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, d...
Low phospholipid-associated cholelithiasis (LPAC) syndrome is one of the syndromes associated with ABCB4/MDR3 mutation. Characteristics of this syndrome include 1,2:
symptomatic cholesterol stones with early onset (<40 years)
recurrent symptoms post cholecys...
LR2 cirrhosis-associated nodules are defined as "probably benign" according to the LI-RADS classification system. They are a common finding in a cirrhotic liver and do not need to be mentioned in the report.
The nodule must demonstrate all of the following:
Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive imaging technique to visualize intra and extrahepatic biliary tree and pancreatic ductal system.
It can provide the diagnostic range equivalent to the ERCP and so it can replace the ERCP in high risk patient to avoid significa...
Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative.
This is a summary article; we do not have a more in-depth reference...
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 ...
Mallory bodies are cytoplasmic eosinophylic inclusions in hepatocytes, associated with ballooning and inflammation, found in:
alcoholic fatty liver disease and hepatitis
non-alcoholic fatty liver disease
hepatocellular carcinoma (HCC)
primary biliary cirrhosis (PBC)
Mastocytosis is a disorder of excessive mast cell proliferation, which is now classified as a myeloproliferative neoplasm. Two clinical entities fall under the mastocytosis umbrella: cutaneous (urticaria pigmentosa) and systemic mastocytosis (with or without cutaneous manifestations). The articl...
Meandering main pancreatic duct (MMPD) comprises of a reverse Z-type and loop-type of pancreatic ducts.
These ductal variants are found in ERCP and MRCP studies. The exact incidence is not known.
Increased incidence of meandering pancreatic duct has been reported in patients with idiopathic re...
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.
Meglumine iotroxate (BiliscopinTM) is an iodinated, intravenous contrast agent that is preferentially excreted into the biliary tree and is used in CT intravenous cholangiography.
The typical dose is 100 mL Biliscopin (105 mg meglumine iotroxate/ml; 5.0 g iodine), which is administered via slow...
The MELD score (Model for End-stage Liver Disease) is a classification used to grade liver dysfunction in preparation for liver transplantation. It is an estimate of 3 month mortality.
The components of the score are:
serum creatinine (mg/dl)
if dialysis twice in last week, then bilirubin is ...
In the gallbladder, the Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2.
Fissures, usually fluid-filled, are present in close to 50% of gallstones. Less than half of these fissured gallstones contain some amo...
The METAVIR scoring system is a system used to assess the extent of inflammation and fibrosis by histopathological evaluation in a liver biopsy of patients with hepatitis C. The grade indicates the activity or degree of inflammation while the stage represents the amount of fibrosis or scarring....
In medical imaging literature, a Mickey Mouse appearance has been given to imaging features that depict that of Mickey Mouse when viewed from the front. It has been described in the following:
progressive supranuclear palsy 1
synonymously with a finger in glove sign
the flared ...
The Milan criteria are a generally accepted set of criteria used to assess suitability in patients for liver transplantation with cirrhosis and hepatocellular carcinoma.
In order to be suitable for a liver transplantation, one needs to have 1:
single tumour with diameter ≤5 cm, or up to 3 tumo...
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...
The Mirizzi syndrome refers to an uncommon phenomenon which results in extrinsic compression of an extrahepatic biliary duct from one or more calculi within the cystic duct or gallbladder. It is a functional hepatic syndrome but can often present with biliary duct dilatation and can mimic other ...
MR liver iron quantification is a non-invasive means of measuring liver iron concentration, a key indicator in the management of patients with haemochromatosis (primary or secondary).
Apart from being non-invasive, sampling occurs in a large cross-section of the liver, as opposed to...
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...
Multiple biliary hamartomas (MBH) are a rare cause of multiple benign hepatic lesions. The condition is also known as von Meyenburg complexes, multiple bile duct hamartomas and biliary micro hamartomas. MBH is asymptomatic and usually found incidentally, where it is important to differentiate fr...
Multiple focal nodular hyperplasia occurs in approximately 20-25% of patients with focal nodular hyperplasia (FNH).
Multiple FNH syndrome is defined by The International Working Party as consisting of two or more FNHs in combination with 1:
liver haemangioma or
Myelofibrosis is a haematological disorder where there is the replacement of bone marrow with collagenous connective tissue and progressive fibrosis. It is also classified as a myeloproliferative disorder. It is characterised by:
extramedullary hematopoiesis (EMH)
Niemann-Pick disease (NPD) is actually a collection of a number of distinct autosomal recessive lysosomal storage diseases.
deficiency of acid sphingomyelinase 1
Niemann-Pick disease type A (NPA)
severe hepatosplenomegaly in infancy
severe central nervous system involvement, with atrophy or...
Niemann-Pick disease type c (NPC) is an autosomal recessive lysosomal storage disorder classed under Niemann-Pick disease on account of clinical similarities, namely hepatosplenomegaly and variable involvement of the central nervous system.
NPC is inherited as a autosomal recessi...
In hepatic imaging, a nodule-in-nodule appearance represents foci of abnormal arterial enhancement within a liver lesion, in cases of a liver regenerative nodule with a focus of hepatocellular carcinoma or high-grade dysplastic nodule. It is so called because of the nodular arterial enhancement ...
Nonalcoholic fatty liver disease (NAFLD) occurs when fat is deposited into hepatocytes without a known cause (such as with alcoholic fatty liver disease). The deposition of fat may lead to hepatic inflammation (hepatitis) and may eventually lead to cirrhosis.
"Nonalcoholic fatty li...
Non-neoplastic solid lesions of the pancreas (NNSLP) are conditions which may mimic pancreatic neoplasms on imaging. They include:
intrapancreatic accessory spleen
congenital anomalies, such as prominent pancreatic lobulations and bifid pancr...
Non visualisation of the fetal gallbladder is often a transient finding and in most bases can be eventually detected. However it can be rarely associated with certain pathological conditions.
agenesis of the gallbladder
The hepatic veins have a characteristic spectral Doppler waveform. Alterations in the normal hepatic vein waveform may reveal or confirm abnormalities in the heart or liver.
The key factor in the shape of the hepatic vein spectral Doppler waveform is the motion of the heart. Multip...
This article lists examples of normal imaging of the liver and biliary tree and surrounding structures, divided by region and modality.
liver silhouette: example
example 1 with shear wave elastography
liver Doppler ultrasound: example ne...
Nubbin sign (also called as cystic duct sign) is an important sign in a HIDA scan (cholescintigraphy using iminodiacetic acid analogues) that may be seen in cases of gallbladder neck obstruction. The "nubbin" refers to a small amount of radiotracer activity in the cystic duct, with absence of tr...
A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...
Obstructive jaundice represents a set of conditions that cause jaundice by obstructing the flow of bile into the duodenum anywhere along the intrahepatic or extrahepatic biliary tree.
This is a summary article; read more in our article on jaundice.
The Okuda staging system was an advance on earlier hepatocellular (HCC) staging classifications, in that it incorporated both cancer-related variables and liver function related variables to determine prognosis 1:
disease involving >50% of hepatic parenchyma
albumin ≤3 mg/dL
Organ Procurement and Transplantation Network (OPTN) is the unified transplantation network in the United States and runs under the administration of United Network for Organ Sharing (UNOS). OPTN classification is the part of the imaging policy of UNOS that consists of in order to determine the ...
Oriental cholangiohepatitis, or recurrent pyogenic cholangiohepatitis, is a condition essentially found in Southeast Asia and is characterised by intra and extrahepatic bile duct strictures and dilatation with intraductal pigmented stone formation.
Diagnosis is made after exclusion of more com...
The PRETEXT system proposed by the International Childhood Liver Tumours Strategy Group (previously called Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumour Study Group - SIOPEL) aims for staging and risk stratification of liver tumours at diagnosis.
It is used to descri...
The pancreas is a retroperitoneal organ that has both endocrine and exocrine functions: it is involved in the production of hormones (insulin, glucagon and somatostatin), and also involved in digestion by its production and secretion of pancreatic juice.
The pancreas can be divid...
Pancreas divisum represents a variation in pancreatic ductal anatomy that can be associated with abdominal pain and idiopathic pancreatitis. It is characterised, in the majority of cases, by the dorsal pancreatic duct (main pancreatic and Santorini ducts) directly entering the minor papilla with...
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 ...
Pancreatic ductal adenocarcinoma makes up the vast majority (~90%) of all pancreatic neoplasms and remains a disease with a very poor prognosis and high morbidity.
On imaging, it usually presents as a hypodense mass on CT that is poorly marginated, which may encase vessels and the common biliar...
Both endocrine and exocrine tumours of the pancreas are now staged by a single pancreatic staging system.
Staging of pancreatic ductal adenocarcinoma is with the TNM system, and as a majority of tumours are not-resectable, this is mostly achieved with imaging (typically CT scan) although laparo...
The diameter of the (main) pancreatic duct is a commonly assessed parameter in imaging.
The duct diameter is greatest at the head and neck region and is slightly narrower towards the body and tail. Its normal reported value ranges between 1-3.5 mm 5, 8:
head: 3.5 mm
body: 2.5 m...
The pancreatic ductal embryology is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant.
The normal arrangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vater through the sphinc...
Pancreatic intraepithelial neoplasia (PanIN) is a precursor lesion to pancreatic ductal adenocarcinoma, but the frequency at which this transition occurs is unknown.
Increasing incidence with age 1. Risk factors:
pancreatic lipomatosis 3
More commonly locat...
Pancreatic lipomatosis refers to fatty replacement of pancreatic parenchyma. This finding is most often associated with obesity and aging.
It tends to be commonest pathological condition involving the pancreas. The condition may occassionally simulate a mass like lesion particularly when fatty...
Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma and is classified as either primary or secondary:
primary pancreatic lymphoma is a rare extranodal manifestation of any histopathologic subtype of B-cell non-Hodgkin's lymphoma, representing < 2% of extranodal lympho...
Pancreatic metastases are uncommon and are only found in a minority (3-12%) of patients with widespread metastatic disease at autopsy . They account for only 2-5% of all pancreatic malignancies.
Although essentially any primary may eventually deposit in the panaceas the most common primaries en...
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...
Pancreatic pseudocysts are common sequelae of acute pancreatitis or chronic pancreatitis, and the most common cystic lesion of the pancreas. They are important both in terms of management and differentiation from other cystic processes or masses in this region.
The following are th...
The pancreas is uncommonly injured in blunt trauma. However, pancreatic trauma has a high morbidity and mortality. Imaging features range between subtle to obvious.
The pancreas is injured in ~7.5% (range 2-13%) of blunt trauma cases 1,3. Motor vehicle accidents account for the va...
A number of pancreatic injury grading systems have been proposed.
American Association for the Surgery of Trauma (AAST)
grade 1: haematoma with minor contusion/laceration but without duct injury
grade 2: major contusion/laceration but without duct injury
grade 3: distal lace...
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.
interstitial oedematous pancreatitis
Pancreatoblastomas are rare paediatric tumours of the pancreas. However, they are the most common pancreatic neoplasm of childhood and are often associated with a raised alpha-fetoprotein.
There is slight male predilection. Usually occurs in the first decade of life with a mean ag...
Paracaval lipoma (or juxtacaval fat collection) can be a frequent finding on CT and can seen in up to 0.5% of examinations 1. Some even consider this as a normal variation5. It occurs at the medial aspect of the intrahepatic portion of the inferior vena cava (IVC) above the caudate lobe and rep...
Paraduodenal pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum and the common bile duct.
The following entities with which it shares clinicopathological features are unified by this term and should no ...
Passive hepatic congestion or congested liver in cardiac disease is the stasis of blood in the hepatic parenchyma, due to impaired hepatic venous drainage which leads to widening and splaying of the central hepatic veins and hepatomegaly.
Passive hepatic congestion is a well-studied result of ...
The pearl necklace sign occurs in adenomyomatosis of the gallbladder, on both oral cholecystograms and MRCP. It represents the contrast / fluid-filled intramural mucosal diverticula (Rokitansky-Aschoff sinuses); lined up, these are reminiscent of pearls on a necklace. It is synonymous with the C...
Pepper syndrome is of interest only (the term is not readily used in day-to-day practice), and refers to primary adrenal neuroblastoma with extensive liver metastases 1. In essence, it refers to stage 4S neuroblastoma (see staging of neuroblastoma).
Percutaneous cholecystostomy is an image-guided placement of drainage catheter into gallbladder lumen. This minimally invasive procedure can aid stabilisation of a patient to enable a more measured surgical approach with time for therapeutic planning.
poor surgical candidate/high r...
Percutaneous transhepatic biliary drainage is an interventional radiology procedure undertaken for those with biliary obstruction.
It is almost exclusively performed in those with malignant obstruction, such as cholangiocarcinoma, ampullary and pancreatic malignancies when retrograde access via...
Percutaneous transhepatic cholangiography (PTC) is a radiographic technique employed in visualisation of the biliary tree and can be used as the first step in a number of percutaneous biliary interventions (e.g. percutaneous transhepatic biliary stent placement)
Purely diagnostic p...
A periampullary diverticulum is a location-specific type of duodenal diverticulum.
The incidence is reported to increase with age with reported rates as high as 27%.
It is located close to the region of the duodenum often involving the D2 segment.
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...
Peripancreatic pseudoaneurysm refers to the formation of a pseudoaneurysm around the pancreatic gland. It is a rare but potentially lethal complication 5.
Formation of pseudoaneurysm can occur in as many as 10% of cases of pancreatitis. The time interval is variable, ranging from ...
Periportal halo or periportal collar sign is a zone of low attenuation seen around the portal veins on contrast-enhanced CT or hypoechogenicity on liver US. Periportal halos may occur around the central portal veins or their peripheral branches and occurs on both sides of the portal triads.
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
Periportal hypoechogenicity can result from many causes:
orthotopic liver transplant rejection
malignant lymphatic obstruction
Peritoneal hydatidosis occurs secondary to seeding of echinococcosis to the peritoneum, usually secondary to rupture of hydatid disease of liver.
Seeding involves the entire peritoneum and gives appearance of an multiloculated mass.
Peritoneal hydatidosis can be pri...
Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance.
A Phrygian cap may be identified in ultrasound, multiphase CT/MRI or in...
Pneumobilia, also known as aerobilia, is the accumulation of gas in the biliary tree. It is important to distinguish pneumobilia from portal venous gas, the other type of branching hepatic gas. There are many causes of pneumobilia and clinical context is often important to distinguish between th...
Pneumobilia and portal venous gas are two causes of an intrahepatic branching gas pattern. The two have different causes and implications and need to be distinguished on imaging.
A simple mnemonic for remembering the difference in appearance is:
portal venous gas: peripheral
Polycystic liver disease (PCLD) is a hereditary condition that may arise either in patients with autosomal dominant polycystic kidney disease (ADPKD) or in patients with a different genetic mutation that results solely in autosomal dominant polycystic liver disease.
Porcelain gallbladder refers to extensive calcium encrustation of the gallbladder wall. The term has been used to emphasise the blue discoloration and brittle consistency of the gallbladder wall at surgery. Often an incidental finding on multiple different modalities, CT can be used to confirm t...
The porta hepatis is a deep fissure in the inferior surface of the liver through which all the neurovascular structures (except hepatic veins) and hepatic ducts enter or leave the liver 1. It contains:
right and left hepatic ducts
right and left branches of hepatic artery
Portal biliopathy or portal ductopathy refers to biliary obstruction that is associated with cavernous transformation of the portal vein due to portal vein thrombosis 1.2.
Portal bilopathy may present as jaundice, cholangitis due to bile duct obstruction, or rarely as hae...
Portal hypertension is defined as portal venous pressure greater than 12 mmHg.
Causes can be split in their relation to the hepatic sinusoids:
portal vein thrombosis
extrinsic compression of portal vein
Schistosomiasis (S. mansoni or S. japonicum)
In portal hypertension, chronic portal venous congestion leads to dilatation and ectasia of the submucosal vessels in the stomach (portal hypertensive gastropathy), small bowel (portal hypertensive enteropathy) and/or large bowel (portal hypertensive colopathy). This may result in upper or lower...
The portal vein (PV) (sometimes referred to as the main or hepatic portal vein) is the main vessel in the portal venous system and drains blood from the gastrointestinal tract and spleen to the liver.
The portal vein, usually measures approximately 8 cm in length in adults. It or...
Portal vein embolisation (PVE) is a technique used to selectively occlude the blood supply to one of the liver lobes diverting portal blood flow to the other lobe, allowing this future liver remnant (FLR). This will increase the size of the post hepatectomy future liver remnant (FLR) and improve...
Portal vein thrombosis may be seen in a variety of clinical contexts, and when acute can be a life-threatening condition. It is a major cause of non-cirrhotic presinusoidal portal hypertension. Portal vein thrombus may be either bland and/or malignant (i.e. tumour thrombus), and it is a critical...
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...
Portopulmonary hypertension (POPH/PPHTN) refers to pulmonary artery hypertension that develops in the setting of portal hypertension (with or without underlying liver disease). It falls under group 1.4 under the Dana point 2008 pulmonary hypertension classification system.
Portosystemic collateral pathways (also called varices) develop spontaneously via dilatation of pre-existing anastomoses between the portal and systemic venous systems. This facilitates shunting of blood away from the liver into the systemic venous system in portal hypertension, as a means for r...
The posterior right subhepatic space (also known as the hepatorenal fossa or Morison's pouch) separates the liver from the right kidney. It is a potential space that is not filled with any fluid in normal conditions.
Posterior right subhepatic space is a subcompartment of the sup...
Post transplant lymphoproliferative/lymphoproliferation disorder (PTLD) is increasing in prevalence as the number and survival length of solid organ and bone-marrow transplant recipients also increases.
It represents a variety of conditions varying from lymphoid hyperplasia to malignancy but is...
Primary biliary cholangitis (PBC) is a chronic progressive cholestatic liver disease that is the cause of 1-2% of deaths from cirrhosis and constitutes the third most common indication for liver transplantation in adults.
The name of this disease was changed from primary biliary ci...
Primary hepatic lymphoma (PHL) is rare accounting for roughly 100 described cases. If it is being considered as a diagnosis, distal lymphadenopathy, splenomegaly, bone marrow disease, and leukaemia should not be present for at least 6 months after the liver tumour is detected (see: secondary hep...
Primary hyperoxaluria, also referred as primary oxalosis, is a congenital autosomal recessive disease related to a liver enzyme deficiency leading to massive cortical nephrocalcinosis and renal failure.
Please, refer on secondary oxalosis for a discussion on the acquired form of hyperoxaluria....
Primary sclerosing cholangitis (PSC) is an uncommon idiopathic inflammatory condition, which affects the biliary tree resulting in multiple strictures and eventual cirrhosis.
The diagnosis can be made when there are classical imaging features in the correct clinical context, and secondary cause...
A pseudocalculus sign is a term coined to describe a mimic of a distally impacted common bile duct stone on MRCP and CT cholangiography.
It results from the forceful contraction of ampulla of Vater with secondary pouting into the lower end of the CBD. This impression is superiorly rounded and ...