Brunner glands are compound tubular submucosal glands found in the duodenum. They are only found proximal to the sphincter of Oddi.
Brunner gland hyperplasia
Brunner gland adenoma
Bucket handle mesenteric injuries are avulsions of the mesentery off a bowel segment (the handle) due to shearing forces in blunt trauma to the bowel and mesentery. Laceration of the mesenteric vessels results in intestinal ischemia.
The most common mechanism of injury in...
Bulging duodenal papilla is a conical or cylindrical protuberance at the medial aspect of the descending or horizontal duodenum at the site of the sphincter of Oddi. It is a finding on small bowel follow-though (and endoscopy) and has a relatively long differential. On cross-sectional imaging, ...
Buried bumper syndrome (BBS) is a rare but important complication in patients with a percutaneous gastrostomy tube, occurring by migration of the internal bumper along its track. The tube may get lodged anywhere between the gastric wall and the skin and lead to life-threatening complications inc...
Busoga hernias, also known as Gill-Ogilvie hernias in Europe 1 (alternative plural: herniae), are a variant of the direct inguinal hernia involving the conjoint tendon.
Busoga herniae have been noted to occur most commonly in young, athletic men with a well-developed abdominal mus...
CA 19-9 (carbohydrate antigen 19-9 or cancer antigen 19-9) is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepatopancreaticobiliary origin. It is non-specific, however, and can rise in both malignant and non-maligna...
The cecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled cecum.
Cecal bascule is an uncommon type of cecal volvulus in which the cecum folds up over itself in an anteromedial orientation. In contrast to the more common forms of volvulus, there is no axial "twisting" component 4. A cecal bascule may occur in the setting of a large and mobile cecum and can re...
Cecal volvulus describes torsion of the cecum around its mesentery which often results in obstruction. If unrecognised, it can result in bowel perforation and fecal peritonitis.
Cecal volvulus accounts for ~10% of all intestinal volvuluses, and generally occur in somewhat younger ...
The cecum (plural: ceca or cecums) is the first part of the large bowel and lies in the right lower quadrant of the abdomen.
Blind-ending sac of bowel that lies below the ileocecal valve, above which the large intestine continues as the ascending colon. The cecum measures 6 cm i...
Candida esophagitis is the most common cause of infectious esophagitis that commonly affects immunocompromised patients. On imaging, it is characterized by irregular plaque-like lesions separated by normal mucosa and small (<1 cm) ulcers, which are assessed on esophagogram studies.
Capsule endoscopy is a non-invasive means of investigating the small bowel, principally for identifying the underlying cause of occult gastrointestinal tract bleeding, such as due to arteriovenous malformations, small bowel tumors, and ulcers. It is also used for the detection of the earliest ma...
The symptoms of carbolic acid poisoning can be recalled using the mnemonic:
C: CNS depression
C: constricted pupil
C: carboluria (smoky urine)
C: corneal deposition
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionizing radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
Carcinoid syndrome refers to a spectrum of symptoms that result from excessive hormone (mainly serotonin) secretion.
Occurs equally between the sexes, most commonly in the 40-70 year age group 3.
Diarrhea is the most common and earliest symptom but others ...
Carcinoid tumors are a type of neuroendocrine tumor that can occur in a number of locations. Carcinoid tumors arise from endocrine amine precursor uptake and decarboxylation (APUD) cells that can be found throughout the gastrointestinal tract as well as other organs (e.g. lung). In general, they...
Carcinosarcomas are highly malignant biphasic tumors with both carcinomatous (epithelial) and sarcomatous (bone, cartilage, or skeletal muscle) components.
It can arise in many organs:
lung 5: pulmonary carcinosarcoma
esophagus 1: esophageal carcinosarcoma
genitourinary tract 2
The Carman meniscus sign describes the lenticular shape of barium in cases of large and flat gastric ulcers, in which the inner margin is convex toward the lumen. It usually indicates a malignant ulcerated neoplasm; in cases of benign gastric ulcers, the inner margin is usually concave toward th...
Carney-Stratakis syndrome is a rare autosomal dominant condition comprising of familial paraganglioma and gastric stromal sarcoma.
It is considered to be distinct from, but perhaps related to, the Carney triad 1. Neither should be confused with the unrelated Carney complex.
Carney triad is a rare syndrome defined by the coexistence of three tumors:
extra-adrenal paraganglioma (e.g. spinal paraganglioma)
initially, only functioning extra-adrenal paragangliomas were included, but subsequent work includes non-functioning extra-adrenal paragangliomas 1
Awesome cases will be selected by our editorial board t...
The cases featured in these video lectures are specifically selected to teach important concepts in radiology over a broad range of topics. The tutorials vary in difficulty from basic to advanced. For maximum learning, try the cases for yourself in Radiopaedia quiz mode first.
We love this ser...
The Casoni skin test is a hypersensitivity based skin test used to detect hydatid disease. Although once a major test in diagnosing hydatid disease it has largely been superseded by newer more sensitive, specific and safer serological tests.
Sterile fluid (0.25 mL) of hydatid cyst or...
Castleman disease, also known as angiofollicular lymph node hyperplasia or giant lymph node hyperplasia, is an uncommon benign B-cell lymphoproliferative condition. It can affect several regions of the body but is commonly described as a solitary mediastinal mass.
There are two distinct subtype...
The caterpillar sign is a radiological sign described in pyloric stenosis.
It refers to the appearance of the stomach on an upper gastrointestinal radiographic series or plain abdominal radiograph 1,2. On these imaging modalities in a patient with pyloric stenosis, the stomach appears distended...
A catchy and early learnt mnemonic for recalling some of the causes of pancreatitis is:
I GET SMASHED
G: gallstones, genetic - cystic fibrosis
E: ethanol (alcohol)
M: mumps (and other infections)/malignancy
S: scorpion stings/s...
Cavernous venous malformation, also traditionally referred to as a cavernous hemangioma (despite it not being a tumor) or cavernomas, are non-neoplastic slow flow venous malformations found in many parts of the body.
Despite the ubiquity of use of the traditional terms cavernoma, ...
Cavitary mesenteric lymph node syndrome is seen in association with celiac disease and is characterized by the triad of:
low-attenuation lymphadenopathy that sometimes contains fat-fluid levels
Serum CEA (carcinoembryonic antigen) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumor markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue.
Normal range of CEA is ...
CEC syndrome refers to the combination of celiac disease, epilepsy and bilateral occipital calcifications. This is also known as Gobbi syndrome. Patients with cerebral calcifications and celiac disease without epilepsy are considered as having an incomplete form of CEC syndrome 1.
The centipede sign is seen as engorged mesenteric vessels in cases of acute sigmoid diverticulitis which gives an appearance similar to a centipede 1.
The cervix sign of pyloric stenosis describes the indentation of the pylorus into the fluid-filled antrum, seen in pyloric stenosis on ultrasound examination.
antral nipple sign (pyloric stenosis)
target sign (pyloric stenosis)
Chagas disease, also known as American trypanosomiasis (plural: trypanosomiases), is a tropical parasitic infection with a wide spectrum of clinical manifestations since it can virtually affect any organ, but there are characteristic radiological features.
Chagas disease is endemi...
Chalasia is a condition most commonly identified in infants and young children, and is related to congenital incompetence of the lower esophageal sphincter, allowing unrestricted reflux of gastric contents. This contrasts with achalasia, where there is restriction at the gastro-oesphageal juncti...
The champagne sign (also known as the effervescent gallbladder sign) is a pathognomonic sonographic sign of gas in the gallbladder.
The sign refers to multiple small echogenic foci which are seen to migrate from a dependent to non-dependent position within the gallbladder as the patient changes...
Chemical shift artifact or misregistration is a type of MRI artifact. It is a common finding on some MRI sequences and used in MRS. This artifact occurs in the frequency-encoding direction and is due to spatial misregistration of fat and water molecules.
Chemical shift is due to the difference...
The chicken intestine is a term used to describe the appearance of a hypersegmented barium column. This appearance is characteristic of intestinal tuberculosis 1.
Other radiographic findings such as accelerated intestinal transit, flocculation and dilution of the barium and, luminal stenosis wi...
Chilaiditi sign refers to the interposition of the bowel, usually colon, between the inferior surface of the right hemidiaphragm and the superior surface of the liver. It may be misinterpreted as a true pneumoperitoneum resulting in unnecessary further investigations and/or therapy (so-called ps...
Chilaiditi syndrome is the anterior interposition of the colon to the liver reaching the under-surface of the right hemidiaphragm with associated upper abdominal pain; it is one of the causes of pseudopneumoperitoneum.
Colonic gas in this position may be misinterpreted as true pneumoperitoneum ...
Chinese dragon sign is a radiological sign in abdominal radiograph and CT describing the radiologic appearance of calcified tortuous splenic artery that resembles the Chinese dragon. The tortuous splenic artery segment on the splenic hilum side represents the dragon head while the other arterial...
The solitary use of the size of the tumor during evaluation for response to chemotherapy has some pitfalls and limitations, especially for specific tumors such as gastrointestinal stromal tumor (GIST).
The Choi response criteria for GIST proposed that tumor attenuation could provide an addition...
Cholecystoduodenal fistula refers to a fistulous connection between the gallbladder and the duodenum. It is considered the most common type of enterobiliary fistulation.
Can vary but some can present with Bouveret syndrome 3 or a gallstone ileus.
Cholera is an acute infective diarrheal illness caused by Vibrio cholerae. Severe cholera causes large volume liquid stools, which may rapidly lead to hypovolemic shock and death, unless intensive rehydration therapy is instituted. Prevention of cholera depends upon access to clean water and eff...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Chronic appendicitis is defined by inflammation of the appendix over time with symptoms lasting for more than three weeks duration 1. The condition should be differentiated from recurrent appendicitis, in which one or more episodes of flares of symptoms last 24 to 48 hours and subside on their o...
Chronic mesenteric ischemia, also known as intestinal angina, is an uncommon type of intestinal ischemia usually affecting elderly patients as a result of significant stenosis of two or more mesenteric arteries.
Normally seen in patients older than 60 years of age and is three tim...
Chronic pancreatitis represents the end result of a continuous, prolonged, inflammatory, and fibrosing process that affects the pancreas. This results in irreversible morphologic changes and permanent endocrine and exocrine pancreatic dysfunction.
The most common cause of chronic ...
Chylous ascites (also known as chyloperitoneum) is defined as the abnormal intraperitoneal accumulation of milky lymphatic fluid with a triglyceride level >110 mg/dL 1. Etiologically it is due to a disruption of the lymphatic system, most commonly obstructive due to a mass or traumatic (which ma...
Circumferential resection margin (CRM) is a term used to denote the standard plane of excision of total mesorectal excision, used for resection of rectal cancers. The anatomic correlate is the mesorectal fascia. The distance between tumor tissue or satellite tumor deposits and the mesorectal fas...
The cloaca is the terminal portion of the hindgut. It is an embryonic structure (weeks 4-7) in which the distal ends of the gastrointestinal tract and urogenital system share a common channel. The most distal aspect of the cloaca is termed the cloacal membrane.
The cloaca, or portions of it, ca...
Closed loop obstruction is a specific type of bowel obstruction in which two points along the course of a bowel are obstructed, usually but not always with the transition points adjacent to each other at a single location. The closed loop refers to a segment of bowel without proximal or distal o...
Clostridioides difficile colitis, also known as pseudomembranous colitis and previously known as Clostridium difficile colitis 10, is a common cause of antibiotic-associated diarrhea, and increasingly encountered in sick hospitalized patients. If undiagnosed and untreated, it continues to have h...
Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn disease.
Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones.
There are several described cockade signs in radiology:
cockade sign (intraosseous lipoma)
cockade sign (aorto-left ventricular tunnel) 1
cockade sign (appendicitis) 2
cockade sign (hypertrophic pyloric stenosis) 3
cockade sign (GI tumors) 4
The celiac artery, also known as the celiac axis or celiac trunk, is a major visceral artery in the abdominal cavity supplying the foregut. It arises from the abdominal aorta and commonly gives rise to three branches: left gastric artery, splenic artery, and common hepatic artery.
Celiac artery compression syndrome, also known as median arcuate ligament syndrome, Dunbar syndrome, or Harjola-Marable syndrome, is a rare condition characterized by upper abdominal pain in the setting of compression of the celiac trunk by the diaphragmatic crurae.
Although well-recognized as ...
Celiac disease, also known as non-tropical sprue, is the most common gluten-related disorder and is a T-cell mediated autoimmune chronic gluten intolerance condition characterized by a loss of villi in the proximal small bowel and gastrointestinal malabsorption (sprue).
It should always be cons...
The celiacomesenteric trunk (CMT) represents an uncommon vascular anatomical variant where both the celiac trunk and the superior mesenteric artery have a common origin from the abdominal aorta as a single trunk. Its frequency has been reported to occur in about 1.5% of the population 1,2.
Celiac plexus block under image guidance is an easy and safe percutaneous procedure with good outcomes for pain palliation in patients who have chronic abdominal pain related to the celiac ganglia.
This usually includes patients with advanced cancers, especially from upper abdominal viscera, s...
The coffee-bean sign (also known as the kidney bean sign or bent inner tube sign 4) is a sign on an abdominal plain radiograph of a sigmoid volvulus although some authors have also used the term to refer to closed loop small bowel obstructions. Cecal volvulus may be mistaken with sigmoid volvulu...
The collar sign, also called the hourglass sign, is a helpful sign for diagnosis of diaphragmatic rupture on coronal or sagittal CT/ MR images and barium studies. It refers to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm.
Small tear on the right side ...
A colo-enteric fistula is a type of gastrointestinal fistulation wherein there is abnormal communication between the colon and the small bowel.
It can occur from a number of causes which include:
Crohn disease - considered one of the commonest causes
The colon cut-off sign describes gaseous distension seen in the proximal colon associated with abrupt termination of gas within the colon usually at the level of the splenic flexure and decompression of the more distal part of the colon. Though originally described in abdominal radiographs, this...
Colonic anastomotic leaks occur in the early or late postoperative phase, in which the enteric anastomosis fails. This may be a small leak that can be managed conservatively or less commonly complete dehiscence requiring repeat surgery.
In one large surgical series, the incidence ...
Colonic diverticulitis (plural diverticulitides), is a complication of colonic diverticulosis, and one of the presentations of diverticular disease. Differentiating one from the other is critical since uncomplicated diverticulosis is mostly asymptomatic and acute diverticulitis is a potentially ...
Colonic diverticulosis (plural diverticuloses) refers to the presence of multiple diverticula. It is quite distinct from diverticulitis which describes inflammation and infection of one or multiple diverticula.
Diverticulosis is very common in westernised countries and is typicall...
Colonic leiomyomas are uncommon benign smooth muscle tumors that can mimic a more aggressive tumor on imaging, such as a GIST. They can be pedunculated, simulating a colonic polyp. Their characteristics are similar to leiomyomas in general.
There are no specific findings ...
Colonic esophageal interposition is a now rarely performed upper gastrointestinal tract surgical procedure, in which colon is used to replace the distal esophagus.
This was performed for long esophageal strictures or in some cases malignancy.
The haustra of the colon are illustrated on plain r...
Colonic pseudo-obstruction (also known as Ogilvie syndrome) is a potentially fatal condition leading to an acute colonic distention without an underlying mechanical obstruction. It is defined as an acute pseudo-obstruction and dilatation of the colon in the absence of any mechanical obstruction....
Colonic strictures can be long (>10 cm) or short.
scirrhous colorectal carcinoma (apple core sign)
post surgical (anastamotic stricture)
scirrhous colorectal carcinoma
inflammatory bowel disease
The colonic transit study is an older technique to estimate colonic transit time.
Various names are used for this type of study including shapes study, colon motility test, Sitz marker study and Transit-PelletsmethodTM, and variations thereof.
In constipation, it ca...
Colon polyps are mucosal outgrowths of the colon wall. They are of interest to physicians and radiologists because of the accepted progression of adenomatous polyps to colon carcinoma.
adenomatous colon polyps
villous colon polyps
Colorectal cancer (CRC) is the most common cancer of the gastrointestinal tract and the second most frequently diagnosed malignancy in adults. CT and MRI are the modalities most frequently used for staging. Surgical resection may be curative although five-year survival rate is 40-50%.
Colorectal carcinoma staging can be performed using two systems. The traditional Dukes staging system has largely been replaced by the TNM system but is nonetheless often used clinically.
Dukes (Astler-Coller modification)
stage A: confined to mucosa
stage B: through muscularis propr...
This is a basic article for medical students and other non-radiologists
Colorectal cancer, also called colorectal carcinoma (CRC), is the most common cancer of the gastrointestinal tract and the second most frequently diagnosed malignancy in adults. CT and MRI are the modalities most frequently...
Colorectal villous polyps refer to villous adenomas of the large intestine. They are most commonly found in the rectum and are the least common of all types of colon polyps.
The prevalence of advanced polyps including villous polyps on screening colonography is ~5% (range 3-7%) 3,...
Colostomies are a surgically created stoma between the colon and the abdominal wall. It can be performed for both malignant and benign conditions.
temporary end colostomy as part of a Hartmann procedure
double barrel colostomy
end colostomy with mucous f...
Colovaginal fistula is one form of genitourinary fistula. It is also sometimes classed under a type of gastro-intestinal fistula.
It refers to a communication between the colon (typically the rectum or sigmoid colon) with the vagina.
At times, specific terms are used dependent on th...
Colovesical fistulas are communications between the lumen of the colon and that of the bladder, either directly or via an intervening abscess cavity (foyer intermediaire). When the communication is between the rectum and urinary bladder, the term rectovesical fistula is used.
The comb sign refers to the hypervascular appearance of the mesentery in active Crohn disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel,...
The common bile duct (CBD), which is sometimes simply known as the bile duct, is formed by the union of the cystic duct and common hepatic duct (CHD).
On ultrasound imaging, it is not always possible to confidently see where the cystic duct enters the common hepatic duct to form t...
The common hepatic artery (CHA) is one of the 3 branches of the celiac artery.
The common hepatic artery is normally a terminal branch of the celiac artery, the largest branch coursing to the right.
It passes anterior to the pancreas, and then inferiorly to the r...
The common hepatic duct (CHD) is formed by the junction of the right and left hepatic ducts. It joins the cystic duct to form the common bile duct (CBD). It is approximately 4 cm long and 4 mm in diameter.
Together with the cystic duct (laterally) and cystic artery (superiorly), they form Calo...
There are many complications that can occur following gastric banding. It is helpful to divide these into early and late post-surgical complications.
Although the exact mode of presentation can vary depending on the underlying complication common modes of presentation tha...
Complications of sleeve gastrectomy are often evaluated by imaging. For details about the surgical procedure, please see the parental article on sleeve gastrectomy.
Postoperative complications can be classified by etiology or temporality.
staple line leakage
Complications post optical colonoscopy are most commonly assessed by CT if patients present with abdominal symptoms post colonoscopy. Complications include:
bowel perforation (most common)
lower gastrointestinal hemorrha...
Computed tomographic (CT) colonography, also called CTC, virtual colonoscopy (VC) or CT pneumocolon, is a powerful minimally invasive technique for colorectal cancer screening.
screening test for colorectal carcinoma
colon evaluation after incomplete or unsuccessful conventional c...
Computed tomographic (CT) gastrography, also called virtual gastroscopy (VG), is a noninvasive procedure for the detection of gastric abnormalities.
rapid and noninvasive exam
offers information about local tumor invasion, lymph node and distant metastasis in cases of gastric cance...
A cone-shaped cecum refers to a loss of the normal rounded appearance of the cecum, which instead becomes narrow and cone-shaped with the apex pointing towards the base of the appendix. It is encountered in a number of conditions including:
This congenital extrahepatic portosystemic shunt classification was proposed by Morgan and Superina in 1994 1:
type 1: complete diversion of portal blood into the inferior vena cava with congenital absence of the portal vein
1a: superior mesenteric vein and splenic vein do not join to form a c...
This congenital intrahepatic portosystemic shunt classification was proposed by Park et al. in 1990 1:
type 1: single large vessel of constant diameter connecting the right portal vein to the inferior vena cava
type 2: localized, peripheral shunt with one or more communications in a single hep...
Congenital peritoneal encapsulation (CPE) is an extremely rare condition of abnormal embryonic gastrointestinal development. It is characterized by congenital development of an accessory peritoneal layer partially or entirely encapsulating the small bowel.
Congenital peritoneal en...
Congenital portosystemic shunts are rare, extrahepatic or intrahepatic, anatomical abnormalities shunting blood from the portal venous system to the systemic venous system and, thus, avoiding passage through the hepatic acinus.
The term “portosystemic shunt” can be used to refer t...