreign bodies and bezoars in the adult population Page 39 of 82

40 Adults can also present with foreign bodies in the upper gastrointestinal tract. The ingestion of foreign bodies can be accidental but it is often done deliberately. Patients with foreign bodies in the stomach or small intestine may present with vague symptoms such as fever, abdominal pain or vomiting as a consequence of GOO. Fig. 40: Body packing. (A) CT topogram demonstrates a markedly distended stomach with slightly dense tubular structures within it. (B) Axial CT with lung window settings better depicts the air-filled stomach and the foreign bodies. (C) Picture during the surgical procedure showing the removal of the foreign bodies. (D) Picture of the foreign bodies which corresponded to packs of illicit drugs. References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal GOO induced by bezoar in the adult population is uncommon and its diagnosis is sometimes challenging. It should be suspected in patients with increased risk factors such as: previous gastric surgery gastric dismotility poor dentition mental retardation Page 40 of 82

41 history suggestive of increased fibre intake. Fig. 41: GOO caused by bezoar. Non-enhanced contrast CT shows a dilated stomach containing an accumulation of indigestible substances (b-bezoar). References: J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 41 of 82

42 Images for this section: Fig. 1: Contrast-enhanced CT images depict the cross-sectional anatomy of the stomach and its adjacent organs. D-duodenum; Gb-gallbladder; P-pancreas. C. N. Tentugal, Department of Radiology, CHBA, Portimão, Portugal Page 42 of 82

43 Fig. 2: Peptic ulcer causing GOO in a 57-year-old patient. (A) Axial non-enhanced, (B) Axial contrast-enhanced and (C) coronal contrast-enhanced CT images reveal a very dilated stomach (s) caused by focal narrowing of the gastric antrum and pylorus. Note the enhancing wall (arrow) and the adjacent small air bubbles which suggest an active peptic ulcer. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Fig. 3: Paraduodenal pancreatitis in a 52-year-old male patient who presented with epigastric pain and vomiting.(a) Axial contrast-enhanced CT shows a very dilated stomach (s). (B)Contrast-enhanced CT caudal to (A) reveals an inflammatory process within the paraduodenal groove (arrowhead), consistent with paraduodenal pancreatitis which is the cause of the gastric outlet obstruction. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 43 of 82

44 Fig. 4: 46-year-old woman with Crohn's disease.(a) and (B) contrast-enhanced abdominal CT shows a distended, in keeping with gastric outlet obstruction. There is a stricture in the 2nd portion of the duodenum which shows the "target" sign (curved arrow in B), that corresponds to the enhanced mucosa and serosa with a hypodense and oedematous submucosa between them.(c) Barium study demonstrates the short stricture (curved arrow) and dilatation of the proximal duodenum.(d) Pathologic study of the surgical specimen revealed typical transparietal features of Crohn's disease, with a very thickened submucosal layer. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 44 of 82

45 Fig. 5: 50-year-old alcoholic man with chronic pancreatitis. (A-E) Axial contrast-enhanced CT images show marked thickening and intense enhancement of the duodenal wall observed in both the arterial (A) and portal venous phase (B-E), displaying a pseudotumoral appearance (arrows). Note also ascites and severe gastritis, which manifests by thickening and layering of the gastric wall with enhancing mucosa and low attenuating submucosa due to oedema and inflammation. The retroperitoneal fluid collection in (A) corresponds to a pancreatic pseudocyst. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 45 of 82

46 Fig. 6: Bouveret syndrome. (A) and (B) Transabdominal ultrasound obtained over the epigastric region shows a dilated stomach (s) and a curvilinear focus of increased echogenicity with posterior shadowing (arrowhead), suggestive of a gallstone in the gastric antrum, near the pylorus. (C) Non-enhanced CT clearly demonstrates a calcified gallstone within the antrum (arrowhead) causing GOO, which is manifested by a very dilated stomach (s). (D-F) CT scan additionally shows pneumobilia in the common bile duct, gallbladder and intrahepatic bile ducts (arrows). These features suggest the existence of a fistula between the billiary system and the stomach. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 46 of 82

47 Fig. 7: Gastric carcinoma. (A) Axial non-enhanced and (B) axial contrast-enhanced CT at the same level of acquisition reveals thickening and enhancement of the gastric antrum (arrow) that results in GOO. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Fig. 8: 74-year-old male with gastric carcinoma. (A) and (B) axial contrast-enhanced CT demonstrates circumferential wall thickening of the gastric antrum (arrowheads) extending through the pylorus to the duodenum, where polypoid-like lesions (thin arrow) narrow the lumen. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 47 of 82

48 Fig. 9: 67-year-old man with melena and abdominal pain.(a) Non-enhanced,(B) and (C) contrast-enhanced axial CT demonstrates an irregular and asymmetric thickening of the 3rd portion of the duodenum, which causes destortion of the lumen (arrowheads). Encasement of the superior mesenteric artery (thin arrow in B) turns the lesion surgically unresectable. It is also evident the encasement and thrombosis of the superior mesenteric vein (thick arrow in C). (D) Endoscopy clearly shows a bleeding neoplasm. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 48 of 82

49 Fig. 10: 65-year-old woman presenting with melena and iron deficiency anemia. (A) Barium study shows well-circumscribed mass (arrow) in the transition from the 2nd to the 3rd portion of the duodenal loop. (B) Endoscopy confirms the presence of a submucosal tumor (curved arrow) covered with normal mucosa. (C) Axial non-enhanced, (D) axial contrast-enhanced and (E) coronal contrast-enhanced abdominal CT images show a well-defined soft-tissue mass (arrowheads) with intense and homogeneous enhancement. The absence of exoenteric growth is best appreciated in the coronal image.(f) Histological analysis (100x) reveals c-kit (CD117) expression by tumor cells. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 49 of 82

50 Fig. 11: 48-year-old male presenting with melena and iron deficiency anemia.(a) Axial non-enhanced CT displays a bulky polypoid lesion originating in the duodenal bulb and reaching the 4th portion of the duodenum, with soft tissue density and a lobulated contour (arrowheads).(b-d) On MR imaging the lesion (arrows) is heterogeneously hypointense on T1-weighted images (B), hyperintense on fat saturated T2-weighted images (C), enhancing after intravenous administration of gadolinium chelates. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 50 of 82

51 Fig. 12: Peutz-Jaeghers syndrome. (A) Sagittal contrast-enhanced CT shows a large polyp in the 4th portion of the duodenum. (B) Barium study of the stomach and small bowel demonstrates multiple filling defects troughout the intestinal tract. (C) Endoscopy frame showing the image of small polyps in the stomach. (D) Picture demonstrating the mucocutaneous pigmentation in a patient with Peutz-Jaeghers syndrome. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 51 of 82

52 Fig. 13: 46-year-old man with juvenile polyposis of the stomach and duodenum. (A) Abdominal radiograph shows a distended stomach (arrowhead) due to GOO. (B) Nonenhanced and (C) contrast-enhanced axial CT images reveal several polyps. The larger is located in the duodenal bulb and presents central fluid density (asterisk), a feature also observed in endoscopic ultrasound (D) as anechoic images corresponding to fluid-filled cavities (asterisk). (E) Endoscopy frame shows the multiplicity of polypoid lesions. (F) Gross specimen clearly shows the major polyp (asterisk) prolapsed through the pylorus (thick arrows) to the duodenal bulb. (G) Histology showing the empty cavities of the polyps (asterisks). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 52 of 82

53 Fig. 14: 50-year-old man with ampullary carcinoma. (A) Contrast-enhanced CT reveals an enhancing soft-tissue mass (arrowhead) protruding into the water-filled duodenum. (B) Endoscopic ultrasound shows a solid hypoechoic mass. (C)Endoscopic frame reveals the protruding lesion. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 53 of 82

54 Fig. 15: 85-year-old woman with Neurofibromatosis type 1. (A) and (B) contrastenhanced axial CT shows a mass (arrows) in the medial wall of the 2nd portion of the duodenum. The tumor displays intense contrast enhancement in the arterial phase (A), with retention in the venous phase (B) of this dynamic study. The high spatial resolution provided by CT clearly shows that the lesion is independent from the pancreas. (C-G) MR images. The lesion (arrows) displays low signal intensity on T1-weighted images (C) and high signal intensity on T2-weighted images (D). The dynamic study following gadolinium shows intense enhancement of the lesion in the arterial phase (E), with retention in the portal venous phase (F) and some loss during the equilibrium phase (G). (H) Transabdominal and (I) endoscopic ultrasound demonstrates a well-defined and hypoechoic lesion.(j) Somatostatin-receptor (octreotide) scintigraphy confirms the neuroendocrine nature of the tumor. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 54 of 82

55 Fig. 16: 64-year-old woman with duodenal lymphoma. (A) and (B) Contrast-enhanced abdominal CT shows concentric thickening of the duodenal wall (arrowheads) with irregular narrowing of the lumen. Lymphadenopathy (thin arrows) also suggests the diagnosis of lymphoma. (C) Barium study shows widening of the C-loop with mucosal irregularity but no evidence of obstructive signs. (D) Endoscopy shows luminal narrowing and extense mucosal ulceration. (E) Histology (H&E 100x) revealed a non-hodgkin's Tcell type lymphoma. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 55 of 82

56 Fig. 17: Assymptomatic duodenal lipoma in a 66-year-old woman. (A) Non-enhanced and (B) contrast enhanced axial CT images show a polypoid mass in the descending duodenum with homogeneous fat attenuation that does not enhance after intravenous contrast administration (arrowhead). (C) Coronal T2-weighted image demonstrates the intraluminal mass with high signal intensity similar to mesenteric fat (arrow). (D) Endoscopic ultrasound shows the parietal mass with a heterogeneously echogenic texture suggestive of fat content (arrowhead). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 56 of 82

57 Fig. 18: 80-year-old woman with biliary obstruction. (A) Ultrasound showed a hypoechoic mass in the pancreatic head (arrow). (B) Non-enhanced, (C) and (D) contrast-enhanced CT reveals a soft-tissue density mass (arrows), which remains hypodense during all phases of the dynamic study. CT clearly reveals tumor invasion of the medial wall of the 2nd portion of the duodenum, best recognised in the arterial phase (C). (E) and (F) Percutaneous transhepatic cholangiogram shows complete obstruction of the common bile duct by the tumor. A percutaneously applied metallic prosthesis crossed the tumour re-establishing bilioenteric flow. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 57 of 82

58 Fig. 19: 69-year-old man with neoplasm of the hepatic flexure of the colon. (A) and (B) Axial contrast-enhanced CT shows an undefined mass apparently including the duodenum (asterisk) and the colon. A small amount of positive oral contrast agent (arrowhead in A) is present within the mass. The oral contrast agent is seen in the colon (thick arrow in B) without evidence of contrast in the jejunum (thin arrow), a feature related to colo-duodenal fistula. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Fig. 20: 55-year-old man with a sigmoid colon cancer. (A) and (B) abdominal and pelvic CT performed to stage the disease clearly demonstrated the sigmoid tumor (arrows) but failed to show distant metastases. However, MPR and retrospective analysis revealed a discrete circumferential thickening in the 4th portion of the duodenum (arrowheads) which was not recognised initially.(c) Barium study performed 2 months later shows that the carcinoma progressed to become an "apple core" lesion (arrowheads) causing obstructive symptoms. Pathology revealed similar features on both lesions. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 58 of 82

59 Fig. 21: Acute gastric volvulus in a 78-year-old female patient who presented with acute abdominal pain and nausea. Contrast-enhanced CT shows herniation of part of the stomach above the diaphragm. The stomach is very distended, with air-fluid levels due to GOO. The gastric pylorus (arrow) is seen above the gastroesophageal junction (arrowhead), in keeping with mesenteroaxial rotation of the stomach. F - gastric fundus; A - gastric antrum. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 59 of 82

60 Fig. 22: Gastric volvulus in a 72-year-old patient who presented with abdominal fullness after meals. (A) Chest radiograph reveals an air- filled structure in the right hemithorax (arrow). (B) Barium study confirms the presence of a gastric volvulus which resulted in reversed positions of the greater and lesser curvatures of the stomach (organoaxial rotation). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 60 of 82

61 Fig. 23: Gastric volvulus. CT scan shows a rotated and right-sided intrathoracic stomach. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 61 of 82

62 Fig. 24: Acute traumatic diaphragmatic hernia. Chest radiograph demonstrates a round air-filled structure in the left hemithorax (arrowhead) consistent with stomach herniation. The mediastinum is pushed to the right (arrow). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 62 of 82

63 Fig. 25: Acute traumatic diaphragmatic hernia. (A) CT topogram reveals the tip of the nasogastric tube (arrow) in the left hemithorax in keeping with a herniated stomach. (B) Contrast-enhanced CT confirms the presence of an intrathoracic stomach and the nasogastric tube within it (arrow). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 63 of 82

64 Fig. 26: Gastroduodenal intussusception caused by GIST in the gastric fundus. (A) Abdominal radiograph demonstrates a dilated duodenum with dense material within it. (B) Color-Doppler ultrasound shows a hypoechogenic and vascularized mass. (C) Coronal, (D) axial and (E) sagittal contrast-enhanced CT images better depict the gastroduodenal intussusception. Note the invagination of the stomach mucosa into the lumen of the contiguous duodenum (arrow in C). The GIST is clearly seen at a lower level (arrow in D). The characteristic "target" sign is also seen (arrow in E). (F) Endoscopy reveals submucosal lesion arising from the gastric fundus. (E) Gross specimen. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Fig. 27: Left paraduodenal hernia. (A) Abdominal radiograph shows a dilated stomach with air-fluid level. (B) and (C) Contrast enhanced CT displays a herniated small bowel loop (arrowhead) to the left of the duodenum with inflammatory features that include thickened hyperenhancing wall, fat stranding (arrow in B) and engorged vessels (arrow in C). (D) Barium study also demonstrates the left paraduodenal hernia and the features of inflammatory changes of the herniated bowel. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 64 of 82

65 Fig. 28: Superior mesenteric artery syndrome in a 83-year-old female with history of weight loss. (A) Barium study showing a dilated stomach. (B) and (C) Axial contrastenhanced CT depicts the dilatation of the stomach (s) and proximal duodenum (d) caused by the compression of the transverse portion of the duodenum between the superior mesenteric artery (arrow) and the aorta (arrowhead). J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 65 of 82

66 Fig. 29: Malposition of adjustable gastric band in a patient who complained of postprandial vomiting. Barium study reveals the gastric band (arrowheads) in the distal stomach causing large dilatation of the stomach pouch (s). Reservoir port (long arrow) and the connector tube (short arrow) of the adjustable gastric banding system are also seen. C. N. Tentugal, Department of Radiology, CHBA, Portimão, Portugal Page 66 of 82

67 Fig. 30: Contrast-enhanced CT of a retroanastomotic internal hernia after Roux-en-Y anastomosis, causing GOO. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 67 of 82

68 Fig. 31: Hypertrophic pyloric stenosis. Abdominal radiograph shows a dilated stomach (arrow) in this young child. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 68 of 82

69 Fig. 32: Ultrasound reveals pyloric thickening and increased length of the pyloric channel consistent with hypertrophic pyloric stenosis. The asterisks depict the length of the pyloric channel and the ultrasound callipers the muscle thickness of the pylorus. J. Brito, Department of Radiology, CHBA, Portimão, Portugal Page 69 of 82

70 Fig. 33: "Double bubble" sign in an infant with duodenal atresia. s-stomach; d-proximal duodenum P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Page 70 of 82

71 Fig. 34: Duodenal atresia. (A) Markedly distended stomach and proximal duodenum (double bubble sign). Note that no gas is evident in the rest of the intestinal tract. (B) and (C) Fluoroscopy images of a barium study show no progression of oral contrast beyond the duodenum (arrowhead). P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Page 71 of 82

72 Fig. 35: Duodenal stenosis. (A) Control, (B) and (C) fluoroscopy images of barium study show abrupt narrowing of the duodenum (arrowhead), with proximal dilatation. Note that gas and contrast are seen after the stenosis (arrow). (D) Small bowel loops filled with gas after treatment. P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Page 72 of 82

73 Fig. 36: Duodenal web. Fluoroscopy image of a barium study demonstrates moderate dilatation of the proximal duodenum and difficult progression of contrast beyond the duodenum. P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Page 73 of 82

74 Fig. 37: Annular pancreas.barium study shows a distended stomach and proximal duodenum and a focal narrowing in the 2nd portion of the duodenum (arrow). Nevertheless,there is a filiform progression of contrast after that area, consistent with partial obstruction. P. Humphries, Department of Radiology, Great Ormond Street Hospital, London, UK Page 74 of 82