Inflammatory hepatic adenomas are a genetic and pathological subtype of hepatic adenoma. Their appearance and prognosis is different than other subtypes and has the highest incidence of hemorrhage amongst hepatic adenoma subtypes.
Most common subtype of hepatic adenoma (40-50%). O...
Inflammatory myofibroblastic tumors (IMT), also known as plasma cell granulomas, are rare neoplasms that have a diverse spectrum of biological behavior.
These tumors were previously referred as inflammatory pseudotumour.
They can occur at any age and there is curr...
Inflammatory polyps of the gallbladder are a subtype of gallbladder polyps, representing ~10% of polyps.
Thought to develop from chronic inflammation, with deposition of cholesterol in the gallbladder wall and mucosal irritation, leading to a fibrous reaction 2.
There is no evidence...
Insulinomas are the most common sporadic endocrine tumor of the pancreas. On imaging, they usually present as small well-defined hypervascular tumors that may be found anywhere along the pancreas.
Account for 40% of syndromic pancreatic endocrine tumors. The overall incidence is ...
Interstitial edematous pancreatitis is one of the two subtypes of acute pancreatitis. It is normally referred to as "acute pancreatitis" or "uncomplicated pancreatitis" in day-to-day use. Please refer to the article on acute pancreatitis for further details.
Intrabiliary rupture of hepatic hydatid cyst is a common complication associated with hepatic hydatid cysts. It is important to appreciate the direct and indirect signs of this condition.
The radiological features of intrabiliary rupture of a hepatic hydatid cyst can be c...
Intraductal papillary mucinous neoplasms or tumors (IPMNs or IMPTs) are cystic tumors of the pancreas.
These tumors are most frequently identified in older patients (50-60 years of age) 6, and thus are sometimes colloquially referred to as the "grandfather lesion". Main duct type ...
Intrahepatic arterioportal shunts represent abnormal flow between the portal venous system and a hepatic arterial system within the liver. They can be a reversible cause of portal hypertension.
Clinical features will depend on size and other underlying pathology. Small sh...
Irreversible electroporation (IRE), also known as non-thermal irreversible electroporation (NTIRE), is a non-invasive soft-tissue ablation technique used for tumor ablation in regions that require very high precision and preservation of surrounding structures.
In IRE electrodes are p...
Jaundice refers to a clinical sign of hyperbilirubinemia (>2.5 mg/dl) which has many causes. It is often a clue to a diagnosis. It can be largely divided into two types:
non-obstructive, i.e. pre-hepatic and hepatic causes
obstructive, i.e. post-hepatic causes
Imaging has a major role in dete...
Kasai classification is used to describe the three main anatomical types of biliary atresia.
type I: obliteration of common bile duct (patent cystic and common hepatic duct)
IIa: obliteration of common hepatic duct (patent cystic and common bile duct), sometimes with a...
Klatskin tumor is a term that was traditionally given to a hilar cholangiocarcinoma, occurring at the bifurcation of the common hepatic duct. Typically, these tumors are small, poorly differentiated, exhibit aggressive biologic behavior, and tend to obstruct the intrahepatic bile ducts.
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....
This article lists a series of labelled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
MR head: T2 axial
The term lamellated (or laminated) is a radiopathological term used to describe the layered appearance of many calculi, including those of the renal tract, the salivary glands, and the biliary tree. The internal structure of these calculi has been likened to that of an onion with multiple concen...
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 spp. The condition can have multiorgan manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Leukemic infiltration of the liver can occur with several forms of leukemia inclusive of acute myeloid leukemia (AML), acute lymphoid leukemia (ALL) and chronic myeloid leukemia (CML).
Described features are non-specific but include:
periportal low att...
The ligamentum venosum is a fibrous remnant which travels superiorly from the porta hepatis of the liver to the inferior vena cava. It is often obliterated in adults.
In the fetus, it is patent and known as the ductus venosus which shunts blood returning from the placenta in the umbilical vein...
The light bulb sign of a hepatic hemangioma is a feature than can be seen on MRI imaging with a classic hepatic hemangioma. This refers to marked hyperintensity seen on heavily T2 weighted sequences that has been likened to a glowing light bulb.
light bulb sign - shoulder
light bulb ...
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...
Lipase, more specifically pancreatic lipase, is an enzyme produced in the pancreas and is responsible for the digestion of fat molecules. It may be raised (hyperlipasaemia) in numerous pancreatic, hepatobiliary and other diseases but is most commonly associated with acute pancreatitis.
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 standardized 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 tumor 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.
transjugular intrahepatic portosystemic shunt (TIPS)
transjugular liver biopsy (TJLB)
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 tumor extent
Liver lesions represent a heterogeneous group of pathology ranging from solitary benign lesions to multiple metastases from a variety of primary tumors.
Liver lesions may be infiltrative or have mass effect, be solitary or multiple, benign or malignant.
Assessment of liver lesions takes into c...
Pediatric liver lesions are a heterogeneous group that include infiltrative lesions and those that demonstrate mass effect. Moreover, they may be solitary or multiple, benign or malignant:
benign liver tumors
malignant liver tumors
There are differing frequencies of both benign ...
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 tumors, like tumors 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 tumors, due...
The lollipop sign is seen in hepatic epithelioid hemangioendothelioma (HEHE). It represents hepatic/portal vein and/or their tributaries/branches tapering and terminating at or just within the edge of a well defined peripherally enhancing (or non-enhancing) lesion with an avascular core on CT or...
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:
Macroamylasaemia is the presence of serum amylase of a large molecular size, seen in both otherwise healthy individuals, and also in various diseases. Amylase seems to be able to self-polymerise and/or form complexes with other blood proteins, e.g. immunoglobulins.
Macrolipasaemia is the presence of serum lipase of a large molecular size, seen occasionally in otherwise healthy individuals, but more commonly in various diseases. Lipase is able to self-polymerise and/or form complexes with other blood proteins e.g. immunoglobulins.
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.
Pediatric malignant liver tumors are rare, some of which occur only in children but that are similar to those that occur in adults.
Malignant liver tumors account for ~1% of pediatric malignancies 2.
Broadly, any malignant liver mass can be defined as a metastasis or p...
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 tumor with a diameter of ≤5 cm, or up to 3 ...
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 hemochromatosis (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). It is defined by The International Working Party as consisting of two or more FNHs in combination with 1:
liver hemangioma or
vascular malformations (most frequent types: hepatic...
Myelofibrosis is a haematologic 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 characterized by:
The classification of gallbladder perforation was proposed by Neimeier and later modified by Anderson et al. in 1987, which at the time of writing (July 2016) remains the most widely accepted classification for gall bladder perforation.
According to this classification, there are three main cli...
In general taking large doses of water-soluble vitamins has not been found to have a deleterious clinical effect. However niacin (vitamin B3) excess can be problematic, usually when greater than 100 mg niacin is taken per day. To put this in context the recommended daily allowance (RDA) in the U...
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 A (NPD-A) is one of a group of autosomal recessive lysosomal lipid storage disorders (see Niemann-Pick disease) that presents in early childhood and usually progresses to death within a few years. It shares the same enzyme deficiency as Niemann-Pick disease type B (NPD-...
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 ...
Non-alcoholic 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.
"Non-alcoholic fatty ...
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 visualization 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 analogs) 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 trac...
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
An omentum is a double layer of peritoneum that attaches the stomach to another viscus:
the greater omentum hangs from the greater curvature of the stomach like an apron
the lesser omentum attaches the lesser curvature of the stomach to the liver superiorly
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 Tumors Strategy Group (previously called Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumor Study Group - SIOPEL) aims for staging and risk stratification of liver tumors at diagnosis.
It is used to describe ...
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 characterized, 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 tumors of the...
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 mm...
The ductal embryology of the pancreas 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 s...
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 aging.
It tends to be commonest pathological condition involving the pancreas. The condition may occasionally simulate a mass-like lesion particularly when fa...