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...
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 ...
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 tumour since it may occur in a setting of diffuse liver inj...
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...
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...
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...
Bile duct dilatation can be due to several aetiologies.
Variable, depending on underlying cause, but usually:
right upper quadrant pain
Harmonic imaging is useful when assessing the biliary system, as it improves the clarity ...
Thickening of the bile duct wall can stem from a variety of aetiologies.
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...
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...
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 tumour marker for epithelial ovarian cancer 6. Importantly, it may also be elevated in several other conditions (see differential diagnosis section b...
CA 19-9 (carbohydrate antigen 19-9 or cancer antigen) 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-malignant co...
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...
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
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...
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 ...
Cystic lesions of liver carry a broad differential diagnosis. These include:
simple hepatic cyst
adult polycystic liver disease
ciliated hepatic foregut duplication cyst 6
infectious: inflammatory conditions
pyogenic hepatic ...
The differential for cystic lesions of the pancreas includes:
intraductal papillary mucinous neoplasm (IPMN)
serous cystadenoma uncommonly uni/macrolocular
simple pancreatic cyst
pancreatic cysts occur in association with
von Hippel Lindau syndrome
Diffuse thickening of the gallbladder wall can occur in a number of situations:
gallbladder empyema 7
xanthogranulomatous cholecystitis 11
postprandial physiological state (pseudothickening)
The term epidermoid cyst can refer to a:
epidermal inclusion cyst
intracranial epidermoid cyst
splenic epidermoid cyst
spinal epidermoid cyst
testicular epidermoid cyst
Exophytic hepatic mass or tumour is a lesion which predominantly lies outside the margins of liver but originates from within the liver.
Causes include 1:
focal nodular hyperplasia
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 ...
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 ...
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
autosomal dominant polycystic disease
Focal gallbladder wall thickening is an imaging finding that includes both benign and malignant aetiologies.
gallbladder carcinoma: look for infiltration into adjacent organs, metastases, lymphadenopathy, bile duct di...
Focal hypodense hepatic lesions on a non-contrast CT scan can result from a number of pathological entities, including:
biliary hamartoma: von Meyenberg complexes 2
hepatoma/hepatocellular carcinoma (HCC)
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
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 ...
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
Causes of generalised reduction of liver echogenicity on ultrasound include:
diffuse malignant infiltration
generalised increase in liver echogenicity
hepatic attenuation on CT
Glycogen storage disease (GSD) refers to a number of syndromes which are characterised by a defect in synthesis, metabolism or storage of glycogen.
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...
Haemobilia refers to the presence of blood in the biliary tree.
The classical clinical triad, only seen in ~50% of cases, consists of:
melaena (i.e. upper gastrointestinal bleeding)
iatrogenic: surgical or percutaneous pro...
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.
A hepatic lymphangioma is a rare benign condition that corresponds to focally dilated lymphatic channels in the liver.
Most cases are asymptomatic.
A lymphangioma is a benign lesion that can occur at almost any location in the body. Hepatic involvement is les...
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...
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.
In the set...
Hepatolithiasis is the presence of bile duct stones within the intrahepatic bile ducts, specifically before the confluence of the right and left hepatic ducts.
Hepatolithiasis is common Asia and the Pacific, with a prevalence of ~40%. It is rare in the West with a prevalence of ~...
Hypertrophy of the caudate lobe is seen in a number of conditions, including:
cirrhosis: most common
primary sclerosing cholangitis (PSC) (end stage)
congenital hepatic fibrosis
cavernous transformation of the portal vein
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.
This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
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 ...
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
There are differing frequencies of both beni...
The liver is one of the most frequently damaged organs in blunt trauma, and liver trauma is associated with a significant mortality rate.
In blunt abdominal trauma, the liver is injured ~5% (range 1-10%) of the time 1,3.
Patients can present with right uppe...
Liver tumours, like tumours of any organ, can be classified as primary or secondary.
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, ...
Paediatric malignant liver tumours are rare, some of which occur only in children but that are similar to those that occur in adults.
Malignant liver tumours account for ~1% of paediatric malignancies 2.
Broadly, any malignant liver mass can be defined as a metastasis ...
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.
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
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...
Non-neoplastic solid lesions of the pancreas are conditions which may mimic pancreatic neoplasms on imaging. They include:
intrapancreatic accessory spleen
peripancreatic lymph node
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 ...
There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.
Classification based on function
exocrine: ~99% of all primary pancreatic neoplasms
pancreatic ductal adenocarcinoma ~90-95%
intraductal papillary muc...
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, aetiological agent or associated pathology.
interstitial oedematous pancreatitis
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 that will be approached in their specific articles:
pancreatic head/uncinate process tumours: includes pancreatic ductal ade...
Periportal hyperechogenicity can result from many causes including:
schistosomiasis of the portal region
recurrent pyogenic cholangitis (oriental)
inflammatory bowel disease: has been described to give "echo-rich" periportal cuffing 2
It may also be observed in ...
Periportal hypoechogenicity can result from many causes:
orthotopic liver transplant rejection
malignant lymphatic obstruction
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...
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...
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)
Dyspnoea and arterial hypoxemia are the most common symptoms.
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...
Splenic abscesses, like abscesses elsewhere, are localised 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...
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...
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...
Splenomegaly is a term which refers to enlargement of the spleen. The normal adult splenic length upper limit is usually around 12-15 cm. It can also be helpful to know how to calculate splenic index, volume and mass by CT and MR techniques. Massive splenomegaly is a term used when the spleen we...
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.
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...
Ultrasound appearance of liver metastases can have bewildering variation, and the presence of hepatic steatosis can affect the sonographic appearance of liver lesions.
Patterns do exist between ultrasound appearance of the liver metastases and the likely prima...