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
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 Although once a major test in diagnosing hydatid disease it has largely been superseded by newer more sensitive, specific and safer serological tests.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 although commonly described as a solitary mediastinal mass.
There are two distinct subty...
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 indentation of the pylorus into the fluid-filled antrum, seen in pyloric stenosis on ultrasound examination.
antral nipple sign
target sign of 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...
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 ...
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 mesenteric ischemia 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 times more common in women.
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 p...
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...
The circumferential resection margin (CRM) is a term used in rectal carcinoma excision surgery (such as total mesorectal excision (TME)).
Pathologic evaluation of the resection margin on the excised rectum has been considered important for determining the risk of local recurrence. A margin of ≤...
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
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 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.
dependent viscera s...
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 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 sig...
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 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.
In constipation, it can help distinguish between slow colonic transit and a defecation disorder.
The patient ingests a number of radiopaque markers (plastic rings containing radiopaque ma...
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 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 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 used for staging. Surgical resection may be curative although five-year survival rate is 40-50%.
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,...
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.
Origin and course
The CHA is a terminal branch of the celiac arter. It passes over the top of the pancreas, and downwards to the right in the lesser sac towards the first part of duodenum. It gives of...
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 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 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...
Congenital tracheo-esophageal fistula is a congenital pathological communication between the trachea and esophagus.
Tracheo-esophageal fistula and esophageal atresia have a combined incidence of approximately 1 in 3500 live births 1-3,5. There is only a minimal hereditary/geneti...
The conjoint tendon forms when the medial fibers of the internal oblique aponeurosis unite with the deeper fibers of the transversus abdominis aponeurosis. The conjoint tendon then turns inferiorly and attaches onto the pubic crest and pecten pubis 1. It forms part of the posterior wall of the i...
Corkscrew sign can refer to:
corkscrew sign (midgut volvulus)
corkscrew sign (tertiary esophageal contractions)
corkscrew sign (corkscrew cochlea)
The corkscrew sign describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus 1.
In patients with malrotation and volvulus, the distal duodenum and proximal jejunum do not cross the midline and instead pass in an inferior direction. These loops twist on ...
Cornual ectopic pregnancies are rare and represent a gestational sac within the cornua of a bicornuate or septate uterus.
Although sometimes interchangeably used with interstitial pregnancy, cornual pregnancy specifically refers to the presence of a gestational sac within a rudime...
Corrosive esophagitis usually occurs from accidental or suicidal ingestion of caustic substances (e.g. lye, household cleaners, bleaches, washing soda), and is harmful to the esophagus due to their alkali medium. The stomach is not affected as the gastric acid can neutralize these substances, ho...
Cowden syndrome, also known as multiple hamartoma syndrome, is characterized by multiple hamartomas throughout the body and increased risk of several cancers.
Type 2 segmental Cowden syndrome is the association of Cowden syndrome with a Cowden nevus when it is considered a type of ...
The crescent in a doughnut sign refers to the transverse ultrasound appearance of intestinal intussusception, and is a variation of the target sign (which is also known as the doughnut sign)
The doughnut is formed by concentric alternating echogenic and hypoechogenic bands. The echogenic bands ...
Cricopharyngeal bar refers to the radiographic appearance of a prominent cricopharyngeus muscle contour on barium swallow.
The terms cricopharyngeal bar and cricopharyngeal muscle spasm/achalasia are often used synonymously but this is incorrect because studies have demonstrated th...
Cricopharyngeal muscle spasm is also known as cricopharyngeal achalasia, although some authors distinguish between these entities, and may present as a cause of dysphagia.
There is confusing use of the terms cricopharyngeal muscle spasm, cricopharyngeal achalasia and cricopharyngea...
Crohn disease, also known as regional enteritis, is an idiopathic inflammatory bowel disease characterized by widespread discontinuous gastrointestinal tract inflammation. The terminal ileum and proximal colon are most often affected. Extraintestinal disease is common.
A mnemonic to remember the radiological features of Crohn disease is:
C: cobblestone appearance of mucosa
R: rose-thorn ulcers
O: obstruction of bowel
H: hyperplasia of mesenteric lymph nodes
N: narrowing of intestinal lumen
S: skip lesions
Due to the overlap in clinical presentation of Crohn disease (CD) and ulcerative colitis (UC), imaging often has a role to play in distinguishing the two. Distinguishing features include:
CD: small bowel 70-80%, only 15-20% have only colonic involvement
UC: rectal involvement 9...
Cronkhite-Canada syndrome is a type of non-neoplastic, non-hereditary hamartomatous polyposis syndrome characterized by rash, alopecia, and watery diarrhea.
There is a recognized male predilection. Patients typically are middle age (50-60 years of age) 1.
A crus (plural: crura) is an anatomical term used for a structure which resembles a leg.
crus (internal capsule)
crus (semicircular duct)
Cryptococcomas are a rare complication of infection by the Cryptococcus genus of invasive fungi, where a discreet, encapsulated lesion of immune infiltrates and pathogen forms. Cryptococcus gattii is most often isolated but Cryptococcus neoformans may also form cryptococcomas.
This is a basic article for medical students and other non-radiologists
CT abdomen is an increasingly common investigation that is used to help make diagnoses of a broad range of pathologies. A CT abdomen in its simplest form is a CT from diaphragm to symphysis pubis performed 60 seconds after ...
Multi-slice CT angiography of the splanchnic vessels is a powerful minimally invasive technique for evaluation of the splanchnic vascular system.
The actual procedure will vary depending on institutional protocol/guidelines but below is a typical description 2, 4:
The interpretation of CT colonography can sometimes be difficult because of pitfalls, which may be a source of false negative and false positive findings. When suboptimal CT colonography techniques are applied, the number and severity of interpretive pitfalls can rapidly multiply. However, when ...
CT colonography reporting and data system is a method devised to standardize CT colonography reporting.
It primarily classifies abnormalities into colonic (C) and extra-colonic (E).
C0: inadequate study
C1: normal colon/benign lesion: routine screening ...
Computed tomographic (CT) enteroclysis refers to a hybrid technique that combines the methods of fluoroscopic intubation-infusion small bowel examinations with that of abdominal CT 1.
CT enteroclysis is complementary to capsule endoscopy in the elective investigation of small-bowel...