Komi classification of bile duct cysts, as stated by Komi et al, divides anomalous union of the pancreatico-bile ducts (AUPBD) into 3 types based on the angle of union of the ducts 1.
type I: union of the ducts at a right angle to each other
type Ia: without dilatation or
The Krenning score is a proposed semi-quantitative method of assessing the degree of tracer uptake on octreotide scintigraphy.
Initially designed for assessment of 111In-DTPA on planar imaging, the Krenning score is applicable to SPECT or SPECT/CT using various radiopharmaceuticals....
The left hepatic artery (LHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver.
The PHA bifurcates into the left and right hepatic arteries at or before reaching the porta hep...
The left triangular ligament is a peritoneal suspensory ligament of the liver. It is formed by the fusion of the superior and inferior reflections of the coronary ligament.
It is shorter than the right triangular ligament and does not separate the left subphrenic space from the subhepatic space.
Lemmel syndrome is defined as an obstructive jaundice caused by a periampullary duodenal diverticulum (of the second part of the duodenum) compressing the intrapancreatic part of the common bile duct with resultant upstream dilatation of the extra- and intrahepatic bile ducts.
Leptospirosis results from infection of the zoonoses Leptospira sp. The condition can have multi-organ manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Leukaemic infiltration of the liver can occur with several forms of leukaemia inclusive of acute myeloid leukaemia (AML), acute lymphoid leukaemia (ALL) and chronic myeloid leukaemia (CML).
Described features are non-specific but include:
The light bulb sign of a hepatic haemangioma is a feature than can be seen on MRI imaging with a classic hepatic haemangioma. This refers to marked hyperintensity seen on heavily T2 weighted sequences that has been likened to a glowing light bulb.
light bulb sign - shoulder
Limy bile stands for the presence of a viscous substance in the dependent parts of the gallbladder and/or bile ducts, almost entirely composed of calcium carbonate, and therefore highly radiopaque.
The terms limy bile and calcium milk gallbladder can be used interchangeably for inc...
Liquefactive necrosis is a form of necrosis where there is transformation of the tissue into a liquid viscous mass.
In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes leading to a soft, circumscribed lesion which can consist of fluid with remains...
LI-RADS (Liver Imaging Reporting and Data System) is both a set of standardised terminology and a classification system for imaging findings in liver lesions. The LI-RADS score for a liver lesion is an indication of its relative risk for hepatocellular carcinoma (HCC). The classification system ...
Littoral cell angioma of the spleen (LCA) is a rare and relatively recently (1991) described vascular tumour of the spleen.
Littoral cell angiomas may occur at any age and have no gender predilection.
Typically, patients with littoral cell angioma are found...
The liver is the largest abdominal organ that plays a major role in metabolism and has a number of functions, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. It is one of the very few organs that has the ability to r...
There is a wide range of liver and biliary interventional procedures, both diagnostic and therapeutic, most commonly using CT-guidance or ultrasound-guidance.
Percutaneous transhepatic biliary interventions
percutaneous transhepatic cholangiography (PTC)
percutaneous transhepatic biliary dr...
Transjugular liver biopsy (TJLB) is an alternative to a percutaneous liver biopsy in patients with diffuse liver disease, coagulopathy and ascites.
It is sometimes done in combination with a transjugular intrahepatic portosystemic shunt (TIPSS) or venography.
Barcelona clinic liver cancer (BCLC) staging uses a set of criteria to guide management of patients with hepatocellular carcinoma (HCC).
The classification takes the following variables into account 1,2:
performance status (PS)
radiologic tumour extent
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...
Liver lobules are the basic functional units of the liver. They are classically described ('classic lobules') as hexagonal structures made of six vertically aligned portal canals with a central vein. However, microscopic evaluation of the liver usually shows a lack of classic liver lobule as a w...
Examination of the liver with MRI requires numerous sequences and imaging at multiple times after the administration of gadolinium. Many variations exist, but a typical protocol would include:
T2 fat sat
T1 weighted gradient echo in and out of phase
T1 2D or 3D gradient ech...
Liver sinusoids are a type of fenestrated/porous blood vessel which compose the 'capillary bed' of the liver parenchyma. They receive terminal branches of the oxygen-rich hepatic artery (terminal hepatic arterioles) and nutrient-rich portal vein (terminal portal venules). They facilitate vascula...
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...
This is a basic article for medical students and other non-radiologists
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.
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 ...
Melioidosis is an infectious disease caused by Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei) and is a multisystem disorder which may affect the lungs, brain, visceral organs, or musculoskeletal system.
Melioidosis is a disease of the monsoon season in th...
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 middle hepatic artery (MHA) is an intrahepatic hilar arterial branch, usually arising from the left hepatic artery, which supplies segments IVa and IVb. It runs towards the right side of the umbilical fissure.
it may arise from the right hepatic artery 1,2
it may arise as ...
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...
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
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. They are divided into two groups of two based on the underlying metabolic deficiency:
deficiency of acid sphingomyelinase 1,3,4
Niemann-Pick disease type A (NPD-A)
Niemann-Pick disease type c (NPD-C or just 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.
NPD-C is inherited as a a...
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 are conditions which may mimic pancreatic neoplasms on imaging. They include:
intrapancreatic accessory spleen
peripancreatic lymph node
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...
This is a basic article for medical students and other non-radiologists
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 a...
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 ...
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...
Staging of pancreatic ductal adenocarcinoma is traditionally done according to American Joint Committee on Cancer (AJCC) / Union for International Cancer Control (IUCC) TNM system. In 2017 new edition (8th edition) AJCC published with some major changes; now exocrine and endocrine tumours of th...
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
Mostly flat lesions ...
Pancreatic lipomatosis refers to the fatty replacement of pancreatic parenchyma. This finding is most often associated with obesity and ageing.
It tends to be commonest pathological condition involving the pancreas. The condition may occasionally simulate a mass-like lesion particularly when f...
Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma.
Typically seen in middle-aged patients: mean of 55 years; range, 35-75 years and in immunocompromised patients.
Presentation is often non-specific. reported symptoms include 1:
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...
Pancreaticopleural fistulas are a rare complication of acute or chronic pancreatitis whereby enzymatic pancreatic fluid, either from a pancreatic pseudocyst or directly from a disrupted duct, dissects into the pleural cavity. Pancreaticopleural fistulas may also develop in the setting of trauma ...
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 from 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 vast ...
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 (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
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...
The papillary process of the caudate lobe, also known as the medial papillary process, represents a division of the inferior caudate lobe of the liver 1. The inferior aspect of the caudate may be divided into medial and lateral processes. While the lateral or caudate process is contiguous with ...
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, also known as congested liver in cardiac disease, describes the stasis of blood in the hepatic parenchyma, due to impaired hepatic venous drainage, which leads to dilation of central hepatic veins and hepatomegaly.
Passive hepatic congestion is a well-studied result...
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 a malignant obstruction, such as cholangiocarcinoma, ampullary and pancreatic malignancies when retrograde access v...
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 that will be approached in their specific articles:
pancreatic head/uncinate process tumours: includes pancreatic ductal ade...
Peribiliary cysts occur in the setting of chronic liver disease where it is a rare, benign and often asymptomatic disorder. It occurs when there is cyst formation around the intrahepatic biliary ductules primarily in a hilar distribution 1. Unlike choledochal cysts (for example in Caroli disease...
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.