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.

65 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 hepatitis

Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. The cause of the injury can occur in multiple different ways, and imaging findings are often non-specific. Ultrasound and MRI may be useful imaging modalities to suggest the diagnosis, but often the d...
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AFP elevation

Human alpha fetoprotein (AFP) elevation may occur in a vast number of conditions: liver tumours (hepatocellular carcinoma, hepatoblastoma) <10 ng/ml is within normal limits >20 ng/ml is above normal limits but has low specificity for tumor since it may occur in a setting of diffuse liver inju...
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Ampullary tumour

The term ampullary tumour 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, ampu...
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Benign liver tumours (paediatric)

Paediatric benign liver tumours are a relatively rare, but important group of conditions. Importantly, the commonest cause of a benign liver tumour is specific to the paediatric population. The list in descending order of frequency is: infantile hepatic hemangioma (previously haemangioendotheli...
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Benign tumours and tumour-like lesions of the gallbladder

The gallbladder and extrahepatic bile ducts play host to a surprisingly large number of benign tumours and tumour-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 (ob...
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Bile duct dilatation (differential)

Bile duct dilatation can be due to several aetiologies. 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 ...
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Bile duct wall thickening (differential)

Thickening of the bile duct wall can stem from a variety of aetiologies. 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 debr...
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Bulging duodenal papilla

Major duodenal papilla is a conic or cylindric 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, the unde...
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CA-125

Serum CA-125 is well recognised as an ovarian cancer-associated marker and is an antigen determinant on a high-molecular-weight glycoprotein. The normal range of CA-125 is 0-35 U/mL. Serum CA-125 levels can also be used to monitor the response to treatment as well as a prognostic indicator sinc...
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CA 19-9 elevation

CA 19-9 is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepato-pancreatico-biliary origin. It is nonspecific, however, and can rise in both malignant and nonmalignant conditions. Elevation of serum CA 19-9 has been...
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Carcinoembryonic antigen

Serum carcinoembryonic antigen (CEA) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumour 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 infectious: inflammatory conditions hepatic abscess pyogenic hepatic abscess amoebic hepatic abscess hepatic hyd...
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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 neoplasms (IPMN) serous cystadenoma uncommonly uni/macrolocular pancreatic cysts occur in association with  von Hippel Lindau syndrome autosomal dominant polycysti...
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Diffuse gallbladder wall thickening (differential)

Diffuse thickening of the gallbladder wall can occur in a number of situations. They include: cholecystitis acute cholecystitis chronic cholecystitis gallbladder empyema 7 xanthogranulomatous cholecystitis acalculous cholecystitis postprandial physiological state (pseudothickening) sec...
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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 tumour is a lesion which predominantly lies outside the margins of liver but originates from within the liver. Pathology Causes include 1: benign  hepatic haemangioma hepatic adenoma hepatic cyst hepatic angiomyolipoma focal nodular hyperplasia malignant  hepa...
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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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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 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 haemangioma adenoma biliary hamartoma: von Meyenberg complexes 2 malignant hepatoma/hepatocellular carcinoma (HCC) hepatic lymphoma hepatic h...
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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 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 1.  These precipitates consist of cholesterol ...
Article

Gallbladder volvulus

Gallbladder volvulus is a relatively rare condition in which there is a rotation of the gallbladder around the axis of the cystic duct and artery. Clinical presentation Symptoms are non-specific, however right upper quadrant pain and vomiting are similar to biliary colic. Laboratory evaluation...
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Generalised increase in hepatic echogenicity

Causes of generalised 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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Generalised reduced hepatic echogenicity

Causes of generalised reduction of liver echogenicity on ultrasound include: acute hepatitis diffuse malignant infiltration See also generalised 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 characterised 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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Haematopoietic stem cell transplantation (abdominal complications)

Abdominal complications of haematopoietic stem cell transplantation can occur early (0-100 days) or late (>100 days) post transplant.  Complications Early bacterial infections, e.g. pseudomembranous colitis fungal infections, often affecting the oesophagus or as hepatic/splenic microabscesse...
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Haemobilia

Haemobilia refers to the presence of blood in the biliary tree. Clinical presentation The classical clinical triad, only seen in ~50% of cases, consists of: melaena (i.e. upper gastrointestinal bleeding) jaundice abdominal pain Pathology Aetiology iatrogenic: surgical or percutaneous pro...
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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...
Article

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...
Article

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-visualisation of the gallbladder on sonography. Pathology In the set...
Article

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 ~...
Article

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 (PSC) (end stage) congenital hepatic fibrosis cavernous transformation of the portal vein
Article

IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease that is characterised 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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Liver lesions

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

Liver lesions (paediatric)

Paediatric 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 tumours malignant liver tumours Epidemiology There are differing frequencies of both beni...
Article

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 tumours

Liver tumours, like tumours 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 tumours, d...
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Malignant liver tumours (paediatric)

Paediatric malignant liver tumours are rare, some of which occur only in children but that are similar to those that occur in adults. Epidemiology Malignant liver tumours account for ~1% of paediatric malignancies 2. Pathology Broadly, any malignant liver mass can be defined as a metastasis ...
Article

Medical devices in the abdomen and pelvis

Medical devices in the abdomen and pelvis are important to be recognised, 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...
Article

Milk of calcium

Milk of calcium (MOC) is a term 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 cysts: milk of calcium in renal cyst (most common) breast cysts: milk of calcium in bre...
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...
Article

Non-neoplastic solid lesions of the pancreas

Non-neoplastic solid lesions of the pancreas (NNSLP) are conditions which may mimic pancreatic neoplasms on imaging. They include: focal pancreatitis fatty infiltration-replacement intrapancreatic accessory spleen congenital anomalies, such as prominent pancreatic lobulations and bifid pancr...
Article

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 ...
Article

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...
Article

Pancreatitis

Pancreatitis refers to inflammation involving the pancreas.  It has various forms which can be classified in many many ways according to time of onset, aetiological agent or associated pathology. acute pancreatitis interstitial oedematous pancreatitis necrotising pancreatitis haemorrhagic p...
Article

Periampullary tumours

Periampullary tumours are those that arise within 2 cm of the ampulla of Vater in the duodenum. Tumours that fall under this group include four main types of tumours 1,4: pancreatic head / uncinate process tumours: includes pancreatic ductal adenocarcinoma involving head and uncinate process o...
Article

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
Article

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, cent...
Article

Pseudocirrhosis

Pseudocirrhosis is a complication of treated hepatic metastases, mainly those of breast cancer, which mimics liver cirrhosis radiologically. It has been reported in up to 50% of patients with breast cancer and liver metastases who underwent chemotherapy treatment 1. It is seen in the weeks or mo...
Article

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 Dyspnoea and arterial hypoxemia are the most common symptoms. Pat...
Article

Retained gallstone

Retained 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. When recognised intraoperatively spilled stones should be retrieved to avoid potential complications includ...
Article

Splenic abscess

Splenic abscesses, like abscesses elsewhere, are localised collections of necrotic inflammatory tissue caused by bacterial, parasitic or fungal agents. Epidemiology Splenic abscesses are uncommon, and their incidence in various autopsy series is estimated at ~0.4% (range 0.14-0.7%) 2,15. The i...
Article

Splenic calcification

Splenic calcifications can occur is various shapes and forms and can occur from a myriad of aetiological 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...
Article

Splenic cyst

Splenic cysts, although not particularly common, are the most common focal lesion of the spleen. They may be congenital or secondary. Epidemiology The incidence is ~0.75 per 100,000. Clinical features Usually asymptomatic and incidentally discovered at imaging. Left upper quadrant pain and t...
Article

Splenomegaly

Splenomegaly is a term which refers to enlargement of the spleen. The normal adult splenic length upper limit is usually around 12-15 cm. Also one should know how to calculate splenic index, volume and mass by CT and MR techniques. Massive splenomegaly is a term used when the spleen weighs >1000...
Article

Thorotrast

Thorotrast is a radioactive radiographic contrast agent containing thorium dioxide first produced in Germany in 1928 and was in use until the 1950s. It was used primarily for cerebral angiography, and 90% of the estimated 50,000-100,000 patients who received it were studied for this purpose.  T...
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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. Patterns do exist between ultrasound appearance of the liver metastases and the likely primary, which is sometimes helpful in directing a search for an unknown primary, as well as helping distinguish between benign lesion...

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