- ANATOMIC LANDMARKS OF THE DUODENUM
Anatomical landmarks of the duodenum: the duodenum is divided into four segments and extends to both retro and intraperitoneal spaces. And has two flexures, the superior and the inferior duodenal flexures.
Anatomic relationships of the first duodenal segment
Anatomic relationships of the second duodenal segment
Anatomic relationships of the third duodenal segment
Anatomic relationships of the fourth duodenal segment
Common duodenal conditions by duodenal segment.
- CONGENITAL ANOMALIES
Annular Pancreas
Annular pancreas may be an incidental finding or may manifest with duodenal obstruction early in life or with acute or recurrent pancreatitis in adults.
Axial CT image shows an annular pancreas in an asymptomatic 54-year-old man: pancreatic tissue (yellow) completely encircling the duodenum (red).
- INFLAMMATORY DISEASES
Duodenal Peptic Disease
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 wall thickening, periduodenal fluid, retroperitoneal air, or free intraperitoneal air.
On rare occasions, severe duodenal ulcers can result in strictures and obstruction of the gastric outlet. Postbulbar ulcers are rare, and when they occur, alternate causes such as Crohn disease and Zollinger-Ellison syndrome should be considered.
- NEOPLASTIC DISEASE
The most common malignant tumor of the duodenum is adenocarcinoma, and the most common benign tumor is gastrointestinal stromal tumor (GIST).
Duodenal Lipoma
Duodenal lipomas are benign lesions that can be reliably diagnosed on CT scans as a smooth-margined mass with a fat density in Hounsfield unit measurement.
Carcinoid tumor
Duodenal carcinoids represent fewer than 3% of all carcinoid tumors and are depicted on contrast-enhanced CT images as intraluminal masses or focal circumferential wall thickening with homogeneous hyperenhancement in the arterial and venous phases.
Gist Tumor
Fewer than 5% of GISTs affect the duodenum, nearly always in the second through fourth segments.
- VASCULAR PATHOLOGY
Superior mesenteric artery syndrome / Wilkie's syndrome
Compression of the third segment of the duodenum between the aorta and the SMA.It is caused by loss of retroperitoneal fatty tissue, which leads to narrowing of the distance and angle between the aorta and the SMA.
- IATROGENIC AND OTHER CONDITIONS
Gallstone ileus/ Bouveret syndrome
Iatrogenic duodenal perforation
Iatrogenic duodenal perforation is a 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 endoscopic procedure.