Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

77 results found
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Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...
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Acute abdominal pain

Acute abdominal pain is a common acute presentation in clinical practice. It encompasses a very broad range of possible etiologies and diagnoses, and imaging is routinely employed as the primary investigative tool in its modern management. Terminology A subgroup of patients with acute abdomina...
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Acute hepatitis

Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. The cause of the injury can happen in multiple different ways, and imaging findings are often non-specific. Acute hepatitis is a clinical diagnosis and normal imaging appearance of the liver does not ...
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Alpha fetoprotein

Alpha fetoprotein (AFP) is an important plasma protein synthesized by the yolk sac and fetal liver. In adults its main utility is as a tumor marker, primarily for hepatocellular carcinoma or teratoma. Functionally it is the fetal homologue of albumin, i.e. it acts as a major carrier protein in t...
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Ampullary tumor

The term ampullary tumor generally refers to either benign or malignant neoplasms that arise from the glandular epithelium of the ampulla of Vater, including 1: ampullary adenoma (adenoma of ampulla of Vater) ampullary carcinoma (carcinoma of ampulla of Vater) According to some authors, ampul...
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Benign liver tumors (pediatric)

Pediatric benign liver tumors are a relatively rare, but important group of conditions. Importantly, the commonest cause of a benign liver tumor is specific to the pediatric population. The list in descending order of frequency is: infantile hepatic hemangioma (previously hemangioendothelioma) ...
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Benign tumors and tumor-like lesions of the gallbladder

The gallbladder and extrahepatic bile ducts play host to a surprisingly large number of benign tumors and tumor-like lesions which may be visible on imaging. In the gallbladder, most of them are detected incidentally, whereas in the bile ducts they are usually found in symptomatic patients (obst...
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Bile duct dilatation (differential)

Bile duct dilatation can be due to several etiologies. Clinical presentation Variable, depending on underlying cause, but usually: right upper quadrant pain jaundice Radiographic features Ultrasound Harmonic imaging is useful when assessing the biliary system, as it improves the clarity o...
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Bile duct wall thickening (differential)

Thickening of the bile duct wall can stem from a variety of etiologies. Radiographic features Ultrasound bile duct wall thickening bile duct walls are typically not visible when normal possible narrowing of the ducts with obstruction possible secondary signs of cholangitis, including debri...
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Bulging duodenal papilla

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 finding on small bowel follow-though (and endoscopy) and has a relatively long differential. On cross-sectional imaging, th...
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CA-125

CA-125 is a high-molecular-weight glycoprotein found on the surface of Mullerian and coelomic epithelial-derived cell types, and is the best known tumor marker for epithelial ovarian cancer 6. Importantly, it may also be elevated in several other conditions (see differential diagnosis section be...
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CA 19-9

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...
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CEA

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 ...
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Cholangitis

Cholangitis is a relatively broad descriptive term term referring to inflammation of the bile ducts.  It has many forms and can arise from a number of situations: primary sclerosing cholangitis chemotherapy induced cholangitis eosinophilic cholangitis 5 infective cholangitis EBV cholangiti...
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Congestive hepatopathy

Congestive hepatopathy includes a spectrum of hepatic derangements that can occur in the setting of right-sided heart failure (and its underlying causes). If there is subsequent hepatic fibrosis the term cardiac cirrhosis may be used. The condition can rarely occur as a result of non-cardiac cau...
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Cystic hepatic metastases

Cystic hepatic metastases are included in the differential for new cystic liver lesions. The internal cystic component may represent necrosis as the tumor outgrows its hepatic blood supply, or it may represent a mucinous component, similar to the primary tumor. The liver and lungs are the most ...
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Cystic lesions of the liver (differential)

Cystic lesions of liver carry a broad differential diagnosis. These include: simple cysts simple hepatic cyst biliary hamartoma Caroli disease adult polycystic liver disease ciliated hepatic foregut duplication cyst 6 infectious: inflammatory conditions hepatic abscess pyogenic hepatic ...
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Cystic lesions of the pancreas (differential)

The differential for cystic lesions of the pancreas includes: unilocular pancreatic pseudocyst intraductal papillary mucinous neoplasm (IPMN) serous cystadenoma uncommonly uni/macrolocular simple pancreatic cyst pancreatic cysts occur in association with  von Hippel Lindau syndrome autos...
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Diffuse gallbladder wall thickening (differential)

Diffuse thickening of the gallbladder wall can occur in a number of situations: cholecystitis acute cholecystitis chronic cholecystitis gallbladder empyema 7 xanthogranulomatous cholecystitis 11 acalculous cholecystitis11 postprandial physiological state (pseudothickening) gallbladder o...
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Epidermoid cyst

The term epidermoid cyst can refer to a: epidermal inclusion cyst intracranial epidermoid cyst splenic epidermoid cyst spinal epidermoid cyst testicular epidermoid cyst
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Exophytic hepatic mass

Exophytic hepatic mass or tumor is a lesion which predominantly lies outside the margins of liver but originates from within the liver. Pathology Causes include 1: benign  hepatic hemangioma hepatic adenoma hepatic cyst hepatic angiomyolipoma focal nodular hyperplasia malignant  hepati...
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Fat containing liver lesions

A variety of benign and malignant liver lesions may contain macroscopic and/or intracytoplasmic fat in sufficient quantities enabling characterization on imaging studies. Most fat containing liver lesions (80%) in patients with cirrhosis are malignant, most of which are hepatocellular carcinoma ...
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Fetal intrahepatic calcification

Fetal intrahepatic calcification can be a relatively common finding. Calcifications in the liver can be single or multiple and in most cases in which isolated hepatic calcific deposits are detected, there is usually no underlying abnormality. The presence of isolated intrahepatic calcification ...
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Fibropolycystic liver disease

Fibropolycystic liver disease is a collective term for a group of congenital liver and biliary abnormalities resulting from abnormal development of the ductal plates.  Disease in this group include: congenital hepatic fibrosis biliary hamartomas autosomal dominant polycystic disease Caroli d...
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Focal gallbladder wall thickening (differential)

Focal gallbladder wall thickening is an imaging finding that includes both benign and malignant etiologies. cholecystoses cholesterolosis adenomyomatosis masses gallbladder polyps gallbladder carcinoma: look for infiltration into adjacent organs, metastases, lymphadenopathy, bile duct dil...
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Focal gas collection in right upper quadrant (differential)

Focal gas collection in right upper quadrant on plain radiographs can occur from a number of pathologies. Things to consider are: enterobiliary fistula: common types include cholecystoduodenal fistula and cholecystocolic fistula. It may occur with: gallstone ileus (being most common) 3 perfor...
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Focal hypodense hepatic lesions on non-enhanced CT (differential)

Focal hypodense hepatic lesions on a non-contrast CT scan can result from a number of pathological entities, including: neoplasms benign hepatic hemangioma adenoma biliary hamartoma: von Meyenberg complexes 2 malignant hepatoma/hepatocellular carcinoma (HCC) hepatic lymphoma hepatic ha...
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Gallbladder adenoma

Gallbladder adenomas are uncommon gallbladder polyps that, although benign, have a premalignant behavior.  Terminology As the distinction of adenomas and intracholecystic papillary-tubular neoplasms (ICPN) is not entirely clear, with important overlap between both entities, some authors have p...
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Gallbladder ghost triad

Gallbladder ghost triad is a term used on ultrasound studies when there is a combination of three gallbladder features on biliary atresia: atretic gallbladder, length less than 19 mm irregular or lobular contour  lack of smooth/complete echogenic mucosal lining with an indistinct wall
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Gallbladder inflammatory polyps

Gallbladder inflammatory polyps are a benign subtype of gallbladder polyps, representing ~10% of all polyps. They appear as a result of chronic inflammation (chronic cholecystitis).  For further details, please refer to the parental article on gallbladder polyps.  Pathology Thought to develop...
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Gallbladder sludge

Gallbladder sludge, also known as biliary sand, biliary sediment, or thick bile, is a mixture of particulate matter and bile, normally seen as a liquid-liquid level in the gallbladder on ultrasound, corresponding to the precipitate of bile solutes.  Pathology These precipitates consist of chol...
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Generalized increase in hepatic echogenicity

Causes of generalized increased liver echogenicity include: diffuse fatty infiltration cirrhosis: can be coarsened as well chronic hepatitis 3: can be coarsened as well diffuse infiltration or deposition malignant process granulomata  tuberculosis brucellosis sarcoidosis glycogen stora...
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Generalized reduced hepatic echogenicity

Causes of generalized reduction of liver echogenicity on ultrasound include: acute hepatitis diffuse malignant infiltration See also generalized increase in liver echogenicity hepatic attenuation on CT
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Glycogen storage disease

Glycogen storage disease (GSD) refers to a number of syndromes which are characterized by a defect in synthesis, metabolism or storage of glycogen. Pathology There are many types of GSD: type I: von Gierke disease type II: Pompe disease type III: Cori or Forbes disease type IV: Andersen di...
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Hemobilia

Hemobilia refers to the presence of blood in the biliary tree. Clinical presentation The classical clinical triad, only seen in ~50% of cases, consists of: melena (i.e. upper gastrointestinal bleeding) jaundice abdominal pain Pathology Etiology iatrogenic: surgical or percutaneous proced...
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Hepatic attenuation on CT

Hepatic attenuation on CT, reflected by Hounsfield values, depends on a combination of factors including the presence or absence, as well as the phase, of IV contrast administration. Allowing for all these factors, the mean unenhanced attenuation value is around 55 HU 4. Pathology Several int...
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Hepatic lymphangioma

A hepatic lymphangioma is a rare benign condition that corresponds to focally dilated lymphatic channels in the liver.  Clinical presentation Most cases are asymptomatic. Pathology A lymphangioma is a benign lesion that can occur at almost any location in the body. Hepatic involvement is les...
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Hepatic osteodystrophy

Hepatic osteodystrophy is an often forgotten metabolic bone disease seen in patients with chronic liver disease, in particular cirrhosis, primary biliary cirrhosis, and primary sclerosing cholangitis. These patients have increased risk factors for developing osteoporosis such as hypogonadism, al...
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Hepatisation of the gallbladder

Hepatisation of the gallbladder is a sonographic entity in which the gallbladder lumen is entirely filled with tumefactive sludge giving the gallbladder a similar appearance to liver parenchyma. It is one of the causes of non-visualization of the gallbladder on sonography. Pathology In the set...
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Hepatolithiasis

Hepatolithiasis is the presence of bile duct stones within the intrahepatic bile ducts, specifically before the confluence of the right and left hepatic ducts.  Epidemiology Hepatolithiasis is common Asia and the Pacific, with a prevalence of ~40%. It is rare in the West with a prevalence of ~...
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Hepatosplenic candidiasis

Hepatosplenic candidiasis is a manifestation of disseminated candidiasis in immunosuppressed patients, particularly those receiving chemotherapy for hematological malignancies. Both hepatic and splenic infection usually happens simultaneously, the reason why they are approached together.   On i...
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Hepatosplenomegaly

Hepatosplenomegaly is simply the simultaneous presence of a pathologically-enlarged liver (hepatomegaly) and spleen (splenomegaly). Pathology Etiology Infection Many, many infections can produce a mild concurrent enlargement of the liver and spleen. This list is by no means exhaustive! vira...
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Hypertrophy of the caudate lobe

Hypertrophy of the caudate lobe is seen in a number of conditions, including: cirrhosis: most common Budd-Chiari syndrome primary sclerosing cholangitis (end stage) congenital hepatic fibrosis cavernous transformation of the portal vein Radiographic features The caudate-right lobe ratio m...
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IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs. Terminology This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
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Intracholecystic papillary neoplasm

Intracholecystic papillary neoplasms (ICPN), also referred to as intracholecystic papillary-tubular neoplasms, are rare recently described pre-invasive neoplasms of the gallbladder. On imaging, these lesions resemble adenomas of the gallbladder or have features suspicious for gallbladder carcin...
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Intraductal neoplasms of the bile ducts

Intraductal neoplasms of the bile ducts are basically divided in those lesions that are a precursor to adenocarcinoma of the bile ducts, also referred to as preinvasive lesions, and the invasive tumors, which are made basically by cholangiocarcinomas of intraductal growing type. preinvasive  b...
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Intraductal papillary neoplasm of the bile duct

Intraductal papillary neoplasm of the bile duct (IPNB) is a pre-invasive biliary tree neoplasm considered to be a precursor of cholangiocarcinoma.  Terminology Biliary papillary adenoma and noninvasive papillary carcinoma of the biliary tract were terms used to refer to localized low-grade and...
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Intraductal tubulopapillary neoplasm of the bile ducts

Intraductal tubulopapillary neoplasms of the bile ducts are rare intraluminal mass forming pre-invasive biliary neoplasms with no mucin production.  Epidemiology ITPNs of the bile ducts are rare tumors of unknown incidence, found more frequently in women at their 60s 1,2.  Pathology These tu...
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Liver lesions

Liver lesions represent a heterogeneous group of pathology ranging from solitary benign lesions to multiple metastases from a variety of primary tumors. Liver lesions may be infiltrative or have mass effect, be solitary or multiple, benign or malignant. Assessment of liver lesions takes into c...
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Liver lesions (pediatric)

Pediatric liver lesions are a heterogeneous group that include infiltrative lesions and those that demonstrate mass effect. Moreover, they may be solitary or multiple, benign or malignant: benign liver tumors malignant liver tumors Epidemiology There are differing frequencies of both benign ...
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Liver trauma

The liver is one of the most frequently damaged organs in blunt trauma, and liver trauma is associated with a significant mortality rate. Epidemiology In blunt abdominal trauma, the liver is injured ~5% (range 1-10%) of the time 1,3. Clinical presentation Patients can present with right uppe...
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Liver tumors

Liver tumors, like tumors of any organ, can be classified as primary or secondary. Metastases Liver metastases are by far the most common hepatic malignancy, with many of the most common primaries readily seeding to the liver. This is especially the case with gastrointestinal tract tumors, due...
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Malignant liver tumors (pediatric)

Pediatric malignant liver tumors are rare, some of which occur only in children but that are similar to those that occur in adults. Epidemiology Malignant liver tumors account for ~1% of pediatric malignancies 2. Pathology Broadly, any malignant liver mass can be defined as a metastasis or p...
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Mass-forming intrahepatic cholangiocarcinoma

Mass-forming intrahepatic cholangiocarcinomas (MF-ICC), also referred as peripheral cholangiocarcinomas, compromise one of the three recognized growth patterns of intrahepatic cholangiocarcinomas.  On imaging, these tumors usually present as large and relatively well-defined hepatic masses with...
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Medical devices in the abdomen and pelvis

Medical devices in the abdomen and pelvis are important to be recognized, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications. Gastrointestinal tubes stomac...
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Milk of calcium (disambiguation)

The term milk of calcium (MOC) is given to dependent, sedimented calcification within a cystic structure or hollow organ. This sort of colloidal calcium suspension layering can occur in various regions: renal: milk of calcium in renal cyst (most common) breast: milk of calcium in breast cyst ...
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Mucinous cystic neoplasm of the gallbladder

Mucinous cystic neoplasms of the gallbladder are extremely rare epithelial cystic tumors formed by mucin-producing cells. They are histologically similar to the other mucinous cystic tumors found elsewhere in the body. For the lesions involving the bile ducts, please refer to: biliary cystaden...
Article

Mucocele

A mucocele simply refers to accumulation and expansion of a structure by mucus. It occurs in a variety of locations which are discussed separately: paranasal sinus mucocele oral cavity e.g. ranula, mucous retention cysts mucocele of the appendix 1 mucocele of the gallbladder mucocele of the...
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Non-neoplastic solid lesions of the pancreas

Non-neoplastic solid lesions of the pancreas are conditions which may mimic pancreatic neoplasms on imaging. They include: focal pancreatitis autoimmune pancreatitis fatty infiltration-replacement intrapancreatic accessory spleen peripancreatic lymph node congenital anomalies prominent pa...
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Pancreatic atrophy

Pancreatic atrophy is non-specific and is common in elderly patients, although in younger patients it can be a hallmark of pathology. Most commonly it is associated with aging, obesity and end-stage chronic pancreatitis.  It occurs principally with fatty replacement of the pancreas (pancreatic ...
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Pancreatic calcifications

Pancreatic calcifications can arise from many etiologies. Punctate intraductal calcifications chronic pancreatitis alcoholic pancreatitis (20-40%) 2  intraductal, numerous, small, irregular preponderant cause of diffuse pancreatic intraductal calcification gallstone pancreatitis (2%) 2 ​m...
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Pancreatic neoplasms

There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components. Classification Classification based on function exocrine: ~99% of all primary pancreatic neoplasms pancreatic ductal adenocarcinoma ~90-95% cystic neoplasm intraductal papillary muc...
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Pancreatitis

Pancreatitis (plural: pancreatitides) refers to inflammation involving the pancreas.  It has various forms which can be classified in many many ways according to time of onset, etiological agent or associated pathology. acute pancreatitis interstitial edematous pancreatitis necrotizing pancr...
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Periampullary tumors

Periampullary tumors are those that arise within 2 cm of the ampulla of Vater in the duodenum. Tumors that fall under this group include four main types of tumors 1,4 that will be approached in their specific articles: pancreatic head/uncinate process tumors: includes pancreatic ductal adenoca...
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Periportal hyperechogenicity

Periportal hyperechogenicity can result from many causes including: pneumobilia cholecystitis schistosomiasis of the portal region recurrent pyogenic cholangitis (oriental) inflammatory bowel disease: has been described to give "echo-rich" periportal cuffing 2​
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Periportal hypoechogenicity

Periportal hypoechogenicity can result from many causes: orthotopic liver transplant rejection congestive hepatomegaly malignant lymphatic obstruction cholangitis viral hepatitis See also periportal hyperechogenicity periportal halo
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Portal venous gas

Portal venous gas is the accumulation of gas in the portal vein and its branches. It needs to be distinguished from pneumobilia, although this is usually not too problematic when associated findings are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, centr...
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Pseudocirrhosis

Pseudocirrhosis is a radiological term used to recapitulate imaging findings of cirrhosis, but occurring in the setting of hepatic metastases. It is most commonly reported following chemotherapeutic treatment of breast cancer metastases, although has also been reported before treatment, and with...
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Pulmonary complications of cirrhosis

There are several pulmonary complications that can arise in the setting of cirrhosis: hepatopulmonary syndrome (HPS): considered the commonest portopulmonary hypertension (POPH) hepatic hydrothorax (HH) Clinical presentation Dyspnea and arterial hypoxemia are the most common symptoms. Path...
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Retained gallstone

Retained gallstones, also called dropped or slipped gallstones, are common during a laparoscopic cholecystectomy, with a reported incidence of 0.1–20%, and occur when gallstones are inadvertently spilled into the peritoneal cavity. Clinical presentation Many cases of dropped gallstones will be...
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Sclerosing cholangitis

There are three forms of sclerosing cholangitis: primary sclerosing cholangitis IgG4-related sclerosing cholangitis secondary sclerosing cholangitis
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Splenic abscess

Splenic abscesses, like abscesses elsewhere, are localized collections of necrotic inflammatory tissue caused by bacterial, parasitic or fungal agents. They uncommonly affect the spleen due to its efficient reticuloendothelial system phagocytic activity and, consequently, are more likely seen in...
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Splenic calcification

Splenic calcifications can occur is various shapes and forms and can occur from a myriad of etiological factors. The usual calcification observed in radiographs are the multiple, miliary form presenting numerous small rounded densities averaging from three to five millimeters in diameter where ...
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Splenic cyst

Splenic epithelial cysts, also referred as splenic epidermoid cysts or primary splenic cysts, are unilocular fluid lesions with thin and smooth walls and no enhancement. They represent ~20% of cysts found in the spleen, and are usually an innocuous incidental imaging finding. Note that most (~8...
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Splenomegaly

Splenomegaly refers to enlargement of the spleen. The upper limit of normal adult splenic length is traditionally cited at 12 cm, but lengths upwards of 14 cm can be seen in normal, taller males 7. Massive splenomegaly is variably defined, including when the spleen is 5 standard deviations abov...
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Transient hepatic attenuation differences

Transient hepatic attenuation differences (THAD) lesions refer to areas of parenchymal enhancement visible during the hepatic artery phase on helical CT. They are thought to be a physiological phenomenon caused by the dual hepatic blood supply. Occasionally they may be associated with hepatic tu...
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Ultrasound appearances of liver metastases

Ultrasound appearance of liver metastases can have bewildering variation, and the presence of hepatic steatosis can affect the sonographic appearance of liver lesions. Radiographic features Ultrasound Patterns do exist between ultrasound appearance of the liver metastases and the likely prima...

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